Effects of intracerebroventricular injection of d-amphetamine on metabolic, respiratory, and vasomotor activities and body temperatures in the rat

Abstract

Systemic and central administration of d-amphetamine both produced dose-dependent hypothermia in the rat at ambient temperature (T_a) 8 °C. The hypothermia was brought about solely by a decrease in metabolic heat production. However, at both T_a 22 and 30 °C, d-amphetamine produced hyperthermia accompanied by behavioral excitation. The hyperthermia was due to cutaneous vasoconstriction and increased metabolic heat production (due to behavioral excitation) at T_a 22 °C, whereas at T_a 30 °C the hyperthermia was due to cutaneous vasoconstriction, decreased respiratory evaporative heat loss, and increased metabolism (due to behavioral excitation). Furthermore, both the thermal and the behavioral responses induced by d-amphetamine were antagonized by pretreatment with intracerebroventricular administration of 6-hydroxydopamine (a depletor of central catecholaminergic nerve fibers). The data indicate that, by eliminating the interference of behavioral responses induced, d-amphetamine leads to an alteration in body temperature of rats by decreasing both metabolic heat production and sensible heat loss, probably via the activation of central catecholaminergic receptors.