kaolinite and Pain

The chiral pharmacokinetics and pharmacodynamics of ketoprofen were investigated in a placebo-controlled study in piglets after intramuscular administration of 6 mg/kg racemic ketoprofen. The absorption half-lives of both enantiomers were short, and S-ketoprofen predominated over R-ketoprofen in plasma. A kaolin-induced inflammation model was used to evaluate the anti-inflammatory, antipyretic and analgesic effects of ketoprofen. Skin temperatures increased after the kaolin injection, but the effect of ketoprofen was small. No significant antipyretic effects could be detected, but body temperatures tended to be lower in the ketoprofen-treated piglets. Mechanical nociceptive threshold testing was used to evaluate the analgesic effects. The piglets in the ketoprofen-treated group had significantly higher mechanical nociceptive thresholds compared to the piglets in the placebo group for 12-24 h following the treatment. Pharmacokinetic/pharmacodynamic modelling of the results from the mechanical nociceptive threshold testing gave a median IC(50) for S-ketoprofen of 26.7 μg/mL and an IC(50) for R-ketoprofen of 1.6 μg/mL. This indicates that R-ketoprofen is a more potent analgesic than S-ketoprofen in piglets. Estimated ED(50) for racemic ketoprofen was 2.5 mg/kg.

Topics: Animals; Anti-Inflammatory Agents, Non-Steroidal; Body Temperature; Female; Fever; Inflammation; Kaolin; Ketoprofen; Male; Models, Biological; Pain; Pain Measurement; Swine; Swine Diseases

A pressure analgesiometric device was developed for unrestrained cats. Eleven cats were studied. Stimulation was via three rounded pins within a bracelet on the forearm. The pins were advanced by manual bladder inflation. Bladder pressure was measured using a strain gauge pressure transducer. The threshold was recorded at the behavioural end point. Thresholds were measured at 5 and 15min intervals for 2-4h, after removal/replacement of the cuff, for 120min after SC butorphanol (0.4mg/kg), and with mild skin inflammation at the testing site. Data were analysed using ANOVA. Pressure thresholds in untreated cats were around 150mmHg. The minimum interval for testing was established as 15min. Data were reproducible over 4h and beyond 24h. Thresholds in 5 cats increased (P<0.05) above baseline for 45min after butorphanol with a maximum increase of 270+/-182mmHg at 10min. Thresholds decreased with inflammation. The method appears suitable for feline analgesia investigations.

Topics: Analgesics; Animals; Butorphanol; Cat Diseases; Cats; Female; Inflammation; Kaolin; Male; Pain; Pain Measurement

A prospective, double-blind study compared the effectiveness of sucralfate suspension with diphenhydramine syrup plus kaolin-pectin in reducing severity and pain of radiation-induced oropharyngeal mucositis. Fourteen patients who received at least 4600 cGy to the oral cavity used one of the mouth rinses four times a day, beginning at 1600 cGy. Data were collected on daily perceived pain and helpfulness of mouth rinse, weekly mucositis grade, weight change, and interruption of therapy. Analysis of data revealed no statistically significant differences between the two groups in any parameter. A retrospective review of 15 patients who had received at least 4600 cGy radiation to the oropharynx but had not used a daily mouth-coating rinse, was compared with the study group. Comparison of the two groups suggested that consistent daily oral hygiene and use of a mouth-coating agent will result in less pain and may reduce weight loss and interruption of radiation because of severe mucositis.

Topics: Adult; Carcinoma, Adenoid Cystic; Carcinoma, Squamous Cell; Cobalt; Diphenhydramine; Double-Blind Method; Humans; Kaolin; Mouth Mucosa; Mouth Neoplasms; Mouthwashes; Pain; Palliative Care; Pectins; Prospective Studies; Radioisotope Teletherapy; Retrospective Studies; Stomatitis; Sucralfate

Topics: Amino Acids; Amygdala; Animals; Arthralgia; Arthritis, Experimental; Behavior, Animal; Bridged Bicyclo Compounds, Heterocyclic; Carrageenan; Central Amygdaloid Nucleus; Excitatory Amino Acid Agonists; Excitatory Amino Acid Antagonists; Kaolin; Nociception; Pain; Posterior Horn Cells; Rats; Receptors, Metabotropic Glutamate; Spinal Cord; Vocalization, Animal; Xanthenes

In the present study we investigated the role of sodium butyrate (butyrate), and its more palatable derivative, the N-(1-carbamoyl-2-phenyl-ethyl) butyramide (FBA), in animal models of acute and chronic pain. We found that oral administrations of butyrate (10-200mg/Kg) or equimolecular FBA (21.2-424mg/Kg) reduced visceral pain in a dose- and time-dependent manner. Both drugs were also effective in the formalin test, showing an antinociceptive effect. This analgesic effect was blocked by glibenclamide, suggesting the involvement of ATP-dependent K(+) channels. Moreover, following repeated administration butyrate (100-200mg/Kg) and FBA (212-424mg/Kg) retained their analgesic properties in a model of neuropathic pain, reducing mechanical and thermal hyperalgesia in the chronic constriction injury (CCI) model. The involvement of peroxisome proliferator-activated receptor (PPAR) -α and -γ for the analgesic effect of butyrate was also investigated by using PPAR-α null mice or the PPAR-γ antagonist GW9662. Western blot analysis, confirmed the role of peroxisome receptors in butyrate effects, evidencing the increase of PPAR-α and -γ expression, associated to the reduction of inflammatory markers (COX-2, iNOS, TNF-α and cFOS). In conclusion, we describe the role of butyrate-based drugs in pain, identifying different and converging non-genomic and genomic mechanisms of action, which cooperate in nociception maintenance.

Topics: Acetic Acid; Amides; Analgesics; Anilides; Animals; Butyric Acid; Formaldehyde; Hot Temperature; Hyperalgesia; Kaolin; Magnesium Sulfate; Male; Mice; Mice, Knockout; Pain; Physical Stimulation; PPAR alpha; PPAR gamma; Sciatic Nerve; Spinal Cord

Neuroplastic changes in the amygdala account for emotional-affective aspects of pain and involve neuropeptides such as calcitonin gene-related peptide and corticotropin-releasing factor. Another neuropeptide system, central arginine vasopressin, has been implicated in neuropsychiatric disorders, but its role in pain-related emotional expression and neuroplasticity remains to be determined. Here, we tested the hypothesis that arginine vasopressin in the amygdala contributes to pain-related emotional-affective responses, using stereotaxic applications of arginine vasopressin and antagonists for G-protein coupled vasopressin V1A and oxytocin receptors in adult male Sprague-Dawley rats. In normal animals, arginine vasopressin increased audible and ultrasonic vocalizations and anxiety-like behavior (decreased open-arm preference in the elevated plus maze). The facilitatory effects were blocked by a selective V1A antagonist (SR 49059, Relcovaptan) but not by an oxytocin receptor antagonist (L-371,257). L-371,257 had some facilitatory effects on vocalizations. Arginine vasopressin had no effect in arthritic rats (kaolin/carrageenan knee joint pain model). SR 49059 inhibited vocalizations and anxiety-like behavior (elevated plus maze) in arthritic, but not normal, rats and conveyed anxiolytic properties to arginine vasopressin. Arginine vasopressin, SR 49059, and L-371,257 had no significant effects on spinal reflexes. We interpret the data to suggest that arginine vasopressin through V1A in the amygdala contributes to emotional-affective aspects of pain (arthritis model), whereas oxytocin receptors may mediate some inhibitory effects of the vasopressin system.

