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Effects of chemical exposures on testis cell-cell interactions and endocrine function
Published in C. Yan Cheng, Spermatogenesis, 2018
Rachel C. Knight, Jennifer R. Panizzi, Benson T. Akingbemi
Chemical exposure effects are presumably exerted in multiple testicular cells with implications for exocrine and endocrine function. The primary androgen T stimulates sexual differentiation in the prenatal period, promotes development of male secondary sex characteristics, supports hormonal imprinting of the liver, prostate, and hypothalamus, and maintains the male phenotype and fertility.6
Estrogen in Gender-Specific Neural Differentiation
Published in Akira Matsumoto, Sexual Differentiation of the Brain, 2017
The third difficulty with the organizational hypothesis to be considered is whether hormonal “activation” of sexual behavior in adulthood, and “organization” during perinatal development are separable processes. The difference between these processes lies in the transient nature of steroid effects in the adult on mature brain mechanisms compared with the permanent organizational effects of hormones early in life. There are a number of possibilities that could, in theory, account for physiological differences. The sites of steroid action in the brain differ between the juvenile and adult; the cellular mechanisms, including steroid metabolism and receptor binding, differ; steroids exert separable actions depending on the developmental condition of the target areas in the brain at the time of steroid exposure, possibly in terms of both enzyme and steroid receptor constituents. It has been argued28 that the distinction between organizational and activation processes is no longer tenable. This change in outlook has occurred because research on the avian brain provides evidence that does not agree with the idea that permanent organizing effects occur only during the critical sensitive period of early development. E2 demasculinizes mechanisms underlying copulatory behavior in female Japanese quail embryos.21 Therefore, females treated with E2 as embryos do not show complete male copulatory behavior. However, if female Japanese quail are ovariectomized at hatching, a demasculinizing effect of E2 can be demonstrated in adulthood.29,30 This interesting finding suggests that in the absence of E2 during the post-hatching period, the brain mechanisms underlying male sexual behavior remain receptive to the organizing effects of E2 until maturity. Two aspects of the organizational hypothesis have to be reconsidered, therefore: (1) there appears to be no restricted time limit for the “critical period” for the differentiating effects of estrogen, and it is interesting to compare a similar lack of a rigidly fixed period for behavioral imprinting with hormonal imprinting in the brain; (2) the important conclusion can be drawn that, given the right conditions, mechanisms underlying behavior can be organized by steroids in the adult animal.30,31 There is no fixed period for the hormonal imprinting effects on brain organization. The conclusion that steroid hormones can organize the adult brain has been supported by steroid effects involving the structural organization of the adult brain that previously have been thought to occur only in juveniles.
Long-term reproductive effects of benzo(a)pyrene at environmentally relevant dose on juvenile female rats
Published in Drug and Chemical Toxicology, 2023
Ana Carolina Casali Reis, Bárbara Campos Jorge, Beatriz Rizzo Paschoalini, Jéssica Nogueira Bueno, Julia Stein, Suyane da Silva Moreira, Beatriz de Matos Manoel, Glaura Scantamburlo Alves Fernandes, Hamilton Hisano, Arielle Cristina Arena
Despite the alterations exhibited by the females on the puberty installation, the estrous cyclicity was not changed. However, the juvenile exposure to BaP provoked a decrease in sexual activity in the treated females, evidenced by a reduced lordosis quotient. The lordosis is a classical reproductive behavior in female rodents, and depends on an activational action of estrogen in the brain (Pfaff et al.1994). Studies have revealed that the exposure to endocrine disruptors during pubertal development can influence the sexual behavior in the adulthood. These compounds are able to reprogram the response to sexual hormones in adult life, through a second sexual differentiation period (Sisk and Zehr 2005). Previous studies already reported that the perinatal treatment with a single dose of BaP (0.25 mg/animal) changed the number of steroid receptors (Csaba et al.1991) and resulted in a compromised sexual behavior in adult life (Csaba and Karabelyos 1995). In the present study, the BaP exposure could have influenced the lordosis quotient via changes in the estrogen receptors in the brain, reinforcing the importance of this period for hormonal imprinting with steroids. Based on these findings, further evaluation of the role of BaP in the quality and quantity of estrogen receptors in the brain is needed.
Transsexualism and hormones
Published in Gynecological Endocrinology, 2022
The etiology of transsexualism is not known even today. Some hypotheses include: the effects of gonadal steroids on hypothalamus during the first trimester of pregnancy, disorder of androgen to estrogen conversion, receptor disorders and aromatase changes [4]. Hormonal imprinting can prenatally influence psychosexual differentiation [5]. Swaab et al. [6] found changes in the volume of both suprachiasmatic and striae terminalis nucleus [6]. The ratio between transfemale and transmale changed from 6:1 to 1:1 [7,8].