L-Tryptophan administration in man: effects on gonadotrophin, growth hormone and cortisol secretion and on sexual motivation.

Long-lasting administration of L-tryptophan in neurologic patients caused a slight reduction of plasma luteinizing hormone levels without modifications of sexual motivation. Plasma follicle stimulating hormone concentrations were not altered by L-tryptophan. Short-lasting loading of L-tryptophan caused a statistically significant increase of plasma growth hormone levels, and a fall of plasma cortisol values in neurologic patients without neuroendocrine disorders. The pattern of plasma cortisol response to L-tryptophan loading was different in patients with neuroendocrine disorders. Plasma gonadotrophins seemed to be slightly reduced after the L-tryptophan loading.