Hyperphagia following intraventricular p-chlorophenylalanine-, leucine- or tryptophan-methyl esters: lack of correlation with whole brain serotonin levels.

The methylester hydrochlorides of DL-p-chlorophenylalanine (PCPA), L-leucine and L-tryptophan were intraventricularly administered to rats. All compounds produced increased food intake compared to saline administration. PCPA and leucine administration significantly decreased serotonin levels by 15--18%, while no serotonin depletion occurred following tryptophan injections. The data suggest that intraventricular injections of large quantities of neutral amino acid methyl esters may cause hyperphagia in rats through non-serotonergic effects on brain function.