Central Dopaminergic Mechanisms of Alcohol and Opiate Withdrawal Syndromes
Rats made dependent on ethanol show, upon suspension of treatment, a reduction of dopamine outflow in the nucleus accumbens, as measured by microdialysis, to which corresponds a lowered electrophysiological activity of mesolimbic dopaminergic neurons. Administration of ethanol increases biochemical and electrophysiological indices of dopaminergic function. Similarly, morphine dependent rats display a reduction of dopamine efflux and an abrupt abatement of dopaminergic neuronal activity in the mesolimbic system. As in the case of ethanol, administration of the suspended morphine increases neuronal function and its biochemical correlate in the terminal area. The results, irrespective of the substance abused, are interpreted as indicating a common substrate which becomes hypofunctional upon suspension of chronic administration of an addicting substance. These findings may be viewed as the neurophysiological correlate of the dysphoria associated to drug withdrawal in humans.
KeywordsFiring Rate Nucleus Accumbens Ventral Tegmental Area Withdrawal Syndrome Ethanol Treatment
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