THE EFFECT OF ENDOGENOUS AND EXOGENOUS GONADOTROPHIN‐RELEASING HORMONE ON THE PROLACTIN RESPONSE TO TRH

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Abstract
The prolactin response to TRH in a group of patients with Kallmann''s syndrome was significantly lower compared to a group of hypergonadotropic hypogonadal patients. Since levels of testicular products are comparably low in both groups, high endogenous LHRH production might be associated with an increased prolactin response to TRH. A positive correlation between the magnitude of the prolactin response to TRH and basal and LHRH-stimulated LH/FSH levels was established (the latter serving as an index of endogenous LHRH production) in: eugonadal men, men with Kallmann''s syndrome, estrogen-treated agonadal men, men with severely impaired spermatogenesis and agonadal men. A direct relation between LHRH and the prolactin response to TRH was demonstrated in a group of eugonadal men, the prolactin response to TRH being greater after prolonged LHRH pretreatment. An increase of endogenous or exogenous LHRH might be associated with decreased hypothalamic dopamine secretion which could directly increase prolactin synthesis. Indirectly, decreased dopamine secretion could augment the potency of TRH in releasing prolactin.