The downregulation of hormone-sensitive lipase and dysregulation of cholesterol receptors/transporter affect testicular lipid homeostasis and function in HFD-induced oligoasthenospermia mice.

Background: Obesity-induced oligoasthenospermia is associated with testicular lipid metabolism. However, the mechanisms underlying the lipid homeostasis imbalance of obesity-induced oligoasthenospermia are unclear.

Methods: Male C57BL/6 mice fed a high-fat diet were established for the in vivo model. TM3/TM4 cells were treated with palmitic acid (PA) in vitro. Proteomics analyzed differential proteins in the testis. The Oil red O and Nile red were used to observe lipid droplets (LDs). Filipin staining was used to observe free cholesterol (FC). Hormone-sensitive lipase (HSL), Low-density lipoprotein receptor (LDLr), Scavenger receptor class B type I (SR-BI), and ATP-binding cassette transporter A1 (ABCA1) expressions were analyzed using qRT-PCR, WB, Immunofluorescence, and immunohistochemistry. Testosterone synthesis and Blood-testis barrier (BTB) integrity were evaluated by ELISA, Transmission electron microscope, and WB.

Results: HFD mice exhibited elevated blood lipid, reduced sperm quality, and hormonal imbalances. Meanwhile, testosterone synthesis was impaired, and BTB was damaged in HFD mice. In vivo and in vitro models, LDs deposition was observed, and HSL expression was down-regulated in Leydig and Sertoli cells. However, the expressions of cholesterol uptake receptors and efflux transporters, as well as the levels of FC, in the two cells were inconsistent. In Leydig cells, the expression of cholesterol uptake receptors (LDLr and SR-BI) was upregulated, resulting in increased FC levels. In Sertoli cells, cholesterol efflux transporter (ABCA1) expression was upregulated, and FC levels decreased. Overexpression of HSL ameliorated LDs accumulation and increased testosterone levels.

Conclusion: The down-regulation of HSL and dysregulation of cholesterol receptors/transporter may affect lipid homeostasis, thereby damaging testicular function.