Tue, Feb 28, 2017 | updated 07:54 PM IST

New study uses brain receptors to suppress cocaine addiction

Updated: Oct 13, 2016 08:37 IST

Washington D.C. [USA], Oct. 13 (ANI): Researchers at the Medical University of South Carolina (MUSC) have used viruses to infect neurons with genes that allow them to switch on brain receptors involved in suppressing addiction relapse.

The technology called designer receptors exclusively activated by designer drugs or DREADDs is one of the most promising gene therapies for future treatment of addiction in humans.

The brains of people, who use cocaine, become hijacked by drug cues.

Powerful memories are formed between these cues-such as using environment and drug paraphernalia-and the dopamine flood that occurs from using the drug itself.

In users trying to quit, these drug cues activate an intense desire to seek cocaine again.

Resistance to relapse is partly mediated in the ventromedial prefrontal cortex-the brain region slightly above and behind our eyes, where previously learned associations are broken.

This region of the brain stores extinction memory, which works to suppress the emotional response to drug, cues, according to Jamie Peters, the lead researcher of the study.

"Extinction doesn't overwrite the original memory. It just helps suppress the pathological component of the response," explained Peters.

The team wanted to know if the response to drug cues associated with the dopamine rush of cocaine could be suppressed when the extinction memory region was activated.

To test their hypothesis, they obtained viruses carrying the DREADD gene.

The viruses work by inserting the DREADD gene directly into the genome of cells, causing them to grow receptors on their surface that are normal except for a slight alteration.

These receptors express a protein encoded by the DREADD gene that allows them to be activated by a single drug designed to bind that protein.

In this case, the Peters lab infused a virus carrying a DREADD gene designed to change surface receptors on neurons.

After the neurons were infected, they would fire in response to administration of the designer drug. Because the body's other cells had not been infected with the DREADD gene, they would remain unaffected.

"This new approach for treating drug addiction is exactly what is needed because it is targeted to a specific circuit in the brain regulating addiction. This may allow the circuit to be selectively regulated with minimum side effects on other circuits and brain functions," said Kalivas.

The researchers allowed rats to self-administer cocaine by pressing one of two levers, one active and one inactive.

Once a rat pressed the active lever, cocaine was delivered along with a brief audio tone and a pulse of light that would serve as the drug cues.

After a series of daily cocaine exposure sessions, the rats had learned to associate the simple drug cues with cocaine availability.

Then they were removed from the drug. Next a surgical technician infused virus carrying the DREADD gene directly into the rats' ventromedial prefrontal cortices.

After two weeks of cocaine abstinence, the rats were placed back in front of the two levers in ten daily sessions, but this time the levers produced neither cues nor cocaine.

The next day, rats were subjected to a relapse test where the cues were returned. Before testing, half of the rats were given designer drug and half were not.

Next, rats underwent an additional relapse test where they were given a low dose of cocaine to trigger relapse.

The experiments worked. Rats that were given the designer drug relapsed less in the presence of drug reminder cues.

However, when exposed to cocaine again, rats relapsed regardless of whether they were given the designer drug. In other words, Peters' hypothesis was correct: rats with activated extinction memories weren't as susceptible to relapse triggered by cocaine-associated cues but were still vulnerable when exposed to cocaine again.

This meant that extinction memory retrieval reduced relapse triggered by reminder cues.

This study shows that it is possible to use this technology to target a small population of cells in the brain that is important for regulating addiction, thereby inhibiting the drive to relapse to addictive drug use.

In the future, Peters hopes that safe and effective viruses of this kind can be infused into the brains of human addicts during neurosurgery.

A person would simply take a pill to activate the extinction memory region of their brain, helping them to suppress the urge to seek out drug in the face of those reminder cues.

Since extinction memory isn't as powerful as the emotional response to a drug, this strategy could work when paired with effective psychological counseling approaches such as cognitive behavioral therapy.

Clinicians interested in using DREADDs in humans will have to remain patient, however. DREADDs have to be designed to match drugs that suppress only memories of drug cues while leaving other memories unaffected.

And the crystal structure of newer human-appropriate designer drugs bound with the special receptors is being actively investigated in order to visualize exactly how they might work some day in patients with cocaine addiction.

