neurokinin-a and Pain

The long-standing belief that the spinal cord serves merely as a conduit for information traveling to and from the brain is changing. Over the past decade, research has shown that the spinal cord is sensitive to response-outcome contingencies, demonstrating that spinal circuits have the capacity to modify behavior in response to differential environmental cues. If spinally transected rats are administered shock contingent on leg extension (controllable shock), they will maintain a flexion response that minimizes shock exposure. If, however, this contingency is broken, and shock is administered irrespective of limb position (uncontrollable shock), subjects cannot acquire the same flexion response. Interestingly, each of these treatments has a lasting effect on behavior; controllable shock enables future learning, while uncontrollable shock produces a long-lasting learning deficit. Here we suggest that the mechanisms underlying learning and the deficit may have evolved from machinery responsible for the spinal processing of noxious information. Experiments have shown that learning and the deficit require receptors and signaling cascades shown to be involved in central sensitization, including activation of NMDA and neurokinin receptors, as well as CaMKII. Further supporting this link between pain and learning, research has also shown that uncontrollable stimulation results in allodynia. Moreover, systemic inflammation and neonatal hindpaw injury each facilitate pain responding and undermine the ability of the spinal cord to support learning. These results suggest that the plasticity associated with learning and pain must be placed in a balance in order for adaptive outcomes to be observed.

Topics: Animals; Calcium-Calmodulin-Dependent Protein Kinase Type 2; Conditioning, Operant; Inflammation; Neurokinin A; Neuronal Plasticity; Pain; Protein Biosynthesis; Signal Transduction; Spinal Cord

Topics: Animals; Central Nervous System Diseases; Drug Combinations; Gastrointestinal Diseases; Humans; Lung Diseases; Neurokinin A; Neurokinin B; Pain; Receptors, Tachykinin; Substance P; Urologic Diseases; Vomiting

Advances in our understanding of the activation of peripheral damage-sensing neurons (nociceptors) over the past year have been complemented by electrophysiological and imaging studies of central nervous system pain-related centres. The manipulation of gene expression in a reversible and cell type specific way combined with imaging and electrophysiological studies holds promise for helping us to identify the spatial and molecular substrates of pain perception with increasing precision and gives hope for improved analgesic therapies.

Topics: Analgesics; Animals; Brain; Genetic Therapy; Humans; Neurokinin A; Neurons, Afferent; Pain; Pain Management; Radionuclide Imaging

To address the neurochemistry of the mechanisms that underlie the development of acute and persistent pain, our laboratory has been studying mice with deletions of gene products that have been implicated in nociceptive processing. We have recently raised mice with a deletion of the preprotachykinin-A gene, which encodes the peptides substance P (SP) and neurokinin A (NKA). These studies have identified a specific behavioral phenotype in which the animals do not detect a window of "pain" intensities; this window cuts across thermal, mechanical, and chemical modalities. The lowered thermal and mechanical withdrawal thresholds that are produced by tissue or nerve injury, however, were still present in the mutant mice. Thus, the behavioral manifestations of threshold changes in nociceptive processing in the setting of injury do not appear to require SP or NKA. To identify relevant neurochemical factors downstream of the primary afferent, we are also studying the dorsal horn second messenger systems that underlie the development of tissue and nerve injury-induced persistent pain states. We have recently implicated the gamma isoform of protein kinase C (PKCgamma) in the development of nerve injury-induced neuropathic pain. Acute pain processing, by contrast, is intact in the PKCgamma-null mice. Taken together, these studies emphasize that there is a distinct neurochemistry of acute and persistent pain. Persistent pain should be considered a disease state of the nervous system, not merely a prolonged acute pain symptom of some other disease conditions.

Topics: Acute Disease; Animals; Chronic Disease; Humans; Isoenzymes; Mice; Mice, Knockout; Neurochemistry; Neurokinin A; Pain; Protein Kinase C; Protein Precursors; Substance P; Tachykinins

Topics: Acetylcholine; Animals; Brain; Neurokinin A; Pain; Receptors, Glutamate; Receptors, Neurokinin-1; Receptors, Neurokinin-2; RNA, Messenger; Substance P

Topics: Animals; Biphenyl Compounds; Hypnotics and Sedatives; Neurokinin A; Neurons; Pain; Receptors, Neurokinin-2; Reflex; Spinal Cord; Substance P

Topics: Animals; Benzamides; Brain; Kinetics; Neurokinin A; Pain; Piperidines; Receptors, Neurokinin-2; Respiratory Physiological Phenomena; Respiratory System

Topics: Humans; Hydrocortisone; Infant; Infant, Newborn; Neurokinin A; Neuropeptide Y; Pain; Prospective Studies; Substance P

The present study focused on the interactive effects of (Mpa(6))-γ2-MSH-6-12 (Mpa, spinal level) and endokinin A/B (EKA/B, supraspinal level) on pain regulation in mice. EKA/B (30 pmol) only weakened 100 pmol Mpa-induced hyperalgesia at 5 min, but could enhance it during 20-30 min. However, EKA/B (100 pmol) antagonized all dose levels of Mpa significantly at 5 min and blocked them completely at 10 min. EKA/B (3 nmol) co-injected with Mpa presented marked analgesia at 5 min and enduring hyperalgesia within 20-60 min. To investigate the underlying mechanisms between Mpa and EKA/B, SR140333B and SR142801 (NK1 and NK3 receptor antagonists, respectively) were utilized. SR140333B had no influence on Mpa, while SR142801 potentiated it during 20-30 min. Whereas, SR140333B and SR142801 could block the co-administration of Mpa and EKA/B (30 pmol) separately at 5 min and 30 min. These phenomena might attribute to that these two antagonists promoted the antagonism of EKA/B (30 pmol) at the early stage, while antagonized EKA/B preferentially in the latter period. SR140333B weakened the analgesia of EKA/B (3 nmol), but produced no effect on Mpa. However, SR140333B failed to affect the co-injection of Mpa and EKA/B, which implied that EKA/B cooperated with Mpa prior to SR140333B. These results could potentially help to better understand the interaction of NK and MrgC receptors in pain regulation in mice.

