conducted at the Perelman School of Medicine at the University of Pennsylvania
and Massachusetts General Hospital (MGH) have shown that male off springs of
masculine cocaine-addicted rats are resistant to the rewarding effect of
The study revealed
that cocaine-induced alterations in the genes are passed on from father to son.
It was published in the December edition of Nature
R. Christopher Pierce,
PhD, associate professor of Neuroscience in Psychiatry at Penn mentioned,
"We know that genetic factors contribute significantly to the risk of
cocaine abuse, but the potential role of epigenetic influences -- how the
expression of certain genes related to addiction is controlled -- is still
He added, "This
study is the first to show that the chemical effects of cocaine use can be
passed down to future generations to cause a resistance to addictive behavior,
indicating that paternal exposure to toxins such as cocaine can have profound
effects on gene expression and behavior in their offspring."
The scientists used an
animal model for the current study.
Male rats were given
cocaine for 60 days while controls were given saline. The male rats were given
a chance of mating with females who were unexposed to cocaine and were
separated soon after mating.
The off-springs were
closely monitored to evaluate whether they themselves started to
self-administer cocaine when it was given to them or not.
observed that as compared to female
off-springs, when offered cocaine, male off-springs acquired cocaine
self-administration more slowly and had low levels of cocaine intake
animals were willing to work significantly harder for a single cocaine dose
than the offspring of cocaine-addicted rats, suggesting that the rewarding
effect of cocaine was decreased.'
The researchers in
association with Ghazaleh Sadri-Vakili, MS, PhD, from MGH, assessed the
animals' brains and noted increased level of brain-derived neurotrophic factor
(BDNF), a protein in the prefrontal cortex, in the male off-springs of
cocaine-addicted male rats. This protein is known to blunt cocaine's behavioral
Prof Pierce said,
"We were quite surprised that the male offspring of sires that used
cocaine didn't like cocaine as much."
Pierce further stated,
"While we identified one change in the brain that appears to underlie this
cocaine resistance effect, there are undoubtedly other physiological changes as
well and we are currently performing more broad experiments to identify them.
We also are eager to perform similar studies with more widely used drugs of
abuse such as nicotine and alcohol."
The study suggested
that cocaine can result in epigenetic alterations in sperm, hence causes reprogramming
of information transmission among generations. The researchers however do not
know the exact cause for male off-springs receiving the cocaine-resistant
traits from their fathers.
They suggested that
sex hormones are responsible for this genetic transmission from fathers to
Resistance to Cocaine Addiction May Be Passed
Down from Father. Science Daily