Effects Of Hypoxia On Reproduction In Male Rats

With the life improving in recent years, people have higher requirements for quality of life. The changes of reproduction in altitude migrants are causing attention now. The limited previous studies indicate that hypoxia affected the secretion of some sex hormones in men and male animals, and cause the structural changes of spermatogenic epithelium in male animals. Little has been known about the changes of spermatogenesis in testis. The changes of fertilization capacity of sperms when exposured to hypoxia have not been reported before. In order to explore the effects of hypoxia on male reproduction more deeply and completely, we measured sex hormones in male rat during exposure to 5000m simulated altitude, investigated the quantities and qualities of epididymal sperms, detected sperm acrosome reaction rate and acrosin activity, investigated biochemical changes in testis and epididymis, researched the changes of spermatogenesis in testis. The main results and conclusions are as following:1. Quantities of epididymal sperm decreased significantly after 15d and 30d hypoxic exposure. Epididymal sperm motility and viability decreased significantly in 5d, 15d and 30d hypoxic groups. Epididymal abnormal sperms increased significantly in hypoxic groups. Hypoxia caused the formation of folded, coiled and bent tailed sperm. These findings indicate that hypoxia inhibits the maturation of sperm in epididymis, and the release of sperm from testicular spermatogenic epithelium.2. The acivity of α-glucosidase in epididymal semen decreased after exposed to hypoxia for 5d or 30d. It suggests that hypoxia depresses the epididymal functions in promoting the maturation of sperm. The ratio of LDH-X/LDH in testis decreased in hypoxic 30d group. The result indicates that chronic hypoxia inhibits spermatogenesis in testis. Hypoxia caused MDA level decrease and GGT activity unchanged in testis. These results indicate that free radical has no function in depression of spermatogenesis caused by hypoxia.3. Hypoxia inhibited sperm acrosome reaction significantly in vitro. The activity of sperm acrosin decreased in hypoxic groups. These findings indicate that hypoxia depressed the fertilization capacity of sperm.4. PRL level increased significantly in serum after acute hypoxic exposure. Circulating concentrations of LH decreased in 15d hypoxic group and 30d hypoxic group. Serum level of testosterone decreased significantly after exposed to hypoxia for 30d. The results suggest that hypoxic affect the secretion fuction of pituitary, and it plays a role in depressing the functions of testis and epididymis by inhibiting the secretion of testosterone.5. The expression of P450scc mRNA decreased in hypoxic 15d group, while the expression of 3β-HSD mRNA was depressed in 30d group. The low circulating concentration of testosterone in 30d hypoxic group, may be due to the down-regulated expression of 3β-HSD mRNA in testis.6. Microscopic examination of the hypoxic testises indicated swelling and congestion in the testicular interstitial tissue. The numbers of spermatocytes, spermatogonias and spermatozoa are decreased in the seminiferous tubules after exposed to hypoxia for 15d and 30d. Alteration of testis celluar ultrastructure in hypoxic groups was found, such as cellular denaturation, intercellular edema, mitochondria swelling, liposome and lysosome hyperplasia. These changes may affect the testicuar fuction of spermatogenesis.7. Hypoxia induced the apoptosis of spermatogonias and spermatocytes. The expression of Bax protein increased significantly after hypoxic exposure for 30d, while the expression of Bcl-2 protein was unchanged. These results suggest that the depressed spermatogenesis in hypoxic groups is caused by increased apoptosis of spermatogonias and spermatocytes. The increased Bax may play a role in promoting apoptosis of germ cells in 30d hypoxic group.8. The flow cytometry examination indicated that hypoxia caused tetraploid spermatogenic cells loss, and the proliferation capacity of testicular germ cell...