Effects of Vertically Transferred 3,3',4,4',5-Pentachlorobiphenyl (PCB-126) on the Reproductive Development of Female Rats

Abstract

Abstract. In order to study the effects of vertically transferred coplanar polychlorinated biphenyls on female reproductive development, female rat offspring from dams of Sprague-Dawley strain, which received daily oral administration of vehicle (corn oil) or 1 or 3 µg/kg of 3,3',4,4',5-pentachlorobiphenyl (PCB-126) from 2 weeks prior to mating with intact males until 20 days after delivery were examined from birth until puberty. Hepatic expression of the aryl hydrocarbon receptor (AhR)-inducible enzyme cytochrome P450 1A1 (CYP1A1) was detected in all offspring from PCB-126-exposed dams, indicating vertical transfer of PCB-126. Furthermore, quantification of ovarian mRNAs encoding CYP1A1, AhR and ARNT demonstrated that the ovary equipped the AhRsignaling system through which transcription of the CYP1A1 gene was enhanced in a dose-dependent manner. Exposure to PCB-126 retarded the growth of offspring in both exposed groups, while the viability of the neonates of the exposed groups was comparable to that of the oil-exposed controls.The exposure to 3 µg/kg/day reduced the ovarian weight on postnatal day (PND) 24, with atresia of most of the antral follicles and delayed vaginal opening. Exposure to 1 µg/kg/day did not produce such effects; however, both doses of PCB-126 induced external urogenital anomalies, such as vaginal thread and hypospadias, in all of the PCB-126-exposed female offspring. These results indicate that vertically transferred PCB-126 is potent enough to exert a direct effect on the ovary and adversely affect female puberty by altering the morphological and functional development of the female reproductive system.

Changes of Cyclic AMP Levels and Phosphodiesterase Activities in the Rat Ovary

“…1E). The ovaries of the immature rats primed with gonadotropin and those of the adult rats during normal estrous cycles showed typical histological changes as described in previous studies (data not shown) [9,10,18]. The ovaries of the PE rats contained many follicular cysts and failed to ovulate (Fig.…”

“…Four rat models, the postnatal, immature, adult and acyclic aged persistent estrous (PE) rat models, are widely used in the literature [9][10][11][12][13][14][15][16][17][18][19][20][21]. Since follicular development in the rat occurs postnatally [11][12][13], we examined the postnatal rat model to determine the relationships between ovarian cAMP l e v e l , c A M P -P D E a c t i v i t y a n d f o l l i c u l a r development.…”

“…The immature rats primed with gonadotropin model offers the synchronous nature o f f o l l i c u l a r d e v e l o p m e n t , o v u l a t i o n a n d luteinization [14][15][16]. Adult rats usually display typical estrous cycle patterns [17,18]. Acyclic aged PE rats display follicular growth, but preovulatory f o l l i c l e s f a i l t o o v u l a t e d u e t o i m p a i r e d neuroendocrine control of luteinizing hormone secretion [19][20][21].…”

Effects of Vertically Transferred 3,3',4,4',5-Pentachlorobiphenyl on Gene Expression in the Ovaries of Immature Sprague-Dawley Rats

“…The ovaries analyzed in this study were collected in a previous study [8]. The breeding conditions of the animals and the experimental design were presented previously.…”

“…The results of these studies suggest that e x p o s u r e t o T C D D i m p a i r s r e p r o d u c t i v e development and function in female rats. We have previously shown that in utero and lactational exposure to PCB-126 reduces the ovarian weight of offspring, with atresia of most of the antral follicles a l o n g w i t h d e l a y e d v a g i n a l o p e n i n g [ 8 ] . Furthermore, transcription of the cytochrome P450 1A1 (CYP1A1) gene, a representative target gene of aryl hydrocarbon receptor (AhR), is enhanced in a dose-dependent manner in the ovary, which is also the location of the AhR-signaling system.…”