Topics: Animals; Dose-Response Relationship, Drug; gamma-MSH; Hyperalgesia; Injections, Intraventricular; Injections, Spinal; Male; Mice; Neurokinin A; Neurokinin B; Neurokinin-1 Receptor Antagonists; Pain; Pain Measurement; Piperidines; Receptors, Neurokinin-3; Tropanes

Glycyrrhetinic acid (GA), an aglycone of glycyrrhizin, isolated from the licorice root (Glycyrrhizia), and its semi-synthetic derivatives have a wide range of pharmacological effects. To investigate whether GA derivatives may be used as a new class of analgesics, we examined the effects of these compounds on human tachykinin receptors expressed in CHO-K1 cells. Among the GA derivatives examined, the disodium salt of olean-11,13(18)-dien-3β,30-O-dihemiphthalate inhibited the mobilization of [Ca(2+)](i) induced by substance P, neurokinin A, and neurokinin B in CHO-K1 cells expressing the human NK(1), NK(2), and NK(3) tachykinin receptors, respectively. In an inflammatory pain model, Compound 5 suppressed the capsaicin-induced flinching behavior in a dose-dependent manner. Compound 5 was also effective in suppressing pain-related behaviors in the late phase of the formalin test and reducing thermal hyperalgesia in the neuropathic pain state caused by sciatic nerve injury. Collectively, Compound 5 may be an analgesic candidate via tachykinin receptor antagonism.

Topics: Analgesics; Animals; Calcium; Capsaicin; CHO Cells; Cricetinae; Disease Models, Animal; Formaldehyde; Glycyrrhetinic Acid; Hot Temperature; Humans; Hyperalgesia; Inflammation; Ligation; Male; Neuralgia; Neurokinin A; Neurokinin B; Pain; Rats; Rats, Sprague-Dawley; Receptors, Tachykinin; Sciatic Nerve; Substance P

Although morphine is a very effective analgesic, its narrow therapeutic index and severe side effects limit its therapeutic use. Previous studies indicated that the pharmacological responses of opioids are modulated by genetic and pharmacological invalidation of tachykinin receptors. Here we address the role of substance P and neurokinin A, which are both encoded by the tachykinin 1 (tac1) gene, as modulators of opioid effects.. The analgesic and side effect potential of morphine was compared between wild-type and tac1 null mutant mice.. Morphine was a more potent analgesic in tac1 null mutant mice, that is, in the absence of substance P/neurokinin A signalling. Interestingly, the most serious side effect of acute morphine, that is respiratory depression, was reduced in tac1(-/-) animals. Comparing the addictive potential of morphine in wild-type and knockout animals we found that morphine preference was similar between the genotypes. However, the aversive effect of withdrawal precipitated by naloxone in morphine-dependent animals was significantly reduced in tac1 knockout mice. Behavioural sensitization, the underlying mechanism of addiction, was also significantly lower in tac1(-/-) mice.. The analgesic potential of morphine was increased in tac1 knockout mice. In contrast, both the ventilatory suppressing effect and the addictive potential of morphine were reduced. These results suggest that reducing activity of the tachykinin system may be a possible strategy to improve the pharmacological potential of morphine.

Topics: Analgesics, Opioid; Animals; Behavior, Addictive; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Morphine; Naloxone; Narcotic Antagonists; Neurokinin A; Pain; Pain Measurement; Respiratory Insufficiency; Substance P; Tachykinins

Substance P (SP) and neurokinin A (NKA) are neuropeptides that have been researched as pain markers in adults, as they are involved in transmission and modulation of pain signals. There is a potential role for them as neurochemical markers of pain in neonates, but this has never previously been investigated.. To establish normative values of SP and NKA in neonates.. Longitudinal once-daily morning blood samples were collected over two weeks from 142 neonates, gestation 23-40 weeks. Peptides were extracted, and then quantified using an in-house radioimmunoassay. Infants with presumed painful conditions were excluded.. SP concentrations ranged from <0.98 to 11.2 pmol/L (median 1.7 pmol/L) and NKA concentrations from <1.95 to 74.6 pmol/L (median 6.0 pmol/L). Gestation and birth weight had no significant correlation with peptide concentrations. Postnatally, there was a gradual rise in median SP during the first three days, which decreased again by day 14. Median NKA showed a similar rise, but was not statistically significant. This postnatal rise and fall were more apparent in preterm infants < or = 32 weeks gestation.. This is the first description of normative values of SP and NKA in neonates. SP and NKA show changes with postnatal age, which are more marked in preterm infants.

