Scientists identify brain circuit responsible for cocaine seeking behavior during relapse.

I always thought cocaine was garbage anyways, yet it's something that is hard to turn down. I came across this article and thought it should be shared with the DF community. Hope it helps!

I attached a PDF also of these findings.

Approximately 1.5 million Americans use cocaine in a given year, according to
the National Institute on Drug Abuse. Many are repeat users. Unfortunately,
there are currently no FDA approved medicinal treatments for cocaine
addiction.

Behavioral therapy is the only treatment option for patients with cocaine
addiction. Unfortunately, many treated patients remain susceptible to relapse
when re-exposed to cues, such as settings or specific places, which remind
them of the drug experience.

"If a cocaine addict who is used to doing cocaine in his or her sports car goes
through behavioral therapy, it will be difficult to remove the cue of the sports
car when he or she finishes therapy. That can result in a relapse," explains
noted addiction researcher Peter W. Kalivas, Ph.D.

Kalivas is a distinguished university professor and chair of the Department of
Neuro-science at the Medical University of South Carolina (MUSC).
Kalivas and his colleagues report in the March 13, 2019 issue of the
Journal of Neuro-science that they have identified a type of neuron that is critical for
cocaine seeking behaviors in rodents.

These neurons, known as dopamine D1 receptor expressing medium spiny
projection neurons (D1MSNs), are located in a well known area of the
reward system, the nucleus accumbens. The team also discovered that these
neurons drive drug seeking through their projections to a specific part of the
brain, the ventral pallidum (VP).

The team includes senior author Jasper Heinsbroek, Ph.D., a postdoctoral
scholar at MUSC working with Kalivas, and first author Thibaut PardoGarcia.
PardoGarcia was a post baccalaureate student in the Kalivas laboratory when
the study was conducted and is currently a graduate student at the University
of Michigan.
Reviewed by
James Ives, MPsych
Mar 19 2019

"It's kind of a breakthrough that Jasper has shown very definitively that this
ventral pallidum output is actually carrying the drive to engage in the drug
seeking behavior," explains Kalivas.

D1MSN coexist in the nucleus accumbens alongside another cell type, the
D2MSNs. Both cells play a critical role in the brain system that regulates
goal directed behavior. Goal directed behavior can be geared towards looking
for shelter, finding a mate, or even getting high. As such, D1MSNs activity
could reinforce behaviors that would lead to drug relapse, while D2MSNs
instead may help avert these behaviors.

"There is a clear distinction between the function of these two types of
neurons within the nucleus accumbens," explains Heinsbroek.

"Increased activity of D1MSNs after drug use leads to higher motivation to
seek drugs. Exposure to drugs reduces the capacity of D2MSNs to limit
excessive motivation. This can lead to a strong drive to seek drugs over
natural rewards such as food and shelter in the presence of drug cues."

To investigate how D1MSNs drive the motivation to seek drugs, the MUSC
team traced the connections of these neurons. They showed that individual
neurons project to both the VP and another major area that regulates
motivation, the ventral mesencephalon (VM).

To help identify whether the VP or VM projection is responsible for cocaine
seeking behavior, the researchers used a transgenic rat model provided by
collaborators at the National Institute of Drug Abuse. This animal model
allowed the researchers to inhibit the activity of D1MSNs and their
projections to the VP versus the VM.

The MUSC team found that cocaine seeking continued to exist when the VM
projections were inhibited. However, inhibiting projections to the VP strongly
diminished the motivation to seek cocaine.

"These transgenic rats allowed us to specifically target the projections of D1
MSNs using genetic technology," explains Heinsbroek. "Without them,
identifying D1 projections to the VP as important drivers of cocaine seeking
would not have been possible."

These findings open a new avenue of research into cocaine addiction. They
also point to novel therapeutic targets that merit further investigation. Kalivas
and his laboratory aim to continue to explore the mechanisms that underlie
drug addiction because, as with these findings, they could hold the key to
future therapies.

"We need to find out how drugs change the brain so that we can actually cure
people who are afflicted," says Kalivas. "We have discovered a circuit that is
critical for relapse and identified a specific target, which we could potentially
go in and modify and have a chance at curing addiction."

Source: http://www.musc.edu/