Effects of neonatal exposure to a high-dose p-tert-octylphenol on the male reproductive tract in rats.
Time-course alterations in morphological changes of the reproductive tract including spermatogenesis as well as pituitary and gonadal hormones, reproductive ability, and the size of the sexually dimorphic nucleus of the preoptic area (SDN-POA) were investigated in male rats neonatally exposed to 100 mg/kg p-tert-octylphenol (OP) subcutaneously. OP treatment affected hormone levels of follicle stimulating hormone (FSH) and testosterone, reproductive organ weights and sperm counts. Slightly depressed FSH levels at prepuberty and prolonged suppression of testosterone till 7 weeks of age were observed as two hormonal alterations. The lasting reduction in testosterone appeared to be associated with growth inhibition of male reproductive organs such as the testis, prostate and epididymis, these demonstrating low organ weights compared with those of age-matched controls till 7 weeks of age. The FSH concentrations after puberty showed a rise to values equal to or higher than those of the control group, suggesting recovery of maturation of the reproductive tract. No morphological abnormalities, even with morphometric stage analysis of spermatogenesis, were detected in the male reproductive tract throughout the study. Size of the SDN-POA and reproductive ability was comparable to those in controls. At the termination (18 weeks of age), however, a reduction in the sperm count in the epididymis of OP-treated animals demonstrated a possibility that the male reproductive system might be still affected by neonatal exposure to OP. The results observed demonstrate that neonatal exposure to a high-dose OP exerts estrogenic action directly or indirectly, resulting in slight but prolonged impairment of the male reproductive tract. The suppression of FSH caused by modulation of the hypothalamus-pituitary control system may be the trigger for the impairment, while the possibility of direct estrogenic action of OP is not ruled out. Our results also indicate that more sensitive endpoints should be established to detect the effects of neonatal exposure to estrogens or estrogenic compounds on the male reproductive tract.
Yoshida
M
M
Department of Pathology, Sasaki Institute, 2-2 Kanda-Surugadai, Chiyoda-ku, 101-0062, Tokyo, Japan. pathol@sasaki.or.jp
Katsuda
S
S
Takenaka
A
A
Watanabe
G
G
Taya
K
K
Maekawa
A
A
D000818:Animals; D000831:Animals, Newborn / Q000502:physiology*; D001835:Body Weight / Q000187:drug effects; D005837:Genitalia, Male / Q000187:drug effects* / Q000254:growth & development / Q000473:pathology; D012739:Gonadal Steroid Hormones / Q000097:blood; D008297:Male; D009929:Organ Size / Q000187:drug effects; D010636:Phenols / Q000633:toxicity*; D010907:Pituitary Hormones / Q000097:blood; D011301:Preoptic Area / Q000187:drug effects; D051381:Rats; D012708:Sertoli Cells / Q000187:drug effects; D013076:Sperm Count; D013091:Spermatogenesis / Q000187:drug effects; D013093:Spermatogonia / Q000187:drug effects; D013737:Testis / Q000166:cytology / Q000187:drug effects / Q000254:growth & development
D012739:Gonadal Steroid Hormones; D010636:Phenols; D010907:Pituitary Hormones; C105260:4-tert-octylphenol