Metabotropic glutamate 5 receptor blockade may attenuate cocaine self-administration by decreasing brain reward function in rats
Kenny PJ, Boutrel B, Gasparini F, Koob GF, Markou A.
Department of Neuropharmacology,
CVN-7, The Scripps Research Institute,
10550 North Torrey Pines Road,
La Jolla, CA, 92037, USA,
[email protected].
Psychopharmacology (Berl). 2004 Dec 16


RATIONALE: Evidence is accumulating that metabotropic glutamate 5 (mGlu5) receptors play an important role in regulating the reinforcing actions of drugs of abuse. OBJECTIVES: We examined the effects of the mGlu5 receptor antagonist MPEP on cocaine consumption and cocaine-enhanced brain reward function in rats. METHODS: Cocaine consumption was measured in rats with 1 h (short-access; ShA) or 6 h (long-access; LgA) daily access to intravenous cocaine (0.25 mg/infusion) self-administration. Cocaine-enhanced brain reward function was measured by cocaine-induced lowering of intracranial self-stimulation (ICSS) thresholds. RESULTS: Cocaine consumption remained stable and unaltered over successive self-administration sessions in ShA rats. In contrast, cocaine consumption progressively "escalated" in LgA rats. MPEP (1-9 mg/kg) dose-dependently decreased responding similarly in ShA and LgA rats. These data suggest that mGlu5 receptors regulate the reinforcing properties of cocaine, and that this action of mGlu5 receptors is independent of the escalation in consumption associated with extended access to cocaine self-administration. MPEP doses (1-9 mg/kg) that decreased cocaine self-administration elevated brain reward thresholds to a similar degree in cocaine- and vehicle-treated rats, indicating that MPEP induced a negative affective state. The additive effects of MPEP and cocaine on thresholds resulted in attenuation of the magnitude of cocaine-induced (10 mg/kg) lowering of ICSS thresholds. CONCLUSIONS: Overall, mGlu5 receptors appear to play an important role in regulating cocaine consumption, and also in regulating brain reward function. Further, it is likely that blockade of mGlu5 receptors may attenuate cocaine consumption, at least in part, by decreasing the baseline activity of brain reward circuitries.

Crack and crime
Dopaminergic flies?
Dopaminergic agents
The coke-craving brain
Monoamines, cocaine and rats
Freebasing flies go hyperkinetic
Glutamate, dopamine and cocaine addiction
Glutamate transmission and addiction to cocaine
Glutamate receptor antagonism reduces cocaine-seeking

01 02 03 04 05 06 07 08 09 10 11 12
13 14 15 16 17 18 19 20 21 22 23 24

Future Opioids
BLTC Research
Wirehead Hedonism
The Hedonistic Imperative
MDMA: Utopian Pharmacology
When Is It Best to Take Crack Cocaine?

swan image
The Good Drug Guide
The Responsible Parent's Guide To
Healthy Mood Boosters For All The Family