Endocrine response to pregnanolone

Neuroendocrine effects of the neurosteroids, pregnanolone and allopregnanol one have been demonstrated in rats. The endocrine effects of pregnanolone i n humans have so far not been fully elucidated. This study has evaluated th e effects of pregnanolone administration on part of the hypothalamus-pituit ary-gonadal (HPG) axis throughout the menstrual cycle in control subjects a nd patients with premenstrual syndrome (PMS). Intravenous pregnanolone and vehicle were given to eight women with, and eight women without, PMS during the mid-follicular and late luteal phase. Following the drug administratio ns, progesterone, estradiol, luteinizing hormone (LH), follicle-stimulating hormone (FSH), and prolactin plasma levels were measured. Intravenous pregnanolone induced a rise in progesterone levels in the folli cular phase. In the luteal phase progesterone levels decreased in response to pregnanolone provocation. Pregnanolone did not induce any changes in est radiol, LH, FSH or prolactin plasma levels in either cycle phase. PMS patie nts and control subjects did not differ with respect to the endocrine effec ts of pregnanolone. In conclusion, our data show that pregnanolone, in moderate doses, appears not to have any adverse effects on the HPG axis, irrespective of cycle phas e.