NOV 15, 2016 9:40 AM PST

Scripps Florida Scientists Pinpoint Regulator of Amphetamine Induced Motor Activity

Image Credit: Shutterstock

JUPITER, FL – November 15, 2016 – In new findings that could have an impact the development of therapies for a number of currently untreatable brain disorders such as Parkinson’s and Huntington’s diseases, scientists from the Florida campus of The Scripps Research Institute (TSRI) have found, for the first time, that a specific signaling circuit in the brain is deeply involved in motor activity.

The study, which was led by TSRI’s Associate Professor Srinivasa Subramaniam, was published November 15 in the journal Science Signaling.

Despite many advances, the precise signaling mechanisms that regulate motor function in the striatum, that part of the brain responsible for motor activity, remain unknown. The new study identified for the first time a protein interaction network that helps control these functions by inhibiting the signaling of dopamine, a neurotransmitter involved in regulating movement.

“A pair of proteins operates through a protein-protein interaction network—what we call a 'Rhesactome'—in the striatum,” Subramaniam said. “This may have much broader implications in neurological, psychiatric and addictive disorders. Drugs that bind to either of these proteins may have therapeutic benefits for the diseases that affect this part of the brain.”

The study focused on amphetamine-induced activity affected by what is known as RasGRP1-Rhes signaling circuitry. Drugs like amphetamine, which trigger dopamine release in the striatum, enhance locomotor activity. Rhes acts as a kind of brake on the amphetamine-induced locomotion; in order for normal motor activity to occur, the RasGRP1 and other protein partners in the Rhesactome network induced by amphetamine have to block Rhes. It is the calibrated interaction of Rhes with the protein RasGRP1 that adjusts striatal control of motor functions.

In the study, the researchers succeeded in using RasGRP1 to inhibit Rhes-mediated control of striatal motor activity in animal models. Animal models that were Rhes-deficient had a much stronger active behavioral response to amphetamines. But all that changed if RasGRP1 was depleted.

“It’s a delicate and highly complex relationship,” Subramaniam said. “Imagine that you are running. This protein complex carefully controls that motor function by modulating the effect of Rhes. That’s why you need to have the double control elements of both RasGRP1 and Rhes to fine-tune those motor functions. Our study captures this dynamic complex, so that now for the first time we can biochemically visualize it at the network level.”

What remains unknown at this point is how RasGRP1 actually modulates Rhes.

“We speculate that both transcriptional and post-transcriptional mechanisms are involved,” said TSRI Staff Scientist Neelam Shahani, the first author of the study. “Considering that the Rhes protein is enhanced predominantly at synaptic locations, one intriguing possibility is that RasGRP1 regulates local translation of Rhes messenger RNA at the synapse.”

In addition to Subramaniam and Shahani, other authors of the study, “RasGRP1­ Promotes Amphetamine-Induced Motor Behavior through a Rhes Interaction Network (“Rhesactome”) in the Striatum,” are Supriya Swarnkar, Vincenzo Giovinazzo, Jenny Morgenweck, Laura M. Bohn, Catherina Scharager-Tapia, Bruce Pascal and Pablo Martinez-Acedo of TSRI; and Kshitij Khare of the University of Florida, Gainesville.

The study was supported by the National Institutes of Health (grant R01-NS087019).

This article was originally published on Scripps.edu.
About the Author
  • The Scripps Research Institute (TSRI) is one of the world's largest independent, not-for-profit organizations focusing on research in the biomedical sciences. TSRI is internationally recognized for its contributions to science and health, including its role in laying the foundation for new treatments for cancer, rheumatoid arthritis, hemophilia, and other diseases. An institution that evolved from the Scripps Metabolic Clinic founded by philanthropist Ellen Browning Scripps in 1924, the institute now employs about 2,700 people on its campuses in La Jolla, CA, and Jupiter, FL, where its renowned scientists-including two Nobel laureates-work toward their next discoveries. The institute's graduate program, which awards PhD degrees in biology and chemistry, ranks among the top ten of its kind in the nation. For more information, see www.scripps.edu.
You May Also Like
SEP 15, 2020
Drug Discovery & Development
Turmeric Better than Placebo for Osteoarthritis Pain
SEP 15, 2020
Turmeric Better than Placebo for Osteoarthritis Pain
Researchers from the University of Tasmania in Australia have found that an extract from turmeric is more effective than ...
SEP 21, 2020
Neuroscience
Insufficient Sleep Makes It Harder to Enjoy Life, Study Says
SEP 21, 2020
Insufficient Sleep Makes It Harder to Enjoy Life, Study Says
A growing body of research stresses the importance of getting a good night's sleep- whether it's to bolster your ...
OCT 05, 2020
Genetics & Genomics
A Rare Form of Dementia is Discovered
OCT 05, 2020
A Rare Form of Dementia is Discovered
There are different types of dementia, a term for a loss of cognitive function, including Alzheimer's disease and Le ...
OCT 15, 2020
Cannabis Sciences
Can Cannabis Treat Traumatic Brain Injury?
OCT 15, 2020
Can Cannabis Treat Traumatic Brain Injury?
Traumatic brain injury (TBI) happens when the head is violently hit by an object or when an object pierces the skull and ...
NOV 13, 2020
Cell & Molecular Biology
Astrocytes are Star Players in the Brain
NOV 13, 2020
Astrocytes are Star Players in the Brain
As neurons fire, they enable us to think and move. They signal to one another where they meet at synapses, and at chemic ...
NOV 14, 2020
Cell & Molecular Biology
Towards a Better Characterization of Neurons
NOV 14, 2020
Towards a Better Characterization of Neurons
The human body is made up of a wide array of different types of cells, and if we want to understand human diseases and t ...
Loading Comments...