Perinatal exposure to low-dose DE-71 increases serum thyroid hormones and gonadal osteopontin gene expression.

Polybrominated diphenyl ethers (PBDEs) are flame retardants that have been widely used in manufacturing. They are major household and environmental contaminants that bioaccumulate. Humans are exposed primarily through dust inhalation and dietary ingestion of animal products. In animal studies, high doses of penta-brominated diphenyl ethers (penta-BDEs) in the mg/kg body weight (BW) range negatively impact brain development, behavior, memory, circulating thyroid hormone concentrations, the reproductive system and bone development. We investigated the effects of ingestion of a relatively low dose of the penta-BDE mixture DE-71 by pregnant and lactating rats on reproductive and thyroid parameters of the F1 offspring. F0 mothers received 60 µg/kg BW of DE-71 or vehicle daily by gavage from Day 1.5 of pregnancy through lactation (except the day of parturition). F1 pups were sacrificed at 21 d of age or outbred at approximately 80 d of age. Bred F1 females were sacrificed at Day 14.5 of pregnancy or at five months of age. Bred F1 males were sacrificed at five months of age. DE-71 treatment of the mothers affected the F1 females as evidenced by lower body weights at 80 d and five months of age, elevated serum T3 and T4 concentrations at Day 14.5 of pregnancy and increased thyroid gland weight and ovarian osteopontin mRNA at five months of age. Perinatal DE-71 exposure also increased testicular osteopontin mRNA in 21-day-old F1 males. Utilizing a granulosa cell in vitro model, we demonstrated that DE-71 activated the rat osteopontin gene promoter. Our results are the first to demonstrate that PBDEs increase rodent circulating T3 and T4 concentrations and gonadal osteopontin mRNA, and activate the osteopontin gene promoter. These changes may have clinical implications as others have shown associations between human exposure to PBDEs and subclinical hyperthyroidism, and overexpression of ovarian osteopontin has been associated with ovarian cancer.

Expression of sperm protein 22 (SP22) in the rat ovary during different reproductive states.

Sperm protein 22 (SP22) is correlated with fertility in rats. It has been identified in testis and implicated in sperm-egg interaction, protection against oxidative stress, and androgen receptor function. SP22 is widespread in rat and human tissues but has not yet been reported in the ovary. Using reverse transcription polymerase chain reaction, we identified the presence of SP22 transcripts in the rat ovary. We assessed the cellular distribution of the SP22 protein by collecting ovaries from rats in each of the following groups: 30, 60, and 90 days old; Days 9.5, 14.5, 16.5, 18.5, and 20.5 of pregnancy; and Days 1, 2, 8, and 19 of lactation. Tissue sections were stained immunohistochemically for SP22, and some serial sections were stained for relaxin or cytochrome P450 cholesterol side-chain cleavage enzyme (SCC). Weak staining for SP22 was evident in some corpora lutea (CL) and some interstitial gland cells in nonpregnant adult rats. At Day 9.5 of pregnancy, SP22 was detected in all CL, but staining intensity was weak. Staining intensity for SP22 in CL increased from Day 9.5 to 20.5 of pregnancy but was low on postpartum Day 1 and thereafter. A similar temporal pattern of staining intensity in CL was observed for relaxin. Strong immunoreactivity for SCC was present in the CL throughout pregnancy, and the spatial distribution of staining for SP22 in CL and in some areas of ovarian stroma was similar to that for SCC. There was weak staining of some theca cells in some antral follicles of pregnant and early postpartum rats when heat-induced antigen retrieval was used. There was inconsistent staining of oocytes for SP22, particularly in 30-day-old rats. In summary, the expression of SP22 was most prevalent in the CL and increased during pregnancy.

Localization of fertility factor SP22 to specific cell types within the anterior pituitary gland.

Sperm protein 22 (SP22) was recently identified in the anterior pituitary gland (AP) of male Golden Syrian hamsters using ion trap mass spectrometry. SP22 has been implicated in apoptosis, androgen receptor function, fertility, and ontogeny of early-onset Parkinson's disease. However, the role of SP22 in the pituitary has not been investigated. We cloned the cDNA for full-length SP22 from AP and posterior lobe (posterior pituitary and intermediate lobe) of the pituitary gland in adult male rats and Golden Syrian hamsters, confirming the presence of SP22 mRNA in the AP and posterior lobe. Because gonadal steroids are important regulators of AP function, and SP22 is associated with androgen receptor function, we used Western blots to compare SP22 in the AP of intact and orchidectomized male rats given placebo or a low or high dose of testosterone. SP22 did not differ with treatment, indicating that AP SP22 concentration was not regulated by testosterone. To localize SP22 to specific cells of the AP, mirror-image paraffin sections were labeled against SP22 and either luteinizing hormone (LH)beta, thyroid-stimulating hormone (TSH)beta, prolactin, adrenocorticotropic hormone (ACTH), or growth hormone (GH) using peroxidase-conjugated secondary antibody. Additional sections were colabeled with SP22 and one of the AP hormones using fluorescent secondary antibodies. SP22 colocalized in somatotropes and thyrotropes in rat and hamster. We identified SP22 in a small percentage of corticotropes, gonadotropes, and lactotropes. This is the first report that SP22 mRNA is present specifically in the AP, and SP22 is localized primarily in somatotropes and thyrotropes. SP22 may help regulate AP function and be particularly important for the control of GH and TSH secretion.

Expression of the GATA-4 and GATA-6 transcription factors in the fetal rat gonad and in the ovary during postnatal development and pregnancy.

Immunohistochemical studies were undertaken to determine the distribution of GATA-4 and GATA-6 in rat fetal gonad and the postnatal ovary during development and pregnancy. In the undifferentiated gonad, GATA-4 was expressed in the somatic cells of both sexes. After differentiation of the ovary and testis, GATA-4 expression continued in both ovarian and testicular somatic cells; whereas, GATA-6 was expressed in both somatic and germ cells. In the ovary of postnatal rats, granulosa and thecal cells of healthy follicles expressed both GATA factors. In the adult rat, GATA-4 expression was lower in corpora lutea as compared to follicles; whereas, GATA-6 was strongly expressed in both structures. GATA-4 expression was greater in functional corpora lutea than regressing corpora lutea. GATA-6 was expressed in both functional and regressing corpora lutea. In all postnatal ovaries, the expression of P450scc localized with tissue expressing GATA-4 and/or GATA-6, but GATA expression also occurred in P450scc negative cells.

Effects of 4-tert-octylphenol given in drinking water for 4 months on the male reproductive system of Fischer 344 rats.

The environmental pollutant 4-tert-octylphenol (OP) is both toxic and estrogenic to mammalian cells, and injection of OP into adult male rats has devastating effects on their reproductive system. We now report the effects of OP in drinking water ( 1 x 10(-5), 1 x 10(-7) or 1 x 10 (-9) M) on the male reproductive system. Exposure of adult male rats for 4 months to any tested dose of OP had no significant effect on water or food consumption; body weight gain; hematocrit; reproductive organ weights; mean serum LH, FSH or testosterone concentrations; germ cell yield or relative numbers of different classes of testicular cells; or testicular sperm number. In contrast, all doses of OP caused an increase in epididymal sperm with tail abnormalities that would interfere with sperm motility, and the highest dose decreased epididymal sperm number. Our findings raise the possibility that consumption of OP in drinking water may adversely influence male reproductive fertility.