Abstract: High fat diet-induced elevation of blood glucose impairs the microvascular function of testis in C57BL/6 mice ZHANG Xiao-yan, LI Bing-wei, SHANG Fei, LIU Shu-ying, SHENG You-ming, LI Hong-wei, XIU Rui-juan1* （Institute of Microcirculation, Peking Union Medical College, Chinese Academy of Medical Sciences , Key Laboratory of Microcirculation, Ministry of Health, CAMS & PUMC, Beijing, 100005, China） Abstract：Objective To observe the effects of high fat diet-induced elevation of blood glucose on the microvascular function of testis and male reproduction in C57BL/6 mice. Methods A total of 40 male C57BL/6 mice were randomly divided into control group and high fat group(High Fat Diet，HFD)，n = 20. The mice in control group were fed with normal diet, and the mice in HFD group were fed with high fat diet for 20 weeks. Blood glucose and body weight were measured weekly. Testicular blood testosterone barrier permeability was evaluated by intraperitoneal injection of Evans blue. The blood flow of testicular microcirculation and the testicular microvascular vasomotion were detected by laser Doppler blood flow imaging system. The expression of CD31 on testicular microvascular endothelial cells was detected by HE staining and immunohistochemistry. The proliferation and apoptosis of spermatogenic cells were observed by immunohistochemistry and TUNEL (TdT-mediated dUTP Nick-End Labeling) staining. Results The body weight and blood glucose of HFD group were significantly higher than those in control group (P <0.01). Evans blue staining showed that the integrity of blood testis barrier of HFD group was damaged, and red fluorescent substance was observed in seminiferous tubules. In HFD group, the mean blood flow of testis and the frequency and amplitude of microvascular vasomotion were significantly lower than those in control group(P<0.01). HE staining showed that the number of spermatogenic epithelial cells and the thickness of seminiferous epithelium were decreased than those in control group. The expression of CD31 in microvascular endothelial cells was significantly lower in HFD group than that in control group (P<0.01). The expression of PCNA expression in spermatogenic cells was lower than that in the control group (P <0.05), and the apoptosis level evaluated by TUNEL staining was higher than that in the control group (P <0.05). Conclusion Increased blood glucose level induced by high fat diet in mice can impair the testicular microvasculature and damage the integrity of blood testosterone barrier and injure the structure of seminiferous epithelium in mice.

Key words: Key words: High fat diet, Hyperglycemia, Testicular microvascular, Blood testicular barrier, Spermatogenic cells injury