An abnormality of oestrogen feedback in amenorrhoea-galactorrhoea.

An acute increase in serum prolactin does not modify gonadotropin release in female rats.

“…These findings are in agreement with the earlier reports (Glass et al, 1975;Aono et al, 1979;Van Campenhout, 1980) in which a normal or exaggerated response to LHRH in hyperprolactinemic women is observed, although others were unable to comfirm this (Bohnet et al, 1976). Corbey et al (1977) have reported that, in general, the hyperprolactinemic women demonstrating a high gonadotropin response to LHRH have higher basal concentrations of serum estrogen than in the low gonadotropin-responding women.…”

“…Excessive PRL might also act at the hypothalamic level to interfere with spontaneous episodic gonadotropin release (Boyar et al, 1974;Bohnet et al, 1976) and inhibit the normal positive feedback effect of estrogen on gonadotropin secretion (Glass et al, 1975;Faglia et al, 1977;Aono et al, 1979). In addition, L'Hermite and coworkers (1978) have reported that hyperprolactinemia induced experimentally by sulpiride administration is associated with an impaired positive estrogen feedback mechanism.…”

“…It has also been suggested that PRL has an inhibitory effect on gonadotropin secretion at the hypothalamo-pituitary level. Several investigators (Glass et al, 1975 ;Faglia et al, 1977;Aono et al, 1979) have demonstrated an impaired hypothalamic response to positive estrogen feedback in hyperprolactinemic women and have reported a restoration of the response when serum PRL levels are lowered following surgical or bromocriptine treatment. In addition, a decrease in pituitary responsiveness to luteinizing hormone-releasing hormone (LHRH) has been reported in hyperprolactinemic women (Bohnet et al, 1976) and in lactating rats with an elevated serum PRL concentration (Muralidhar et al, 1977).…”

Pituitary Responsiveness to LH-RH in Post-partum Ewes Treated With Oestradiol-17ß and Failing to Show a Plasma LH Surge

“…Failure of the positive feedback effect of oestrogens on LH release has been associated with ovarian acyclicity in post-partum ewes (Wright and Findlay 1977), women (Baird et al 1979), monkeys (Yamaji et al 1971) and cows (Radford et al 1978), and in non-parturient amenorrhoeic women (Glass et al 1975;Aono et al 1976).…”

Disorders of prolactin secretion.

“…3) has not been fully elucidated. A central effect of hyperprolactinaemia on gonadotrophin secretion is suggested by the modification of pulsatile secretion,especiallyofLH (Boyer et al, 1974;Bohnet et al, 1976), and by the interference with feedback control (Glass et al, 1975). However, an initial assumption that gonadotrophin secretion is deficient has not been borne out by our experience, since our hyperprolactinaemic patients have normal gonadotrophin levels and a normal or even exaggerated response to GnRH (Mortimer et al, 1973;Thorner et al, 1974;Child et al, 1975).…”