Sons of cocaine users less likely to develop the habit: study

A new study 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.

Researchers discovered that male offsprings of rats who are exposed to cocaine become resistant to the rewarding 'highs' of the drug, the 'Daily Mail' reported.

The findings suggest that sons of male cocaine addicts have undergone physiological changes to protect them from the harmful addiction.

"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," Christopher Pierce, the study's lead author and associate professor of Neuroscience in Psychiatry at Pennsylvania University, said.

"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," Pierce said.

In the study, male rats took cocaine for 60 days and then mated with females that had never been exposed to the drug.

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.

"We were quite surprised that the male offspring of sires that used cocaine didn't like cocaine as much," Pierce said.

"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," Pierce added.

The findings published in journal Nature Neuroscience suggest cocaine use causes epigenetic changes in sperm, reprogramming the information transmitted between generations.