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Neuroendocrine Factors
Published in Michael H. Stone, Timothy J. Suchomel, W. Guy Hornsby, John P. Wagle, Aaron J. Cunanan, Strength and Conditioning in Sports, 2023
Michael H. Stone, Timothy J. Suchomel, W. Guy Hornsby, John P. Wagle, Aaron J. Cunanan
During the menstrual cycle, production and secretion of estrogens by the ovaries is regulated by cyclical LH and FSH production of the pituitary. LH stimulates androgen production by the follicle during the follicular phase (days 1–13); during the ovulatory phase (day 14), there is a large surge in FSH that subsequently influences the conversion of androgens to estrogens by the corpus luteum in the luteal phase (days 15–28). Thus, the menstrual cycle consists of two phases and double peaks in estrogen concentrations over an average of 28 days (Figure 3.4). Because of the cyclical fluctuation in estrogens and other hormones, as well as normal individual variation, it is difficult to ascertain the exact estrogen status of a woman at any one point in time (29). Estrogens stimulate primary and secondary female characteristics and fat accretion and have marked metabolic effects (46).
Paper III
Published in Justin C Konje, Complete Revision Guide for MRCOG Part 3, 2020
Follicular phase hormone profile FSH – 5.8 iu/L (3.0–9.0 iu/L)LH – 6.1 iu/L (2.5–9.0 iu/L)Prolactin – 520 miu/L (normal <400 miu/L)Testosterone – 0.4 iu/L (0.2–2.5 iu/L)Sex hormone binding globulin – 48 nmol/L (40–120 nmol/L)
Ultrasonographic Monitoring of Follicle Growth in Controlled Ovarian Hyperstimulation
Published in Arianna D'Angelo, Nazar N. Amso, Ultrasound in Assisted Reproduction and Early Pregnancy, 2020
Follicular phase occurs at the beginning of each cycle, when a group of the most mature follicles (also known as “antral follicles”) are recruited. This phase usually lasts 6–8 days. During this phase, the follicles most sensitive to follicle-stimulating hormone (FSH) undergo further development, producing estradiol (E2) and inhibin B while the remaining follicles become atretic. This phase is followed by the ovulatory phase that occurs in midcycle. The E2 produced by the dominant follicle triggers through a positive feedback mechanism the massive release of the luteinizing hormone (LH) by the pituitary gland. The LH surge triggers ovulation within 34–38 hours. The wall of the preovulatory follicle is broken, and the oocyte is rapidly released. In the last phase known as the luteal phase, the corpus luteum secretes both E2 and progesterone, resulting in a negative feedback mechanism that suppresses the FSH release until the next menstruation. The fall in the level of circulating progesterone causes menstruation in the absence of fertilization, embryo implantation, and human chorionic gonadotropin (hCG) secretion. This physiological process is described in Figure 8.1.
Evaluating thyroid function in pregnant women
Published in Critical Reviews in Clinical Laboratory Sciences, 2022
K. Aaron Geno, Robert D. Nerenz
Perhaps most critical for reproductive health, the expression and reactivity of gonadotropins in the setting of hyperthyroidism are altered. Luteinizing hormone (LH) concentrations increase relative to euthyroid patients throughout the menstrual cycle, though the pulsatile nature of LH and follicle-stimulating hormone (FSH) remains unaffected [8,9]. Aggregated data from small studies also suggest that baseline and peak follicular phase FSH increases [10]. The mechanism for these increases remains unclear, but it was proposed that the increase in gonadotropins was due to increased sensitivity to gonadotropin-releasing hormone (GnRH). However, this was not confirmed in a subsequent study [9,10]. Nonetheless, gonadotropin secretion following thyrotropin-releasing hormone (TRH) and GnRH administration remained increased for at least four months after a euthyroid state was reached [11]. Prolactin does not appear to be impacted by hyperthyroidism [8].
Influences of ovarian hormones on physiological responses to cold in women
Published in Temperature, 2022
Andrew M. Greenfield, Nisha Charkoudian, Billie K. Alba
While the roles of estrogens and progesterone are more thoroughly described, follicle stimulating hormone (FSH) may also influence BAT thermogenesis. FSH is a gonadotropic hormone produced by the anterior pituitary gland that stimulates the growth of ovarian follicles [176]. FSH begins to rise at the end of the luteal phase and continues in the early follicular phase, with a rapid rise in the pre-ovulatory phase [177]. In rodents, FSH influences energy metabolism by stimulating adipocyte lipid biosynthesis [178]. Interestingly, there is new evidence to suggest that FSH negatively regulates BAT thermogenesis, such that FSH blockade increases BAT activation and thermogenesis in mice [179]. This finding is supported by data demonstrating that FSH inhibits adipocyte UCP1 expression through reduced cAMP signaling [180]. However, no mechanistic studies examining FSH in humans with regard to BAT or thermoregulation have been performed. Therefore, significant research questions remain to whether there is a potential modulation of thermoregulatory function by FSH across the menstrual cycle.
Menstrual cycle phase and elite female soccer match-play: influence on various physical performance outputs
Published in Science and Medicine in Football, 2021
Ross Julian, Sabrina Skorski, Anne Hecksteden, Christina Pfeifer, Paul S Bradley, Emiel Schulze, Tim Meyer
The menstrual cycle is a vital biological rhythm that occurs monthly from ~13 years of age (Ozbar et al. 2016). This can be separated into specific menstrual cycle phases (MCP) that are based on the magnitude of respective hormones. The follicular phase (FP) is defined as the onset of menses until ovulation. This phase can be divided into early FP (both key hormones oestrogen and progesterone are minimal) and mid FP (an increased concentration of oestrogen with a low concentration of progesterone). Typically, the luteal phase (LP) is associated with an elevation of both oestrogen and progesterone; therefore, progesterone is often measured to confirm the transition between the FP to the LP (Janse de Jonge 2003). These hormones interact and affect physiological and metabolic mechanisms (Lebrun et al. 2013). For example, substrate availability and metabolism have appeared to be affected across the menstrual cycle (Constantini et al. 2005), with increased rates of glycogen depletion observed during the FP (Hackney 1999; Campbell et al. 2001). In view of previous literature suggesting that muscle glycogen is likely the prominent substrate for energy production in soccer (Nedelec et al. 2012), and the link to reductions in high-intensity distance (Mohr et al. 2003; Krustrup et al. 2006); it could be suggested that the changes in substrate metabolism could relate to changes in physical performance.