Enhancement by haloperidol of the locomotor response induced by naloxone in morphine-treated guinea pigs.
Guinea pigs given naloxone hydrochloride, 15 mg/kg subcutaneously (s.c.) 2 h after a single dose of morphine sulphate, 15 mg/kg s.c. exhibit a withdrawal response which is characterized by a marked increase in locomotor activity. In this study the effects of haloperidol on the morphine locomotor withdrawal response of guinea-pigs were investigated. Locomotor activity was measured in a cage fitted with a single infra-red photocell and detector. Haloperidol, at a dose of 1 mg/kg, s.c., given 0.5 h prior to administration of naloxone slightly enhanced the morphine locomotor withdrawal response, and at a dose of 10 mg/kg, markedly enhanced the response. Chronic pretreatment of guinea pigs with haloperidol, 1 mg/kg, daily for 21 days did not alter the locomotor withdrawal response. It remains to be established whether the enhancement by haloperidol of the opiate withdrawal response is a functional reflection of its interaction with dopamine, sigma or other receptors.
Chahl
L A
LA
Neuropharmacology Laboratory, Faculty of Medicine, University of Newcastle, N.S.W., Australia.
Kavanagh
C A
CA
Corlis
A
A
D000818:Animals; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D005260:Female; D006168:Guinea Pigs; D006220:Haloperidol / Q000494:pharmacology*; D008297:Male; D009020:Morphine / Q000009:adverse effects / Q000494:pharmacology*; D009043:Motor Activity / Q000187:drug effects*; D009270:Naloxone / Q000494:pharmacology*; D013375:Substance Withdrawal Syndrome / Q000503:physiopathology*; D013997:Time Factors
D009270:Naloxone; D009020:Morphine; D006220:Haloperidol