| Abstract: | Studies were made of the effects of D(+)-glucose, L-lactate and pyruvate on in vitro capacitation and acrosome reactions (AR) of hamster sperm using a more “defined” medium that that used in previous similar studies. In the absence of glucose or lactate, sperm underwent very few AR and activation (whiplash-like motility characteristic of capacitated hamster sperm) was reduced compared to those events in sperm preincubated in the presence of glucose plus lactate plus pyruvate. Glucose and pyruvate supported more AR than glucose alone, but less than glucose, lactate, and pyruvate. The glycolytic inhibitor α-chlorohydrin (10 μm) inhibited AR by 50% and reduced activation by less. When glucose was added to sperm incubated 2 hr with pyruvate and lactate, the number of AR observed after 4 hr was the same as that obtained when glucose was present throughout the incubation. When glucose was added after 3.5 hr, AR were delayed for 1 hr and lower numbers of sperm underwent AR. In the presence of lactate and pyruvate, 0.38 mM glucose was able to support activation and AR as well as 3.24 mM glucose. These results indicate that exogenous glucose and lactate are necessary for in vitro capacitation and AR of hamster sperm; only low levels of exogenous glucose are required; exogenous glucose is not required during the first 2 hr of capacitation; and glycolytic activity is necessary for capacitation and the AR. |
