Authors Explore the Role of the SRY Gene in Male Fight-Or-Flight Response
The pulse quickens, the heart pounds and adrenalin courses through the
veins, but in stressful situations is our reaction controlled by our
genes, and does it differ between the sexes? Australian scientists,
writing in BioEssays,
believe the SRY gene, which directs male development, may promote
aggression and other traditionally male behavioural traits resulting in
the fight-or-flight reaction to stress.
Research has shown how the body reacts to stress by activating the
adrenal glands which secrete catecholamine hormones into the bloodstream
and trigger the aggressive fight-or-flight response. However, the
majority of studies into this process have focused on men and have not
considered different responses between the sexes.
“Historically males and females have been under different selection
pressures which are reflected by biochemical and behavioural differences
between the sexes,” said Dr Joohyung Lee, from the Prince Henry’s
Institute in Melbourne. “The aggressive fight-or-flight reaction is more
dominant in men, while women predominantly adopt a less aggressive
tend-and-befriend response.”
Dr Lee and co-author Professor Vincent Harley, propose that the
Y-chromosome gene SRY reveals a genetic underpinning for this difference
due to its role in controlling a group of neurotransmitters known as
catecholamines. Professor Harley’s earlier research had shown that SRY
is a sex-determining gene which directs the prenatal development of the
testes, which in turn secrete hormones which masculinise the developing
body.
“If the SRY gene is absent the testes do not form and the foetus
develops as a female. People long thought that SRY’s only
function was to form the testes” said Professor Harley. “Then we found
SRY protein in the human brain and with UCLA researchers led by
Professor Eric Vilain, showed that the protein controls movement in
males via dopamine.”
“Besides the testes, SRY protein is present in a number of vital organs
in the male body, including the heart, lungs and brain, indicating it
has a role beyond early sex determination,” said Dr Lee. “This suggests SRY
exerts male-specific effects in tissues outside the testis, such as
regulating cardiovascular function and neural activity, both of which
play a vital role in our response to stress.”
The authors propose that SRY may prime organs in the male body to
respond to stress through increased release of catecholamine and blood
flow to organs, as well as promoting aggression and increased movement
which drive fight-or-flight in males. In females oestrogen and the
activation of internal opiates, which the body uses to control pain, may
prevent aggressive responses.
The role of SRY regulation of catecholamines also suggests the
gene may have a role in male-biased disorders such as Parkinson’s
disease.
“New evidence indicates that the SRY gene exerts ‘maleness’ by
acting directly on the brain and peripheral tissues to regulate movement
and blood pressure in males,” concluded Lee. “This research helps
uncover the genetic basis to explain what predisposes men and women to
certain behavioural phenotypes and neuropsychiatric disorders.”