Topics: Amygdala; Animals; Arthritis; Benzoxazines; Carrageenan; Disease Models, Animal; Hormone Antagonists; Indoles; Kaolin; Male; Maze Learning; Microdialysis; Pain; Piperidines; Pyrrolidines; Rats; Rats, Sprague-Dawley; Receptors, Oxytocin; Receptors, Vasopressin; Reflex; Vocalization, Animal

The medial prefrontal cortex (mPFC) serves executive control functions that are impaired in neuropsychiatric disorders and pain. Therefore, restoring normal synaptic transmission and output is a desirable goal. Group II metabotropic glutamate receptors mGluR2 and mGluR3 are highly expressed in the mPFC, modulate synaptic transmission, and have been targeted for neuropsychiatric disorders. Their pain-related modulatory effects in the mPFC remain to be determined. Here we evaluated their ability to restore pyramidal output in an arthritis pain model. Whole-cell patch-clamp recordings of layer V mPFC pyramidal cells show that a selective group II mGluR agonist (LY379268) decreased synaptically evoked spiking in brain slices from normal and arthritic rats. Effects were concentration-dependent and reversed by a selective antagonist (LY341495). LY379268 decreased monosynaptic excitatory postsynaptic currents (EPSCs) and glutamate-driven inhibitory postsynaptic currents (IPSCs) in the pain model. Effects on EPSCs preceded those on IPSCs and could explain the overall inhibitory effect on pyramidal output. LY379268 decreased frequency, but not amplitude, of miniature EPSCs without affecting miniature IPSCs. LY341495 alone increased synaptically evoked spiking under normal conditions and in the pain model. In conclusion, group II mGluRs act on glutamatergic synapses to inhibit direct excitatory transmission and feedforward inhibition onto pyramidal cells. Their net effect is decreased pyramidal cell output. Facilitatory effects of a group II antagonist suggest the system may be tonically active to control pyramidal output. Failure to release the inhibitory tone and enhance mPFC output could be a mechanism for the development or persistence of a disease state such as pain.

Topics: Amino Acids; Animals; Arthritis, Experimental; Bridged Bicyclo Compounds, Heterocyclic; Excitatory Amino Acid Agonists; Excitatory Amino Acid Antagonists; Excitatory Postsynaptic Potentials; Inhibitory Postsynaptic Potentials; Kaolin; Miniature Postsynaptic Potentials; Pain; Patch-Clamp Techniques; Prefrontal Cortex; Pyramidal Cells; Rats, Sprague-Dawley; Receptors, Metabotropic Glutamate; Synaptic Transmission; Tissue Culture Techniques; Xanthenes

Recently discovered neuropeptide S (NPS) has anxiolytic and pain-inhibiting effects in rodents. We showed previously that NPS increases synaptic inhibition of amygdala output to inhibit pain behaviors. The amygdala plays a key role in emotional-affective aspects of pain. Of clinical significance is that NPS can be applied nasally to exert anxiolytic effects in rodents. This study tested the novel hypothesis that nasal application of NPS can inhibit pain-related behaviors in an arthritis model through NPS receptors (NPSR) in the amygdala. Behaviors and electrophysiological activity of amygdala neurons were measured in adult male Sprague Dawley rats. Nasal application of NPS, but not saline, inhibited audible and ultrasonic vocalizations and had anxiolytic-like effects in the elevated plus-maze test in arthritic rats (kaolin/carrageenan knee joint arthritis model) but had no effect in normal rats. Stereotaxic application of a selective non-peptide NPSR antagonist (SHA68) into the amygdala by microdialysis reversed the inhibitory effects of NPS. NPS had no effect on hindlimb withdrawal thresholds. We showed previously that intra-amygdala application of an NPSR antagonist alone had no effect. Nasal application of NPS or stereotaxic application of NPS into the amygdala by microdialysis inhibited background and evoked activity of amygdala neurons in arthritic, but not normal, anesthetized rats. The inhibitory effect was blocked by a selective NPSR antagonist ([D-Cys(tBu)5]NPS). In conclusion, nasal application of NPS can inhibit emotional-affective, but not sensory, pain-related behaviors through an action in the amygdala. The beneficial effects of non-invasive NPS application may suggest translational potential.

Topics: Administration, Intranasal; Amygdala; Analgesics; Animals; Arthritis; Carrageenan; Disease Models, Animal; Hyperalgesia; Kaolin; Knee Joint; Male; Maze Learning; Neurons; Neuropeptides; Pain; Rats; Rats, Sprague-Dawley; Reflex; Spinal Cord; Vocalization, Animal

We propose that a clay derived class of materials, known as geopolymers, may solve the problem of finding materials for controlled release with the right combination of properties necessary for a safe and sustained oral delivery of highly potent opioids. We show that the opioid Fentanyl, and its structurally similar sedative Zolpidem, can be embedded into metakaolin based geopolymer pellets to provide prolonged release dosage forms with mechanical strengths of the same order of magnitude as that of human teeth. The results presented in the current work may open up new opportunities for future development of drug delivery for high potency drugs employing high-strength and variable-pore-structure geopolymers and materials alike.

Topics: Analgesics, Opioid; Chronic Disease; Compressive Strength; Delayed-Action Preparations; Fentanyl; Humans; Hypnotics and Sedatives; Kaolin; Pain; Polymers; Pyridines; Zolpidem

The amygdala plays an important role in the emotional-affective component of pain and in pain modulation. Group III metabotropic glutamate receptors (mGluRs) regulate pain-related activity in the amygdala, but the behavioral consequence and contribution of individual subtypes are not known yet. This study determined the effects of mGluR7 and mGluR8 activation in the central nucleus of the amygdala (CeA) on nocifensive and affective pain responses and on pain-related anxiety-like behavior of adult rats. The pain state was induced by intraarticular injections of kaolin/carrageenan into one knee joint to produce a localized monoarthritis. Subtype-selective agonists were administered into the CeA by microdialysis in normal rats and in rats with arthritis. An mGluR7-selective agonist (N,N'-dibenzyhydryl-ethane-1,2-diamine dihydrochloride, AMN082, 25microM) decreased spinal withdrawal reflex thresholds and increased audible and ultrasonic vocalizations evoked by brief (15s) compression of the knee. AMN082 also decreased the open-arm preference in the elevated plus maze (EPM) test, suggesting anxiety-like behavior. In arthritic animals, however, AMN082 failed to modulate the increased spinal reflexes and vocalizations and anxiety-like behavior. An mGluR8-selective agonist (S-3,4-dicarboxyphenylglycine, S-3,4-DCPG, 10microM) had no effect in normal animals but inhibited the increased spinal reflex responses and audible and ultrasonic vocalizations of arthritic rats. S-3,4-DCPG also increased the open-arm choices of arthritic rats, suggesting anxiolytic effects. The results suggest that under normal conditions mGluR7, but not mGluR8, facilitates pain responses and has anxiogenic properties whereas mGluR8, but not mGluR7, can inhibit nocifensive and affective behaviors and anxiety in a model of arthritic pain.

