Failure of metergoline to affect the circadian periodicity of plasma cortisol levels in healthy man.

To investigate the role of serotoninergic system on the control of circadian periodicity of human hypothalamic-pituitary-adrenal axis, effect of a potent 5-HT antagonist, metergoline, on diurnal variation in plasma cortisol levels was studied in five male volunteers. The administration of metergoline did not result in a significant change of plasma cortisol concentrations and its circadian rhythmicity. These results suggest that metergoline does not influence the diurnal secretion of cortisol in normal subjects.