13 April 2010

"Striking" link between omega-3 fatty acid and male fertility

by Kate Melville

The dramatic effect that a little-known omega-3 fatty acid has on sperm may have important implications for treating male infertility, say University of Illinois (UI) scientists.

"In our experiment, we used 'knockout' mice that lacked the gene responsible for an enzyme important in making docosahexaenoic acid [DHA]. In the absence of DHA, male mice are basically infertile, producing few if any misshaped sperm that can't get where they need to go," explained UI's Manabu Nakamura.

Nakamura, reporting his findings in the Journal of Lipid Research, said that the DHA-deficient knockout mice had extremely low sperm counts and the sperm were round instead of elongated. However, when DHA was introduced into the diet, fertility was completely restored. "It was very striking. When we fed the mice DHA, all these abnormalities were prevented," he said.

Previous studies have suggested that male fertility patients with low sperm counts and less motile sperm tend to have low levels of this fatty acid, but this is the first time that the importance of DHA to male fertility has been shown directly.

The DHA study is part of the Nakamura team's efforts to understand the function of the omega-3 and -6 fatty acids. As part of that work, they have developed a mouse model to help them understand a particular fat's physiological role. "Knocking out the gene for the delta-6-desaturase enzyme has led to some surprising discoveries, including this one about the importance of DHA in sperm formation and mobility," Nakamura said.

Nakamura's team plan to continue focusing on this omega-3's effects on fertility, as there are still things they don't understand. "We get hints from looking at sperm in the DHA-deficient animals about what type of pathology we may be looking at and why these polyunsaturated fatty acids are important. But we're still at the starting point in understanding the mechanisms that are involved, and we need to do more research at the cellular level," he concluded.

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Source: University of Illinois at Urbana-Champaign