Topics: Amygdala; Animals; Arthritis; Behavior, Animal; Benzhydryl Compounds; Benzoates; Disease Models, Animal; Excitatory Amino Acid Agonists; Glycine; Kaolin; Male; Maze Learning; Microdialysis; Pain; Pain Measurement; Pain Threshold; Physical Stimulation; Rats; Rats, Sprague-Dawley; Receptors, Metabotropic Glutamate; Reflex

Hydrogen sulfide (H(2)S) is an endogenous gaseous mediator with the ability to modulate tissue inflammation and pain. The aim of this study was to determine the effect of an H(2)S donor (Na(2)S) on leukocyte-endothelium interactions, blood flow, and pain sensation in acutely inflamed knee joints. Acute arthritis was induced in urethane anesthetized C57bl/6 mice by intra-articular injection of kaolin/carrageenan (24-h recovery), and the effect of local administration of Na(2)S on leukocyte trafficking was measured by intravital microscopy. Synovial blood flow was measured in inflamed knees by laser Doppler perfusion imaging. Finally, the effect of an intra-articular injection of Na(2)S on joint pain in control and inflamed rats was determined by hindlimb incapacitance and von Frey hair algesiometry. Local administration of an H(2)S donor to inflamed knees caused a dose-dependent reduction in leukocyte adherence and an increase in leukocyte velocity. These effects could be inhibited by coadministration of the ATP-sensitive K(+) channel blocker glibenclamide. Local administration of Na(2)S to inflamed joints caused a pronounced vasoconstrictor response; however, there was no observable effect of Na(2)S on joint pain. These findings establish H(2)S as a novel signaling molecule in rodent knee joints. H(2)S exhibits potent anti-inflammatory properties, but with no detectable effect on joint pain.

Topics: Acute Disease; Animals; Arthritis; Behavior, Animal; Carrageenan; Cell Movement; Hydrogen Sulfide; Kaolin; Knee Joint; Leukocytes; Male; Mice; Mice, Inbred C57BL; Pain; Physical Stimulation; Proprioception; Signal Transduction; Sulfides

Nociceptive impulse activity was recorded extracellularly from single A delta and C primary afferents of the guinea pig's medial articular nerve after induction of an experimental osteoarthritis in the knee joint by partial medial menisectomy and transection of the anterior cruciate ligament (PMM+TACL). Also, the analgesic effects of intra-articular hyaluronan solutions were evaluated. Healthy, PMM+TACL operated, sham-operated (opening of the joint capsule without PMM and TACL surgery) and acutely inflamed (intra-articular kaolin-carrageenan, K-C) animals were used. The stimulus protocol consisted of torque meter-controlled, standardized innocuous and noxious inward and outward rotations of the joint. This stimulus protocol of 50 s duration was repeated every 5 min for 70 min. One day, one week and three weeks after PMM+TACL, the movement-evoked discharges of A delta articular afferents were increased significantly over values found in sham-operated animals. The discharges of C fibers were significantly augmented only one week after PMM+TACL surgery. Filling of the joint cavity with a high viscosity hyaluronan solution (hylan G-F 20, Synvisc) immediately and three days after surgery reduced significantly the enhanced nerve activity observed in joint afferent fibers one day and one week after surgery. Augmentation of movement-evoked discharges in K-C acutely inflamed knee joints was similar to that observed one week after PMM+TACL. Our results indicate that in the PMM+TACL model of osteoarthritis in guinea pigs, enhancement of nociceptive responses to joint movement was primarily associated to post-surgical inflammation. Intra-articular injection of an elastoviscous hyaluronan solution reduced the augmented nerve activity.

Topics: Adjuvants, Immunologic; Animals; Anterior Cruciate Ligament; Carrageenan; Disease Models, Animal; Evoked Potentials, Motor; Female; Guinea Pigs; Hyaluronic Acid; Injections, Intra-Articular; Joint Instability; Kaolin; Knee Joint; Male; Menisci, Tibial; Movement; Neural Conduction; Nociceptors; Osteoarthritis, Knee; Pain; Solutions

Corticotropin-releasing factor receptor CRF1 has been implicated in the neurobiological mechanisms of anxiety and depression. The amygdala plays an important role in affective states and disorders such as anxiety and depression. The amygdala is also emerging as a neural substrate of pain affect. However, the involvement of the amygdala in the interaction of pain and anxiety remains to be determined. This study tested the hypothesis that CRF1 receptors in the amygdala are critically involved in pain-related anxiety. Anxiety-like behavior was determined in adult male rats using the elevated plus maze (EPM) test. The open-arm preference (ratio of open arm entries to the total number of entries) was measured. Nocifensive behavior was assessed by measuring hindlimb withdrawal thresholds for noxious mechanical stimulation of the knee. Measurements were made in normal rats and in rats with arthritis induced in one knee by intraarticular injections of kaolin/carrageenan. A selective CRF1 receptor antagonist (NBI27914) or vehicle was administered systemically (i.p.) or into the central nucleus of the amygdala (CeA, by microdialysis). The arthritis group showed a decreased preference for the open arms in the EPM and decreased hindlimb withdrawal thresholds. Systemic or intraamygdalar (into the CeA) administration of NBI27914, but not vehicle, inhibited anxiety-like behavior and nocifensive pain responses, nearly reversing the arthritis pain-related changes. This study shows for the first time that CRF1 receptors in the amygdala contribute critically to pain-related anxiety-like behavior and nocifensive responses in a model of arthritic pain. The results are a direct demonstration that the clinically well-documented relationship between pain and anxiety involves the amygdala.

Topics: Amygdala; Aniline Compounds; Animals; Anxiety; Arthritis, Experimental; Carrageenan; Hindlimb; Kaolin; Male; Maze Learning; Pain; Pyrimidines; Rats; Rats, Sprague-Dawley; Receptors, Corticotropin-Releasing Hormone

Anorexia, nausea/emesis and peripheral sensorial neuropathy are frequent adverse effects associated with chemotherapy. Cannabinoids have been proposed to alleviate these effects, but their preventive properties in long-term experimental models have not been tested. This study was conducted to determine whether or not a cannabinoid agonist (WIN-55,212-2) can prevent anorexia, pica (an indirect marker of nausea in non-vomiting species, consisting of the ingestion of non-nutritive substances such as kaolin) and mechanical allodynia (a marker of peripheral neuropathy) induced by the antineoplastic drug cisplatin chronically administered. Isolated rats with free access to food and kaolin received either saline, cannabinoid vehicle, WIN-55,212-2 (1-2 mg kg(-1)), cisplatin (1-2 mg kg(-1)), or both drugs once per week for five consecutive weeks. Modifications in temperature, body weight gain, food and kaolin intake, and the threshold for mechanical allodynia were recorded. Additionally, the acute psychoactive effects of the cannabinoid (hypomotility, hypothermia, analgesia and catalepsia) were assayed by means of the cannabinoid tetrad. WIN 55,212-2 prevented the development of mechanical allodynia but not anorexia, pica and reduction in weight gain induced by chronic cisplatin. The effect of WIN 55,212-2 was evident even at a dose lacking activity in the cannabinoid tetrad. The preventive effect on cisplatin-induced mechanical allodynia exerted by the cannabinoid could be due to a neuroprotective role, as has been suggested for other conditions. The present results support the interest in the evaluation of cannabinoids for treatment of patients suffering or likely to suffer neuropathic pain.

Topics: Analgesics; Animals; Antidiarrheals; Antineoplastic Agents; Benzoxazines; Body Temperature; Body Weight; Cisplatin; Feeding Behavior; Kaolin; Male; Morpholines; Naphthalenes; Pain; Peripheral Nervous System Diseases; Pica; Rats; Rats, Wistar

Kaolin-induced writhing reaction is a simple and convenient model of bradykinin-induced pain for assessment of analgesic actions. In this study, we demonstrated that the number of kaolin-induced writhing reaction was fluctuated in a circadian manner that peaked at the end of the resting period (dusk) and reduced during the active (dark) period in mice. Circadian rhythm of the writhing intensity was completely phase-shifted by a time-imposed restricted feeding. On the other hand, 24 h of food deprivation did not affect the writhing intensity, suggesting that the endogenous clock that can be entrained to the scheduled feeding is responsible to the circadian intensity of the writhing reaction. Day/night fluctuation of the writhing intensity was completely abolished and the writhing reaction was significantly reduced in the circadian clock deficient Clock-mutant mice, although the kaolin-induced bradykinin production and blood pressure suppression were not affected in these mutant mice. Our present study suggested that the circadian variation of the pain sensitivity is governed by the food-entrainable endogenous clock and by the circadian clock molecules in mammals.

