Changes in Brain Assisting Cocaine Addiction

A new research led by Scripps research institute revealed a phenomenon because of which addiction to cocaine occurs in individuals

The brain while ramping up its use shifts from moderate cocaine use to addiction due to this phenomenon. During the experiment in rats, the scientist showed that how moderate use of cocaine is converted to compulsive cocaine intake by transmission of serotonin from two different regions.

Serotonin is mainly produced from 2 major parts of brain i.e. dorsal raphe nucleus (DRN) Medial Saphe Nucleus (MRN) and when the use of cocaine increases, transmission of serotonin from the DRN predominates its transmission from MRN which in turn changes the level of corticotrophin-releasing factor(CRF) also known as a stress hormone. This results in a compulsive aspect of drug taking.

A recent study published in journal Biological Psychiatry revealed the reasons why some get addicted to cocaine more likely. They showed that these individuals which get addicted to cocaine more likely. They showed that these individuals more likely carry gene polymorphism which reduces the expression of a protein called serotonin transporter. This protein is responsible for eradicating serotonin from synapses.

In a laboratory, they discovered that if SERT is missing in the rat, it consumes more cocaine, as well as its CRF, are more sensitive and its level change is triggered by cocaine.

The specific role of DRN an MRN was not known although they knew that low levels of SERT expression increase anxiety and cocaine intake in both humans and rats.

Researchers silenced the SERT expression in the DRN or MRN by RNA interference technique. After silencing gene alternatively, they were able to know how serotonin transmission from those two regions impacts cocaine consumption. They also found that when SERT expression is reduced then MRN stimulates to ramp up cocaine intake but when it is silenced, there was no effect under a condition that produces increasing uncontrollable intake. When SERT expression reduced in DRN increased compulsive cocaine use, there was no effect on moderate cocaine use. In the light of this, the scientist suggested that cocaine consumption is increased due to the influence of DRN or MRN i.e. DNA begins to dominate the influence of MRN.

During this study, they also found that it is important to maintain balance the activity of serotonin between MRN and DRN. Being aware of this, MRN can be targeted in the early stages of drug and DRN in later stages so that the shift from moderate intake to addiction can be stopped.