01 June 2017

Drug addiction by inheritance

Addiction to cocaine addiction can be transmitted epigenetically

Chinese scientists have found a new mechanism for the inheritance of addiction in rats

Natalia Pelezneva, Naked Science

When using cocaine, there are many negative effects, including the development of addiction. Cocaine affects three neurotransmitter systems that are fundamentally important for nervous activity: dopamine, noradrenaline and serotonin. Disorders of dopamine metabolism caused by the use of the substance can lead to the development of specific psychoses. Cocaine is included in List I of the UN Single Convention on Narcotic Drugs – compounds from this list require the strictest control.

Studies show that addiction to cocaine addiction can be inherited. Many works are devoted to this phenomenon. Rats are often the model animals for such studies – they can also develop drug addiction.

The authors of the new study stated that they were able to detect the mechanisms of epigenetic inheritance of addiction in rats. With epigenetic inheritance, the DNA sequence does not change, inherited changes in the phenotype or gene expression are caused by other mechanisms.

During the experiment, a group of 134 male rats were given free access to the drug. The animals could get it at any moment by pressing the lever. Then the scientists identified a group of rats more prone to addiction. To get the drug, the animals had to press the lever several times: addicted rats pressed it more often. According to scientists, the development of addiction was not related to the dose of the drug, but to the level of motivation of the animal. After that, both dependent and non-dependent rats were crossed with females who had no dependence.

The offspring were examined in the same way. The cubs of dependent males turned out to be more prone to developing addiction – they pressed the lever more often and could make more clicks than the cubs of rats without addiction. 

a, b – the development of dependence, c – inheritance, d – the development of dependence in descendants
(Le et al., Drug-seeking motivation level in male rats determines offspring susceptibility
or resistance to cocaine-seeking behaviour // Nature Communications).

Using bisulfite sequencing, scientists investigated the DNA methylation of dependent and non-dependent rats and their descendants. When DNA is methylated, the nucleotide sequence does not change, but a methyl group is attached to the cytosine in the DNA. Methylation can regulate gene expression, it is one of the mechanisms of epigenetic inheritance. Scientists found a difference in methylation of 1244 CpG islets in dependent and non-dependent rats. This suggested that addiction may be associated with epigenetics. Further research will show exactly how this mechanism affects the body of animals.

Previously, scientists managed to weaken the manifestations of cocaine addiction in rats by suppressing TrkB protein receptors.

Portal "Eternal youth" http://vechnayamolodost.ru  01.06.2017

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