Topics: Animals; Antidiarrheals; Appetite Regulation; Biological Clocks; Blood Pressure; Bradykinin; Circadian Rhythm; CLOCK Proteins; Food Deprivation; Hypothalamus; Kaolin; Mice; Mice, Inbred BALB C; Mice, Inbred C57BL; Mice, Inbred ICR; Mice, Neurologic Mutants; Mutation; Pain; Pain Measurement; Pain Threshold; Trans-Activators

The behavioral assessment of experimental pain is essential for the analysis of pain mechanisms and the validation of therapeutic targets. Arthritic pain, in particular, is significantly associated with negative affective states and disorders. Here we present a standardized method for the quantitative analysis of audible and ultrasonic (25 +/- 4 kHz) vocalizations in awake rats as a measure of higher integrated behavior in a model of arthritic pain. A bat detector and a condenser microphone were used to record ultrasonic and audible vocalizations, respectively, in response to innocuous and noxious mechanical stimulation of the knee before and after induction of acute arthritis in one knee. A computerized system was used to analyze number and duration of the filtered signals. For the behavioral tests, the animal was placed in a customized recording chamber to ensure consistent stimulus application and stable recordings and to eliminate any movement-induced noise. Noxious stimuli produced stronger vocalizations than innocuous stimuli. Both audible and ultrasonic vocalizations to innocuous (allodynia) and noxious (hyperalgesia) stimuli increased after the induction of acute arthritis. These changes were accompanied by increased knee joint circumference, lowered hind limb withdrawal thresholds and reduced exploratory behavior in the same animals. The computerized analysis of audible and ultrasonic vocalizations is a valid, quantitative, reliable and convenient method to measure pain-related behavior.

Topics: Analysis of Variance; Animals; Arthritis, Experimental; Behavior, Animal; Carrageenan; Disease Models, Animal; Exploratory Behavior; Kaolin; Knee Joint; Male; Numerical Analysis, Computer-Assisted; Pain; Pain Measurement; Physical Stimulation; Rats; Rats, Sprague-Dawley; Reaction Time; Time Factors; Ultrasonics; Vocalization, Animal; Weights and Measures

Dosing-time-dependent changes in the effect and toxicity of morphine were examined in mice housed under alternating 12 h light (07:00 to 19:00 h) and dark (19:00 to 07:00 h) cycles. Morphine (0.5 mg/kg) was injected intraperitoneally (i.p.) in animals to assess its beneficial effect (i.e., protection against the kaolin-induced, bradykinin-mediated, writhing reaction) and its toxicity (i.e., alteration of the hepatic enzymes of aspartate aminotransferase [AST] alanine aminotransferase [ALT], and glutathione [GSH] in separate experiments). The magnitude of the analgesic effect of morphine depended on dosing time, with minimum effect at 02:00 h and maximum effect at 14:00 h. The serum hepatic enzyme levels of AST and ALT increased after dosing morphine (100 mg/kg) at 02:00 and 14:00 h. Time courses of these enzymes did not differ between the two trials. However, hepatic GSH, which is involved in the detoxification of chemical compounds, significantly decreased after i.p. morphine injection at 02:00 but not at 14:00 h. Overall, the results suggest that the analgesic effect of morphine is greater after dosing during the resting than during the activity phase of mice that have been induced with bradykinin-mediated pain. Drug-induced hepatic damage as inferred by GSH alteration, however, may be greater after dosing during the active phase.

Topics: Alanine Transaminase; Animals; Antidiarrheals; Aspartate Aminotransferases; Circadian Rhythm; Glutathione; Kaolin; Liver; Male; Mice; Morphine; Narcotics; Pain; Photoperiod; Time Factors

Inflammatory pain is caused by sensitization of peripheral and central nociceptive neurons. Prostaglandins substantially contribute to neuronal sensitization at both sites. Prostaglandin E2 (PGE2) applied to the spinal cord causes neuronal hyperexcitability similar to peripheral inflammation. Because PGE2 can act through EP1-EP4 receptors, we addressed the role of these receptors in the spinal cord on the development of spinal hyperexcitability. Recordings were made from nociceptive dorsal horn neurons with main input from the knee joint, and responses of the neurons to noxious and innocuous stimulation of the knee, ankle, and paw were studied after spinal application of recently developed specific EP1-EP4 receptor agonists. Under normal conditions, spinal application of agonists at EP1, EP2, and EP4 receptors induced spinal hyperexcitability similar to PGE2. Interestingly, the effect of spinal EP receptor activation changed during joint inflammation. When the knee joint had been inflamed 7-11 hr before the recordings, only activation of the EP1 receptor caused additional facilitation, whereas spinal application of EP2 and EP4 receptor agonists had no effect. Additionally, an EP3alpha receptor agonist reduced responses to mechanical stimulation. The latter also attenuated spinal hyperexcitability induced by spinal PGE2. In isolated DRG neurons, the EP3alpha agonist reduced the facilitatory effect of PGE2 on TTX-resistant sodium currents. Thus pronociceptive effects of spinal PGE2 can be limited, particularly under inflammatory conditions, through activation of an inhibitory splice variant of the EP3 receptor. The latter might be an interesting target for controlling spinal hyperexcitability in inflammatory pain states.

Topics: Animals; Arthritis; Carrageenan; Cell Separation; Dinoprostone; Disease Models, Animal; Ganglia, Spinal; Kaolin; Knee Joint; Male; Neurons; Pain; Patch-Clamp Techniques; Physical Stimulation; Protein Isoforms; Rats; Rats, Wistar; Receptors, Prostaglandin E; Receptors, Prostaglandin E, EP3 Subtype; Spinal Cord

The latero-capsular division of the central nucleus of the amygdala (CeA) is now defined as the 'nociceptive amygdala' because of its high content of neurons activated exclusively or preferentially by noxious stimuli. Multireceptive (MR) neurons that respond to innocuous and, more strongly, to noxious stimuli become sensitized in arthritis pain. This form of nociceptive plasticity involves presynaptic group I metabotropic glutamate receptors, which increase glutamate release. Here we address the role of N-methyl-D-aspartate (NMDA) and non-NMDA receptors. Extracellular single-unit recordings were made from 25 CeA neurons in anesthetized rats. The neurons' responses to graded brief (15 s) mechanical stimuli, background activity, receptive field size and threshold were measured before and after the induction of kaolin/carrageenan arthritis in one knee and before and during drug applications into the CeA by microdialysis. All neurons examined received excitatory input from the knee(s) and were MR neurons. A selective NMDA receptor antagonist (AP5) inhibited responses to noxious stimuli more potently in the arthritic pain state (n = 6) than under control conditions before arthritis (n = 8) AP5 also inhibited the enhanced background activity and increased responses to normally innocuous stimuli in arthritis, but had no significant effects on these parameters under control conditions. A selective non-NMDA receptor antagonist (NBQX) inhibited background activity and evoked responses under normal control conditions (n = 6) and in arthritis (n = 8) These data suggest that activation of both NMDA and non-NMDA receptors contributes to pain-related sensitization of amygdala neurons.

