u-50488 and Morphine-Dependence

A series of 17-cyclopropylmethyl-3,14β-dihydroxy-4,5α-epoxy-6α-(isoquinoline-3'-carboxamido)morphinan (NAQ) analogues were synthesized and pharmacologically characterized to study their structure-activity relationship at the mu opioid receptor (MOR). The competition binding assay showed two-atom spacer and aromatic side chain were optimal for MOR selectivity. Meanwhile, substitutions at the 1'- and/or 4'-position of the isoquinoline ring retained or improved MOR selectivity over the kappa opioid receptor while still possessing above 20-fold MOR selectivity over the delta opioid receptor. In contrast, substitutions at the 6'- and/or 7'-position of the isoquinoline ring reduced MOR selectivity as well as MOR efficacy. Among this series of ligands, compound 11 acted as an antagonist when challenged with morphine in warm-water tail immersion assay and produced less significant withdrawal symptoms compared to naltrexone in morphine-pelleted mice. Compound 11 also antagonized the intracellular Ca(2+) increase induced by DAMGO. Molecular dynamics simulation studies of 11 in three opioid receptors indicated orientation of the 6'-nitro group varied significantly in the different 'address' domains of the receptors and played a crucial role in the observed binding affinities and selectivity. Collectively, the current findings provide valuable insights for future development of NAQ-based MOR selective ligands.

Topics: Animals; CHO Cells; Cricetulus; Drug Design; Humans; Isoquinolines; Ligands; Mice; Molecular Dynamics Simulation; Morphinans; Morphine Dependence; Narcotic Antagonists; Receptors, Opioid, mu; Structure-Activity Relationship

Based on an established 3D pharmacophore, a series of quinoline derivatives were synthesized. The opioidergic properties of these compounds were determined by a competitive binding assay using (125)I-Dynorphine, (3)H-DAMGO and (125)I-DADLE for kappa, mu, and delta receptors, respectively. Results showed varying degree of activities of the compounds to kappa and mu opioid receptors with negligible interactions at the delta receptor. The compound, S4 was the most successful in inhibiting the two most prominent quantitative features of naloxone precipitated withdrawal symptoms - stereotyped jumping and body weight loss. Determination of IC(50) of S4 revealed a greater affinity towards mu compared to kappa receptor. In conclusion, quinoline derivatives of S4 like structure offer potential tool for treatment of narcotic addictions.

Topics: Acetanilides; Aminoquinolines; Animals; Cell Line, Tumor; Competitive Bidding; Humans; Ligands; Mice; Mice, Inbred BALB C; Morphine Dependence; Narcotic Antagonists; Quinolines; Rats; Receptors, Opioid, kappa; Receptors, Opioid, mu

The effects of a novel kappa-opioid receptor agonist, TRK-820, on the development of physical dependence on morphine were investigated in mice in comparison with those of U-50,488H. A marked body weight loss and several withdrawal signs were observed following naloxone challenge in morphine-dependent mice. Co-injection of TRK-820 (0.003-0.03 mg/kg, s.c.) but not U-50,488H (1-10 mg/kg, s.c.) during chronic morphine treatment dose-dependently suppressed the naloxone-precipitated body weight loss, jumping, wet dog shakes and diarrhea. These results suggest that TRK-820-sensitive kappa-opioid receptor subtypes may play a significant role in modulating the development of physical dependence on morphine.

