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Endocrine Functions of Brain Dopamine
Published in Nira Ben-Jonathan, Dopamine, 2020
The pulsatile release of GnRH and LH is essential for fertility in all mammals. This notion is based on the findings that a constant stimulation of the pituitary gonadotropes with GnRH, both under in vivo and in vitro conditions, suppresses LH secretion. This suppression occurs because of down-regulation and desensitization of the GnRH receptors in response to continuous exposure to GnRH. In patients with functional hypothalamic amenorrhea, the ovulatory cycle can be restored by pumps that deliver GnRH pulses. Recently, some success was achieved with a constant infusion of kisspeptin, which presumably restored pulsatile GnRH release.
The Menstrual Cycle
Published in Jane M. Ussher, Joan C. Chrisler, Janette Perz, Routledge International Handbook of Women’s Sexual and Reproductive Health, 2019
There is a continuum of women’s potential reproductive responses to physiological and psychosocial experiences (Table 3.1). The so-called “functional” hypothalamic amenorrhea (no menstrual flow for 3–6 months) and oligomenorrhea (cycles longer than 35 days but less than 3 months) are rare in the spectrum of adaptive reproductive suppression. The most common are regular menstrual cycles with anovulation or with short luteal phases. Across a year, short luteal phases (≥2 per year) occur for 42% of women initially documented in two cycles to be normally ovulatory (Prior et al., 1990a). Anovulation is less common, and occurs for 20% of initially ovulatory women (Prior et al., 1990a). This continuum has not yet been recognized by most women’s health experts (Gordon et al., 2017), who continue to discuss only low estrogen/estradiol and ignore low or absent progesterone levels.
Applied exercise physiology and health
Published in Nick Draper, Helen Marshall, Exercise Physiology, 2014
There is a common misconception that the absence of regular menstrual cycles is a normal consequence of training and competing at the elite level. This, however, should not be sustained and amenorrhea, brought on by low energy availability, forms one of the points of the Triad triangle (Figure 14.1). If menstrual cycles have been absent for three or more months the condition is termed secondary amenorrhea, whereas primary amenorrhea relates to a delayed age of menarche. In the Triad, menstrual disorders result from the impaired secretion of luteinising hormone from the pituitary gland and, this type of amenorrhea is referred to as functional hypothalamic amenorrhea. The relationship between amenorrhea and sports training appears to remain unclear, although one study found ballet dancers to experience menarche at a later age, albeit at the same height and weight as in non-dancers (Warren, 1980).
The influence of estro-progestin therapy on neurohormonal activity in functional hypothalamic amenorrhea
Published in Gynecological Endocrinology, 2022
Anna Szeliga, Agnieszka Podfigurna, Gregory Bala, Blazej Meczekalski
Functional hypothalamic amenorrhea (FHA) is a chronic endocrine disorder caused by a disturbance of the pulsatile secretion of hormones in the hypothalamus, which in turn results in suppression of the hypothalamic-pituitary-ovarian axis. Inhibition of pulsatile gonadotropin-releasing hormone (GnRH) secretion in the hypothalamus results in suppression of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) secretion from the pituitary gland. This sequence leads to the suppression of the hormonal and reproductive functions of the ovary [1, 2]. Secondary amenorrhea, which is the most common symptom, is characterized as amenorrhea occurring in a previously menstruating woman. It affects approximately 3-5% of the female population in reproductive age. FHA accounts for 25% to 35% of secondary amenorrhea, making it the most common cause of secondary amenorrhea in our population. At the same time, FHA is known to be the causative agent in only about 3% of primary amenorrhea, ceding to gonadal dysgenesis and polycystic ovary syndrome as leading causes. It is estimated that up to about 17 million women worldwide suffer from FHA [3, 4].
Menopause, anti-Müllerian hormone and cognition in a cohort of women with persistent symptoms following TBI: a case for future research
Published in Brain Injury, 2021
Melissa Biscardi, Reema Shafi, Nora Cullen, Gillian Einstein, Angela Colantonio
Future research, with a larger and sufficiently powered sample, should consider the inclusion of other hormones in addition to AMH. Lower AMH may hint at an altered AMH-GnRH loop which may disrupt homeostasis and trigger several early aging mechanisms in females; therefore, hormones levels for GnRH, E2, FSH, LH and prolactin would be important for elaborating on the relationship between TBI, the hypothalamic-pituitary-gonadal axis and help highlight the elusive relationship with AMH changes reported here. Assessment of cortisol levels should also be considered given that it relies on the common precursor cholesterol. By including cortisol levels, researchers will also be able to rule out functional hypothalamic amenorrhea, or stress induced anovulation. The use of orthopedic-injury (non-TBI) controls will be useful to further elucidate the mechanism of changes (60) The use of a naturally menopausal control group might help in understanding whether these changes are due to premature menopause or its own condition with a unique constellation of cognitive and functional changes. Finally, this study included only women with mild TBI and therefore we were not able to assess the relationship between TBI severity and the outcomes of interest. Future research should investigate women across all levels of severity.
Factors of mineral homeostasis impairment and bone mineral density loss in women with central hypogonadism
Published in Climacteric, 2020
I. Ilovayskaya, V. Zektser, L. Lazebnik
Functional hypothalamic amenorrhea poses a considerable risk in terms of non-achievement of peak bone mass1. Other factors (such as undernutrition and malabsorption, and stress-induced elevated cortisol level) could play a role in low bone density in these cases6,7; however, estrogen levels are critical. In postmenopausal women, physical activity has a positive effect on BMD and could improve BMD8. Nevertheless, BMD was lower in young female athletes with hypogonadotropic amenorrhea in comparison with women with regular menstrual cycles despite the same level of physical exercise9–11. Growth hormone (GH) deficiency is a well-known risk factor for osteoporosis in premenopausal women. However, among adult patients with GH deficit, low BMD and vertebral deformations on X-ray images were found more frequently in patients with untreated CH than in those with intact or treated gonadal function12,13. These findings point to the significance of estrogen deficiency for bone health in patients with central (hypogonadotropic) hypogonadism of different origins.