Topics: Age Factors; Biomarkers; Female; Humans; Infant, Newborn; Neurokinin A; Pain; Pregnancy; Premature Birth; Reference Values; Substance P

The mas-related genes (Mrgs, also known as sensory neuron-specific receptors, SNSRs) are specifically expressed in small diameter sensory neurons in the trigeminal and dorsal root ganglia, suggesting an important role of the receptors in pain transmission. The present study aimed to investigate the underlying mechanism of the nociceptive effects after activation of MrgC, and the interaction between MrgC and N/OFQ-NOP receptor system in modulation of nociception in mice. Intrathecal (i.t.) administration of [Tyr(6)] gamma2-MSH(6-12), the most potent agonist for MrgC receptor, produced a significant hyperalgesic response as assayed by tail withdrawal test and a series of characteristic nociceptive responses, including biting, licking and scratching, in a dose-dependent manner (0.01-10 pmol and 0.01-10 nmol, respectively) in mice. These pronociceptive effects induced by [Tyr(6)] gamma2-MSH(6-12) were inhibited dose-dependently by co-injection of competitive NMDA receptor antagonist D-APV, non-competitive NMDA receptor antagonist MK-801, and nitric oxide (NO) synthase inhibitor L-NAME. However, the tachykinin NK(1) receptor antagonist L-703,606, and tachykinin NK(2) receptor antagonist MEN-10,376, had no influence on pronociceptive effects elicited by [Tyr(6)] gamma2-MSH(6-12). In other groups, [Tyr(6)] gamma2-MSH(6-12)-induced nociceptive responses were bidirectionally regulated by the co-injection of N/OFQ. N/OFQ inhibited nociceptive responses at high doses (0.01-1 nmol), but potentiated the behaviors at low doses (1 fmol-3 pmol). Furthermore, both hyperalgesia and nociceptive responses were enhanced after the co-administration with NOP receptor antagonist [Nphe(1)]N/OFQ(1-13)-NH(2). These results suggest that intrathecal [Tyr(6)] gamma2-MSH(6-12)-induced pronociceptive effects may be mediated through NMDA receptor-NO system in the spinal cord, and demonstrate the interaction between MrgC and N/OFQ-NOP receptor system in pain transmission.

Topics: Animals; Dose-Response Relationship, Drug; Excitatory Amino Acid Antagonists; gamma-MSH; Hormones; Hyperalgesia; Injections, Spinal; Male; Mice; Narcotic Antagonists; Neurokinin A; Nitric Oxide; Nitric Oxide Synthase Type I; Nociceptin; Nociceptin Receptor; Nociceptors; Opioid Peptides; Pain; Pain Measurement; Peptide Fragments; Receptors, G-Protein-Coupled; Receptors, N-Methyl-D-Aspartate; Receptors, Opioid; Spinal Cord

Premature newborn may feel different kinds of pain, thus incomplete diagnostics and unjustified therapy may lead to unfavourable physiological effects. All the pain feelings that a child experiences are acute and recurrent or persistent leading to a pain syndrome if there is no intervention. Currently a huge arsenal of pharmacological drugs is available to control pain. There are a lot of researches described in the literature on the effectiveness of the pharmacodynamics, pharmacokynetics and complications related to administration of different analgetics in newborns. However the unfavorable complications identified prevent their use in newborns. Analgesic effect can be made not only by proper analgetics, but combined homeopathic medications as well. One of such medications, which has no side effects is traumel S. The current paper reflects outcomes of the clinical research took place over the 79 pre-term newborns with infringement of the CNS who are subject of a big number of the prescribed treatment manipulation and procedures whereas most of them are quite painful. There is necessity of applying anesthesia treatment for avoiding clinical and biochemical consequences of the pain syndrome. Application of the traumel C intramuscularly or traumel C ointment per os just before and during painful manipulation affect drop pain level of a newborn. Appreciation of pain is subject to the level of CNS lesions because during severe disorders behavioral reaction to pain is certainly reduced. Premature newborns from control group, in the dynamics of neonatal period, manifested reliable reduction (R<0,05) of neurokinin A from 17.52 to 2.08 ng/ml, substance P from 2.5 to 0.3 n/ml compare to seek newborns. During comparison of the results it was revealed that premature newborns, with hypoxemic-ischemic lesion of CNS, treated based on traditional allopathic therapy from the first day of life, manifest significantly high level of neurokinin A and substance P, maintained until the end of first month of life. It was also determined that during the use of allopathic therapy on 7-10th days of life neurokinin A and substance P form 76.86 and 14.46 ng/ml respectively, confirming the development of pain syndrome.

Topics: Female; Homeopathy; Humans; Hypoxia-Ischemia, Brain; Infant, Newborn; Infant, Premature; Male; Minerals; Neurokinin A; Pain; Pain Measurement; Plant Extracts

In a previous report, we compared the properties of lamina V neurons of the spinal cord dorsal horn in wild-type mice and in mice with a deletion of the preprotachykinin-A (PPT-A) gene, which encodes substance P (SP) and neurokinin A (NKA). The mutant mice had pronounced deficits in the response to thermal stimulation, both before and after mustard oil induced sensitization. Here, we extended our analysis to the properties of lamina I neurons and also examined responsiveness to mechanical stimulation. Consistent with the properties of lamina V neurons, in the PPT-A mutant mice we found significantly reduced responses of lamina I neurons to noxious thermal stimulation, and mustard oil sensitization of these neurons to heat was lost. In contrast, not only were the responses of lamina I neurons to noxious mechanical stimulation unchanged in the mutant mice, but in neither the wild-type nor the mutant mice could sensitization be induced. However, mustard oil profoundly sensitized lamina V neurons to mechanical stimulation in both wild-type and mutant mice. We conclude that SP and/or NKA are required for the transmission of noxious thermal stimulation by lamina I and V neurons, both before and after tissue injury. The persistence of mechanical sensitization of lamina V neurons in the mutant mice further shows that mustard oil induces mechanical and thermal sensitization through different mechanisms. Finally, we conclude that lamina I sensitization to mechanical stimulation is not required for this form of injury-increased responsiveness of lamina V neurons.

