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.

Drs Vilain and Harley believe that the variations in genes that
control SRY or in the SRY gene itself may be linked to the onset of
Parkinson's disease. Men with low levels of SRY may be at greater
risk of developing the disease.

"We were surprised to find a function for SRY outside the testes,"
said Dr Harley.

Scientists at Prince Henry's Institute are collaborating with
Associate Professor Catriona McLean, Director of the National Neural
Tissue Resource Centre at the Alfred Hospital, Melbourne, to
investigate SRY levels in the brains of males with Parkinson's
disease.

Drs Harley and Vilain suspect that the normal role of SRY in the
male brain could be to provide a protective effect against
Parkinson's disease.

"The SRY gene may also explain the sex differences in other dopamine-
linked disorders with a higher incidence in males, such as
schizophrenia or addiction," said Dr Vilain.

One in seven people with Parkinson's disease are diagnosed before
the age of 50 years, and the prevalence increases with age.
Parkinson's disease worsens over time, and there is no known cause
or cure. The severity and progression of the disease can vary
greatly. Symptoms can be managed with medication and surgery.

Main Category: Parkinson's Disease News
Article Date: 23 Feb 2006 - 19:00pm (UK