Topics: 2-Amino-5-phosphonovalerate; Action Potentials; Amygdala; Analysis of Variance; Animals; Arthritis; Disease Models, Animal; Dose-Response Relationship, Drug; Excitatory Amino Acid Antagonists; Kaolin; Male; Neural Inhibition; Neurons; Nociceptors; Pain; Pain Measurement; Physical Stimulation; Quinoxalines; Rats; Rats, Sprague-Dawley; Receptors, AMPA; Receptors, N-Methyl-D-Aspartate

Phosphorylation of a subunit of N-methyl-D-aspartate (NMDA) receptor by protein tyrosine kinase (PTK) Src or Trk is known to enhance its channel activity. We examined whether a spinally administered selective PTK inhibitor, lavendustin A, which has high affinity for Src and Trk tyrosine kinases, could influence the development and maintenance of inflammatory hyperalgesia or NMDA-induced hyperalgesia. Inflammation was induced by injection of a mixture of carrageenan and kaolin into the tail base of rats. In another group of rats, hyperalgesia was induced by intrathecal administration of NMDA. Intrathecal administration of lavendustin A (1.0 microg) or NMDA receptor antagonist, (+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cycloheptane-5,10-iminemaleate, MK-801 (3.0 microg) before injection of a mixture of carrageenan and kaolin or after the development of inflammation inhibited carrageenan-kaolin-induced mechanical hyperalgesia. Intrathecal injection of 1.0 microg NMDA produced thermal and mechanical hyperalgesia. Co-administration of 1.0 microg lavendustin A with NMDA significantly reduced the duration of spontaneous pain behaviour and inhibited NMDA-induced hyperalgesia. Lavendustin A itself did not cause any sedation, motor impairment or analgesia. Our results suggest that inhibition of PTK could be therapeutically effective as an analgesic in some NMDA receptor-mediated hyperalgesic states.

Topics: Animals; Carrageenan; Dizocilpine Maleate; Hot Temperature; Hyperalgesia; Inflammation; Injections, Spinal; Kaolin; Male; N-Methylaspartate; Pain; Pain Measurement; Phenols; Protein-Tyrosine Kinases; Rats; Rats, Sprague-Dawley; Receptors, N-Methyl-D-Aspartate; Spinal Cord

We previously showed that the kaolin-induced writhe reaction exhibits 24 h variation with a peak at the end of the resting period (14:00-18:00 h) in mice maintained under light from 07:00 to 19:00 h. In this study, we used this model to evaluate the administration-time-dependent (chronopharmacodynamic) effect of indomethacin. Indomethacin (0.5 mg/kg) was given orally to mice at 02:00, 08:00, 14:00, or 20:00 h, and the suppressive effect on kaolin-induced writhing was determined after each timed dosing. After dosing at 08:00 h, indomethacin remarkably reduced the number of writhes during the critical span of 14:00-18:00 h--the time when writhing reaction was greatest during the 24 h, while the suppressive effect of the medicine after dosing at the other clock times was relatively small. These data suggest the analgesic effect of indomethacin in mice with the kaolin-induced writhing is greater after dosing in the early resting period, which is similar to that reported in patients with nocturnalpain. The kaolin-induced pain mouse model seems to be useful for the chronopharmacodynamic evaluation of analgesic agents.

Topics: Animals; Anti-Inflammatory Agents, Non-Steroidal; Circadian Rhythm; Humans; Indomethacin; Kaolin; Male; Mice; Pain; Pain Measurement; Time Factors

Since pain is an important symptom in arthritis, useful behavioral indices for pain in experimental arthritis animal models are important tools for investigative work on arthritis. The purpose of this study was to develop simple and quantifiable behavioral tests, which would represent the level of arthritic pain that develops after induction of inflammation in the knee. Two models of knee joint arthritis were produced: (1) KC model-injection of kaolin and carrageenan into the synovial cavity of the knee, and (2) CFA model-injection of complete Freund's adjuvant into the synovial cavity of the knee. The following three variables were measured before and at various times after the induction of arthritis. As an estimate of the degree of edema, the circumference of the knee was measured. As pain indices, (1) the vocalization threshold of compression force applied to the knee joint was measured to represent tenderness of the joint, and (2) the struggle threshold of the knee extension angle was measured to represent a reduction in range of motion in the arthritic joint. A time course study showed that behavioral changes last for at least 1 week for the KC model and at least 2 weeks for the CFA model. Correlation studies showed that all three variables significantly correlated with each other in both the KC and CFA arthritic models. Systemically injected morphine produced a partial reversal of these indices with the expected time course and dose response of a morphine-induced analgesic. It is concluded that two variables, the struggle threshold for knee extension and the vocalization threshold for knee compression, could be used as simple and useful pain indices in experimental models of arthritis.

Topics: Analgesics, Opioid; Animals; Arthritis; Biomechanical Phenomena; Carrageenan; Disease Models, Animal; Edema; Freund's Adjuvant; Kaolin; Knee Joint; Male; Morphine; Motor Activity; Pain; Pain Measurement; Pain Threshold; Range of Motion, Articular; Rats; Rats, Sprague-Dawley; Stress, Psychological; Vocalization, Animal

Effects of the angiotensin-converting enzyme (ACE) inhibitors, imidapril and enalapril, on kaolin-induced writhing reaction, which is believed to be caused by bradykinin (BK), were examined in mice. The number of writhes was increased significantly by 200 microg/kg of imidapril and by 100 and 200 microg/kg of enalapril. The intensity of writhing reaction was significantly suppressed by 1,000 nmol/kg of icatibant, a selective bradykinin B2 receptor antagonist, in the imidapril-, but not in the enalapril-treated groups. These results suggest that the potentiating effect of enalapril on kaolin-induced writhing reaction is greater than that of imidapril. This might depend on the difference of their inhibitory effects on BK degradation.

Topics: Angiotensin-Converting Enzyme Inhibitors; Animals; Bradykinin; Bradykinin Receptor Antagonists; Disease Models, Animal; Dose-Response Relationship, Drug; Drug Synergism; Enalapril; Imidazoles; Imidazolidines; Kaolin; Male; Mice; Mice, Inbred ICR; Pain

This study examined the release of several amino acids after induction of knee joint inflammation in rats using kaolin and carrageenan. During the initial 10-min collection after knee joint injection with the irritants, the concentration of glutamate and the nitric oxide metabolites, arginine and citrulline, doubled. This increase persisted for at least two hours. During the same time period aspartate concentrations remained unchanged. Direct knee joint administration of lidocaine prevented the increases in amino acid concentration measurable by microdialysis probe inserted into the joint. These data suggest the possibility that glutamate may be released by neuronal endings in the joint.

Topics: Amino Acids; Anesthetics, Local; Animals; Arginine; Arthritis; Carrageenan; Chromatography, High Pressure Liquid; Citrulline; Glutamic Acid; Hindlimb; Injections, Intra-Articular; Joints; Kaolin; Lidocaine; Male; Pain; Rats; Rats, Sprague-Dawley; Synovial Fluid

In anaesthetized rats, the intraspinal release of immunoreactive prostaglandin E2 was measured using antibody microprobes. We addressed the question of whether the release of immunoreactive prostaglandin E2 is altered during development of acute inflammation in the knee evoked by intra-articular injections of kaolin and carrageenan. We also examined cyclo-oxygenase-1 and cyclo-oxygenase-2 protein levels in the spinal cord during the development of inflammation using the same model of arthritis. Densitometric analysis of microprobes showed that basal release of immunoreactive prostaglandin E2 in the period 175-310 min after kaolin was slightly higher than in the absence of inflammation. A pronounced enhancement of basal release of immunoreactive prostaglandin E2 was observed 430-530 min after kaolin. Enhanced levels of immunoreactive prostaglandin E2 were observed throughout the dorsal and ventral horns. Release of immunoreactive prostaglandin E2 was not altered further by the application of innocuous and noxious pressure onto the inflamed knee. Western blot analysis revealed that cyclo-oxygenase-2 but not cyclo-oxygenase-1 protein levels were elevated in the spinal cords of animals with inflammation compared to normal animals. This effect was evident as early as 3 h after the induction of arthritis. The maximum elevation of cyclo-oxygenase-2 protein levels (six-fold) was observed 12 h after the induction of arthritis. The results show that there is a tonic release of immunoreactive prostaglandin E2 from the spinal cord following the induction of arthritis, which is accompanied by enhanced expression of cyclo-oxygenase-2 protein in the spinal cord. We suggest that intraspinal prostaglandins may play a role in inflammation-evoked central sensitization of spinal cord neurons.