Topics: Animals; Female; Hot Temperature; Male; Mice; Mice, Knockout; Neurokinin A; Pain; Pain Measurement; Physical Stimulation; Posterior Horn Cells; Spinal Cord Injuries; Substance P

Intrathecal (i.t.) administration of D-cycloserine (100 and 300 fmol), a partial agonist of the glycine recognition site on the N-methyl-D-aspartate (NMDA) receptor ion-channel complex, produced a behavioral response mainly consisting of biting and/or licking of the hindpaw and the tail along with slight hindlimb scratching directed toward the flank in mice, which peaked at 5 - 10 min and almost disappeared at 15 min after the injection. The behavior induced by D-cycloserine (300 fmol) was dose-dependently inhibited by an intraperitoneal injection of morphine (0.5-2 mg/kg), suggesting that the behavioral response is related to nociception. The nociceptive behavior was also dose-dependently inhibited by i.t. co-administration of 7-chlorokynurenic acid (0.25-4 nmol), a competitive antagonist of the glycine recognition site on the NMDA receptor ion-channel complex; D-(-)-2-amino-5-phosphonovaleric acid (62.5-500 pmol), a competitive NMDA receptor antagonist; MK-801 (62.5-500 pmol), an NMDA ion-channel blocker; ifenprodil (0.5-8 nmol); arcaine (31-125 pmol); and agmatine (0.1-10 pmol), all being antagonists of the polyamine recognition site on the NMDA receptor ion-channel complex. However, [D-Phe7,D-His9]-substance P(6-11), a specific antagonist for substance P (NK1) receptors, and MEN-10,376, a tachykinin NK2-receptor antagonist, had no effect on D-cycloserine-induced nociceptive behavior. These results in the mouse spinal cord suggest that D-cycloserine-induced nociceptive behavior is mediated through the activation of the NMDA receptor ion-channel complex by acting on the glycine recognition site and that it does not involve the tachykinin receptor mechanism.

Topics: 2-Amino-5-phosphonovalerate; Agmatine; Animals; Cycloserine; Dizocilpine Maleate; Dose-Response Relationship, Drug; Injections, Spinal; Ion Channels; Kynurenic Acid; Mice; Morphine; Neurokinin A; Nociceptors; Pain; Peptide Fragments; Piperidines; Receptors, Glycine; Receptors, N-Methyl-D-Aspartate; Receptors, Tachykinin; Substance P

Previous research has demonstrated that spinally transected rats can acquire a prolonged flexion response to prevent the delivery of shock. However, rats that receive shock irrespective of leg position cannot learn to maintain the same response. The present experiments examined the role of neurokinin receptors in this learning deficit. Results demonstrated that neurokinin (NK1 and NK2) antagonists blocked the induction of the learning deficit, whereas NK agonists induced a learning deficit. The study found that NK agonist administration did not substitute for uncontrollable shock exposure. Finally, administration of an NK1 agonist prior to uncontrollable shock prevented the induction of the deficit. These results provide additional evidence that engaging nociceptive plasticity undermines the capability of spinal neurons to support adaptive changes.

Topics: Adaptation, Psychological; Animals; Electroshock; Female; Learning; Neurokinin A; Neurokinin-1 Receptor Antagonists; Neuronal Plasticity; Pain; Peptide Fragments; Quinuclidines; Rats; Rats, Sprague-Dawley; Receptors, Neurokinin-1; Receptors, Neurokinin-2; Receptors, Tachykinin; Spinal Cord; Spinal Cord Injuries; Substance P; Vocalization, Animal

Using an indirect immunoperoxidase technique, the location of cell bodies and fibers containing substance P, neurokinin A and neurokinin B was studied in the cat spinal cord. The former two neuropeptides showed a widespread distribution throughout the whole spinal cord, whereas the distribution of neurokinin B was more restricted. Neurokinin A-immunoreactive structures showed a more widespread distribution and a higher density than the immunoreactive structures observed to contain substance P. In the cat spinal cord, we observed cell bodies containing neurokinin A, but no cell bodies containing neurokinin B or substance P were found. These cell bodies were located in laminae V (sacral 1 and 2 levels), VI (sacral 1 and 3), VII (lumbar 7, sacral 1 and 3, caudal 1) and X (sacral 1). Laminae I and II showed the highest density of immunoreactive fibers for each of the three tachykinins studied, being in general lamina IV who showed the lowest number of immunoreactive fibers containing substance P, neurokinin A or B. The anatomical distribution of the three tachykinins studied in the cat spinal cord indicates that the neuropeptides could be involved in the neurotransmission and/or in the neuromodulation of nociceptive information, as well as in autonomic and affective responses to pain. Moreover, the involvement of substance P, neurokinin A or B in other functions unrelated to the transmission of pain is also possible (autonomic and motor functions). The distribution of the neuropeptides studied in the cat is compared with the location of the same neuropeptides in the spinal cord of other species. The possible origin of the tachykinergic fibers in the cat spinal cord is also discussed.