Topics: 3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer; Analgesics, Non-Narcotic; Analgesics, Opioid; Animals; Male; Mice; Morphinans; Morphine Dependence; Receptors, Opioid, kappa; Spiro Compounds

U-50,488, a selective kappa-opioid receptor agonist, has been reported to inhibit the development of antinociceptive tolerance to morphine in mice, rats and guinea pigs, but the mechanism involved in this action remains unknown. Since U-50,488 has been reported to suppress the plasma vasopressin level, we investigated the role of vasopressin with U-50,488 in the male Sprague Dawley rat in this study. Animals (230-270 g) were chronically treated with morphine (10 mg/kg, i.p.) twice a day for 6 days in order to induce tolerance to antinociceptive effect measured by tail-flick test. Withdrawal symptoms were precipitated by naloxone (10 mg/kg, i.p.) on day 7. U-50,488 (i.p.) or AVP (i.p. or i.c.v.) or U-50,488 and AVP was (were) coadministered with chronic morphine to investigate their effects on morphine tolerance and dependence. We found that coadministration of 8 mg/kg U-50,488 (i.p.) with morphine almost completely block morphine tolerance and partially block withdrawal symptoms. In contrast, coadministration of AVP (0.3 microgram/kg, i.p., or 0.01 microgram, i.c.v.) with morphine and U-50,488, the effects of U-50,488 to block morphine tolerance and dependence were reversed. In addition, treatment of AVP antagonist (dPTyr(Me)AVP, 0.5 microgram/kg, i.p. or 0.5 microgram, i.c.v.) has the similar effect as U-50,488 to block morphine tolerance. In summary, the effect of U-50,488 to block morphine tolerance and dependence may relate to its inhibitory effect on AVP release.

Topics: 3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer; Analgesics; Animals; Arginine Vasopressin; Drug Tolerance; Injections, Intraperitoneal; Injections, Intraventricular; Male; Morphine; Morphine Dependence; Pain Measurement; Pyrrolidines; Rats; Rats, Sprague-Dawley

1. Single neurones of the rat supraoptic nucleus were recorded during microdialysis of naloxone onto the ventral surface of the nucleus in anaesthetized rats. We used this combination of techniques to test whether the acute or chronic effects of systemically or centrally applied opioids upon oxytocin cell activity were due to actions of the opioids within the nucleus itself. 2. Supraoptic nucleus oxytocin neurones were identified antidromically and by an excitatory response to intravenously injected cholecystokinin. Acute intravenous injection of the kappa-agonist U50488H or the mu-agonist morphine (1-5 mg kg-1) reduced the firing rate of identified oxytocin neurones by 97.7 +/- 4.8% (n = 6) and 94.1 +/- 4.1% (n = 7), respectively. The inhibition by each of these opioids was completely reversed after administration by microdialysis (retrodialysis) of the opioid antagonist naloxone (0.1-1.0 microgram microliter-1 at 2 microliters min-1) onto the exposed ventral surface of the supraoptic nucleus. 3. Retrodialysis of naloxone (0.1-10.0 micrograms microliter-1) onto the supraoptic nucleus of rats made dependent by intracerebroventricular morphine infusion for 5 days increased the firing rate of oxytocin neurones from 0.9 +/- 0.4 to 3.1 +/- 0.7 spikes s-1 (P < 0.05, n = 6). This increase in firing rate from basal was 58.5 +/- 15.1% of that following subsequent intravenously injected naloxone (5 mg kg-1). 4. Thus, the acute inhibition of supraoptic nucleus oxytocin neurones which results from systemic administration of opioid agonists primarily occurs within the supraoptic nucleus itself, since the antagonist naloxone was effective when given into the supraoptic nucleus. Furthermore, oxytocin neurones develop morphine dependence by a mechanism which is distinct from an action on their distant afferent inputs. Nevertheless, withdrawal excitation of these afferent inputs may enhance the magnitude of oxytocin neurone withdrawal excitation.

