Gender Gap: Male-Only Gene Affects Men's Dopamine Levels

Article excerpt

A gene found only in men is key to regulating the brain's production of dopamine, a new study shows. The finding offers a clue to why men are more likely than women to develop dopamine-related illnesses such as Parkinson's disease, schizophrenia, and addiction. Together with another new study, the work suggests that women and men have distinctive dopamine-regulating systems.

The gene, called Sry, is found on the Y chromosome and is therefore exclusive to men. Sry determines gender, signaling an embryo's gonads to develop into testes rather than ovaries.

Unexpectedly, the gene also performs a function not related to sex, says geneticist Eric Vilain of the University of California, Los Angeles. The researchers found that Sry makes a protein that controls concentrations of dopamine, a neurotransmitter produced in a central brain region called the substantia nigra. Dopamine carries signals from the brain to the body that control movement and coordination.

In people with Parkinson's disease, dopamine-producing neurons in the substantia nigra start to die off, and the brain gradually loses control of physical movements. Tremors and eventually paralysis result. Men are 1.5 times as likely as women to develop the degenerative disease.

To test the effect of Sry, the researchers suppressed the gene's expression in one side of the substantia nigra of male rats. The rats lost 38 percent of the dopamine-producing neurons on that side, the team reports in the Feb. 21 Current Biology. The rats also suffered Parkinson's-like loss of motor function on the side of the body controlled by the altered portion of the brain. …