Low doses of ipsapirone increase growth hormone but not oxytocin secretion in normal male and female subjects

Objective: The present study investigated whether administration of a 5- HT(1A) receptor agonist would increase growth hormone (GH) and oxytocin levels in normal human subjects, and whether the responses would be modified according to the age and gender of the subjects. Methods: Ipsapirone (0.3 mg/kg body weight), or placebo was administered to 30 normal subjects (14 males, 19-74 years and 16 females, 22-69 years) using a randomized, double blind design. Results: Stimulation of GH secretion by ipsapirone was significantly greater in male compared to female subjects, with no apparent effect of age. Oxytocin secretion was not stimulated by ipsapirone compared to placebo in any of the groups. Conclusions: The effects of gender and age on the degree of stimulation of GH secretion by 5-HT(1A) agonists in human subjects differ from their effects on secretion of the hormones ACTH and cortisol. A higher dose of ipsapirone is required to stimulate oxytocin secretion in normal human subjects.