Endocrinological, neurochemical, and anabolic effects of polybrominated biphenyls in male and female rats

Pregnant rats were placed on a control diet or on a diet containing 100 ppm polybrominated biphenyls (PBBs, Firemaster PB-6) on Day 8 of gestation. On Day 28 postpartum the pups were weaned onto the same diet as their mothers, and maintained on this diet until sacrificed during the ninth week. Body weight gain was reduced in both the male and female rats exposed to PBBs. The absolute weights of some organs (ventral prostate and seminal vesicles in males, and adrenal and pituitary glands in females) were reduced in animals maintained on the PBB diet, but when expressed as a percentage of body weight only the ventral prostate weight remained significantly reduced. Exposure to PBBs did not affect plasma concentrations of luteinizing hormone, prolactin, or corticosterone; nor did it affect the increase in the plasma concentration of the latter two hormones in response to a mild environmental stress. Exposure to PBBs did not alter the steady-state concentrations of norepinephrine or dopamine in the posterior pituitary or selected brain regions. Furthermore, treatment with PBBs did not alter the rates of synthesis of these catecholamines (as estimated by the rate of accumulation of dihydroxyphenylalanine following inhibition of dihydroxyphenylalanine decarboxylase) in the brains of female rats on the day of diestrus or estrus. On the basis of vaginal cytology, exposure to PBBs significantly lengthened the estrous cycle of female rats.