sincalide and Morphine-Dependence

Cholecystokinin octapeptide (CCK-8), a brain-gut peptide, plays an important role in several opioid addictive behaviors. We previously reported that CCK-8 attenuated the expression and reinstatement of morphine-induced conditioned place preference. The possible effects of CCK-8 on the negative affective components of drug abstinence are not clear. There are no studies evaluating the effect of CCK-8 on emotional symptoms, such as anxiety, in morphine-withdrawal animals. We investigated the effects of CCK-8 on the anxiety-like behavior in morphine-withdrawal rats using an elevated plus-maze. Morphine withdrawal elicited time-dependent anxiety-like behaviors with peak effects on day 10 (5 days after induction of morphine dependence). Treatment with CCK-8 (0.1 and 1 μg, i.c.v.) blocked this anxiety in a dose-dependent fashion. A CCK1 receptor antagonist (L-364,718, 10 μg, i.c.v.) blocked the effect of CCK-8. Mu-opioid receptor antagonism with CTAP (10 μg, i.c.v.) decreased the 'anxiolytic' effect. CCK-8 inhibited anxiety-like behaviors in morphine-withdrawal rats by up-regulating endogenous opioids via the CCK1 receptor in rats. This study clearly identifies a distinct function of CCK-8 and a potential medication target of central CCK1 receptors for drugs aimed at ameliorating drug addiction.

Topics: Animals; Anti-Anxiety Agents; Anxiety; Benzodiazepinones; Central Nervous System Agents; Devazepide; Dose-Response Relationship, Drug; Male; Morphine; Morphine Dependence; Narcotics; Opioid Peptides; Phenylurea Compounds; Random Allocation; Rats, Wistar; Receptors, Cholecystokinin; Receptors, Opioid, mu; Sincalide; Substance Withdrawal Syndrome

Cholecystokinin octapeptide (CCK-8), a gut-brain peptide, regulates a variety of physiological behavioral processes. Previously, we reported that exogenous CCK-8 attenuated morphine-induced conditioned place preference, but the possible effects of CCK-8 on aversively motivated drug seeking remained unclear. To investigate the effects of endogenous and exogenous CCK on negative components of morphine withdrawal, we evaluated the effects of CCK receptor antagonists and CCK-8 on the naloxone-precipitated withdrawal-induced conditioned place aversion (CPA). The results showed that CCK2 receptor antagonist (LY-288,513, 10 µg, i.c.v.), but not CCK1 receptor antagonist (L-364,718, 10 µg, i.c.v.), inhibited the acquisition of CPA when given prior to naloxone (0.3 mg/kg) administration in morphine-dependent rats. Similarly, CCK-8 (0.1-1 µg, i.c.v.) significantly attenuated naloxone-precipitated withdrawal-induced CPA, and this inhibitory function was blocked by co-injection with L-364,718. Microinjection of L-364,718, LY-288,513 or CCK-8 to saline pretreated rats produced neither a conditioned preference nor aversion, and the induction of CPA by CCK-8 itself after morphine pretreatments was not significant. Our study identifies a different role of CCK1 and CCK2 receptors in negative affective components of morphine abstinence and an inhibitory effect of exogenous CCK-8 on naloxone-precipitated withdrawal-induced CPA via CCK1 receptor.

Topics: Animals; Conditioning, Psychological; Devazepide; Male; Morphine Dependence; Naloxone; Pyrazoles; Rats; Rats, Wistar; Receptors, Cholecystokinin; Sincalide; Spatial Behavior; Substance Withdrawal Syndrome

The possible effect of a cholecystokinin-8 agonist (caerulein) and antagonists (MK-329 and L365,260) on the development of morphine dependence and withdrawal were investigated in rats. Caerulein treatment (0.01 and 0.1 mg/kg) increased the incidence of naloxone-induced withdrawal syndromes and delayed the extinction of morphine-conditioned place preference in morphine-dependent animals. The signs of the morphine withdrawal syndromes and the formation of morphine-conditioned place preference were suppressed by pretreatment with L365,260 (0.1 and 1 mg/kg) and not affected by pretreatment with MK-329 (0.1 and 1 mg/kg). The present study demonstrated CCK, acting on CCK-B receptors, participates in the development of the opiate dependence. These findings suggest that CCK-B receptor antagonists might be of some value in the treatment and prevention the relapse of opiate addicts.

Topics: Animals; Benzodiazepinones; Ceruletide; Conditioning, Psychological; Devazepide; Hormone Antagonists; Male; Morphine Dependence; Phenylurea Compounds; Rats; Rats, Sprague-Dawley; Receptor, Cholecystokinin A; Receptor, Cholecystokinin B; Receptors, Cholecystokinin; Sincalide; Substance Withdrawal Syndrome

Morphine inhibits oxytocin neurones via G(i/o)-protein-linked mu-opioid receptors. Following chronic morphine administration oxytocin cells develop dependence, shown by withdrawal excitation after administration of the opioid antagonist, naloxone. Here, inactivation of G(i/o)-proteins by pre-treatment of morphine-dependent rats with pertussis toxin injected into the left supraoptic nucleus reduced withdrawal-induced Fos protein expression within the injected nucleus by 41+/-10% compared to the contralateral nucleus, indicating that functional G(i/o)-proteins are essential for the development and/or expression of morphine dependence by oxytocin cells in the supraoptic nucleus. In another group of rats, pertussis toxin did not alter the responses to either systemic cholecystokinin administration or systemic hypertonic saline administration, indicating that pertussis toxin does not prevent oxytocin cells from responding to stimuli that are not mediated by G(i/o)-proteins. Finally, pertussis toxin reduced acute morphine inhibition of systemic hypertonic saline-induced Fos protein expression in the supraoptic nucleus, confirming that pertussis toxin effectively inactivates G(i/o)-proteins in the supraoptic nucleus. Thus, the expression of morphine withdrawal excitation by supraoptic nucleus oxytocin cells requires the functional integrity of G(i/o)-proteins within the nucleus.

