( SRY in the substantia nigra they saw ...)UCLA scientists find male gene in brain area targeted by Parkinson's

In a surprise finding, the drop in TH occurred only in the male rats. The female rats remained unaffected.

"When we reduced SRY levels in the rats' brains, the male animals began experiencing the movement problems caused by insufficient dopamine," Vilain said. "Low levels of SRY triggered Parkinson's symptoms in the male rats, cutting their physical agility by half in a week.

"Initially, the rat could walk 14 steps in 10 seconds," he noted. "After we lowered the SRY levels in its brain, the rat could only manage seven steps in the same amount of time."

Vilain believes that variations in SRY levels may be linked to the onset of Parkinson's and could offer insights into who is at risk for the disease.

"SRY may serve as a protective agent against Parkinson's," he said. "Men who contract the disease may have lower levels of the gene in the brain."

Because SRY is found only in males, Vilain thinks women must possess another physiological mechanism that protects dopamine-producing cells in the substantia nigra.

"We suspect that estrogens in women could play the same role as SRY in protecting the female brain from Parkinson's disease," he said. "Our lab is currently studying this hypothesis in an animal model."

Sex differences in other dopamine-linked disorders, such as schizophrenia or addiction, may also be explained by the SRY gene, Vilain said.

"It's possible that dopamine-related disorders that reveal dramatic differences in severity and rates in the genders could depend on the SRY levels in the brain," he said.