Study implicates dopamine in food restriction, drug abuse
Contact: Will Sansom, 210-567-2579
SAN ANTONIO (Oct. 15, 2013) — Scientists have reported a possible reason for why animals whose food has been restricted show an increased susceptibility to drugs of abuse. This association has puzzled researchers since it was first observed more than 30 years ago.
Senior author Michael Beckstead, Ph.D., from the School of Medicine at The University of Texas Health Science Center at San Antonio, said the team found that dopamine neurons in a brain region called the substantia nigra fire bursts more than twice as frequently in mice whose food had been restricted for a long period of time. The team also found that cocaine significantly enhanced this neural firing of dopamine neurons, but only in mice that were fed less.
Dopamine involved in motivating behavior
“Dopamine neurons are part of what we consider the main reward pathway in the brain,” said Dr. Beckstead, an assistant professor of physiology. “They play a strong role in motivated behavior. There is an overlapping process between natural rewards and drug rewards that we studied here.”
Charles France, Ph.D., professor of pharmacology in the School of Medicine, was on the team in 1979 that first reported the connection between food restriction and behavioral effects from drugs of abuse. He is not associated with the new research, which came out Aug. 20 in The Journal of Neuroscience.
“We’ve had no idea how this happens in the brain,” Dr. Beckstead said. “This study identifies dopamine neurons of the substantia nigra as a convergence point for the interaction between feeding state and the effects of drugs of abuse. Food restriction is changing the system.” The substantia nigra is a structure located in the midbrain.
No approved treatments exist for psychostimulant abuse ― drugs such as cocaine, amphetamine and methamphetamine. “We first need to understand how adaptations in the brain contribute to drug use in order to better design drugs,” Dr. Beckstead said. “However this finding, by giving us a clue as to how we might ‘adjust the gain’ on the system, is a very important early step in the development of therapy.”
The study authors are from the UT Health Science Center, The University of Texas at San Antonio (UTSA) Neurosciences Institute and the University of the Incarnate Word in San Antonio. Partial funding is from the San Antonio Life Sciences Institute, a joint initiative of the UT Health Science Center, UTSA and The University of Texas System that received funding from the Texas Legislature in 2010.
The University of Texas Health Science Center at San Antonio, one of the country’s leading health sciences universities, ranks in the top 3 percent of all institutions worldwide receiving National Institutes of Health funding. The university’s schools of medicine, nursing, dentistry, health professions and graduate biomedical sciences have produced more than 29,000 graduates. The $736 million operating budget supports eight campuses in San Antonio, Laredo, Harlingen and Edinburg. For more information on the many ways “We make lives better®,” visit www.uthscsa.edu.
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