Topics: Acute Disease; Animals; Arthritis, Experimental; Blotting, Western; Cyclooxygenase 1; Cyclooxygenase 2; Dinoprostone; Gene Expression Regulation, Enzymologic; Immunohistochemistry; Injections, Intra-Articular; Isoenzymes; Kaolin; Male; Membrane Proteins; Pain; Physical Stimulation; Prostaglandin-Endoperoxide Synthases; Rats; Rats, Wistar; Serum Albumin, Bovine; Spinal Cord; Up-Regulation

Effect of captopril, an angiotensin-converting enzyme (ACE) inhibitor, on the time-dependent variation of kaolin-induced writhing reactions was examined in mice kept under conditions of light from 07:00 to 19:00 and dark from 19:00 to 07:00. The number of writhes was counted for 60 minutes after a single intraperitoneal injection of kaolin at 01:00, 07:00, 13:00, and 19:00. The number of writhes showed a time-dependent variation, with a peak at 19:00 and a trough at 07:00 in the control group. Captopril significantly increased the number of writhes after dosing at 01:00 and 07:00 (during the active period). The ACE activity following captopril dosing was significantly lower in the 07:00 than the 19:00 trial. These results suggest that the pharmacological effect of captopril varies with the dosing time, and the enhancement of the kaolin-induced writhing reaction is greater following dosing of the agent at nighttime in mice.

Topics: Angiotensin-Converting Enzyme Inhibitors; Animals; Captopril; Circadian Rhythm; Darkness; Kaolin; Light; Male; Mice; Mice, Inbred ICR; Pain; Peptidyl-Dipeptidase A

For years, physical therapists have been utilizing a variety of modalities, including transcutaneous electrical nerve stimulation (TENS), in an attempt to manage pain associated with inflammation. However, the data on clinical effectiveness is conflicting and the neurophysiological mechanism of action is not known. The purpose of this study was to investigate the effects of high and low frequency TENS on the secondary hyperalgesia that occurs after joint inflammation. Secondary hyperalgesia is thought to reflect changes in central neurons and is thus a measure of activity of central neurons. This study utilized the kaolin and carrageenan model of knee joint inflammation and measured the effects of TENS treatment on paw withdrawal latency to radiant heat (secondary hyperalgesia), spontaneous pain behaviors and joint circumference. Either high (100 Hz) or low (4 Hz) frequency TENS was applied to the knee joint for 20 min after the development of hyperalgesia. Both high and low frequency TENS resulted in a reversal of the hyperalgesia immediately following treatment. The effects of high frequency TENS lasted through at least 24 h while those of low frequency TENS lasted through 12 h. There was no effect of TENS on spontaneous pain behaviors or joint swelling when compared to controls. Thus, TENS appears to be more effective in reducing referred pain (or secondary hyperalgesia) without affecting guarding or splinting of the affected limb. Thus, clinically, the choice to use TENS may depend on patient symptoms; specifically TENS should be effective in reducing referred or radiating pain.

Topics: Animals; Behavior, Animal; Carrageenan; Hindlimb; Hyperalgesia; Injections, Intra-Articular; Kaolin; Knee Joint; Male; Pain; Rats; Rats, Sprague-Dawley; Reaction Time; Transcutaneous Electric Nerve Stimulation

The daily variation in an intensity of kaolin-induced writhing reaction was examined in mice kept under conditions of light; 07:00 - 19:00 and dark; 19:00 - 07:00. The number of writhes was counted for 30 minutes after a single intraperitoneal injection of kaolin at 00:00, 02:00, 04:00, 06:00, 08:00, 10:00, 12:00, 14:00, 16:00, 18:00, 20:00 and 22:00. The number of writhes showed a daily variation with a peak at 18:00 and a trough at 06:00. The intensity of writhing reaction was significantly reduced by pretreatment with the bradykinin B1 (Des-Arg9-[Leu8]-BK) and B2 (icatibant) receptor antagonists. Significant daily variation in this parameter was still observed in the group with the B1 antagonist, but disappeared in the B2 antagonist-treated group. These results suggest that the kaolin-induced writhing reaction shows the daily variation with a peak at the end of the resting period and a trough at the end of the active period. The B2 receptor mediated stimuli appears to be involved in this phenomenon.

Topics: Analgesia; Animals; Bradykinin; Bradykinin Receptor Antagonists; Circadian Rhythm; Kaolin; Kinetics; Male; Mice; Mice, Inbred ICR; Pain; Photoperiod

1. The effects of a novel, potent and orally active nonpeptide bradykinin B2 receptor antagonist, FR167344 (N-[N-[3-[(3-bromo-2-methylimidazo[1,2-a]pyridin-8-yl)oxymethyl]-2 ,4-dichlorophenyl]-N-methylaminocarbonylmethyl]-4-(dimethylamin ocarbonyl) cinnamylamide hydrochloride) were tested in three different in vivo models of inflammation. 2. Oral administration of FR167344 inhibited carrageenin-induced paw oedema in rats (carrageenin: 1%, 0.1 ml per animal, intraplantar), with an ID50 of 2.7 mg kg(-1) at 2 h after carrageenin injection (n=10 or 11). 3. Oral administration of the compound also inhibited kaolin-induced writhing (kaolin: 250 mg kg(-1), i.p.) in mice, with ID50 of 2.8 mg kg(-1) in 10 min writhing and 4.2 mg kg(-1) in 15 min writhing (n=19 or 20). 4. Additionally, oral administration of FR167344 inhibited caerulein-induced pancreatic oedema with an ID50 of 13.8 mg kg(-1) as well as increases in amylase and lipase of blood samples with ID50 of 10.3 and 7.4 mg kg(-1), respectively, in rats (n=10). 5. These results show that FR167344 is an orally active, anti-inflammatory and anti-nociceptive agent in carrageenin-induced paw oedema, kaolin-induced writhing and caerulein-induced pancreatitis. FR167344 may have therapeutic potential against inflammatory diseases by oral administration and it may be a useful tool for studying the involvement of B2 receptors in various in vivo models of inflammation.

Topics: Administration, Oral; Animals; Antidiarrheals; Bradykinin Receptor Antagonists; Carrageenan; Ceruletide; Disease Models, Animal; Excipients; Gastrointestinal Agents; Inflammation; Kaolin; Male; Mice; Mice, Inbred ICR; Pain; Pancreatitis; Pyridines; Rats; Rats, Sprague-Dawley; Receptor, Bradykinin B2; Receptors, Bradykinin

In spinal cord neurons in anesthetized rats, the role on neurokinin A and neurokinin-2 receptors in the processing of nociceptive information from the knee joint was studied. The specific non-peptide antagonist at the neurokinin-2 receptor, SR48968, its inactive R-enantiomer, SR48965, neurokinin A, substance P and (RS)-alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA), were administered ionophoretically close to neurons with input from the knee joint. SR48968 reduced the effects of exogenous neurokinin A, but not those of exogenous substance P and AMPA, indicating selective blockade of neurokinin-2 receptors. In most neurons with input from the normal knee joint, SR48968 reduced dose-dependently the responses to noxious pressure with applied to the knee, and in approximately 50% of the neurons the responses to innocuous pressure. The administration of SR48968 during the induction of an experimental joint inflammation markedly attenuated the development of inflammation-evoked hyperexcitability. In hyperexcitable neurons with input from the inflamed joint, SR48968 reduced the responses to noxious and innocuous pressure. The relative reduction of the responses was more pronounced than in neurons with input from the normal joint. None of the effects of SR48968 was mimicked by SR48965. These data show that neurokinin-2 receptors are involved in the spinal processing of nociceptive information from the normal joint. Furthermore, neurokinin-2 receptors must be coactivated at an early stage of inflammation, to allow the generation of hyperexcitability. Finally, neurokinin-2 receptors are involved in maintenance of hyperexcitability during inflammation. In summary, spinal neurokinin-2 receptors are important in the generation of pain in the normal and inflamed joint.

