Recently, researches 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 cocaine.
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 Neuroscience.
AdvertisementR. 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 relatively unknown,"
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.
The scientists 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.
'Moreover, control 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 effects.
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 sons.
Resistance to Cocaine Addiction May Be Passed Down from Father. Science Daily