The effect of chronic neuroleptic treatment on gonadotrophin release.

Although neuroleptic-induced hyperprolactinaemia is a common cause of amenorrhoea in women, the mechanism by which ovarian function is disturbed is unknown. Previous studies on both hyperprolactinaemic women and rats have indicated that an impairment of the pituitary response to LH-RH may be involved. We have investigated this possibility in female psychiatric patients undergoing chronic treatment with depot neuroleptics. The patients and a group of healthy controls were subjected to a standard LH-RH provocation test. Basal and post-stimulation serum levels of gonadotrophins, prolactin and oestradiol were determined. We have found that the LH responses of the patients fell into three groups: exaggerated, normal and impaired. Differences in the basal levels of gonadotrophins were also observed. The abnormal basal hormone levels and LH-RH responses appear to be related to neuroleptic dose and/or serum prolactin concentration, but no well-defined relationship was found. The results suggest that an action of the neuroleptics which is independent of high serum prolactin levels may be involved in the disruption of pituitary function. Thus the amenorrhoea caused by neuroleptic drug treatment may be etiologically different from that of other forms of hyperprolactinaemic amenorrhoea.