Topics: alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid; Animals; Arthritis; Benzamides; Carrageenan; Hyperalgesia; Iontophoresis; Kaolin; Knee Joint; Male; Neurokinin A; Nociceptors; Pain; Piperidines; Pressure; Rats; Rats, Wistar; Receptors, Neurokinin-2; Spinal Cord; Substance P

To investigate the role of primary afferents, sympathetic postganglionic efferents and descending systems on the central control of peripheral inflammation.. Acute inflammation was induced by intra-articular injection of kaolin and carrageenan into the knee joint cavity of the rat. Before the induction of the arthritis, a unilateral dorsal rhizotomy, a chemical (phentolamine) and/or surgical sympathectomy, or a spinal transection was performed. Joint inflammation (joint circumference and thermographic readings) and behavioural signs were assessed.. Only arthritic animals with a dorsal rhizotomy showed a significant reduction of the inflammatory response compared with control arthritic animals. No significant differences in the inflammatory response occurred following sympathectomy or spinal transection. The animals who received sympathectomy showed similar behavioural manifestations to the arthritic animals.. The central terminals of primary afferents are important in the development of acute joint inflammation since dorsal rhizotomy attenuated the inflammatory response in the knee joint. The sympathetic nervous system is not involved in the acute inflammatory phase of this arthritis model. The central processes controlling acute inflammation involve a local spinal circuit since spinal cord transection at T9 has no effect on the inflammation.

Topics: Acute Disease; Animals; Arthritis; Behavior, Animal; Carrageenan; Kaolin; Male; Neurons, Afferent; Neurons, Efferent; Pain; Rats; Rats, Sprague-Dawley; Spinal Cord; Thermography

In ten cats, single unit electrical activity was recorded in the lumbosacral spinal cord from neurones driven by stimulation of afferent fibres from the ipsilateral knee joint. Tonic descending inhibition (TDI) on the responses of these cells was measured as increases in resting and evoked activity of the neurones following reversible spinalization of the animals with a cold block at upper lumbar level. Acute inflammation of the knee joint was induced in five of the cats by the injection of kaolin and carrageenan into the joint. TDI was observed in 25 of 33 neurones recorded in normal animals (76%) and in 36 of 40 (90%) neurones recorded in animals with acute knee joint inflammation. In both kinds of preparation TDI was more pronounced in neurones recorded in the deep dorsal horn and in the ventral horn than in those recorded in the superficial dorsal horn. There was a tendency in the whole sample for TDI to be greater in neurones with input from inflamed knees. We conclude that the spinal processing of afferent information from joints is under tonic descending influences and that the amount of TDI can be altered during acute arthritis.

Topics: Afferent Pathways; Animals; Carrageenan; Cats; Cold Temperature; Female; Hindlimb; Inflammation; Joint Diseases; Joints; Kaolin; Male; Nerve Fibers; Neurons; Pain; Spinal Cord

The effects of alminoprofen and other non-steroidal antiinflammatory drugs (NSAIDs) on the writhing reaction caused by kaolin, acetylcholine, phenylquinone and zymosan were studied. Aspirin, indomethacin, ibuprofen and diclofenac-Na, as cyclooxygenase inhibitors, showed similar potency ratios on four writhing tests, although, alminoprofen exhibited a somewhat rather higher potency ratio on kaolin- and zymosan-induced writhing models than on acetylcholine- and phenylquinone-induced writhing models. All NSAIDs, cyclooxygenase inhibitors except alminoprofen showed similar shapes in illustrations of potency ratio when the potency of aspirin was expressed as 1.0. The potency of alminoprofen produced a figure unlike those of other cyclooxygenase inhibitors. These results suggest that alminoprofen has a different pharmacological profile from other general NSAIDs in terms of analgesic action. This combination method with potency ratios for writhing reactions caused by the above four inducers could be a simple method for classification of pharmacological profiles of the analgesic actions of NSAIDs.

Topics: Acetylcholine; Animals; Anti-Inflammatory Agents, Non-Steroidal; Benzoquinones; Kaolin; Male; Mice; Mice, Inbred ICR; Pain; Pain Measurement; Propionates; Quinones; Zymosan

The relationship between the kaolin-induced writhing reaction and production of arachidonate metabolites (PGs) in mice was studied. PGs were released into the peritoneal cavity after intraperitoneal injection (i.p.) of kaolin (2.5 mg/mouse) with a peak at 5 min. About 80% of the total amount was 6-keto-PGF1 alpha. There was a significant correlation (r = 0.8237, p less than 0.001) between the number of writhes and the amount of 6-keto-PGF1 alpha. The writhing reaction induced by kaolin was significantly inhibited by simultaneous injection of soybean trypsin inhibitor (SBTI; 2.5 mg/mouse) and increased by simultaneous injection of captopril (50 micrograms/mouse). The writing reaction induced by kaolin which was inhibited by oral administration of indomethacin (1 mg/kg) was restored by exogenous i.p. injection of PGI2-Na (2-10 ng/mouse). Indomethacin, ibuprofen and alminoprofen inhibited the writhing reaction and reduced the level of peritoneal 6-keto-PGF1 alpha in parallel manner. Tiaramide, pentazocine and morphine inhibited the writhing reaction without reducing the revels of 6-keto-PGF1 alpha. These results differentiate the site of action of these analgesics. They suggest that the mechanism of the kaolin-induced writhing reaction in mice involves a synergic pain caused by simultaneously released bradykinin and PGI2. This model is a useful tool which allows differentiation of mode of action of analgesics by simultaneous determination of the writhing response and peritoneal 6-keto-PGF1 alpha.

Topics: 6-Ketoprostaglandin F1 alpha; Analgesics; Animals; Captopril; Epoprostenol; Indomethacin; Kaolin; Male; Mice; Mice, Inbred ICR; Pain; Peritoneal Cavity; Peritoneal Lavage; Prostaglandin-Endoperoxide Synthases; Prostaglandins; Trypsin Inhibitors

A mechanism of writhing reaction induced by kaolin, a known activator of factor XII, was studied. Kaolin induced a distinct writhing response, when injected intraperitoneally into mice (2.5 mg/mouse). The response disappeared in 15 min, but it was reproduced by intraperitoneal injection of captopril, 20 micrograms, into mice who had received the injection of kaolin 60 min before. This later response as well as the early one was not produced when mice were pretreated with bromelain (10 mg/kg, intravenously), 30 min before the kaolin administration. Therefore we determined if bromelain, a known depleter of plasma prekallikrein and a high molecular weight (HMW) kininogen, depletes those in mice. Plasma was collected from mice with or without pretreatment of bromelain, and kinin release of these plasma samples was examined by action of kaolin. The bromelain-treated mouse plasma released kinin amount of less than detection limit when activated with kaolin, whereas normal plasma released about 300 ng/ml of kinin of bradykinin equivalent as assessed by rat uterus contraction. Furthermore, activation of prekallikrein by kaolin was observed in mouse plasma as amidase activity to produce fluorescence from the synthetic substrate. It was completely diminished in the presence of soybean trypsin inhibitor. These results suggest that bromelain could deplete the HMW-kininogen in mouse plasma in the same way as in rat plasma. Furthermore, it is assumed that the kinin released from HMW-kininogen by kaolin could be responsible for inducing the writhing response.

