Presynaptic inhibition of GABA(B)-mediated synaptic potentials in the ventral tegmental area during morphine withdrawal.

ABSTRACT: Opioids increase the firing of dopamine cells in the ventral tegmental area by presynaptic inhibition of GABA release. This report describes an acute presynaptic inhibition of GABAB-mediated IPSPs by mu- and kappa-opioid receptors and the effects of withdrawal from chronic morphine treatment on the release of GABA at this synapse. In slices taken from morphine-treated guinea pigs after washing out the morphine (withdrawn slices), a low concentration of a mu receptor agonist increased, rather than decreased, the amplitude of the GABAB IPSP. In withdrawn slices, after blocking A1-adenosine receptors with 8-cyclopentyl-1, 3-dipropylxantine, mu-opioid receptor activation inhibited the IPSP at all concentrations and increased the maximal inhibition. In addition, during withdrawal, there was a t

SUBMITTER: Shoji Y 

PROVIDER: S-EPMC6782572 | biostudies-literature | 1999 Mar

REPOSITORIES: biostudies-literature