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KMID : 0894520060100020147
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Development & Reproduction
2006 Volume.10 No. 2 p.147 ~ p.154
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Effect of Di(2-ethyl hexyl)phthalate(DEHP) on the Onset of Puberty in Female Rat
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Lee Kyeung-Yeup
Lee Sung-Ho
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Abstract
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Phthalates such as di(2-ethyl hexyl)phthalate(DEHP) are industrial chemicals with wide-ranging human exposures because of their use in plastics and other common consumer products. Consequently, their adverse effects as endocrine disruptor in the reproductive physiology of both laboratory rodents and human have been studied extensively. The present study was undertaken to examine whether prepubertal exposure to DEHP affects on the onset of puberty and the associated reproductive parameters such as hormone receptor expressions in female rats. DEHP(100㎎/㎏/day) was administered daily from postnatal day 25(PND 25) through the day when the first vaginal opening(VO) was observed, and the animals were sacrificed on the next day. Gross anatomy and weight of reproductive tissues were compared to test the DEHP’s effects on the cell proliferation. Furthermore, histological studies were performed to assess the structural alterations in the tissues. Specific radioimmunoassay was carried out to measure serum LH levels. To determine the transcriptional changes in progesterone receptor(PR), total RNAs were extracted and applied to the semi-quantitative reverse transcription polymerase chain reaction(RT-PCR). As a result, delayed VO was shown in the DEHP group(PND 37.3±0.7) compared to the control group(PND 35.3±0.7; p＜0.05). DEHP treatment significantly decreased the wet weight of ovaries and uteri compared to the control group(p＜0.05). Interestingly, elevation of serum LH levels was shown in the DEHP group(p＜0.05). Graafian follicles and corpora lutea were observed only in the ovaries from the control animals. Numerous primary, secondary follicles and small atretic follicles were observed in the ovaries from DEHP-treated animals. Similarly, hypotrophy of luminal and glandular uterine epithelium was found in the DEHP-treated group. These effects were probably due to the inhibitory effects of DEHP on the synthesis and secretion of estrogen from granulosa cells. In the semiquantitative RT-PCR studies, the transcriptional activities of PR in both ovary(p＜0.05) and uterus(p＜0.01) from DEHPtreated animals were significantly lower than those from the control animals. The present studies demonstrated that the acute exposure to DEHP during the critical period of prepubertal stage could inactivate the reproductive system resulting delayed puberty in female rats.
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KEYWORD
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Di(2-ethyl hexyl) phthalate(DEHP), Vaginal opening, Anti-estrogenic, Progesterone receptor, Puberty onset
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