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Actions of cocaine on rat nucleus accumbens neurones in vitro
Author(s) -
Uchimura N.,
North R.A.
Publication year - 1990
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1990.tb12999.x
Subject(s) - dopamine , nucleus accumbens , sulpiride , agonist , chemistry , dopamine uptake inhibitors , pharmacology , dopamine receptor , endocrinology , medicine , membrane potential , neurotransmitter , receptor , dopaminergic , biology , biochemistry
1 Intracellular recordings were made from 103 neurones of the rat nucleus accumbens in vitro . 2 Dopamine (3–100 μ m ; in sulpiride, 1 μ m ) hyperpolarized neurones (79%) by acting at D 1 receptors: dopamine (3–100 μ m ; in SCH23390, 1 μ m ) depolarized neurones (55%) by acting at D 2 receptors. 5‐Hydroxytryptamine (1–100 μ m ) depolarized 86% neurones. 3 Both actions of dopamine as well as the effect of 5‐hydroxytryptamine were potentiated by cocaine (0.3–30 μ m ), which had no effect of its own on membrane potential. 4 Dose‐ratio was computed as [(concentration of agonist causing a 4 mV potential change in cocaine)/(concentration of agonist causing a 4 mV potential change without cocaine)]. Cocaine (1–30 μ m ) caused the same dose‐ratio whether dopamine depolarizations (D 2 ) or hyperpolarizations (D 1 ) were measured; the dose‐ratio ranged from 2 (1 μ m ) to 50 (30 μ m ). 5 Responses to 5‐hydroxytryptamine were increased more than responses to dopamine; cocaine 1 μ m gave a dose‐ratio of 13.4 and at 30 μ m gave a dose‐ratio of 118. 6 It is concluded that cocaine acts to inhibit the uptake of dopamine and 5‐hydroxytryptamine in slices of rat nucleus accumbens; lower concentrations of cocaine (0.3 to 1 μ m ) are particularly effective in potentiating the action of 5‐hydroxytryptamine.