Glucagon-like peptide-1 analog, liraglutide, regulates Sertoli cell energy metabolism

Abstract

Liraglutide, an analog of the incretin hormone, glucagon-like peptide 1 (GLP-1), is widely used for the treatment of obese and type 2 diabetic patients. However, there is scarce information about its effects on testicular function. Within the testis, Sertoli cells (SCs) provide nutritional support for germ cells: they metabolize glucose to lactate, which is delivered to germ cells to be used as a preferred energy substrate. Besides, SCs use fatty acids (FAs) as an energy source and store them as triacylglycerols (TAGs) within lipid droplets (LDs), which serve as an important energy reserve. In the present study, twenty-day-old rat SC cultures were used to assess whether liraglutide affects their metabolic functions related to nutritional support and lipid storage. The results show that liraglutide does not modify glucose consumption or lactate production. However, it increases TAG levels and LD content. These effects are accompanied by an increase in the mRNA levels of the fatty acid transporter FAT/CD36, glycerol-3-phosphate-acyltransferases 3, and perilipins 1 and 4. Then, the participation of the cAMP/PKA signaling pathway was explored. We observed that H89 (PKA inhibitor) decreases LD upregulation elicited by liraglutide, and that dibutyryl cAMP increases LD content and the expression of related genes. In summary, liraglutide promotes lipid storage in SCs through the regulation of key regulatory genes involved in FA transport, TAG synthesis, and LD formation. Considering the importance of lipid storage in the maintenance of SC energetic homeostasis, we postulate that liraglutide might improve the overall energetic status of the seminiferous tubule.