Skip to content

Researchers begin to map the neurogenetics of susceptibility in addiction.

A team from the University of South Carolina have been studying one of the fundamental biomolecules contributing to human addiction, the mu-opioid receptor. It’s a protein in the human body that is affected by many different drugs, from nicotine to alcohol to heroin.  The study is published in the journal Neuropharmacology.

This receptor was brought to the researcher’s attention is that a seemingly small change in its makeup can have a dramatic effect on many of the behaviours of the creature it is part of. Every protein is made of up many individual subunits called amino acids, and a variation in just one of those amino acids can sometimes mean big changes for the whole organism.

Previous studies show that among humans, there are two relatively common versions of the mu-opioid receptor that differ only by one amino acid, sometimes called the A variant and the G variant. In Caucasians, the G variant only makes up perhaps 5 percent to 15 percent of the population. Population studies are still relatively new, however, some associations between individuals having the variant and their behavior are becoming clear. People with the G variant of the protein can quit smoking more readily. They’re less susceptible to alcoholism. They’re less likely to become addicted to heroin and can kick the habit more readily. As children, they seem to be more resilient in the face of stressful situations, such as abuse by elders or bullying.  Organisms that have the G variant of the protein are said to have the G allele.

The current study set out to investigate how this single change in DNA, one point, one nucleotide, translated into such dramatic changes in behaviour, in social responses and in pleasure seeking.  The team addressed one of the fundamental questions researchers have been asking about the difference between individuals with the A and G variant, and investigated whether it is caused by a difference in amount or in function of the mu-opioid receptor.

Working with an animal model that has been shown to replicate addictive behaviours closely analogous to those in humans, the team compared individuals with the two variants. They found evidence that the G variant gives rise to a different kind of neural system in the hippocampus, a substructure in the brain.  The data findings showed that with the G variant the response to added morphine was attenuated in the hippocampal microcircuitry.

The researchers state that an alternate hypothesis, that the differences brought about by the G variant are the result of smaller amounts of the protein being expressed there, wasn’t categorically rejected, however the evidence for loss of function in the opioid receptor is strong.  They go on to add that to the fund of knowledge about the opioid receptor will increase the clinical potential that already exists for precision medicine.  The team conclude that in the future, addicted patients can be tested for these genetic variations and given the appropriate drug.

Source:  South Carolina College of Pharmacy

Microcircuitry in the Brain.  The mu-opioid receptor role in the hippocampal circuit is shown.  Credit:  Adapted from the journal Neuropharmacology.
Microcircuitry in the Brain. The mu-opioid receptor role in the hippocampal circuit is shown. Credit: Adapted from the journal Neuropharmacology.

Healthinnovations View All

Michelle Petersen is the founder of Healthinnovations, having worked in the health and science industry for over 21 years, which includes tenure within the NHS and Oxford University. Healthinnovations is a publication that has reported on, influenced, and researched current and future innovations in health for the past decade.

Michelle has been picked up as an expert writer for Informa publisher’s Clinical Trials community, as well as being listed as a blog source by the world’s leading medical journals, including the acclaimed Nature-Springer journal series.

Healthinnovations is currently indexed by the trusted Altmetric and PlumX metrics systems, respectively, as a blog source for published research globally. Healthinnovations is also featured in the world-renowned BioPortfolio, BioPortfolio.com, the life science, pharmaceutical and healthcare portal.

Most recently the Texas A&M University covered The Top 10 Healthinnovations series on their site with distinguished Professor Stephen Maren calling the inclusion of himself and his team on the list a reflection of “the hard work and dedication of my students and trainees”.

Michelle Petersen’s copy was used in the highly successful marketing campaign for the mega-hit film ‘Jumanji: The Next Level, starring Jack Black, Karen Gilian, Kevin Hart and Dwayne ‘The Rock’ Johnson. Michelle Petersen’s copywriting was part of the film’s coverage by the Republic TV network. Republic TV is the most-watched English language TV channel in India since its inception in 2017.

An avid campaigner in the fight against child sex abuse and trafficking, Michelle is a passionate humanist striving for a better quality of life for all humans by helping to provide traction for new technologies and techniques within healthcare.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.