Ldha-Dependent Metabolic Programs in Sertoli Cells Regulate Spermiogenesis in Mouse Testis.

Sertoli cells are known to support germ cell development through structural and metabolic means. Lactate has been proposed as a key energy source for spermatogenic cells, but its role has not been genetically confirmed. Prior research has shown lactate's presence in testicular metabolism, but no study has directly tested its necessity. This gap motivated investigation into whether lactate production in Sertoli cells is essential for spermatogenesis. No prior work had resolved how lactate depletion affects specific stages of sperm development. It was already known that Sertoli cells secrete metabolites, but the functional role of lactate remained unclear. That uncertainty drove the need to conditionally delete lactate dehydrogenase A in Sertoli cells. This approach allowed researchers to test lactate's role without affecting other cell types.

The aim of this research was to determine if lactate produced by Sertoli cells is necessary for spermatogenesis. Specifically, the study focused on whether lactate depletion in Sertoli cells disrupts sperm development. The motivation came from the lack of genetic evidence supporting lactate's role in this process. Researchers sought to conditionally delete lactate dehydrogenase A in Sertoli cells to observe effects on spermiogenesis. This approach allowed them to isolate lactate's contribution from other Sertoli-cell functions. The study also aimed to identify metabolic pathways affected by lactate depletion. By analyzing sperm metabolites, the researchers could determine if lactate influences specific biochemical processes. This work aimed to clarify lactate's role in testicular metabolism and its implications for fertility.

The researchers used conditional deletion of lactate dehydrogenase A in Sertoli cells to study lactate's role in spermatogenesis. They generated a mouse model where Ldha was deleted specifically in Sertoli cells. Lactate production was measured to confirm depletion in these cells. Spermatogenesis was assessed by examining germ cell development in knockout and control animals. Metabolite profiling was performed on sperm to identify altered biochemical pathways. Lipid and amino acid levels were analyzed to detect dysregulation. Choline supplementation was tested to determine if it could rescue spermiogenesis defects. This approach allowed the researchers to link lactate depletion to specific metabolic changes and functional outcomes.

Ldha deletion in Sertoli cells significantly reduced lactate production in the testis. Spermatogonia and spermatocytes showed no noticeable defects, but spermiogenesis was severely disrupted. Sperm from knockout mice exhibited 2456 altered metabolites compared to controls. Lipid metabolism was notably dysregulated, with changes in choline, oleic acid, and myristic acid levels. Choline supplementation fully rescued the spermiogenesis disorder in knockout mice. These findings suggest lactate depletion affects sperm development through a choline-dependent mechanism. The rescue effect of choline indicates a compensatory pathway in lactate-deficient conditions. This result highlights lactate's indirect role in regulating spermiogenesis via metabolic interactions.

The authors concluded that lactate produced by Sertoli cells is not essential for early stages of spermatogenesis. However, lactate depletion in Sertoli cells severely disrupts spermiogenesis in mice. The study found that lactate's role in sperm development is mediated through choline metabolism. Choline supplementation completely reversed the spermiogenesis defect in knockout mice. These findings suggest lactate functions as a regulator of metabolic pathways in Sertoli cells. The authors propose that lactate's impact on spermiogenesis is indirect and context-dependent. The study highlights a novel function for lactate in testicular metabolism. These results may have therapeutic applications for infertility treatment.