Functional reactivity of different central opioid receptor systems following clomipramine treatments.
Intracerebroventricular administration of the enkephalinase inhibitor, phosphoramidon (PHA, 3.7 X 10(-7) moles, i.c.v.) induced distinct wet-dog-shakes (WDS) behaviour. Naltrexone (NX) given in a low dose (0.25 mg/kg, i.p.) did not antagonize the WDS induced by PHA. A higher dose of NX (2.5 mg/kg i.p.) decreased WDS behaviour. Morphine (25 mg/kg, i.p.) induced marked catalepsy. Ketocyclazocine (0.01-1.0 mg/kg, i.p.) induced a dose related decrease in spontaneous locomotor activity. Chronic (20 mg/kg, i.p. daily for 10 days and withdrawn, 24 h prior, C.CLO) and acute (20 mg/kg, i.p., 60 min prior, A.CLO) clomipramine treatments decreased PHA-induced WDS compared to saline pretreatments. However, C.CLO treatments antagonized the morphine-induced catalepsy and ketocyclazocine-induced sedation whereas A.CLO did not alter the opiate-induced cataleptic/sedative behaviours. It is suggested that chronic clomipramine treatment induced a functional deficiency of central mu and kappa opioid receptor systems without altering the delta opioid mechanisms.
Ukponmwan
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Department of Physiological Sciences, Obafemi Awolowo University, Ile-Ife Oyo State, Nigeria.
Murugaiah
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D000818:Animals; D002375:Catalepsy / Q000139:chemically induced; D002490:Central Nervous System / Q000187:drug effects / Q000378:metabolism*; D002997:Clomipramine / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D016314:Ethylketocyclazocine / Q000494:pharmacology; D006020:Glycopeptides / Q000494:pharmacology; D006993:Hypnotics and Sedatives; D007276:Injections, Intraventricular; D008297:Male; D009020:Morphine / Q000494:pharmacology; D009043:Motor Activity / Q000187:drug effects; D009271:Naltrexone / Q000494:pharmacology; D015260:Neprilysin / Q000037:antagonists & inhibitors; D051381:Rats; D011919:Rats, Inbred Strains; D011957:Receptors, Opioid / Q000187:drug effects*; D017473:Receptors, Opioid, kappa; D017450:Receptors, Opioid, mu; D013239:Stereotyped Behavior / Q000187:drug effects
D006020:Glycopeptides; D006993:Hypnotics and Sedatives; D011957:Receptors, Opioid; D017473:Receptors, Opioid, kappa; D017450:Receptors, Opioid, mu; D016314:Ethylketocyclazocine; D009271:Naltrexone; D009020:Morphine; D015260:Neprilysin; D002997:Clomipramine; C008890:phosphoramidon