Scientists at Prince Henry's Institute, Melbourne, and the University of California, Los Angeles, have discovered that SRY, the male protein that forms the testes is also produced in the brain region affected in Parkinson's disease. This discovery may explain why men are more likely than women to develop this degenerative disorder.
"Our research has shown that a gene only present in males contributes to the control of physical movement, a fundamental brain function," said Associate Professor Vincent Harley, Head of the Human Molecular Genetics Group at Prince Henry's Institute.
Parkinson's disease is a chronic movement disorder that affects an estimated 40,000 Australians. Men are 1.5 times more likely to develop the disease than women.
SRY, the protein that determines male gender, was discovered by British scientists in 1990. Dr Harley joined the team and was the first to show functions of the SRY protein in males. SRY is passed from father to son on the Y chromosome and is not present in females.
Co-investigators Dr Eric Vilain of UCLA and Dr Harley have now traced the SRY protein to a region of the brain called the substantia nigra, which deteriorates in Parkinson's disease.
Parkinson's disease develops when cells in the substantia nigra begin to malfunction and die, producing less dopamine. Dopamine, a chemical messenger, communicates with the brain to control movement and co-ordination. People with Parkinson's disease become unable to initiate or control their physical movements, eventually leading to paralysis.
The Prince Henry's Institute team, led by Dr Harley, developed sensitive new tools to detect SRY protein in the brain. UCLA scientists, led by Dr Vilain, lowered the level of SRY in the substantia nigra in animal models and detected a corresponding drop in tyrosine hydroxylase, which plays a key role in the brain's production of dopamine. The consequent low dopamine levels resulted in Parkinson's-like movement problems.