Hypothalamic infusion of amphetamine increases serotonin, dopamine and norepinephrine.

Microinjections of amphetamine into the lateral hypothalamus are known to cause anorexia and hypodipsia. These effects are thought to be mediated by an action of amphetamine on the catecholaminergic terminals to release dopamine and norepinephrine and block reuptake. Direct evidence of neurochemical release was lacking; therefore microdialysis was used to measure monoamines and their metabolites in the extracellular fluid of the lateral hypothalamus while amphetamine diffused out through the microdialysis probe. Amphetamine infusion significantly increased serotonin, dopamine and norepinephrine; it decreased dihydroxyphenylacetic acid (DOPAC), 5-hydroxyindoleacetic acid (5-HIAA), and did not change homovanillic acid (HVA). These results suggest that amphetamine releases dopamine, norepinephrine and serotonin and blocks reuptake which thereby retards neurotransmitter breakdown. The net effect was a quadrupling of extracellular monoamines which could react with postsynaptic receptors. This supports the hypothesis that the behavioral effects of amphetamine injections into the lateral hypothalamus are mediated by dopamine, norepinephrine and suggests, in addition, serotonin.