Effects of L-deprenyl on human growth hormone secretion

The effects of L-deprenyl on L-dopa-, apomorphine- and L-tryptophan-induced growth hormone (GH) secretion were studied in thirteen healthy male volunteers. An acute 10 mg dose of L-deprenyl did not stimulate the basal GH secretion. Short-term L-deprenyl premedication significantly enhanced the L-dopa-stimulated GH release. In contrast, L-deprenyl premedication did not change the GH response to apomorphine or L-tryptophan. Potentiation of L-dopa-induced GH release by L-deprenyl indicates an increased availability of dopamine at the receptor level without a direct agonistic effect by the drug. Furthermore, L-deprenyl does not change the function of postsynaptic dopamine receptors involved in human GH release.