[Impact of subchronic exposure to low-dose nano-nickel oxide on the reproductive function and offspring of male rats].

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 180－220 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 1∶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 (［9.36 ± 0.98］ vs ［7.49 ± 1.46］ and ［6.30 ± 1.36］ ×10⁶/ml, P < 0.05) and viable sperm (［85.35 ± 9.16］% vs ［68.26 ± 16.63］% and ［65.88 ± 14.68］ %, P < 0.05), increased morphologically abnormal sperm (［8.30 ± 2.47］% vs ［13.99 ± 4.87］% and ［15.38 ± 8.86］ %, 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 (［0.13 ± 0.16］ vs ［0.52 ± 0.34］ and ［0.82 ± 0.44］ mg/L, P < 0.05) and semen nickel content (［0.08 ± 0.13］ vs ［0.35 ± 0.23］ and ［0.63 ± 0.61］ 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 = －0.879, P <0.01) and positively with the percentage of morphologically abnormal sperm (r = －0.898, 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.