Topics: 3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer; Animals; Electrophysiology; Female; Microdialysis; Morphine; Morphine Dependence; Naloxone; Narcotic Antagonists; Neurons; Oxytocin; Rats; Rats, Sprague-Dawley; Receptors, Opioid, kappa; Receptors, Opioid, mu; Supraoptic Nucleus

U-50,488, (trans-3,4-dichloro-N-methyl-N-[2-(1-pyrrolidinyl)-cyclohexyl]- benzeneacetamide hydrochloride), is a selective kappa-opioid receptor agonist. In this study, we found that U-50,488 antagonized morphine-induced antinociception in morphine-naive guinea pigs at doses which did not have any antinociceptive effect by themselves (0.01-3 mg/kg). On the other hand, U-50,488 (3 mg/kg) partially restored morphine-induced antinociception in morphine-tolerant guinea pigs (8 mg/kg/day i.p. morphine HCl for 6 days). Furthermore, the development of tolerance to morphine antinociception was completely blocked by coadministration of U-50,488 at a very low dose (0.003 mg/kg i.p.) which neither exerted an antinociceptive effect by itself nor affected the antinociception induced by 8 mg/kg of morphine HCl. The withdrawal signs induced by 8 mg/kg (i.p.) naloxone HCl on the 7th day were also depressed by coadministration of 0.003 mg/kg U-50,488 with morphine HCl (8 mg/kg i.p.) every day for 7 days. These effects of U-50,488 could be applied to humans to prevent morphine tolerance and dependence.

Topics: 3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer; Analgesics; Animals; Dose-Response Relationship, Drug; Drug Synergism; Drug Tolerance; Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; Enkephalins; Guinea Pigs; Male; Morphine; Morphine Dependence; Nociceptors; Pain; Pyrrolidines; Receptors, Opioid, kappa

The present study was undertaken to determine whether acute physical dependence occurred in guinea-pigs in vivo and guinea-pig isolated ileum following a single dose of the kappa-opioid receptor agonist U50,488H. Administration of naloxone hydrochloride, 15 and 30 mg/kg s.c., to guinea-pigs treated 1 h before with U50,488H, 10 mg/kg s.c., induced increased locomotor activity accompanied by behavioural responses which differed from those previously found in this species with morphine withdrawal. Nor-binaltorphimine, 10 mg/kg s.c., given 1 h after administration of U50,488H, 10 mg/kg s.c., produced a small but significant increase in locomotor activity but no other withdrawal behaviours. The morphine withdrawal response was not significantly affected by U50,488H, 1 or 10 mg/kg s.c. On the guinea-pig isolated ileum, nor-binaltorphimine, 1 microM, produced a withdrawal contracture following 2 min contact of the ileum with U50,488H 1 microM. U50,488H, 1 microM, abolished the [Met5]enkephalin withdrawal response of the ileum. It is concluded that dependence occurs following activation of kappa-opioid receptors, which is largely non-morphine-like in the central nervous system, but which is morphine-like in the enteric nervous system.

Topics: 3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer; Analgesics, Opioid; Animals; Behavior, Animal; Female; Guinea Pigs; Ileum; In Vitro Techniques; Male; Morphine Dependence; Motor Activity; Muscle Contraction; Muscle, Smooth; Naloxone; Naltrexone; Pyrrolidines; Receptors, Opioid, kappa; Substance Withdrawal Syndrome; Substance-Related Disorders

