In this study, we have presented data that further characterize the glucose metabolism of mouse spermatozoa and emphasize its importance in fertilization. We have shown 1) that mouse epididymal spermatozoa have a functional PPP, and 2) that NADPH can substitute for glucose in gamete fusion. These results strongly indicate that sperm need to generate NADPH via the PPP in order to achieve fertilization. ampicillin antibiotic
The presence of a PPP in spermatozoa has been investigated in some species, but its existence has not been unequivocally demonstrated. Activities of glucose 6-phosphate dehydrogenase (G6PDH), the first enzyme of the PPP, have been reported in spermatozoa in humans and mice, but not in bulls. In addition, the transcription of a retroposed gene, encoding for a functional G6PDH and not linked to the X chromosome, has been evidenced in postmeiotic spermatogenic cells in the mouse. The ability of spermatozoa to metabolize labeled glucose through the PPP has been reported in humans and rabbits, but not in mice, rams, or bulls. Although species differences may exist, the techniques used to assess the activity of the PPP are questionable. From studies performed in rams, bulls, and mice, an absence of the PPP in spermatozoa was concluded because the yields of 14CO2 from [1-14C]glucose and [6-14C]glucose were not significantly different and gave ratios of about one.