Protocatechuic acid promotes lactate synthesis in Sertoli cells of Tibetan sheep through AMPK/mTOR-mediated autophagy

Objective This study aimed to investigate the effects of protocatechuic acid (PCA) on Sertoli cells (SCs) in Tibetan sheep, focusing on its impact on cell proliferation, lactate synthesis, and the underlying molecular mechanisms.

Methods Primary SCs were isolated from the testes of Tibetan sheep and cultured. The effects of PCA on SCs function were evaluated through in vitro experiments, and its molecular mechanisms were further explored. Meanwhile, both in vivo and in vitro mouse models were employed to validate the regulatory mechanisms of PCA on male reproductive function and SCs.

Results PCA significantly upregulated the expression of proliferation and lactate synthesis-related genes in Tibetan sheep SCs, and increased the intracellular pyruvate and lactate levels. Mechanistically, PCA activated the AMP-activated protein kinase (AMPK) pathway and inhibited the mechanistic target of rapamycin (mTOR) pathway, thereby inducing autophagy in SCs. The use of autophagy inhibitors and AMPK inhibitors effectively blocked PCA-induced promotion of SCs proliferation and lactate synthesis. In mouse model studies, PCA improved sperm count, pregnancy rate, and litter size, and reduced sperm abnormality rate. It also elevated activin A levels and decreased inhibin B levels in testicular tissues, increased serum follicle-stimulating hormone (FSH), luteinizing hormone (LH), and testosterone (T) levels, enhanced testicular antioxidant enzyme activities, and reduced malondialdehyde (MDA) content. Furthermore, PCA upregulated the expression of proliferation and lactate synthesis-related proteins in mouse testicular tissues and primary SCs, modulated the AMPK/mTOR pathway, and increased autophagic activity.

Conclusion PCA promotes the proliferation and lactate synthesis in SCs of Tibetan sheep through AMPK/mTOR-mediated autophagy.