A Man's Sense of Taste May be Linked to Infertility: A Study

The same proteins that enable us to taste may also play a crucial role in male fertility, according to a new study published in the Proceedings of the National Academies of Sciences.

Conducted by researchers from the Monell Center in Philadelphia, the scientists found that two proteins that allow the body to taste sweet and savory flavors are also active in the man's testes and sperm.

According to Dr. Bedrich Mosinger, a molecular biologist and the study's lead author, the report "is one more demonstration that components of the taste system also play important roles in other organ systems."

The discovery was made while adjusting mice's availability of two taste-sensitivity proteins  - TAS1R3, a component of both the sweet and umami (amino acid) taste receptors, and GNAT3, a molecule needed to convert the oral taste receptor signal into a nerve cell response. Afterward, they them mate.

The scientists first engineered mice that were missing genes for the mouse versions of both proteins but expressed the human form of the TAS1R3 receptor. These mice were fertile.

However, when the human TAS1R3 receptor was blocked in the engineered mice by adding the drug clofibrate to the rodents' diet, thus leaving the mice without any functional TAS1R3 or GNAT3 proteins, the males became sterile due to malformed and fewer sperm.

That sterility was quickly reversed, though, after clofibrate was removed from the diet.

Clofibrate belongs to a class of drugs called fibrates that frequently are prescribed to treat lipid disorders such as high cholesterol or triglycerides.

With worldwide fertility on the decline, Mosinger and speculates that the use of fibrates in modern medicine and the widespread use in agriculture of the structurally-related pheoxy-herbicides, which also block the human TAS1R3 receptor, may be at least partially responsible.

"Like much good science, our current findings pose more questions than answers," comments Monell molecular neurobiologist and study contributor Dr. Robert Margolskee. "We now need to identify the pathways and mechanisms in testes that utilize these taste genes so we can understand how their loss leads to infertility."