Attenuation of the oestrogen positive feedback mechanism with the age in postmenopausal women

Abstract

These results demonstrate for the first time a gradual attenuation of the pituitary response to oestrogenic provocation over a certain period following the menopause, with complete abolition after 20 years. It is suggested that the reserves of pituitary gonadotrophs diminish with age.

Submaximal doses of ghrelin do not inhibit gonadotrophin levels but stimulate prolactin secretion in postmenopausal women

“…It should be also noted that our women were in late postmenopause 22 and as such, due to ageing, their pituitary becomes gradually less sensitive to gonadotrophin suppressing agents as in the feedback mechanisms, 23,24 which may also explain the unchanged levels of LH after oestradiol treatment. A reduced sensitivity of LH secretion to exogenous oestrogen has been also shown in a previous study of a similar setting in which even in relatively younger postmenopausal women serum FSH levels showed a greater reduction than those of LH, which however were markedly suppressed, as compared to FSH, after the addition of progesterone to the oestradiol regimen.…”

“…Additionally, the endocrine environment of the high basal levels of gonadotrophins in our women might have obscured any changes in FSH and LH levels making them less discernible than in the follicular phase, where even subtle but significant alterations can be easily discriminated by statistical methods. It should be also noted that our women were in late postmenopause and as such, due to ageing, their pituitary becomes gradually less sensitive to gonadotrophin suppressing agents as in the feedback mechanisms, which may also explain the unchanged levels of LH after oestradiol treatment. A reduced sensitivity of LH secretion to exogenous oestrogen has been also shown in a previous study of a similar setting in which even in relatively younger postmenopausal women serum FSH levels showed a greater reduction than those of LH, which however were markedly suppressed, as compared to FSH, after the addition of progesterone to the oestradiol regimen .…”

Safety and influence of a novel extract of fenugreek on healthy young women: a randomized, double-blinded, placebo-controlled study

“…Estradiol and testosterone are the major hormones that have been implicated for modulating women's sexual desire and functions [26]. These hormones activate the Hypothalamic-Pituitary-Gonadal (HPG) axis by binding with estrogen receptors and the activation of HPG axis is necessary for fertility [27,28]. Decrease in serum estrogen causes a decrease in clitoral intracavernosal, vaginal, and urethral blood flow, due to diffuse clitoral brosis, thinned vaginal epithelial layers, and decreased vaginal submucosal vasculature [29,30].…”

“…The molecular mechanism behind the beneficial effect of FHE can be mainly attributed to its protodioscin content, a furostanolic saponin molecule having a significant structural similarity with DHEA. It was shown that protodioscin can be converted to DHEA [45], which further [27,28]. Trigonelline, yet another major component in FHE has also been proven to enhance the estrogen level by some unknown mechanisms [48].…”

Hypothalamic–Pituitary–Gonadal Axis Involvement in Learning and Memory and Alzheimer’s Disease: More than “Just” Estrogen

“…Besides, the dysregulation of the HPG axis caused by menopause may be due to a diminished ability of estrogens to inhibit the hypothalamus ( 17 , 18 ). Interestingly, in addition to the negative feedback estrogens have on the HPG axis, estrogens can also produce positive feedback, which is necessary for fertility ( 19 ) and is attenuated with age ( 20 ). This body of work strongly suggests that cognitive function may rely on the levels of sex steroids and gonadotropins, implicating HPG axis dysfunction as a factor in the strong correlation between aging and dementia.…”