[Estrogen-like activity of 4-nonylphenol and bisphenol in immature SD rats]

To investigate the estrogen-like activity of 4-NP and BPA in the immature SD rats.

The vehicle, ethinyl estradiol (EE, 0.3 mg/kg, positive control), 4-NP (50 mg/kg, 100 mg/kg, 200 mg/kg), bisphenol (BPA, 200 mg/kg, 400 mg/kg, 600 mg/kg) were given orally (by gavage) q.d. to immature female Sprague-Dawley rats on the 21st, 22nd, 23rd postnatal days. The rats were sacrificed 24 hours after the last administration. Uterine wet weight, uterine/body weight ratio, height of the luminal epithelium, thickness of the myometrium and protein level of proliferating cell nuclear antigen (PCNA) of rat uterine were analysed by one-way ANOVA.

In animal experiments, uterine wet weight and uterine/body weight ratio were significantly higher in the 4-NP 200 mg/kg and 100 mg/kg, BPA 600 mg/kg and 400 mg/kg (P < 0.05). Height of luminal epithelium, thickness of myometrium, as well as protein level of PCNA of rat uterine were significantly increased in the three groups of 4-NP, the three groups of BPA, and the mixture group (P < 0.05), and a dose-response relationship was observed.

4-NP and BPA had weak estrogen-like activities. They were the main environmental endocrine disruptors, and could influence the healthy of immature animals and children.