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Like father NOT like son: Offspring of cocaine users less likely to develop habit
20:15 GMT, 16 December 2012
The sons of men addicted to cocaine are actually LESS likely to develop the drug habit themselves, according to a new study.
Scientists looked at the offspring of cocaine-addicted male rats and assessed what impact their father's addiction had on their own behaviour when given the Class A drug.
They discovered that sons of male rats who are exposed to cocaine become resistant to the rewarding 'highs' of the drug.
Wrong direction: A son may not follow his dad's path into cocaine-taking, according to a new study
The findings suggest that sons of male cocaine addicts have undergone physiological changes to protect them from the harmful addiction.
Christopher Pierce, the study's lead author and associate professor of Neuroscience in Psychiatry at Pennsylvania University, said: '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.
'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 behaviour, indicating that paternal exposure to toxins such as cocaine can have profound effects on gene expression and behaviour in their offspring.'
The study, published in Nature Neuroscience, used an animal model to study inherited effects of cocaine abuse.
Male rats took cocaine for 60 days and then mated with females that had never been exposed to the drug.
Stay away: Offspring may well develop a resistance to the cocaine habit of their father
To eliminate any influence that the males' behaviour would have on the pregnant females, they were separated directly after they mated.
Researchers discovered that male offspring of rats exposed to the Class A drug took considerably less cocaine and worked less hard to get a dose compared to fellow rodents whose fathers had not taken the drug.
The findings suggest the rewarding effect of cocaine diminished significantly among the male offspring – although these changes were not seen in female rats.
Male offspring of the cocaine-addicted rats had increased levels of a protein in the prefrontal cortex called brain-derived neurotrophic factor (BDNF), which is known to blunt the behavioural effects of cocaine.
Prof. Pierce, said: 'We were quite surprised that the male offspring of sires that used cocaine didn't like cocaine as much.
'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 findings suggest cocaine use causes epigenetic changes in sperm, reprogramming the information transmitted between generations.
Researchers believe sex hormones such as testosterone, oestrogen and progesterone may play a role in this.