Effects of insulin and adrenalectomy on elevation of serum leptin levels induced by 5-hydroxytryptophan in mice.

We previously reported that a serotonin precursor 5-hydroxytryptophan (5-HTP) increases serum leptin levels in mice. In this study, we studied the effects of insulin and adrenalectomy on hyperleptinemia induced by 5-HTP. Co-administration of insulin significantly increased hyperleptinemia elicited by 5-HTP. 5-HTP itself increased serum insulin levels. Adrenalectomy, which depletes corticosterone, did not abolish hyperleptinemic effects of 5-HTP. These results suggest that insulin may participate in hyperleptinemic effects of 5-HTP and that the involvement of corticosterone in effects of 5-HTP may be probably small.