Abstract:

Objective To investigate the expression and localization of glucose transporter 1 (GLUT1) and glucose transporter 2 (GLUT2) in adult boar testis under normal temperature and heat stress conditions. Methods Nine adult boars (Landrace) were randomly divided into three groups. The self-made thermo-controlled 42 ℃ blanket was used in local scrotal heating group (42 ℃ for 1 hour) (n=3). The boars of environmental heat stress group (n=3) were kept in a thermally-controlled hot house (37-40 ℃, 7 days, 3 hours per day). After the daily heat treatment, the boars were back to the normal temperature. Three boars were assigned as control (n=3) and kept in normal temperature house (21-25 ℃). After 6 hours (local scrotal heating group) and 24 hours (environmental heat stress group) of heat treatment, the boar testes were surgically harvested. The expression of GLUT1 and GLUT2 were detected in boar testes by using Real-time PCR, Western blotting and immunohistochemistry. Results The results of Real-time PCR and Western blotting showed that the GLUT1 protein and mRNA expression levels in the environmental heat stress group did not have significantly differences compared with control group. The GLUT1 protein and mRNA expression levels in the local scrotal heating group significantly increased compared with control group. In environmental heat stress group and local scrotal heating group, the expression levels of GLUT2 protein and mRNA significantly increased compared with control group. Immunohistochemical results showed that GLUT1 protein in seminiferous tubules was expressed in spermatocyte and round spermatid before and after heat treatment. In environmental heat stress group, the immunostaining of GLUT1 protein did not have significantly differences compared with control group. After local scrotal heating, the immunostaining of GLUT1 protein was deeper than control group, and the expression level of GLUT1 protein was increased. Before and after heat treatment, the GLUT2 protein in seminiferous tubules was expressed in germ cells and sertoli cells. The environmental heat stress and the local scrotal heating resulted in increase of GLUT2 expression and deeper immunostaining. Conclusion Glucose transporter GLUT1 and GLUT2 are expressed in the seminiferous tubules of boar testes. Environmental heat stress and local scrotal heating result in changes of GLUT1 and GLUT2 expression levels in the boar testis. The result suggests that GLUT1 and GLUT2 play important roles in boar spermatogenesis.

Key words: Heat stress, Glucose transporter 1, Glucose transporter 2, Testis, Western blotting, Immunohistochemistry, Boar