`Macho` gene drives aggressive stress response

Washington: Ever wondered why men react more aggressively than women under stress? It`s because all their response boil down to a single "macho" gene, scientists say.

Australian researchers who discovered the SRY gene said it could explain why men have a "fight or flight" response while women are more likely to try and defuse the situation.

The gene, found only on the Y chromosome, was previously thought to be involved only in the development of male characteristics in the womb.

But new study, led by Prof Joohyung Lee of Prince Henry`s Institute in Melbourne and Prof Vincent Harley of Monash University, showed that its proteins are present in the brain and other organs of adult males, LiveScience reported.

The researchers found that the gene also helps in the release of the neurotransmitter dopamine, which is crucial to movement. It`s also found in the adrenal glands, which secrete norepinephrine and epinephrine.

All three chemicals are important in regulating how our bodies respond to stress, they added. This male-only SRY gene may "prime" the male body for a more aggressive stress response, Lee and Harley reported in the journal BioEssays.

Their idea is still speculative. To find out if it`s true, researchers will need to determine how SRY acts in the brain and in other tissues.

They will need to find out what happens when the SRY gene is blocked from being expressed and also look into other sex-linked genes to understand how they work in tandem with gonadal (sex) hormones to create sex differences in the brain.

If their hypothesis is right, the researchers wrote, "SRY could have medical implications." Disorders such as Parkinson`s disease, autism, attention deficit/hyperactive disorder and schizophrenia are all more common in men than in women, and they all involve alterations in the body chemicals, such as dopamine, that the SRY gene influences, the researchers said.

"Better understanding the degree and nature of interactions between the sex-specific genes, gonadal hormones and epigenetic pathways will undoubtedly shed light on what predisposes men or women to certain behavioural phenotypes and neuro-psychiatric disorders," they wrote.