Comparative Effects of Acute and Chronic Administration of Amphetamine on Local Cerebral Glucose Utilization in the Conscious Rat

Abstract

The 2-deoxyglucose method was employed in rats following either acute or chronic administration of d-amphetamine. The drug was given either by a single intravenous and/or repeated daily intraperitoneal injections or by osmotic pumps implanted subcutaneously. Each mode of administration resulted in a specific constellation of metabolic effects. Acute doses of d-amphetamine, 5 mg/kg, stimulated glucose utilization in a number of cerebral structures, particularly the components of the extrapyramidal motor system. No effects were observed in components of the mesolimbic dopaminergic system. Repeated daily doses of 5 mg/kg for 2 weeks had no effects unless the dosage was progressively increased to toxic levels of 15 mg/kg over a 3-week period. Dosage sustained by osmotic pumps (12–15 mg/kg/day for 1 week or 6–7 mg/kg/day for 2 weeks), however, resulted in a selected increase in glucose utilization in the accumbens, an important component of the mesolimbic system. This finding may be of significance to the mechanism of amphetamine psychosis, which is sometimes regarded as a model of schizophrenia and is considered to be evidence in support of the dopamine hypothesis of the disease.