RESUMO
OBJECTIVE: To investigate the influence of subchronic exposure to low-dose subchronic nano-nickel oxide (NNO) on the reproductive function of male rats and embryonic development of the pregnant rats. METHODS: Fifty normal healthy male SD rats weighing 180ï¼220 g were randomly divided into five groups of equal number, negative control, 4 mg/ml micro-nickel oxide (MNO), and 0.16, 0.8 and 4 mg/ml NNO, those of the latter four groups exposed to MNO or NNO by non-contact intratracheal instillation once every 3 days for 60 days, and then all mated with normal adult female rats in the ratio of 1â¶2. After the female animals were confirmed to be pregnant, the males were sacrificed and the weights of the body, testis and epididymis obtained, followed by calculation of the visceral coefficients, determination of epididymal sperm concentration and viability and the nickel contents in the blood and semen by atomic fluorescence spectrometry. The female rats were killed on the 20th day of gestation for counting of the implanted fertilized eggs and live, dead and resorbed fetuses. RESULTS: After 60 days of exposure, the rats of the NNO groups showed no statistically significant differences from those of the negative control and MNO groups in the weights of the body, testis and epididymis or visceral coefficients. Compared with the negative control group, the animals of the 0.8 and 4 mg/ml NNO groups exhibited markedly decreased sperm concentration (ï¼»9.36 ± 0.98ï¼½ vs ï¼»7.49 ± 1.46ï¼½ and ï¼»6.30 ± 1.36ï¼½ ×106/ml, P < 0.05) and viable sperm (ï¼»85.35 ± 9.16ï¼½% vs ï¼»68.26 ± 16.63ï¼½% and ï¼»65.88 ± 14.68ï¼½ %, P < 0.05), increased morphologically abnormal sperm (ï¼»8.30 ± 2.47ï¼½% vs ï¼»13.99 ± 4.87ï¼½% and ï¼»15.38 ± 8.86ï¼½ %, P < 0.05), and elevated rate of dead and resorbed fetuses (1.18% vs 6.89% and 7.37%, P < 0.05), blood nickel content (ï¼»0.13 ± 0.16ï¼½ vs ï¼»0.52 ± 0.34ï¼½ and ï¼»0.82 ± 0.44ï¼½ mg/L, P < 0.05) and semen nickel content (ï¼»0.08 ± 0.13ï¼½ vs ï¼»0.35 ± 0.23ï¼½ and ï¼»0.63 ± 0.61ï¼½ mg/L, P < 0.05). The nickel level in the semen was correlated significantly with that in the blood (r = 0.912, P <0.01), negatively with the rate of viable sperm (r = ï¼0.879, P <0.01) and positively with the percentage of morphologically abnormal sperm (r = ï¼0.898, P <0.01). CONCLUSIONS: Sixty-day exposure to nano-nickel oxide at 0.8 and 4 mg/ml can produce reproductive toxicity in male rats and result in fetal abnormality in the females, while that at 0.16 mg/ml has no significant toxic effect on the reproductive function of the males.