Neurons and nicotine addiction

Posted 23rd November 2014 by Dave Cross
To date, nicotine addiction was believed to result from two factors: a reward system activated when using nicotine and a stress system triggered by the withdrawal of the stimulant. A new study has discovered that there are neurons in the brain that are active during both nicotine use and withdrawal.

As covered in Nature Neuroscience magazine, a team led by Olivier George, assistant professor at The Scripps Research Institute in San Diego announced the results of their research titled “VTA CRF neurons mediate the aversive effects of nicotine withdrawal and promote intake escalation.” The team says they think these same neurons may be active in response to other addictive substances.

"If we can find a way to target those neurons in humans, maybe we can reduce the 'high' produced by the drug and reduce the withdrawal symptoms."

Olivier George.

The team hold out hopes that their findings will lead to the development of drugs or gene therapies that can target the neurons and aid in addiction quit attempts.

Previously, the region of the brain they were looking at had only been associated with the pleasure/reward aspect of addiction and not the stress/withdrawal system. Further investigation was triggered when Olivier discovered a protein in that region strongly associated with anxiety and depression.

Using radioactive markers, the team observed the region in rat brain samples and eventually discovered the tell tale black dots on X-ray scans in the ventral tegmental area (VTA) - an area of the brain where the neurons are found.

"If you look in a textbook, these neurons don't exist in the VTA. That was the most exciting day of my career."

Olivier George.

The research was expanded to cover mice and rat brains. The rodents had been developed to have nicotine dependence similar to a human using 40 cigarettes per day.

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Results revealed that the neurons in the VTA were activated during withdrawal, and upon examining brain samples from humans, the team found that these same VTA neurons are present.”

Results from previous studies into rodent and human failed quit attempts have shown that both will return to consuming more nicotine than used originally. Researchers looked to see if this was linked to the neuron activity in this region of the brain.

The team found that rodents with fewer of these neurons did not increase their nicotine uptake.

"That changes the whole conceptual framework. We have to look at everything again, going back to the 1970s. It's possible that when you activate those neurons, you have the reward system that's activated - you have this euphoria, this high - but at the same time you activate this stress peptide."

Olivier George.


 Dave Cross
Article by Dave Cross
Freelance writer, physicist, karateka, dog walker
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