Topics: Animals; Antibody Specificity; Brain Mapping; Cats; Cell Shape; Immunohistochemistry; Male; Neurokinin A; Neurokinin B; Neurons; Nociceptors; Pain; Posterior Horn Cells; Presynaptic Terminals; Species Specificity; Spinal Cord; Substance P; Synaptic Transmission; Tachykinins

Using electrophysiological methods, we aimed in the present study to determine whether the NK(2) receptor is involved in the sensitization of articular afferents of the rat. Impulse activity from 27 single fine nerve fibres innervating knee joints was recorded during non-noxious and noxious joint rotations. Close intraarterial application of the NK(2) receptor agonist [beta-Ala(8)]NKA(4-10) at doses of 0.2-200 nmol did not sensitize the afferents from normal knee joints to mechanical stimuli whereas the application of substance P (20 nmol) increased their mechanosensitivity. These data further support the hypothesis that the NK(2) receptor is not involved in the sensitization of primary afferents in normal knee joints to mechanical stimuli.

Topics: Animals; Knee Joint; Male; Mechanoreceptors; Nerve Fibers; Neurokinin A; Neurons, Afferent; Pain; Peptide Fragments; Physical Stimulation; Rats; Rats, Wistar; Receptors, Neurokinin-2; Rotation; Substance P

The spinal processing by which intra-arterial injection of capsaicin (CAP) induces vocalization response (VOR) was investigated in guinea pigs. Intrathecal pre-treatment with CP-96,345 (a selective NK(1) receptor antagonist, 50 nmol) did not affect the CAP-induced VOR. However, significant attenuation of the VOR was observed by intrathecal pre-treatment with a selective NK(2) receptor antagonist MEN-10,376 (40 nmol) accompanied with a significant change in the response modality. MK-801 [an N-methyl-D-aspartate (NMDA) receptor antagonist, 20 and 40 nmol] inhibited the CAP-induced VOR dose-dependently without affecting the response modalities. Furthermore, intrathecal co-treatment with 40-nmol MEN-10,376 and 40-nmol MK-801 resulted in a marked inhibitory effect on the VOR followed by a significant alteration of response modalities. Intrathecal pre-treatment with neurokinin A (NKA; a tachykinin NK(2) receptor agonist, 1 nmol) enhanced the CAP-induced VOR. These behavioral results suggested that spinal NK(2) and NMDA receptors might have priority over NK(1) receptors in the spinal processing of nociceptive information from the CAP-sensitive nociceptor.

Topics: Animals; Avoidance Learning; Biphenyl Compounds; Capsaicin; Dizocilpine Maleate; Excitatory Amino Acid Antagonists; Femoral Artery; Guinea Pigs; Hindlimb; Injections, Intra-Arterial; Male; Neurokinin A; Nociceptors; Pain; Peptide Fragments; Receptors, N-Methyl-D-Aspartate; Receptors, Neurokinin-2; Spinal Cord; Vocalization, Animal

Primary trigeminal neurons of the trigeminal ganglion (TG) innervate major parts of the face and head, including the dura. Electrical stimulation of the TG at specific parameters, can activate its nociceptive neurons and may serve as an experimental pain model. Markowitz [J. Neurosci. 7 (1987) 4129] reported that electrical stimulation of the trigeminal ganglion (TG) causes extravasation of plasma proteins from venules of the trigeminally innervated domain possibly due to the release of vasoactive substances. Neurogenic inflammation (vasodilatation, plasma protein extravasation, release of vasoactive peptides) in dura may serve as one of the possible pathomechanisms underlying vascular head pain [Moskowitz, Ann. Neurol. 16 (1984) 157]. We performed a unilateral electrical stimulation (7.5 Hz, 5 ms, 0.8-1.4 mA for 5 min) of the TG in rat, to induce a neurogenic inflammation in the peripheral trigeminal domain including the dura, looking for calcitonin gene related peptide (CGRP), substance P (SP) and neurokinin A (NKA) immunoreactivity (IR) in the caudal trigeminal nucleus (CTN) into which massive central trigeminal processes terminate. Here, we show patchy depletion(s) of CGRP-, SP- and NKA-IRs in the contralateral CTN of the rat in addition to their ipsilateral depletion. Such depletion is due to the release of these neuropeptides in the CTN leading to the activation of bilateral trigeminal nociceptive pathway. These data afford the possibility that under specific frequencies (which may roughly correlate to the intensity of the painful stimulus) and/or specific intensities (may correlate to specific areas of the peripheral trigeminal domain) of stimulation, activation of one side of the TG may activate bilateral trigeminal nociceptive pathway leading to the perception of an ill localized/generalized pain or headache rather than a unilateral one.

Topics: Animals; Calcitonin Gene-Related Peptide; Electric Stimulation; Female; Functional Laterality; Headache; Male; Neurokinin A; Pain; Rats; Rats, Wistar; Substance P; Trigeminal Ganglion; Trigeminal Nucleus, Spinal

Spinal nociceptive transmission is mediated by glutamate and neuropeptides such as substance P (SP) and neurokinin A (NKA). The neuropeptide-mediated excitatory postsynaptic potentials (EPSPs) had a slow onset and long duration. Here, we demonstrate SP- and NKA-mediated excitatory postsynaptic currents (EPSCs) in dorsal horn neurons of young rats using whole-cell patch-clamp recording techniques. After complete blockade of glutamate receptor-mediated currents, we observed a small residual EPSC. The residual EPSCs exhibited temporal summation in response to a train of stimulation (six pulses delivered at 10-50 Hz). High intensity stimulation (the same or greater than the stimulation threshold for nociceptive fibers in vivo) was required for evoking these summated EPSCs. Summated EPSCs were attenuated or abolished by capsaicin pretreatment, which depletes SP and NKA from presynaptic terminals; SP and NKA pretreatment; NK(1) or NK(2) receptor antagonists; and inhibition of postsynaptic G proteins. EPSCs were neither blocked by a metabotropic glutamate receptor antagonist nor a gamma-aminobutyric acid(B) receptor antagonist. The summated EPSCs were also sensitive to voltage-gated calcium channel antagonists or mu-opioid receptor activation by DAMGO. The present study provides electrophysiological evidence that suggests the possible contribution of SP and NKA to sensory synaptic transmission between primary afferent fibers and dorsal horn neurons.