Topics: Animals; Bromelains; Enzyme Activation; Female; In Vitro Techniques; Kallikreins; Kaolin; Kinins; Male; Mice; Mice, Inbred ICR; Pain; Prekallikrein; Rats; Rats, Inbred Strains; Trypsin Inhibitors

The writhing reaction in mice induced by kaolin, a factor XII activator, was studied. An intraperitoneal injection of kaolin clearly induced a writhing reaction in a dose-dependent fashion, and the reaction disappeared about 10-15 min later. The writhing reaction reached a peak at 5-10 min after the injection of kaolin (0.5 ml/mouse, i.p.; 5 mg/ml saline). A simultaneous intraperitoneal injection of soybean trypsin inhibitor (SBTI, 2.5 mg/mouse) almost completely suppressed the writhing reaction caused by kaolin (2.5 mg/mouse) for the first 10 min. The kaolin-induced writhing reaction was markedly potentiated by a simultaneous intraperitoneal injection of captopril (50 micrograms/mouse). At 60 min after kaolin injection during the disappearance of the writhing reaction, the reaction reappeared when captopril was injected, but reactions observed at this later stage were completely blocked by SBTI. Indomethacin, ibuprofen and alminoprofen inhibited the writhing reaction dose-dependently. Kaolin thus induces a clear and reproducible writing reaction, which might be mainly dependent on the action of bradykinin via activation of factor XII, and should prove to be a simple and convenient model of bradykinin-induced pain for the assessment of analgesic actions.

Topics: Acetylcholine; Animals; Anti-Inflammatory Agents, Non-Steroidal; Captopril; Drug Synergism; Glycine max; Ibuprofen; Indomethacin; Kaolin; Kinetics; Male; Mice; Mice, Inbred ICR; Pain; Pain Measurement; Propionates; Trypsin Inhibitors

Kaolin induced a clear and reproducible writhing reaction when intraperitoneally injected into mice. A simultaneous injection (i.p.) of soybean trypsin inhibitor (SBTI) significantly suppressed the kaolin-induced writhing reaction. This writhing reaction was markedly potentiated by a simultaneous injection (i.p.) of captopril. In an in vitro experiment kaolin caused kinin-release in mouse plasma, possibly through the activation of prekallikrein. This activation of plasma prekallikrein and kinin-release were inhibited in the presence of SBTI. Some non-steroidal anti-inflammatory agents inhibited the kaolin-induced writhing reaction dose-dependently. These results suggest that kaolin-induced writhing reaction may be caused by the released bradykinin through activation of the plasma kallikrein-kinin system. This model is a novel and simple tool for assessment of analgesic agents.

Topics: Acetylcholine; Analgesics; Animals; Behavior, Animal; Benzoquinones; Bradykinin; Disease Models, Animal; Kaolin; Male; Mice; Mice, Inbred ICR; Pain; Quinones

A model for studying the relationship between chronic arachnoiditis and pain sensitivity was developed. Thirty male ICR mice were randomly divided into three groups and the tail-flick test was done using an EMDIE-TF6 apparatus (Emdie Instrument Co., Montpelier, VA). Ten mice were injected intrathecally with 5.0 microL of a kaolin-metrizamide mixture and ten control mice were injected intrathecally with 5.0 microL of an electrolyte solution resembling CSF. A third group, (naive controls) were given no treatment. Six weeks later tail-flick tests were repeated. The kaolin-treated mice had significantly decreased tail-flick latencies (P less than .05) compared with the baseline; the controls had no significant change in tail-flick latency. Histologic examination revealed moderate to severe arachnoiditis in the kaolin-treated animals and no evidence of arachnoid abnormalities in the controls. This study suggests that arachnoiditis may be associated with decreased pain thresholds.

Topics: Animals; Arachnoiditis; Kaolin; Male; Mice; Mice, Inbred ICR; Pain; Sensory Thresholds

Recordings were made from 16 ascending tract cells in the spinal cords of anaesthetized, spinalized cats before and after an acute arthritis was produced by injection of kaolin and carrageenan into the knee joint. The responses tested routinely were to passive flexion of the knee, an innocuous movement. In some cases, responses to other movements were also tested, and changes in background discharge rates were monitored. Control recordings for a period of 1 h or in 3 cases of 3 h indicated that the responses to flexion were reasonably stationary. Four tract cells that initially showed little or no response to flexion of the knee joint developed large responses within 1 to 2 h after inflammation of the joint. Another 9 cells were tested that had responses to flexion of the knee joint prior to inflammation. In 6 cases, inflammation produced enhanced static or transient responses. In 2 cases, the effect of flexion was initially inhibitory or variable, but after inflammation these cells showed large excitatory responses. In the other case, inflammation had no effect. Background discharges were increased by inflammation in 6 of these 9 cells. The effect of inflammation of the knee joint was tested on 3 tract cells that had no clearly defined receptive field in the knee. In 1 case, a response developed to knee flexion after acute inflammation was produced. In the other 2 cases, there were initially responses to knee flexion, but these were unchanged by inflammation. Two of the cells tested had bilateral receptive fields in or around the knee joints. Inflammation of one knee joint enhanced the responses to flexion of the same but not of the contralateral knee in one case but greatly increased the responses to flexion of both knees in the other case. Injections of prostaglandin (PGE2) caused an enhancement of the responses to knee flexion beyond that caused by inflammation in 5 of 7 cases. One cell whose responses to flexion of the knee were unaffected by inflammation showed inhibitory responses to prostaglandin injections into the inflamed knee joint. The effects of inflammation on the responses of ascending tract cells of the spinal cord appear to serve as a useful neural model of the events responsible for the development of arthritic pain.

Topics: Acute Disease; Afferent Pathways; Animals; Arthritis; Carrageenan; Cats; Dinoprostone; Kaolin; Knee Joint; Nociceptors; Pain; Prostaglandins E; Spinal Cord

The mild analgesic activities of aspirin, phenacetin and acetaminophen have been compared in the trypsin, kaolin and carrageenan hyperalgesic assays as well as in the acetic acid writhing test. The trypsin and kaolin hyperalgesic assays were designed to be unaffected by drugs with anti-inflammatory activity. Aspirin and acetaminophen were inactive in these two tests at dose levels devoid of side effects. Phenacetin was active in the trypsin and kaolin assays with oral ED50's of 114 +/- 36.2 and 107 +/- 11.5 mg/kg, respectively. Non-steroidal anti-inflammatory drugs as well as phenacetin and acetaminophen were active in the acetic acid writhing and carrageenan hyperalgesic assays. This led to evaluation of phenacetin and acetaminophen as anti-inflammatory agents. Both of these latter drugs were active in the carrageenan pleurisy and adjuvant arthritis models of inflammation. In all studies phenacetin was equipotent to or more potent than acetaminophen. The data suggest that the analgesia produced by aspirin and acetaminophen results from their anti-inflammatory activity whereas the analgesia produced by phenacetin has two components, one dependent on and one independent of anti-inflammatory activity.

Topics: Acetaminophen; Acetates; Analgesics; Animals; Anti-Inflammatory Agents; Arthritis; Aspirin; Carrageenan; Kaolin; Male; Models, Biological; Pain; Phenacetin; Pleurisy; Rats; Trypsin