China
Africa
Explore chapters and articles related to this topic
Lignin in Biological Systems
Published in Severian Dumitriu, Valentin Popa, Polymeric Biomaterials, 2020
A high intake of enterolignans (enterodiol and enterolactone) on the basis of dietary intake (846 μg/day) combined with a high plasma enterolactone level was associated with a reduction in the risk of breast cancer of 64%. Research has shown enterolactone to stimulate the synthesis and circulating levels of a biochemical called sex hormone-binding globulin (SHBG). Through this activity, enterolactone may reduce the free bioavailable pool of circulating estrogen, thereby reducing estrogen penetration in tissues and the risks of an adverse estrogen balance. There is also evidence that enterolactone may inhibit biosynthesis of estrogen by blocking aromatase, a key enzyme in biosyn-thesis of estradiol. Collectively through these multiple mechanisms of action, lignans appear to have a positive influence on the estrogen balance in the body.
Evaluation of Food and Food Contaminants
Published in William J. Rea, Kalpana D. Patel, Reversibility of Chronic Disease and Hypersensitivity, Volume 5, 2017
William J. Rea, Kalpana D. Patel
There is controversial evidence that the widely used herbicide atrazine (ATZ) may alter gonadal development by affecting gonadal steroidogenesis through alteration of aromatase activity.351 Aromatase (cyp19) is a cytochrome P450 enzyme that converts testosterone into estradiol352 and androstenedione into estrone.353 In numerous fish, reptile, and amphibian species, cyp19 induction or inhibition produces female-biased or male-biased sex ratios, respectively.354–356 Induction of in vitro cyp19 activity has been reported in human cell lines after exposure to ATZ.357,358 However, several other studies have not observed such responses in amphibians.359–362 The underlying reasons for these differences and the mechanism through which ATZ may disrupt vertebrate development remain unclear.
Steroids: Arthritis, Fertility, Heart Attacks, And Home Run Records
Published in Richard J. Sundberg, The Chemical Century, 2017
The second strategy uses aromatase inhibitors, drugs which inhibit the enzyme that aromatizes the A ring of estrogen. Drugs in this group include both steroid analogs such as exemestrane and also nonsteroidal compounds such as letrozole and anastrozole.
Genetic polymorphisms related to muscular strength and flexibility are associated with artistic gymnastic performance in the Japanese population
Published in European Journal of Sport Science, 2023
Hiroshi Kumagai, Tomoko Kaneko, Yuko Shintake, Eri Miyamoto-Mikami, Hiroyuki Tomita, Makoto Fukuo, Wataru Kawai, Mutsumi Harada, Naoki Kikuchi, Nobuhiro Kamiya, Kosuke Hirata, Hirofumi Zempo, Seiji Maeda, Naokazu Miyamoto, Noriyuki Fuku
Women show higher flexibility than men (Kumagai et al., 2019; Morse, 2011). Furthermore, flexibility differs during the menstrual cycle (Bell et al., 2009; Eiling, Bryant, Petersen, Murphy, & Hohmann, 2007), implying that estrogen may be a key determinant of flexibility. Estrogen is biosynthesized from androgen by cytochrome P450 aromatase (CYP19A1), an enzyme responsible for a key step in estrogen biosynthesis, and its effects are primarily mediated by estrogen receptor α (ERα). The C allele of the rs2234693 C/T polymorphism in the estrogen receptor α gene (ESR1) reportedly shows higher ERα expression than the T allele (Herrington et al., 2002), whereas the T allele of the rs936306 C/T polymorphism in CYP19A1 shows higher circulating estradiol levels than the C allele in young men (Kumagai et al., 2022) and postmenopausal women (Hosono et al., 2015). Although we previously demonstrated that the rs2234693T/C polymorphism in ESR1 is associated with flexibility (Kumagai et al., 2019), the effect of the CYP19A1 rs936306 polymorphism on flexibility has not been elucidated.
Effects of 17α-ethinylestradiol on the neuroendocrine gonadotropic system and behavior of European sea bass larvae (Dicentrarchus labrax)
Published in Journal of Toxicology and Environmental Health, Part A, 2023
S Soloperto, S Olivier, A Poret, C Minier, MP Halm-Lemeille, C Jozet-Alves, S Aroua
In vertebrates, the establishment of the neuroendocrine system occurs during early life stages. An impairment or disequilibrium during this period may impact the development and functioning of the neuroendocrine system in young and adult stages (Diamanti-Kandarakis et al. 2009; Vissio et al. 2021). Results from the present study showed that key components of the neuroendocrine gonadotropic axis in sea bass were affected by EE2 exposure. Aromatase b, encoded by the cyp19a1b gene, is an enzyme involved in estrogen synthesis. This enzyme is expressed in radial glial cells (Le Page et al. 2011). An increase in cyp19a1b expression after exposure to XEs was reported in various teleost species (zebrafish: Le Page et al. 2006; medaka: Kuhl, Manning, and Brouwer 2005; rare minnow: Wang et al. 2010) and our results in sea bass larvae are in agreement with these findings. In fish, aromatase b and neuroestrogens were shown to play key roles in brain regulated sexual differentiation, cell proliferative activity, sexual behaviors and might also be involved in sensory perception (Diotel et al. 2010; Shaw 2018). Consequently, deregulation of cyp19a1b transcription by XEs might exert an impact on all these functions/processes, and potentially also on non-reproductive behaviors. Further investigations are necessary to unravel the long-term consequences of such disruption of cyp19a1b.
Effects of prenatal and lactational bisphenol a and/or di(2-ethylhexyl) phthalate exposure on male reproductive system
Published in International Journal of Environmental Health Research, 2022
Aylin Balcı, Gizem Özkemahlı, Pınar Erkekoglu, Dilara Zeybek, Nilgün Yersal, Belma Kocer-Gumusel
In a study by Culty et al. (2008), pregnant Sprague-Dawley rats were exposed to different doses of DEHP (58–1250 mg/kg/day) from GD14 to the day of parturition by oral gavage and exposure did not change plasma estradiols in male offspring (Culty et al. 2008). Another study showed that maternal DEHP (20, 200, 500, or 750 mg/kg/day) exposure from GD11 to birth led to an increase in estradiol and LH levels in adulthood while causing decreases in serum testosterone levels in males (Barakat et al. 2017). It is known that testosterone is converted to estradiol by Cyp19a1 (aromatase). Decreased testosterone levels may reduce estradiol synthesis. However, studies reporting increased serum estradiol levels in DEHP exposure have linked this increase to abnormal hepatic estrogenic metabolism. There are also studies showing that DEHP may cause liver hyperplasia and deterioration of estrogen metabolism (Eagon et al. 1994; Barakat et al. 2017). In various studies, it has been stated that DEHP may have estrogenic effects (Czernych et al. 2017; Watkins et al. 2017). In this study, the increase in estradiol levels in the BPA+DEHP group compared to the control group can be explained by the combined effects of these two EDCs on testosterone and hepatic biotransformation of estrogen.