CHRONIC ADMINISTRATION OF THE ENVIRONMENTAL-POLLUTANT 4-TERT-OCTYLPHENOL TO ADULT MALE-RATS INTERFERES WITH THE SECRETION OF LUTEINIZING-HORMONE, FOLLICLE-STIMULATING-HORMONE, PROLACTIN, AND TESTOSTERONE

4-Tert-octylphenol (OP) is a prevalent environmental pollutant that ha s been shown to exert both toxic and estrogenic effects on mammalian c ells. The effects of OP on the reproductive system of adult male verte brates are virtually unknown. In the present study, we investigated th e effects of chronic exposure to OP on reproductive hormone secretion in the adult male rat and compared the results qualitatively with thos e observed in other male rats treated chronically with estrogen. We in jected corn oil vehicle or OP (20 or 80 mg) or estradiol valerate (EV; 0.8 or 8 mu g) in oil s.c. into 2-mo-old male rats thrice weekly for either 1 or 2 mo. The 80-mg dosage of OP and one or both dosages of EV had the following effects: decreased anterior pituitary gland (APG) a nd serum LH and FSH concentrations; increased APC and serum prolactin (PRL) concentrations; increased APG/body weight ratios; decreased seru m testosterone concentrations; decreased hematocrit; and decreased foo d consumption and body weight gain. To evaluate the response of the hy pothalamus-APG to gonadal removal, we orchidectomized some of the rats after the end of treatment and decapitated them 3 wk later. In orchid ectomized controls, serum LH and FSH concentrations rose markedly and serum PRL concentrations decreased. Similar changes were seen in orchi dectomized rats treated previously with 20 or 80 mg OF. Moreover, ther e were no differences in mean serum LH, FSH, or PRL concentrations bet ween controls and rats treated previously with either dosage of OP at 3 wk after orchidectomy. The results demonstrate that chronic administ ration of OP to adult male rats can adversely affect the secretion of reproductive hormones and strongly suggest that OP exerts these effect s by acting like an estrogen. The opposite changes in LH, FSH, and PRL secretion observed after cessation of treatment with OP and orchidect omy suggest that chronic treatment with OP under the conditions of the present study did not result in any significant permanent deleterious effects on gonadotrophs or lactotrophs or the hypothalamic neurons co ntrolling the secretion of the gonadotropins or PRL.