Topics: 2-Amino-5-phosphonovalerate; 6-Cyano-7-nitroquinoxaline-2,3-dione; Age Factors; Analgesics, Opioid; Animals; Calcium Channel Blockers; Calcium Channels, P-Type; Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; Excitatory Amino Acid Antagonists; Excitatory Postsynaptic Potentials; GABA Antagonists; Guanosine Diphosphate; In Vitro Techniques; Neurokinin A; omega-Conotoxin GVIA; Pain; Patch-Clamp Techniques; Phosphinic Acids; Posterior Horn Cells; Propanolamines; Rats; Rats, Sprague-Dawley; Receptors, Glutamate; Receptors, Neurokinin-1; Receptors, Neurokinin-2; Substance P; Synaptic Transmission; Thionucleotides

The tachykinin neuropeptides, substance P and substance K, are produced in nociceptive primary sensory neurons and in many brain regions involved in pain signaling. However, the precise role and importance of these neuropeptides in pain responses has been debated. We now show that mice that cannot produce these peptides display no significant pain responses following formalin injection and have an increased pain threshold in the hotplate test. On the other hand, the mutant mice react normally in the tail flick assay and acetic acid-induced writhing tests. These results demonstrate that substance P and/or substance K have essential functions in specific responses to pain.

Topics: Acetic Acid; Alleles; Animals; Biomarkers; Calcitonin Gene-Related Peptide; Formaldehyde; Ganglia, Spinal; Gene Deletion; In Situ Hybridization; Mice; Mice, Inbred C57BL; Mice, Knockout; Neurokinin A; Neurons; Pain; Spinal Cord; Substance P

Topics: Analgesics; Animals; Mice; Neurokinin A; Neurokinin-1 Receptor Antagonists; Neurons, Afferent; Pain; Protein Precursors; Receptors, Neurokinin-1; Substance P; Tachykinins

The excitatory neurotransmitter glutamate coexists with the peptide known as substance P in primary afferents that respond to painful stimulation. Because blockers of glutamate receptors reliably reduce pain behaviour, it is assumed that 'pain' messages are mediated by glutamate action on dorsal horn neurons. The contribution of substance P, however, is still unclear. We have now disrupted the mouse preprotachykinin A gene (PPT-A), which encodes substance P and a related tachykinin, neurokinin A. We find that although the behavioural response to mildly painful stimuli is intact in these mice, the response to moderate to intense pain is significantly reduced. Neurogenic inflammation, which results from peripheral release of substance P and neurokinin A, is almost absent in the mutant mice. We conclude that the release of tachykinins from primary afferent pain-sensing receptors (nociceptors) is required to produce moderate to intense pain.

Topics: Animals; Cloning, Molecular; Female; Gene Targeting; Glutamic Acid; Male; Mice; Mice, Inbred C57BL; Neuritis; Neurokinin A; Nociceptors; Pain; Protein Precursors; Receptors, Neurokinin-1; Sensory Thresholds; Sequence Deletion; Stimulation, Chemical; Substance P; Tachykinins

Pain is a common feature of interstitial cystitis (IC). Although the effects of IC on sensory neuron density have been investigated, its influence on substance P receptor (SPR) numbers and function are not well known. To evaluate the role of SPR in cats with IC, we measured the affinity (Kd), numbers (Bmax), and substrate specificity of binding sites for [3H]SP in urinary bladders of healthy cats and cats suffering from IC.. Radioligand binding assays of cat and rat brain, normal cat bladders, and inflamed bladders from cats diagnosed with IC were conducted using [3H]SP to determine SPR affinity and numbers. Binding sites for [125I]SP were identified using autoradiography in slide-mounted frozen tissue sections, and their specificity determined with competition binding studies.. In bladder homogenate binding studies, low affinity SP binding sites for [3H]SP were found both in normal and inflamed tissue, whereas high affinity binding sites were found in inflamed bladder tissue only. Based on autoradiographic studies, high affinity binding appeared to be to small blood vessels, and to be specific for substance P, a pharmacology consistent with the neurokinin-1 receptor (NK1R).. Upregulation of NK1R may be part of the pathophysiology of IC, as it is in some other inflammatory diseases. If so, more specifically targeted therapies for IC may become available.

