China
Africa
Explore chapters and articles related to this topic
Effects of sex steroids on brain cells
Published in Barry G. Wren, Progress in the Management of the Menopause, 2020
L. M. Garcia-Segura, M. C. Fernandez-Galaz, J. A. Chowen, F. Naftolin
It is classically recognized that sex steroids exert organizational effects during the critical period for brain sexual differentiation, and activational effects in the adult brainy20. During the development of the central nervous system, gonadal steroids determine the number of neurons in several structures, resulting in a sexually dimorphic development. One of the best studied examples is the sexually dimorphic nucleus of the preoptic area in rodents, which is larger in volume in males than in females21, 22. This difference in nuclear size is at least partially due to the action of gonadal steroids during the critical period, promoting the survival of a specific population of neurons23. Another example of a sexually dimorphic structure in the central nervous system of rodents is the spinal nucleus of the bulbocavernosus24. Androgens prevent normal cell death of motoneurons of this nucleus25. These studies suggest that sex steroids may act as neurotrophic factors, promoting the survival of specific neurons or regulating apoptosis.
Distribution and Characteristics of Brain Dopamine
Published in Nira Ben-Jonathan, Dopamine, 2020
Several of the hypothalamic nuclei are classified as sexually dimorphic. Few nuclei differ in structure between males and females, e.g., the sexually dimorphic nucleus in the preoptic area, which is larger in males, while most others differ only in function. The most common functional differences among the sexes are in the control of reproduction and sexual behavior, which are determined by the distribution and/or responsiveness of sex steroid receptors in certain hypothalamic nuclei. In addition, the pulsatile pattern of growth hormone (GH) secretion is also sexually dimorphic in terms of pulse regularity, amplitude of the diurnal rhythm, and the magnitude of basal GH release. Sexual dimorphism is determined early in life as a consequence of a timely exposure of the fetus to male and female sex steroids and is irreversible [23].
Dietary Phytoestrogens
Published in Rajesh K. Naz, Endocrine Disruptors, 2004
Heather B. Patisaul, Patricia L. Whitten
Perinatal phytoestrogen exposure also effects sexual differentiation in the rodent brain. The sexually dimorphic nucleus in the preoptic area of the hypothalamus (SND-POA) is normally 2 to 5 times larger in male than female rats, and this estrogen-dependent sexual differentiation occurs between gestation day 16 and postnatal day 5.115 Perinatal exposure of female rats to DES, or high doses (500 µg or 1000 µg) of either zearalenone or genistein during the critical period, results in significantly larger SDN-POA volumes than female controls.124,125 Interestingly, this effect of genistein is only significant in ovariectomized but not intact rat neonates,125 suggesting that the endogenous hormone status of the animal is an important determinant in the biological activity of phytoestrogens on SND-POA volume.
To What Extent are Prenatal Androgens Involved in the Development of Male Homosexuality in Humans?
Published in Journal of Homosexuality, 2022
The presence of such a sexually dimorphic nucleus in humans (Swaab & Fliers, 1985) in the hypothalamic mPOA (Hofman & Swaab, 1989) has led scientists to believe that gay men may exhibit a smaller, and therefore more female-typical, mPOA. Research on cadavers who had died of AIDS showed that the third interstitial anterior nucleus of the hypothalamus (INAH3), which is speculated to be homologous to the ram SDN-POA, was equally large in gay men and straight women and much smaller than that of straight men (LeVay, 1991). However, subject sexual orientation was only theorized from their medical history, especially for the heterosexual women, while AIDS may have also affected these brain structures. A follow-up study by Byne et al. (2001) on Nissl-stained brains of presumed heterosexual men and women and confirmed homosexual men showed no correlation between AIDS and INAH3 size, so AIDS was not a confounding factor. However, while the INAH3 showed significant sexual dimorphism in neuronal number and size and gay men exhibited an intermediate-sized nucleus compared to straight men and women, the effect of sexual orientation was non-significant. Given the similarities between animal and human studies, this result weakly supports the involvement of prenatal androgens, though their effects may be smaller and more complex in humans than other species.
Hormones and visual attention to sexual stimuli in older men: an exploratory investigation
Published in The Aging Male, 2021
Jaime L. Palmer-Hague, Samantha T. S. Wong, Richard J. Wassersug, Alan Kingstone, Erik Wibowo
No studies have investigated E2’s influence on cognitive processing of sexual stimuli in males, but several lines of evidence suggest a possible link. First, estrogen receptors ERα and ERβ are found in various brain centers associated with reproductive function, including the sexually dimorphic nucleus of the preoptic area (SN-POA) and the medial amygdala, both of which are involved in sexual arousal [7]. Second, E2 levels have been positively associated with visual recognition and visual memory in both healthy young men [17], and older men with prostate cancer (PCa) [18]. Third, preclinical evidence shows that estrogen receptors are present in brain regions involved in visual processing, such as the superior colliculus [19,20] which is known to play a role in visual attention and fixation [21]. Lastly, several studies of androgen-deprived men, who received E2 supplements as part of PCa treatment, retain some sexual interest and sexual activity, compared to men who are androgen-deprived, but did not receive E2 [22].
The estrogenic activity of resveratrol: a comprehensive review of in vitro and in vivo evidence and the potential for endocrine disruption
Published in Critical Reviews in Toxicology, 2020
Henry and Witt reported in rats the effects of maternal exposure to resveratrol during lactation on the integrity and function of the neuroendocrine system in the offspring during adult life. Following parturition, dams were exposed throughout lactation to resveratrol in drinking water at levels of 5, 50 and 100 µM. The levels covered the range of resveratrol concentrations found in red wine (range of 1.2–12.1 mg/L). Maternal resveratrol exposure had a greater impact on the adult male offspring. There was a dose dependent reduction in plasma testosterone levels and increase in testicular weight. These effects were accompanied with decreased sociosexual behavior. Histological examination of hypothalamic brain sections revealed significant morphological changes in the sexually dimorphic preoptic nucleus (SDN-POA) and the anteroventral periventricular (AVPV) nucleus. The offspring exhibited significant shrinkage in the SDN-POA nucleus that is typically larger in males compared to females and this was associated with a reciprocal enlargement in the AVPV volume that is relatively smaller in males than females. These morphological changes in the hypothalamic nuclei are the opposite of those produced by E2 suggesting resveratrol produced estrogenic antagonism in the CNS. Importantly, these results indicated that resveratrol disrupted the hypothalamic pituitary gonadal (HPG) axis in the male offspring. In the female offspring, maternal resveratrol exposure during lactation did not affect the size of the hypothalamic SDN-POA and AVPV nuclei, but produced peripheral effects that were typical of an estrogen agonist. These included ovarian hypertrophy and a reduction in body weight throughout the period of investigation until post-natal day 132. Taken together, it seems that the effects of maternal exposure to resveratrol during lactation on reproductive physiology and sociosexual behavior of the offspring during adult life are gender-specific. In addition, the study concluded that resveratrol resembled SERMs in that it produced opposite estrogenic effects in different organ systems, i.e., peripheral estrogenic versus central anti-estrogenic effects (Henry and Witt 2006). To this end, it highly unlikely that resveratrol or any natural dietary supplement is recommended for consumption during pregnancy and lactation. However, the forgoing preclinical studies on the exposure to resveratrol during the prenatal and neonatal periods are insightful because they shed light on the endocrine activity of the compound and its potential to act as an endocrine disruptor if exposure occurs during other physiological stages of the human life.