GH as a co-gonadotropin: the relevance of correlative changes in GH secretion and reproductive state

Abstract

It is now well established that exogenous GH promotes sexual maturation and reproductive function. The possibility that this may reflect physiological actions of endogenous GH has, however, rarely been considered. Correlative changes in GH secretion and reproductive state (puberty, pregnancy, lactation, menopause and ovarian cycles) are thus the primary focus of this review. GH secretion is, for instance, elevated during major transitions in reproductive status such as puberty and pregnancy. In some cases, augmented circulating GH levels are paired with hepatic GH resistance. This interaction may permit selective activation of gonadal responses to GH without activating IGF-I-mediated systemic responses. This selective activation may also be mediated by autocrine, paracrine or intracrine GH actions, since GH is also synthesized in reproductive tissues. Correlative changes in GH secretion and reproductive state may be mediated by events at the hypothalamic, pituitary and gonadal level. In addition to direct effects on gonadal function, GH may influence reproductive activity by increasing gonadotropin secretion at the hypothalamic and pituitary level and by enhancing gonadotropin responsiveness at the gonadal level. The close association between reproductive status and the somatotrophic axis supports the physiological importance of GH in reproductive function.

Interaction between growth differentiation factor 9, insulin-like growth factor I and growth hormone on the in vitro development and survival of goat preantral follicles

“…The development of preantral follicles has generally been considered to be largely independent of gonadotrophins and pituitary hormones. However, increasing evidence indicates that growth hormone (GH), in addition to having metabolic effects, is involved in the regulation of ovarian functions, including the preantral stage of development (14,17). In vitro studies in immature mice showed a stimulatory effect of GH on preantral follicle development and follicular cell proliferation that is synergistic with IGF-I (15,18,19).…”

Paracrine regulation of growth hormone gene expression by gonadotrophin release in grass carp pituitary cells: functional implications, molecular mechanisms and signal transduction

“…However, increasing evidence suggests that GH also plays a role in reproductive functions. Recently, GH has been proposed to be a 'cogonadotrophin' in mammals (Hull & Harvey 2002). This idea is supported by the findings that correlative changes in GH secretion can be observed at various stages of the ovarian cycle, sexual maturation, pregnancy, and seasonal breeding (Hull & Harvey 2000a,b).…”

Aspectos neuroendócrinos na síndrome dos ovários policísticos

“…Em nível ovariano, o GH pode exercer ações sinérgicas com o FSH nas células da granulosa humana para produzir estradiol e progesterona e com LH para estimular a secreção de androgênios tecais (57,58).…”