Environmental Factor, November 2010, National Institute of Environmental Health Sciences
Gary Aston-Jones presents next Distinguished Lecture
By Angelika Zaremba
Gary Aston-Jones, Ph.D., will continue the 2010-2011 Distinguished Lecture Series Nov. 23 at NIEHS by presenting "Seeking reward: Overdoing it with orexin neurons." Patricia Jensen, Ph.D., a principal investigator in the Laboratory of Neurobiology, will host the seminar.
Aston-Jones (http://neurosciences.musc.edu/faculty/full_time/aston.html) is the Murray Chair of Excellence in Neuroscience, and director of the Center for Cognitive Neuroscience at the Medical University of South Carolina (MUSC) in Charleston, S.C. He is also co-director of the MUSC Neuroscience Institute, where the primary focus is to support and develop campus-wide interdisciplinary neuroscience activities and help bridge the gap between basic and clinical science.
The Aston-Jones lab (http://academicdepartments.musc.edu/neuromodulation/index.htm) focuses on neuronal circuits that underlie motivated behavior and reward-based learning and memory. One of the group's interests is to identify the role of neuropeptide transmitters called orexins, also known as hypocretins, which are made exclusively in the hypothalamus.
His team revealed that orexin has a role in learning and expression of stimulus-reward relationships that are important in reward-seeking, drug relapse, and addiction. Using the immediate early gene protein Fos as a marker of neuronal stimulation, the group discovered that Fos-expressing lateral hypothalamus (LH) orexin neurons strongly correlated with preferences for stimuli associated with morphine, cocaine, or a food reward.
Chemical activation of LH orexin neurons reinstated an extinguished conditioned place preference (CPP) for morphine. The Aston-Jones team was able to show that disruption of the projection of orexin neurons to the ventral tegmental area (VTA) prevented learning - a morphine CPP.
Using self-administration methods, his lab also showed that orexin was necessary for stimulus-induced relapse of cocaine-seeking after extinction or abstinence. The team found a similar result for cue-induced reinstatement of extinguished food-seeking. These results led to the conclusion that the orexin system may play an important role in conditioned food craving and obesity.
(Angelika Zaremba, Ph.D., is a visiting postdoctoral fellow in the NIEHS Laboratory of Signal Transduction Inositol Signaling Group.)