"Certainly within my lifetime I would expect to see these virus-mediated gene therapies start to be used in the brain, in a neurosurgical setting. You can envision a person ultimately taking a pill to activate this very specific part of his or her brain," said Peters.

The study was published in the Journal of Neuroscience. (ANI)

New Delhi [India], Feb. 28 (ANI): Society for the Promotion of Indian Classical Music and Culture Amongst Youth (SPIC MACAY) is organising its annual International Convention in its 40th year at IIT Delhi from 5th -11th June, 2017.

Full Story >>

Washington D.C. [USA], Feb. 28 (ANI): A study finds that diagnostic mammography has improved cancer detection rates, but has also increased the abnormal interpretation rate.

Full Story >>

New Delhi [India], Feb. 27 (ANI): Age is just a number, proves Amitabh Bachchan!

Full Story >>

Washington D.C. [USA], Feb. 28 (ANI): A study reveals millennials, pursuing career in public relations, do not feel the need to give advices on moral dilemmas, as for them, ethics are better left to the legal department or that role is beyond their responsibilities.

Full Story >>

Washington D.C. [USA], Feb. 27 (ANI): Eating apples, pears, citrus fruits, salads and green leafy vegetables above ten portions a day may reduce the chances of heart attack, stroke, cancer and early death, suggests a study.

Full Story >>

New Delhi [India], Feb 27 (ANI): India's number one craft beer brand Witlinger has launched its authentic taste and flavors with the new initiative #NowRolling to enhance consumer knowledge about craft beer with an engaging impact on the Indian Craft Beer scene.

Full Story >>

Washington D.C. [US], Feb. 26 (ANI): Beware and get your stress treated, as a study warns people who suffer from long-term stress may be more prone to obesity.

Full Story >>

Karachi [Pakistan], Feb. 26 (ANI): Plans for Lahore Literary Festival 2017 did not go as well as expected.

Full Story >>

Washington D.C. [US], Feb. 26 (ANI): A study finds, eating nutrient-enriched diet during adolescence or childhood development may alter long-term behaviour and learning among ladies.

Full Story >>

New Delhi [India], Feb. 25 (ANI): Vivek Chaand Sehgal, chairman of the Motherson Sumi Systems Limited (MSSL), has recently been named the EY Entrepreneur of 2016 for its outstanding contribution in the world of entrepreneurship.

Full Story >>

New Delhi [India], Feb 25 (ANI): In your free time for book lovers nothing can be more interesting than spending time with some great food paired with an array of teas while having a favorite novel in hand. Located in the prime location of Delhi, Cha Bar located inside Oxford Bookstore has lots to offer to its customers.

Full Story >>

New York [USA], Feb. 25 (ANI): It's not only the peer pressure that makes kids try alcohol or smoke pot!

Full Story >>

'Straight' women tend to orgasm less!

Updated: Feb 25, 2017 06:27 IST

New York [USA], Feb. 25 (ANI): 'Orgasm gap' is something all have experienced while making love.

Full Story >>

New Delhi [India], Feb. 25 (ANI): A European study has revealed that the majority of university students believe it is the social norm to use drugs like Ritalin to enhance academic performance - despite very few having used stimulants themselves.

Full Story >>

New Delhi [India], Feb. 25 (ANI): "What will they say about you? Maybe they'll say you showed them what's possible."- This is what sports brand Nike has to say through their new commercial, which has gone viral on the Internet.

Full Story >>

Washington D.C. [US], Feb. 24 (ANI): Parents, please take note! A study warns teenagers who self-report feeling drowsy during mid-afternoon, are 4.5 times more likely to commit violent crimes a decade and a half later.

Full Story >>

Washington D.C. [USA], Feb. 24 (ANI): A team of US researchers warn, fathers, who do cocaine at the time of conceiving a child, may be putting their son at risk of learning disabilities and memory loss.

Full Story >>

Washington D.C. [USA], Feb. 24 (ANI): Waring for all the sea food lovers! Consuming fish, rich in mercury may double the risk of developing motor neurone disease.

Full Story >>

New Delhi [India], Feb. 23 (ANI): A two- day annual fest "POLITIA" was organised by political science department of Shyama Prasad Mukherjee college for Women, University of Delhi, on February 20 and 21.

Full Story >>