About Helaine Whitman
The activation of the HPG axis in both males and females during puberty also causes individuals to acquire secondary sex characteristics. After ovulation, the corpus luteum produces progesterone, which inhibits GnRH secretion from the hypothalamus and gonadotropin release from the anterior pituitary, thus terminating the estrogen-LH positive feedback loop. In females, the positive feedback loop between estrogen and luteinizing hormone help to prepare the follicle in the ovary and the uterus for ovulation and implantation. Similarly, novel kisspeptin analogs are being developed to modulate the HPO axis more precisely, potentially offering new treatments for infertility and hormone-dependent cancers. The hyperandrogenism creates a self-perpetuating cycle, in which the increased GnRH pulse frequency promotes LH secretion over FSH, resulting in a high LH/FSH ratio. The GnRH pulse generator in PCOS then becomes less sensitive to the normal inhibitory effects of estrogen and progesterone leading to hyperandrogenism. The corpus luteum's lifespan is influenced by LH pulse frequency and amplitude, gonadotropin levels, and luteotropic factors like prolactin, oxytocin, and prostaglandins.An increase in thyroid hormone levels due to therapy with L-thyroxine causes an increase in the Adiponectin gene expression, while the treatment with dexamethasone leads to opposite effect . There is a positive correlation between the adiponectin levels and the T production, because the T synthesis also depends on gonadotropins with LH activity . In addition, the expression of the Adiponectin gene was detected in the pituitary gland 142, 143, 144, whereby the regulators of the adiponectin receptors in gonadotrophs can be both plasma and pituitary adiponectin (Figure 2). The inhibitory effect of adiponectin on LH production can be carried out at the pituitary level, since both adiponectin receptors were detected in the LH-expressing gonadotrophs of human and rats 14, 142, 143. This can be caused by the reduced intratesticular levels of leptin or the decreased sensitivity of testicular cells to this adipokine that participates in the regulation of survival and proliferation of Leydig cells (Figure 1). In men with obesity, metabolic syndrome and DM2, the activity of the male HPG axis and the T production are decreased, which lead to androgen deficiency 95, 96, 97.
Between days 5 and 7, one follicle is selected to continue development while the others undergo atresia, a process influenced by anti-Müllerian hormone (AMH). Additionally, the granulosa cells of the dominant follicle release peptides that may inhibit the growth of nearby follicles through autocrine and paracrine mechanisms. The distinct hormone profiles characterizing each phase represent two stable states, with sharp transitions between them ensuring proper timing of ovulation and endometrial preparation. Insulin sensitivity in GnRH neurons is important for maintaining normal reproductive function, particularly in the face of metabolic challenges such as obesity.
The AdipoR1 binds with a high affinity to the truncated globular form of adiponectin and with a low affinity with the oligomeric and high-molecular forms of full-length adiponectin, while AdipoR2 binds with an intermediate affinity to both the full-length and globular forms. Despite the fact that both these receptors seven times penetrate the plasma membrane, like classical G protein-coupled receptors, they differ significantly from them in membrane topology, having the extracellular C-terminal domain and the intracellular N-terminal domain. High-molecular complexes of adiponectin are stabilized by disulfide bonds formed between the trimers . Using the collagenous repeats, adiponectin molecules interact with each other to form the homotrimeric complexes that aggregate into the hexamers and high-molecular complexes similar to those in the case of tumor necrosis factor-α (TNF-α) . Adiponectin can be synthesized not only by the adipose tissue but also by the brain, pituitary, testes and others 17, 113. Adult knockout mice had a severe form of hyperleptinemia, obesity, hepatic steatosis and the impaired glucose tolerance, and were infertile.
In humans, testosterone appears more to promote status-seeking and social dominance than simply increasing physical aggression. Thus the link between testosterone and aggression and violence is due to these being rewarded with social status. This could explain why some studies find a link between testosterone and pro-social behaviour, if pro-social behaviour is rewarded with social status. Rats who were given anabolic steroids that increase testosterone were also more physically aggressive to provocation as a result of "threat sensitivity". One study found that administering testosterone increased verbal aggression in some participants. The Annals of the New York Academy of Sciences has found that the use of anabolic steroids (which increases testosterone) among teenagers is correlated with increased likelihood of using violence.
Female
