The effects of amphetamine, hyperthermia and increased serum unesterified fatty acids (UFA) were considered as having possible roles in the amphetamine-induced increase in brain tryptophan (Trp) levels. The change in brain Trp of male Sprague-Dawley rats 1 hour after the administration of various amphetamine-like drugs (50 μmoles/kg) correlated with the change in rectal temperature (r = 0.89) but not with the increase in serum UFA (r = 0.04). Also, increases in UFA did not correlate with increases in temperature (r = 0.01). The amphetamine-induced increase in brain Trp was not accompanied by significant changes in the levels of aromatic amino acids in serum. The amphetamine-induced increase in brain Trp also correlated with the increase in body temperature in six strains of mice (r = 0.93). No significant increases in serum UFA were observed in mice 1 hour after the administration of d1-amphetamine (50 μmoles/kg).
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Supported by NIMH Grant MH-25487 and NIMH Postdoctoral Fellowship