"Metabotropic glutamate receptors (mGluRs) are densely expressed in the limbic system of the mammalian brain. Increasing evidence suggests a critical role of mGluRs in the pathogenesis of various mental illnesses, including drug abuse and addiction," scientists in the United States report (see also Addiction Medicine).

"In this study, we investigated the effect of psychostimulant, Cocaine, on protein expression of a specific mGluR subtype, mGluR8, in the rat forebrain in vivo. A rabbit antibody against the extracellular N-terminus of mGluR8 was developed to detect changes in mGluR8 proteins in immunoblot assays. With this antibody, we found that acute systemic injection of Cocaine reduced mGluR8 protein levels in the striatum. The reduction of mGluR8 proteins was rapid and transient as it was induced 25 min after Cocaine injection and returned to the normal level by 6 h. No significant change in mGluR8 protein levels in the prefrontal cortex and the hippocampus was observed following Cocaine administration. These data demonstrate that protein expression of mGluR8 is subject to the modulation by dopamine stimulation," wrote G.C. Zhang and colleagues, University of Missouri, Medical Department.

The researchers concluded: "Acute exposure to Cocaine results in a dynamic and region-specific downregulation of mGluR8 expression in the striatum."

Zhang and colleagues published their study in Neuroscience Letters (Acute administration of Cocaine reduces metabotropic glutamate receptor 8 protein expression in the rat striatum in vivo. Neuroscience Letters, 2009;449(3):224-227).

For additional information, contact J.Q. Wang, University of Missouri, School Medical, Dept. of Basic Med Science, 2411 Holmes St., Kansas City, MO 64108, USA.

The publisher's contact information for the journal Neuroscience Letters is: Elsevier Ireland Ltd., Elsevier House, Brookvale Plaza, East Park Shannon, Co. Clare, Ireland.