Effects of GABAergic system on naloxone-induced jumping in morphine-dependent mice

The effect of GABA (gamma-aminobutyric acid system) receptor agonists and a ntagonists on naloxone-induced jumping in morphine-dependent mice was exami ned. Intraperitoneal (i.p.) or intracerebroventricular (i.c.v.) injection o f different doses of the GABA(B) receptor agonist, baclofen (2.5, 5 and 10 mg/kg), reduced naloxone-induced jumping in morphine-dependent mice. The i. p. administration of the GABA(B) receptor antagonist, CGP35348 (P-[3-aminop ropyl]-p-diethoxymethyl-phosphinic acid), but not the i.c.v. injection of t he drug, increased naloxone-induced jumping. The antagonist also decreased the baclofen response. Administration of the GABA(A) receptor agonist, musc imol, but not the GABA(A) receptor antagonists bicuculline and picrotoxin, decreased the naloxone response in morphine-dependent animals. It is conclu ded that both GABA(A) and GABA(B) receptor subtypes may have an inhibitory influence on naloxone-induced withdrawal jumping in mice. (C) 1999 Elsevier Science B.V. All rights reserved.