Choline dehydrogenase is necessary for normal energy metabolism in mouse sperm

Choline dehydrogenase knockout ( Chdh −/− ) male mice are infertile due to severely compromised sperm motility. We have previously reported that Chdh −/− sperm have abnormal mitochondrial structure, significantly decreased ATP concentrations, are unable to maintain the electrochemical gradient across the inner mitochondrial membrane and are less motile than Chdh +/+ sperm. A viability assay based upon SYBR14 uptake indicated that there were no differences between Chdh +/+ and Chdh −/− sperm samples; however, energy metabolism in the Chdh −/− sperm was decreased compared to Chdh +/+ sperm. Measurements of oxidative phosphorylation (oxygen consumption rate, OCR) and glycolysis (extracellular acidification, ECAR) were measured simultaneously in Chdh +/+ and Chdh −/− sperm using a Seahorse Biosciences Extracellullar Flux analyzer. Chdh −/− sperm OCR was 9% of Chdh +/+ sperm; ECAR in Chdh −/− sperm was 100% less than Chdh +/+ sperm. The reduced activity of both major energy‐producing pathways (mitochondrial oxidative phosphorylation and glycolysis) in Chdh −/− sperm likely accounts for the decreased ATP concentrations and poor motility of these cells. ARJ is supported by a scholarship from Balchem Corporation. Additional funding from the NIH DK55865.