How sperm swim: a clue for male contraception?

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Though sperm are generally considered pretty wriggly little guys, before they are launched into action, so to speak, they aren’t racing around. While researchers have long known that what gets them swimming is a change in internal pH level—the more alkaline their pH, the more aggressively they swim—until now, the mechanism by which sperm rapidly drop protons, which changes their pH from acidic to alkaline, wasn’t clear. According to this new study, published in the journal Cell, sperm are equipped with tons of tiny little pores that, when open, enable them to release protons and get a move on.

These pores—or Hv1 proton channels, as the team of researchers from the University of California, San Francisco, refer to them—swing open in a variety of environments, including when external pH becomes more alkaline or when sperm are exposed to the chemical anandamine, found in both female and male reproductive systems. Researchers say that anandamine may be particularly concentrated closer to the egg, giving sperm that extra, em, encouragement at a critical point in their journey. Gaining a better understanding of what prompts sperm to spring into action could open doors toward developing effective male contraception, or, alternatively, ways to give “slow swimmers” a jolt.

In addition to possibilities for birth control or fertility enhancement, this research may also help shed light on how marijuana decreases male fertility. Anandamine is an endocannibanoid, or basically, the body’s own natural version of the main ingredient—cannibanoids—found in marijuana. If marijuana tricks sperm into acting as though they’re being called to action, then they may prematurely start swimming, tiring themselves out before they’ve made much progress, the researchers speculate.