[Impact of plateau environment on seminal characteristics of native Tibetans and immigrated Tibetan Hans].

Objective: To investigate the characteristics of the semen parameters of native Tibetans and immigrated Tibetan Hans in the high-altitude area and analyze the influence of altitude adaptation on male fertility.

METHODS: This study included 1 563 infertile male patients, including 698 native Tibetans and 865 immigrated Tibetan Hans, and 56 normal fertile men, including 33 native Tibetans and 23 Tibetan Hans. We obtained semen samples from the subjects for routine semen analysis and sperm DNA fragmentation index (DFI) examination and collected peripheral blood for determination of the reproductive hormone levels.

RESULTS: In the infertile patients, the native Tibetans, as compared with the immigrated Hans, showed significantly higher incidence rates of azoospermia (5.87% vs 2.89%, P <0.05), severe oligozoospermia (3.15% vs 1.73%, P <0.05) and abnormal seminal viscosity (43.12% vs 25.89%, P<0.01), but no statistically significant differences in the percentages of normozoospermia (81.08% vs 87.39%, P >0.05), oligozoospermia (5.44% vs 3.93%, P >0.05), severe asthenozoospermia (4.44% vs 4.04%, P >0.05) or severe teratozoospermia (4.58% vs 6.59%, P >0.05). In the normal fertile men, there were no statistically significant differences between the native Tibetans and immigrated Hans in age (［32.42 ± 4.82］ vs ［34.57 ± 6.01］ yr, P >0.05), sperm concentration (［143.69 ± 85.74］ vs ［155.11 ± 82.56］ ×10⁶/ml, P >0.05), straight line velocity (［25.74 ± 3.94］ vs ［27.24 ± 3.46］ μm/s, P >0.05), percentage of morphologically normal sperm (［8.22 ± 4.35］ vs ［7.28±2.46］ %, P >0.05), total testosterone concentration (［17.97 ± 2.98］ vs ［15.72 ± 6.38］ nmol/L, P >0.05), or follicle stimulating hormone level (［5.51 ± 1.62］ vs ［4.17 ± 2.08］ IU/L, P >0.05). However, the immigrated Hans, in comparison with the native Tibetans, exhibited a higher sperm motility (［79.75 ± 14.67］ vs ［66.58 ± 17.21］%, P <0.05), a lower curvilinear velocity (［60.97 ± 2.71］ vs ［71.14 ± 82.13］ μm/s, P <0.05) and a lower level of luteinizing hormone (［4.28 ± 1.20］ vs ［5.84 ± 1.15］ IU/L, P <0.05).

CONCLUSIONS: During the acclimatization to the plateau hypoxia environment, the immigrated Tibetan Hans undergo adaptive changes in sperm concentration and motility and have lower incidence rates of azoospermia and severe oligozoospermia than native Tibetan males.