Reproductive effects of isoflavon in macaques

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Phytoestrogens are particularly interesting to compare to other environmental substances with endocrine action. They are estrogenic by definition and can act as weak estrogens in mammalian systems, giving them the ability to produce a whole range of hormonal effects in a variety of animals.In experiment (1), daidzein was administrated to pregnant macaque monkeys on days 15 through days 60 of gestation. Blood samples were taken before daidzein treat through until delivery and measured reproductive hormones using radioimmunoassay. After delivery, the newborn monkeys were anesthetized and perfused with 4% paraformaldehyde. Then their tissues were used to histological and immunohistological studies. Daidzein did not alter plasma LH, FSH, estradiol and progesterone levels in pregnant macaques. The gestational length and body weight of newborns did not change compared with controls. The teratogenic results of newborns were not observed. A hormone-sensitive period for differentiation of the s … More exually dimorphic nucleus in the preoptic area of the hypothalamus (SDN-POA) occurs before gestation day 30 in macaques. This nucleus is larger in males and plays a role in mating activity. Females exposed to daidzein during the critical period have slightly larger SDN-POA volumes than female controls. The number of steroid receptor immunoreactive nucleus did not change compared with controls.In experiment (2), we administrated daidzein to perimenopause old female macaques. After treatment, levels of plasma estradiol were slightly increased. On the other hand, plasma LH, FSH and progesterone did not change. Asian populations have a much lower incidence of menopause symptom than American populations, suggesting that phytoestrogens such as daidzein may reduce the incidence of these symptoms.The potential reproductive impact for primates is unclear. There are some indications that beneficial effects may require high doses than adverse effects, but further studies in this area must be completed before any definite dietary recommendations can be made Less