Interaction Between Secretion of the Gonadotrophins, Prolactin, Growth Hormone, Thyrotrophin and Corticosteroids in Man: The Effects of Lh/Fsh‐rh, TRH and Hypoglycaemia Alone and in Combination

Abstract

SUMMARY The interaction between the mechanisms involved in the LH, FSH, growth hormone, prolactin, ACTH and TSH responses to the synthetic LH and FSH releasing hormone, thyrotrophin releasing hormone and insulin induced hypoglycaemia was studied in twelve normal male volunteers. Each subject acted as his own control and the test procedures were performed individually and in combination. The simultaneous administration of one releasing hormone with another or with insulin in no way modified the hormonal responses to either releasing hormone or to hypoglycaemia. Clinical testing with these procedures may therefore be performed simultaneously, so that the pituitary reserve for the five anterior pituitary hormones may be assessed together in under 2 hr. In addition it has been shown that TRH releases a small amount of FSH but not LH in male subjects.

Lactation and the physiology of prolactin secretion

“…In contrast, several groups of workers have been unable to show consistent changes in prolactin levels during the cycle (Hwang et al, 1971;Tyson and Friesen, 1973;Jaffe et al, 1973;McNeilly, Evans and Chard, 1973;Ehara eta., 1973;McNeilly and Chard, 1974 (Ehara etal., 1973;McNeilly and Chard, 1974), and prolactin secretion appeared to occur in a spike-like manner, similar to that seen in normal male subjects (Mortimer et al, 1973;McNeilly and Hagen, 1974). In addition, no changes in prolactin levels occur when gonadotrophins are elevated in postmenopausal women (McNeilly, Ormston and Hall, unpublished observations), after clomiphene in normal men (Thorner et al, 1974) (Zarate et al, 1972), or galactorrhoea (Thorner et al, 1974) (Thorner et al, 1974a), indicating removal of a peripheral block to steroidogenesis.…”

Regression of Both Pituitary and Ovarian Cysts after Administration of Thyroid Hormone in a Case of Primary Hypothyroidism.

“…FSHand PRL (16)(17)(18). It was reported that this TRHincrease was the etiologic factor in the so-called "feedback" mechanism, and the condition came to be called "overlap syndrome" ( 16).…”

Disorders of prolactin secretion.

“…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). There is also the possibility that prolactin may in some way interfere with the action of the gonadotrophins on the gonads, in which case lowering the prolactin level should rapidly restore gonadal function to normal.…”