Abstract
Since many of studies have been conducted to elucidate the relationship between energy metabolic pathways (glycolysis and respiration) and flagellar motility in mammalian sperm, contribution of glycolysis to sperm motility has not been fully elucidated yet. In the present study, we performed detailed analysis of mouse sperm flagellar motility for further understanding of the contribution of glycolysis to mammalian sperm motility. Mouse sperm maintained vigorous motility by substrates either for glycolysis or for respiration. By contrast, inhibition of glycolysis by alpha-chlorohydrine (ACH) caused significant decrease in bend angle of flagellar bending wave, sliding velocity of outer doublet microtubules and ATP content even in the presence of respiratory substrates (pyruvate or beta-hydroxybutyrate; BHB). The decrease of flagellar bend angle and sliding velocity are prominent in the distal part of the flagellum, indicating that glycolysis inhibition caused the decrease in ATP concentration especially at the distal part of the flagellum. These results suggest that glycolysis potentially act as a spatial ATP buffering system, transferring energy (ATP) synthesized by respiration at mitochondria located in the basal part of the flagellum to the distal part of the flagellum. In order to validate glycolytic enzymes can transfer high energy phosphoryls, we calculated intraflagellar concentration profiles of adenine nucleotides along the flagellum by computer simulation analysis. The result demonstrated that the involvement of glycolysis for maintaining the ATP concentration at the tip of the flagellum. It is likely that glycolysis plays a key role in energy homeostasis in mouse sperm not only through ATP production but also through energy transfer.
