1,8) Three main pathways appear relevant: a prolactin-GH-thyroidstimulating hormone (TSH) pathway regulated by transcription factor Pit-1, (9-11) a gonadotroph
pathway regulated by steroidogenic factor 1 (SF-1), (12,13) and a corticotroph pathway mediated by T-box transcription factor (Tpit).
Although most clinicians intuitively link the effect of GnRH agonists and antagonist on LH levels to that of FSH, the regulation of these two hormones in the anterior pituitary gonadotroph
cells by GnRH and other stimulus are very different.
21-23) Endogenous GnRH is released from the median eminence of the hypothalamus, binding to receptors on the gonadotroph
, and facilitating the production and secretion of the gonadotropins luteinizing hormone (LH) and follicle-stimulating hormone (FSH) into the systemic circulation.
In this regard it is noteworthy that it has been proposed that an interaction occurs between the somatotroph and gonadotroph
hormonal axes, represented by 17-MT and GH (Holloway & Leatherland 1998, Holloway et al.
tumors usually secrete their products inefficiently and in low concentrations and, thus, very rarely cause any clinical syndrome other than sellar mass effects (3), (4).
It is possible to postulate that high PRL levels suppress LH release, both by antagonizing the hypothalamic release of GnRH and by decreasing gonadotroph
sensitivity to the latter.
In the new study, the researchers investigated by creating mice lacking insulin receptors only in the gonadotroph
Kanner AA, Corn BW, Greenman Y: Radiotherapy of nonfunctioning and gonadotroph
A clinical study of the use of human chorionic gonadotroph
in weight reduction.
GNRH agonists are high-potency analogs of GNRH that work by causing an initial surge of LH followed by down-regulation of gonadotroph
cells, a drop in LH, and a drop in testosterone to castration levels.
Beckett JL, Sakurai H, Adams BM, Adams TE (1997) Moderate and severe nutrient restriction has divergent effects on gonadotroph
function in orchidectomized sheep.