Topics: Animals; Autoradiography; Binding Sites; Binding, Competitive; Blood Vessels; Brain; Cats; Cystitis, Interstitial; Female; Iodine Radioisotopes; Male; Neurokinin A; Neurokinin B; Pain; Radiopharmaceuticals; Rats; Rats, Sprague-Dawley; Receptors, Neurokinin-1; Substance P; Substrate Specificity; Tritium; Up-Regulation; Urinary Bladder

The effect of two calmodulin inhibitors, W-7 (N-(6-aminohexyl)-5-chloro-1-naphtalenesulfonamide) and calmidazolium, on the nociceptive behavior induced by the intrathecal injection of NMDA (N-methyl-D-aspartate), AMPA (alpha-amino-3-hydroxy-5-methyl-4-iso xazolepropionic acid) or of septide is described. Lumbar intrathecal injection of NMDA, AMPA or septide induced a caudally directed nociceptive reaction (biting, scratching and licking). The nociceptive behavior induced by NMDA (4 microg) was dose dependently inhibited when W-7 (0.25-1 micromol/rat) or calmidazolium (0.12-0.5 micromol/rat) was coinjected. Biting, scratching and licking produced by AMPA (2 microg) were unaffected by intrathecal calmodulin inhibitors. Finally, septide-evoked nociceptive behavior (2 microg) was antagonized by W-7 (0.12-0.5 micromol/rat) and calmidazolium (0.06-0.25 micromol/rat). Thus, calmodulin inhibitors prevent the nociceptive reaction evoked by drugs that modify intracellular Ca2+, NMDA and septide, without affecting the nociceptive response induced by AMPA, for which Ca2+ is not the main second messenger.

Topics: alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid; Animals; Calcium-Calmodulin-Dependent Protein Kinases; Calmodulin; Enzyme Inhibitors; Imidazoles; Injections, Intraventricular; Male; N-Methylaspartate; Neurokinin A; Pain; Peptide Fragments; Pyrrolidonecarboxylic Acid; Rats; Rats, Wistar; Spinal Cord; Substance P; Sulfonamides

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

The contribution of the nervous system to the pathophysiology of rheumatoid arthritis has been proposed to be mediated by certain neuropeptides. Neuropeptide Y, calcitonin gene-related peptide, substance P, and neurokinin A are considered modulators of inflammatory joint disease. Parameters of pain, as well as occlusal signs of tissue destruction from the arthritic TMJ and the corresponding neuropeptide concentrations in TMJ synovial fluid, were investigated in patients with various inflammatory joint diseases. The patients with rheumatoid arthritis were also examined in a separate diagnostic group. Visual analog scale, palpatory tenderness, maximal voluntary mouth opening, and anterior open bite were correlated to neuropeptide-like immunoreactivities of the above four neuropeptides. It was found that high concentrations of calcitonin gene-related peptide and neuropeptide Y in TMJ fluid are associated with pain, impairment of mandibular mobility, and occlusal signs of TMJ destruction in patients with rheumatoid arthritis. The results indicated neuropeptide involvement in rheumatoid arthritis, proposing a potentiation of the symptoms and signs by the inflammatory action of calcitonin gene-related peptide and neuropeptide Y.

Topics: Adult; Arthritis; Arthritis, Rheumatoid; Calcitonin Gene-Related Peptide; Female; Humans; Inflammation Mediators; Male; Middle Aged; Neuroimmunomodulation; Neurokinin A; Neuropeptide Y; Neuropeptides; Pain; Pain Measurement; Range of Motion, Articular; Statistics, Nonparametric; Substance P; Synovial Fluid; Temporomandibular Joint Disorders

Topics: Animals; Benzamides; Biphenyl Compounds; Models, Neurological; Neurokinin A; Neurokinin-1 Receptor Antagonists; Oligopeptides; Pain; Piperidines; Rats; Rats, Sprague-Dawley; Receptors, Neurokinin-1; Receptors, Neurokinin-2; Receptors, Neurokinin-3; Receptors, Neurotransmitter; Spinal Cord; Substance P

We evaluated the effect of intrathecal (i.t.) capsaicin (CAP) and the NK-1 selective non-peptidic antagonist, CP,96-345, on the thermal hyperalgesia ordinarily observed after unilateral partial ligation of the sciatic nerve in rats. CAP was injected i.t. 2 days after constriction injury. Seven days after partial ligation, the levels of substance P (sP), calcitonin gene-related peptide (CGRP) and vasoactive intestinal polypeptide (VIP) were the same in the left and right dorsal horns of the lesioned rats which were injected with vehicle (VEH). CAP (75 micrograms/15 microliters of 20% 2-hydroxypropyl-beta-cyclodextrin) resulted in an equal reduction (40-50%) in the dorsal horn levels of sP and CGRP, but not VIP. After 7 days, i.t. CAP increased the paw withdrawal latency (PWL) of the non-injured hind paw. In contrast, there was no change in the PWL of the injured paw when compared to that of VEH-treated animals. Thus, CAP did not abolish the hyperalgesic state. We concluded that the thermal hyperalgesia after sciatic nerve constriction injury is not mediated by CAP-sensitive C fibers. CP,96-345 given i.t. at a dose which is physiologically active (400 micrograms) had little effect on the thermal response latency of either the normal or hyperesthetic paw. This provides further evidence that neither the normal pain response nor hyperalgesic state is dependent upon a dorsal horn action of sP.