1. The present study investigated the mechanisms by which endogenous opioids regulate oxytocin secretion at the level of the posterior pituitary gland. Effects of the selective kappa-agonist U50,488 on oxytocin secretion were studied in urethane-anaesthetized lactating rats. Oxytocin secretion in response to electrical stimulation (0.5 mA, matched biphasic 1 ms pulses, 50 Hz, 60-180 pulses) of the neurohypophysial stalk was bioassayed on-line by measuring increases in intramammary pressure, calibrated with exogenous oxytocin. Intravenous (I.V.) U50,488 inhibited electrically stimulated oxytocin secretion, without affecting mammary gland sensitivity to oxytocin. The inhibition was dose related, with an ID50 of 441 (+194, -136) micrograms/kg and was naloxone reversible. Antagonism of endogenous beta-adrenoceptor activation by propranolol (1 mg/kg) reduced the potency of U50,488. The selective mu-agonist morphine (up to 5 mg/kg), had no effect on electrically stimulated oxytocin secretion, but depressed the mammary response to oxytocin. 2. In lactating rats given intracerebroventricular (I.C.V.) morphine infusion for 5 days to induce tolerance and dependence, I.V. U50,488 still inhibited electrically stimulated oxytocin secretion, but the ID50 was reduced to 170 (+78, -54) micrograms/kg; thus at the posterior pituitary the sensitivity of kappa-receptors is enhanced rather than reduced in morphine-tolerant rats, indicating the absence of cross-tolerance. In these rats, naloxone produced a large, sustained, fluctuating increase in intramammary pressure indicating morphine-withdrawal excitation of oxytocin secretion; I.V. U50,488 diminished this response, confirmed by radioimmunoassay, demonstrating the independence of mu- and kappa-receptors regulating oxytocin secretion. 3. In pregnant rats, I.C.V. infusion of morphine from day 17-18 of pregnancy delayed the start of parturition by 4 h, but did not significantly affect the progress of parturition once established, indicating tolerance to the inhibitory actions of morphine on oxytocin secretion in parturition, and lack of cross-tolerance to endogenous opioids restraining oxytocin in parturition. 4. Neurointermediate lobes from control and I.C.V. morphine-infused virgin rats were impaled on electrodes and perifused in vitro. Vasopressin and oxytocin release from the glands was measured by radioimmunoassay. Each gland was exposed to two periods of electrical stimulation (13 Hz, for 3 min). Naloxone (5 x 10(-6) M

Topics: 3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer; Analgesics; Animals; Biological Assay; Drug Tolerance; Electric Stimulation; Female; Injections, Intraventricular; Labor, Obstetric; Lactation; Morphine; Morphine Dependence; Naloxone; Oxytocin; Pituitary Gland, Posterior; Pregnancy; Propranolol; Pyrrolidines; Radioimmunoassay; Rats; Rats, Sprague-Dawley; Receptors, Opioid, kappa; Vasopressins

The effects of a highly selective kappa antagonist, nor-binaltorphimine (nor-BNI), on the development of tolerance to morphine analgesia and physical dependence on morphine were examined. Pretreatment with nor-BNI (5 mg/kg s.c.) 2 h prior to injection of morphine or a selective kappa agonist, U-50,488H, significantly antagonized the analgesic effect of U-50,488H, but not morphine analgesia in mice. The development of tolerance to morphine analgesia was significantly potentiated by pretreatment of mice with nor-BNI 2 h prior to morphine treatment during chronic morphine treatment for 5 days. Additionally, the pretreatment with nor-BNI during chronic treatment with the high dose of morphine for 5 days significantly potentiated the naloxone-induced body weight loss in morphine-dependent mice and rats. These findings suggest that inactivation of the kappa opioid system may potentiate the development of tolerance to morphine analgesia in mice and may aggravate the naloxone-precipitated body weight loss in morphine-dependent mice and rats.

Topics: 3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer; Analgesia; Analgesics; Analysis of Variance; Animals; Behavior, Animal; Body Weight; Drug Tolerance; Male; Mice; Morphine; Morphine Dependence; Naltrexone; Pyrrolidines; Rats

