Insulinlike growth factor I improves yak (Bos grunniens) spermatozoa motility and the oocyte cleavage rate by modulating the expression of Bax and Bcl-2

• Published in: Theriogenology 2015-09, Vol.84 (5), p.756-762
• Main Authors: Pan, Yangyang, Cui, Yan, Baloch, Abdul Rasheed, Fan, Jiangfeng, He, Junfeng, Li, Guyue, Zheng, Hongfei, Zhang, Yifu, Lv, Peng, Yu, Sijiu
• Format: Article
• Language: English
• Subjects: Animals; Bax; Bcl-2; bcl-2-Associated X Protein - genetics; bcl-2-Associated X Protein - metabolism; Cattle - physiology; Gene Expression Regulation - drug effects; Insulin-Like Growth Factor I - pharmacology; Insulinlike growth factor 1; Motility; Oocytes - drug effects; Proto-Oncogene Proteins c-bcl-2 - genetics; Proto-Oncogene Proteins c-bcl-2 - metabolism; RNA, Messenger - metabolism; Sperm Capacitation - drug effects; Sperm Motility - drug effects; Spermatozoon; Yak
• ISSN: 0093-691X; 1879-3231
• DOI: 10.1016/j.theriogenology.2015.05.007

The aim of our present study was to examine the effects of insulinlike growth factor 1 (IGF-1) on yak sperm motility during in vitro capacitation and the relationship between the effects of IGF-1 on yak sperm motility and apoptosis was evaluated. Frozen–thawed yak spermatozoa were incubated at 38 °C for 1 hour in Tyrode's bicarbonate-buffered medium for sperm culture (Sp-TALP) with different concentrations (0, 50, 100, and 200 ng/mL) of IGF-1. In every treatment, the sperm motility was measured by a computer-assisted sperm analyzer system. The fertilizing ability of spermatozoa was evaluated on the basis of oocyte cleavage rate after insemination. The expression of Bax and Bcl-2 was examined by real-time polymerase chain reaction and Western blot for the messenger RNA and protein levels. It is interesting to note that IGF-1 improved yak spermatozoa motility and the cleavage rate of oocytes; these improvements were highest in the 100 ng/mL IGF-1 group, followed by the 200 ng/mL and 50 ng/mL groups, with the lowest improvements in motility and cleavage rates in groups without IGF-1. The expression level of Bax was downregulated by IGF-1, whereas Bcl-2 was upregulated. Both messenger RNA and Bax proteins were lowest in groups with 100 ng/mL IGF-1, where the Bcl-2 was the highest. Bax expression in the groups with IGF-1 was lower than that in the group without IGF-1, and Bcl-2 expression was higher in groups with IGF-1 than that in the group without IGF-1. In conclusion, this research reports that improvements in yak spermatozoa motility and the oocyte cleavage rate after the addition of IGF-I may be a result of the reduction of spermatozoa apoptosis rates by modulating the expression of Bax and Bcl-2.