Topics: Animals; Biphenyl Compounds; Capsaicin; Hot Temperature; Hypnotics and Sedatives; Injections, Spinal; Male; Neurokinin A; Neuropeptides; Nociceptors; Pain; Radioimmunoassay; Rats; Rats, Sprague-Dawley; Sciatic Nerve; Spinal Cord

Previously we have demonstrated that an intrathecal injection of galanin (GAL) decreases the nociceptive threshold for mechanical stimulation without effect on thermal nociceptive responses. The present experiments were conducted to determine whether substance P (SP) would be involved in such a decrease in the nociceptive threshold produced by GAL. An intrathecal injection of anti-SP monoclonal antibody inhibited the nociceptive threshold-decreasing effect of intrathecal GAL (0.1 nmol/rat). This antibody significantly suppressed the contractile action of SP (3 nM) on the longitudinal muscle and that of neurokinin A (3 nM) to a lesser degree. Binding of [125I]Tyr8-SP to this antibody was inhibited by SP in a concentration-dependent manner in the range 0.1-33 nM without suppression by GAL at a concentration of 3300 nM. In addition, an intrathecal injection of the anti-SP monoclonal antibody increased the nociceptive threshold for mechanical stimulation in carrageenin-inflamed rats without effect on thermal nociceptive behaviors. The capsaicin (0.5 microM)-evoked release of immunoreactive SP from dorsal-half slices of the spinal cord was increased by galanin (1 microM, but not 0.1 microM) without effects on basal release. An intrathecal injection of GAL did not produce aversive responses (biting, licking and scratching) at doses of 0.1 and 1 nmol/rat. GAL (0.1 nmol/rat) did not affect biting/licking behaviors evoked by SP (1 nmol/rat), but inhibited SP-evoked scratching behavior. These results suggest that the nociceptive threshold-decreasing action of intrathecal GAL is at least in part mediated by SP, and that GAL may act on primary afferent terminals to increase the release of SP evoked by stimulation.

Topics: Animals; Antibodies, Monoclonal; Behavior, Animal; Capsaicin; Carrageenan; Galanin; Guinea Pigs; Ileum; In Vitro Techniques; Inflammation; Injections, Spinal; Male; Muscle, Smooth; Neurokinin A; Nociceptors; Pain; Peptides; Rats; Rats, Inbred Strains; Substance P

As well as substance P (SP), neurokinin A (NKA) and neurokinin B (NKB) have recently been found in the superficial dorsal horn of the spinal cord; NKA originating mainly in fine primary afferents. We have investigated the effects of these tachykinins and a range of analogues on somatosensory responses of single identified dorsal horn neurons, when applied ionophoretically to the region of the substantia gelatinosa. Behavioural reflex tests of thermal nociception were carried out in parallel. The role of NK-1, NK-2 and NK-3 receptors was addressed. NK-1-selective agonists attenuated the non-nociceptive responses of identified multireceptive spinocervical tract (SCT) neurons. Of the endogenous tachykinins, both SP and NKB (a weak NK-1 agonist) showed this effect. No role for NK-3 receptors was identified in our experiments. NK-2-selective agonists (including NKA) caused a unique and selective facilitation of thermal nociceptive responses. NKA also reduced reflex response latency in tail-flick and hot plate tests. NKA as a primary afferent transmitter may thus be involved in mediating or facilitating the expression of thermal nociceptive inputs in the substantia gelatinosa. NKA and SP could be considered as acting in concert in the superficial dorsal horn in an effectively pro-nociceptive modulatory role. Evidence from receptor-selective antagonists supports that obtained with agonists for the roles of particular NK receptors in somatosensory processing. NK-2, but not NK-1 or NK-3 antagonists attenuated endogenous thermal nociceptive responses, supporting the hypothesis that an NK-2 agonist (such as NKA) may normally participate in expression of thermal nociception in the superficial dorsal horn. Behavioural experiments showing increased response latencies with a putative NK-2 selective antagonist further supported the involvement of NK-2 receptors in thermal nociception.

Topics: Animals; Axons; Bombesin; Cats; Evoked Potentials, Somatosensory; Glutamates; Glutamic Acid; Hot Temperature; Kinetics; Neurokinin A; Neurons; Pain; Receptors, Neurokinin-2; Receptors, Neurotransmitter; Spinal Cord; Substance P

In barbiturate anaesthetized spinal cats antibody microprobes were used to examine release of immunoreactive neurokinin A following cutaneous thermal and mechanical stimulation. In the absence of peripheral stimuli, microprobes detected a diffuse basal presence of immunoreactive neurokinin A. Noxious mechanical and to a lesser extent noxious thermal stimuli increased the levels of immunoreactive neurokinin A diffusely throughout the dorsal horn which, in many cases, spread into the adjacent white matter. These diffuse stimulus-evoked increases contrast with previous experiments where the same stimuli produced discrete focal increases in levels of immunoreactive substance P. Evidence was obtained that released immunoreactive neurokinin A persisted in the spinal cord for at least 30 min beyond the period of stimulation. Neurokinin A needs consideration as the agent responsible for the long-lasting increases in excitability of some spinal neurons found by several laboratories to follow a brief input from unmyelinated primary afferents.

Topics: Animals; Cats; Immunohistochemistry; Neurokinin A; Nociceptors; Pain; Skin; Spinal Cord

Intrathecal injections of substance P (SP) or neurokinin A (NKA) in the mouse caused dose-dependent reciprocal hindlimb scratching, licking and biting responses directed to the caudal part of the body. NKA decreased the latency in the tail flick assay but like SP, did not alter the reactions in the hot plate test or the hypertonic saline assay. Although immunoreactivity of calcitonin gene-related peptide (CGRP) was detected in mouse spinal cord, CGRP caused no behavioral reactions, nor did it significantly affect thermo- or chemonociception or the scratching induced by SP. Since NKA-like immunoreactivity was found to be present in sensory neurons, NKA as well as SP are likely transmitters of nociceptive primary afferent neurons.

Topics: Animals; Calcitonin Gene-Related Peptide; Female; Injections, Spinal; Mice; Neurokinin A; Neuropeptides; Pain; Peripheral Nerves; Spinal Cord; Substance P; Thermosensing