We have previously reported that chicken embryos injected with a single dose of methadone (Meth) on day 3, 7 or 11 of embryogenesis fail to show dependence on day 14, measured as a significant overshoot in motility above baseline after challenge with the opioid antagonist naloxone (Nx). Constant infusion of Meth from day 7 to 14 also failed to produce evidence of dependence on day 14. To address the question of whether the 14-day-old embryo is capable of expressing withdrawal, isobutylmethylxanthine (IBMX), a compound that produces quasi-opioid withdrawal, was injected directly into the embryo, resulting in a significant increase in motility. To determine whether the 14-day-old embryo could also express true opioid withdrawal, the embryos were injected with various doses of Meth or morphine (Morph), followed at different time intervals by injections of varying doses of Nx. A high dose of Morph followed 24 hours later by a low dose of Nx produced evidence of withdrawal, as did a low dose of Meth followed 1 hour later by a higher dose of Nx, U50488H, a selective kappa agonist, had no effect on motility in the 14-day-old embryo, suggesting that the decrease in motility seen after Meth was not mediated by a kappa receptor. Pretreatment with the irreversible mu antagonist, beta-funaltrexamine (B-FNA), blocked the decrease in motility seen after Meth and also prevented the overshoot in motility when Nx was given 1 hour post-Meth. We were also able to demonstrate dependence/withdrawal in the 12-day-old embryo, but higher doses of both Meth and Nx were required.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: 1-Methyl-3-isobutylxanthine; 3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer; Animals; Chick Embryo; Methadone; Morphine Dependence; Motor Activity; Naltrexone; Narcotic Antagonists; Opioid-Related Disorders; Pyrrolidines; Receptors, Opioid; Substance Withdrawal Syndrome

Rats were made dependent on morphine by mixing the drug with their only source of food. Naltrexone (0.5 mg/kg) injection precipitated a syndrome of withdrawal signs including weight loss. Pretreatment with the selective kappa agonist, U-50,488H (1.0, 30.0 or 10.0 mg/kg), generally had no effects on the signs of morphine withdrawal. In other subjects, U-50,488H was repeatedly administered (1.0, 3.0 or 10.0 mg/kg per 12 h) during the development of morphine dependence. In these subjects, the course of naltrexone-precipitated withdrawal was unchanged. These results suggest that agonist activity at kappa receptors is not sufficient to alter morphine dependence or withdrawal.

Topics: 3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer; Analgesics; Animals; Behavior, Animal; Male; Morphine Dependence; Naltrexone; Pyrrolidines; Rats; Rats, Inbred Strains; Receptors, Opioid; Receptors, Opioid, kappa; Substance Withdrawal Syndrome

Chronic activation of opioid receptors results in the development of tolerance and dependence. Tolerance may be confined to a single receptor type and thus has been termed "selective tolerance". The present investigation reveals that prolonged activation of an inhibitory acting receptor type not only results in dependence associated with this receptor but also brings about cross-dependence. Cross-dependence involves both opioid receptors as well as nonopioid receptors, e.g. adrenoceptors. The experimental design employed did not permit conclusions to be drawn about whether those receptors exhibiting cross-dependence also developed tolerance. Regardless of the receptors and their specific subsequent transduction systems, all the receptors which showed dependence and cross-dependence proved sensitive to pertussis toxin, suggesting a critical function of GTP-binding proteins for the development of not only opioid dependence but also for drug dependence in general. Since multiple transmitter receptors may converge on the same ion channel, the concept of "convergent dependences" may be linked to GTP-binding proteins. However, no conclusions can be drawn with regard to the precise biochemical mechanisms underlying dependence.

Topics: 3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer; Analgesics; Animals; Clonidine; Drug Tolerance; Fentanyl; Guinea Pigs; Male; Morphine Dependence; Muscle Contraction; Myenteric Plexus; Pertussis Toxin; Pyrrolidines; Virulence Factors, Bordetella

The potassium stimulated release of [3H]norepinephrine ([3H]NE) from terminal fields of locus coeruleus projections can be inhibited in a dose-dependent manner by mu and kappa selective opioids. Chronic exposure to morphine for six days decreases the maximum achievable depression by the mu selective agonist Tyr-D-Ala2-Gly-Me(Phe)-Gly-ol (DAGO), but has no effect on the degree of inhibition produced by the kappa selective opioid U50,488H.

Topics: 3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer; Analgesics; Animals; Cerebral Cortex; Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; Enkephalins; Guinea Pigs; In Vitro Techniques; Male; Morphine; Morphine Dependence; Norepinephrine; Pyrrolidines; Receptors, Opioid