Changes in Activities of Glucose Metabolising Enzymes in Germ Cells during Spermatogenesis in Rats:...

The rate of 14 CO2 , liberation from [14 C-1]glucose was identical to that from [14 C-6]glucose in spermatids, but more than the latter in spermatogonia. Rotenone (1 μM) completely inhibited 14 CO2 release from [14 C-1]glucose in spermatids, but decreased it only 30% in spermatogonia. The activity of glucose-6-phosphate dehydrogenase, but not 6-phosphogluconate dehydrogenase, was markedly lower in spermatocytes and spermatids than in spermatogonia. The activities of the glycolytic enzymes, glucosephosphate isomerase, fructose diphosphatase, glyceraldehyde-3-phosphate dehydrogenase and enolase, differed only slightly in spermatids and spermatogonia. It is concluded that the low glucose-6-phosphate dehydrogenase activity may contribute to the low activity of the pentose cycle in spermatocytes and spermatids.