Topics: Animals; Female; Functional Laterality; GTP-Binding Protein alpha Subunits, Gi-Go; Heterotrimeric GTP-Binding Proteins; Microinjections; Morphine; Morphine Dependence; Naloxone; Neurons; Pertussis Toxin; Proto-Oncogene Proteins c-fos; Rats; Rats, Sprague-Dawley; Sincalide; Substance Withdrawal Syndrome; Supraoptic Nucleus; Virulence Factors, Bordetella

We investigated whether the full expression of morphine withdrawal excitation by supraoptic nucleus (SON) oxytocin neurones is a property of the neurones themselves or a partial function of their afferent inputs, by interrupting synaptic input activity via central administration of the L-type Ca(2+) channel blocker verapamil. In morphine-dependent rats, withdrawal-induced release of oxytocin from the posterior pituitary was suppressed by prior administration of intracerebroventricular (i.c.v.) verapamil (160 microg), as was release of oxytocin within the SON measured by microdialysis. During morphine withdrawal the increased electrical activity of SON neurones was also reduced both by i.c.v. verapamil and microdialysis application of verapamil or nifedipine into the SON. Oxytocin secretion evoked by electrical stimulation of the pituitary stalk was unaffected by i.c.v. verapamil suggesting a central site of action. To determine whether the inhibitory actions of verapamil were specific to morphine withdrawal, we also investigated the effects of verapamil on other oxytocin-secreting stimuli. I.C.V. verapamil given to morphine-naïve rats abolished pituitary oxytocin release in response to activation of brainstem or rostral excitatory inputs by cholecystokinin (20 microg kg(-1), i.v.) and 1.5 M saline (4 ml kg(-1), i.p.) respectively, whilst in lactating rats, i.c.v. verapamil reduced suckling-induced release of oxytocin within the SON. These results suggest that verapamil has a central site of action on stimulated oxytocin release (including an action within the SON) and that both pre and post-synaptic L-type Ca(2+) channels are required for the full expression of morphine withdrawal in SON oxytocin neurones.

Topics: Animals; Animals, Suckling; Calcium Channel Blockers; Calcium Channels, L-Type; Electric Stimulation; Female; Hypertonic Solutions; Injections, Intraventricular; Lactation; Membrane Potentials; Microdialysis; Morphine; Morphine Dependence; Naloxone; Narcotic Antagonists; Narcotics; Neurons; Oxytocin; Pituitary Gland; Rats; Rats, Sprague-Dawley; Sincalide; Substance Withdrawal Syndrome; Succinimides; Supraoptic Nucleus; Verapamil

In the present study, effect of cholecystokinin (CCK) agonists and on dependence to morphine in mice has been investigated. The influence of dopaminergic, adrenergic, cholinergic and serotonergic on attenuation of naloxone-induced jumping in morphine-dependent mice by CCK agonists were also considered. Mice were treated subcutaneously with morphine (50, 50 and 75 mg/kg) three times daily (10 a.m. 1 p.m. and 4 p.m.) for 3 days, and a last dose of morphine (50 mg/kg) was administered on the 4th day. Withdrawal syndrome (jumping) was precipitated by naloxone (5 mg/kg) which was administered intraperitoneally 2 hr after the last dose of morphine. To study effects of CCK receptor agonists, 10 injection of morphine (3 administrations each day) for dependence and a dose of 5 mg/kg of naloxone for withdrawal induction were employed. The CCK agonists CCK-8 (0.001-0.1 mg/kg), unsulfated CCK-8 (CCK-8U; 0.001-0.1 mg/kg) and caerulein (0.00001-0.01 mg/kg) were able to prevent withdrawal signs precipitated by naloxone (5 mg/kg). Sulpiride and pimozide increased response induced by CCK-8 agonists. The dopamine antagonists also attenuates jumping by themselves. SCH 23390 did not alter the CCK-8 effect, but decreased the jumping by itself. Phenoxybenzamine, propranolol, methysergide and atropine did not change the caerulein effect significantly. However, single administration of atropine increased and methysergide decreased jumping. It is concluded that CCK mechanism(s) may be involved in morphine dependence, and dopaminergic mechanism(s) may interact with CCK in attenuation of naloxone-induced jumping.

Topics: Adrenergic Antagonists; Animals; Atropine; Benzazepines; Ceruletide; Dopamine Antagonists; Male; Methysergide; Mice; Morphine; Morphine Dependence; Movement Disorders; Muscarinic Antagonists; Naloxone; Narcotic Antagonists; Phenoxybenzamine; Pimozide; Propranolol; Receptors, Cholecystokinin; Serotonin Antagonists; Sincalide; Substance Withdrawal Syndrome; Sulpiride

The present study was done both in vivo by cannulating pancreatic duct of morphine-dependent rats and in vitro using perfused pancreatic slices from morphine-dependent rats. The results were as follows: (1) In morphine-dependent rat the pancreatic amylase secretion induced by CCK-8 was significantly declined; (2) Amylase content of pancreatic tissue in morphine-dependent rats was lower than that of normal rats. It is suggested that the synthesis of amylase in morphine-dependent rat pancreas may be inhibited.

Topics: Amylases; Animals; Morphine Dependence; Pancreas; Rats; Sincalide