The pentose phosphate pathway plays an essential role in supporting human sperm capacitation

In swim-up–selected spermatozoa of 38 normozoospermic patients, capacitated spermatozoa exhibited enhanced pentose phosphate pathway (PPP) activity and increased expression of glucose-6-phosphate dehydrogenase (G6PD). The G6PD inhibitor DHEA and the inhibitors of NADPH oxidase apocynin and diphenylene iodonium (DPI) prevented both superoxide generation and capacitation in human spermatozoa, but whereas DPI and DHEA inhibited PPP, apocynin did not influence it, suggesting that PPP activation during capacitation is not a response to increased oxidative stress but exerts a role by supplying reducing equivalents to oxygen.