Featured Research

from universities, journals, and other organizations

Neurotransmitter Orexin Associated With Pleasure And Reward Pathways In The Brain

Date:
August 28, 2005
Source:
University of Pennsylvania School of Medicine
Summary:
Researchers at the University of Pennsylvania School of Medicine have discovered that the recently identified neurotransmitter orexin (also known as hypocretin) influences reward processing by activating neurons in the lateral hypothalamus region of the brain. By identifying the relationship between orexin neurons and behaviors associated with reward seeking, drug relapse, and addiction, researchers hope to find new treatments for drug addiction.

Philadelphia, PA -- Researchers at the University of PennsylvaniaSchool of Medicine have discovered that the recently identifiedneurotransmitter orexin (also known as hypocretin) influences rewardprocessing by activating neurons in the lateral hypothalamus region ofthe brain. By identifying the relationship between orexin neurons andbehaviors associated with reward seeking, drug relapse, and addiction,researchers hope to find new treatments for drug addiction.

Related Articles


Previous studies have linked orexin activity to sleep and arousal(wakefulness), as well as feeding and appetite. Anatomical studies haveshown that orexin neurons extend into the brain regions associated withreward pathways, including the ventral tagmental area and nucleusaccumbens. Communication between the lateral hypothalamus and thesebrain regions suggests that orexin neurons may have a role inmotivation and reward-seeking behavior. In order to examine therelationship between orexin and reward seeking, Glenda Harris, PhD,working with Gary Aston-Jones, PhD, in the Department of Psychiatry atPenn, examined orexin function in rats using a behavioral test aimed atmimicking food- and drug-reward seeking and drug relapse. This researchappeared online in Nature on August 14.

"The lateral hypothalamus has been tied to reward and pleasurefor decades, but the specific circuits and chemicals involved have beenelusive," says Aston-Jones. "This is the first indication that theneuropeptide orexin is a critical element in reward-seeking and drugaddiction. These results provide a novel and specific target fordeveloping new approaches to treat addiction, obesity, and otherdisorders associated with dysfunctional reward processing."

Harris and Aston-Jones found a strong association between theactivation of orexin neurons in the lateral hypothalamus and rewardseeking of morphine, cocaine, and food. Using Fos, a chemical marker ofneuronal stimulation, the researchers found that the highest levels ofactivity in the orexin neurons appeared in rats demonstrating thegreatest level of reward seeking.

The researchers demonstrated the connection between orexinsand the reward pathway in three ways. First, the activation of orexinneurons is related to preferences by the rats for cues associated withdrug and food rewards. Second, chemical activation of orexin neuronsreinstated an extinguished drug-seeking behavior in rats. And finally,direct injection of orexin reinstated drug-seeking behavior. Inaddition, when the researchers administered a specific orexinantagonist, the initial learning of a drug preference and thereinstatement of extinguished drug-seeking behavior were blocked.

Because of the relationship between orexin activation andreinstatement of reward-seeking behavior, these findings may haveimplications for understanding drug-taking relapse in humans. Ananimal's reward seeking can be extinguished over time by repeatedlyexposing the animal to the environment possessing drug-related cueswithout the previous drug rewards. After extinguishing reward seeking,presenting a stimulus that was previously associated with the drug willlead animals to quickly resume reward seeking, similar to what happenswhen humans have a drug relapse. Using rPP, a neuropeptide thatactivates orexin neurons in the lateral hypothalamus, the researcherswere able to reinstate drug seeking in the rats formerly possessingextinguished drug-seeking behavior.

"These findings indicate a new set of neurons and associatedneuronal receptors that are critical in consummatory rewardprocessing," says Aston-Jones. "This provides a new target fordeveloping drugs to treat disorders of reward processing such as drugand alcohol addiction, smoking, and obesity."

###

Mathieu Wimmer, also in theAston-Jones lab, was a co-author on the study. This research was fundedby the National Institute on Drug Abuse.



Story Source:

The above story is based on materials provided by University of Pennsylvania School of Medicine. Note: Materials may be edited for content and length.


Cite This Page:

University of Pennsylvania School of Medicine. "Neurotransmitter Orexin Associated With Pleasure And Reward Pathways In The Brain." ScienceDaily. ScienceDaily, 28 August 2005. <www.sciencedaily.com/releases/2005/08/050827140339.htm>.
University of Pennsylvania School of Medicine. (2005, August 28). Neurotransmitter Orexin Associated With Pleasure And Reward Pathways In The Brain. ScienceDaily. Retrieved December 18, 2014 from www.sciencedaily.com/releases/2005/08/050827140339.htm
University of Pennsylvania School of Medicine. "Neurotransmitter Orexin Associated With Pleasure And Reward Pathways In The Brain." ScienceDaily. www.sciencedaily.com/releases/2005/08/050827140339.htm (accessed December 18, 2014).

Share This


More From ScienceDaily



More Mind & Brain News

Thursday, December 18, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Yoga Could Be As Beneficial For The Heart As Walking, Biking

Yoga Could Be As Beneficial For The Heart As Walking, Biking

Newsy (Dec. 17, 2014) Yoga can help your weight, blood pressure, cholesterol and heart just as much as biking and walking does, a new study suggests. Video provided by Newsy
Powered by NewsLook.com
1st Responders Trained for Autism Sensitivity

1st Responders Trained for Autism Sensitivity

AP (Dec. 16, 2014) More departments are ordering their first responders to sit in on training sessions that focus on how to more effectively interact with those with autism spectrum disorder (Dec. 16) Video provided by AP
Powered by NewsLook.com
Guys Are Idiots, According To Sarcastic Study

Guys Are Idiots, According To Sarcastic Study

Newsy (Dec. 12, 2014) A study out of Britain suggest men are more idiotic than women based on the rate of accidental deaths and other factors. Video provided by Newsy
Powered by NewsLook.com
Believing in Father Christmas Good for Children's Imaginations

Believing in Father Christmas Good for Children's Imaginations

AFP (Dec. 12, 2014) As the countdown to Christmas gets underway, so too does the Father Christmas conspiracy. But psychologists say that telling our children about Santa, flying reindeer and elves is good for their imaginations. Duration: 01:57 Video provided by AFP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Health & Medicine

Mind & Brain

Living & Well

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins