mice in laboratory  Sometimes the most well-laid scientific plans can take a surprising turn. That happened recently at Philadelphia's Monell Chemical Senses Center, where a team of researchers was experimenting on mice and their taste receptors. Mice and humans have taste receptors all over their bodies, including the testicles. When researchers removed or blocked certain taste receptors from the gonads of male mice, the rodents became infertile.

Molecular biologist Bedrich Mosinger, MD, PhD, led the research team to remove or block the taste receptors for sweet and umami in the mice. Lab mice were engineered not to have two molecules crucial to the process of taste - the TAS1R3 and the GNAT3. What happened as a result is they expressed a human form of the TAS1R3 molecule. And they were fertile.

The mice expressing the human form of the molecule were the given the drug clofibrate to block the mouse's receptor for TAS1R3. Sperm count in the male mice dropped significantly and the sperm was malformed; the mice were now sterile. There was no change in fertility status on the female mice in the study.

What does this weird mouse science mean for humans? Many people take clofibrate to treat disorders of the lipids, such as high triglycerides and high serum cholesterol. Many others take medications structurally similar to phenoxy-herbicides, which also block the receptor for human TAS1R3. Taking these medications could hinder a man's chance of fathering a child.

Mosinger says if his findings "are indeed related to the global increase in the incidence of male infertility, we now have knowledge to help us devise treatments to reduce or reverse the effects." He further suggests the knowledge gleaned from this study could be used to develop a male contraceptive that does not affect hormones.

Mosinger's findings are available online at the National Academy of Sciences website.