Female reproductive hormones, effect

Polybrominated Biphenyls. PBBs have the potential to interact with the endocrine system based on effects that mainly include changes in levels of thyroid and female reproductive hormones. No studies were located that investigated the estrogenic and antiestrogenic activity of PBBs in vitro or in vivo at the level of the estrogen receptor. 

Figure 11.10 Interrelationships between various hormones regulating reproductive function in the male and female. Particular emphasis is placed upon the regulatory effect many have on the production levels of additional reproductive hormones...

Newly proposed test guidelines to specifically address effects on hormone homeostasis and on male and female reproductive organs include the rodent uterotrophic assay to detect estrogenic effects (OECD 2007a) and the rodent Hershberger assay to detect androgenic effects (OECD 2007b). 

Reproductive toxicity to 2,3,7,8-TCDD has been demonstrated in animals. "" The effects include pre- and postimplantation losses in females, morphologic and functional changes in male and female reproductive organs, and hormonal imbalance in both sexes. A number of developmental effects have been observed in animals acutely exposed to 2,3,7,8-TCDD by the oral route. Effects observed in offspring of animals include cleft palate, kidney anomalies, immune system damage (thymic atrophy and immunosuppression), impaired development of the reproductive system, decreased growth, and fetal/newborn mortality. 

Hormonal patterns and their regulation are more complex in females than in males due to the female cycle, the fertilization process, gestation and lactation. All functions ofthe female reproductive system are under endocrine control and therefore can be disrupted by effects on the reproductive endocrine system. 

They were particularly concerned about possible effects of in utero or early postnatal exposures on the development of the male and female reproductive tracts, which are highly sensitive to steroid hormone levels. 

In summary, the menstrual cycle is primarily regulated by the interaction between pituitary and ovarian hormones. Also, releasing hormones from the hypothalamus plays a role in controlling female reproduction through their effects on LH and FSH release from the anterior pituitary.7 A complex series of positive and negative feedback mechanisms control the cyclic release of various female hormones.22,81,97 For instance, increased estrogen secretion in the follicular... 

Endocrine and Reproductive Effects. Because the male and female reproductive organs are under complex neuroendocrine and hormonal control, any toxicant that alters any of these processes can affect the reproductive system (see Chapters 17 and 20). In addition metals can act directly on the sex organs. Cadmium is known to produce testicular injury after acute exposure, and lead accumulation in the testes is associated with testicular degeneration, inhibition of spermatogenesis, and Leydig-cell atrophy. 

Previous studies have claimed that THC delays sexual development in adolescents, interferes with male and female sex hormones, causes infertility, and produces feminine characteristics in males and masculine characteristics in females. Again, much of this research was conducted on animals using very high doses of THC some of these conclusions were also drawn on the basis of very small-scale studies. Thus, many researchers feel that this uncertainty plus a lack of scientific data in humans suggest that there is no clear correlation between marijuana smoking and reproductive effects in humans. 

TCDD was the most potent congener. The effects included increased pre- and postimplantation losses in females, morphological and functional changes in male and female reproductive organs, and hormonal imbalance in both sexes. 

Moore KE, Lookingland KJ, Gunnet JW (1987) Effects of gonadal steroids and pituitary hormones on the activity of tuberoinfundibular dopaminergic neurons. In Genazzam AR (Ed), The Brain and Female Reproduction Function, Front. Gynecol. Endocrine Series, pp. 117-125. Parthenin Pub. Group, New Jersey. 

Monthly cycles of hormones from the pituitary gland cause ovulation, the release of an egg from an ovary. To prevent pregnancy, the two synthetic hormones in many oral contraceptives have different effects on the female reproductive system. 

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