Hyperactivity induced by the dopamine D2/D3 receptor agonist quinpirole is attenuated by inhibitors of endocannabinoid degradation in mice

Int J Neuropsychopharmacol. 2013 Apr;16(3):661-76. doi: 10.1017/S1461145712000569. Epub 2012 May 30.

Abstract

The present study was designed to investigate the effect of pharmacological inhibition of endocannabinoid degradation on behavioural actions of the dopamine D2/D3 receptor agonist quinpirole in male C57Bl/6J mice. In addition, we studied the effects of endocannabinoid degradation inhibition on both cocaine-induced psychomotor activation and behavioural sensitization. We analysed the effects of inhibition of the two main endocannabinoid degradation enzymes: fatty acid amide hydrolase (FAAH), using inhibitor URB597 (1 mg/kg); monoacylglycerol lipase (MAGL), using inhibitor URB602 (10 mg/kg). Administration of quinpirole (1 mg/kg) caused a temporal biphasic response characterized by a first phase of immobility (0-50 min), followed by enhanced locomotion (next 70 min) that was associated with the introduction of stereotyped behaviours (stereotyped jumping and rearing). Pretreatment with both endocannabinoid degradation inhibitors did not affect the hypoactivity actions of quinpirole. However, this pretreatment resulted in a marked decrease in quinpirole-induced locomotion and stereotyped behaviours. Administration of FAAH or MAGL inhibitors did not attenuate the acute effects of cocaine. Furthermore, these inhibitors did not impair the acquisition of cocaine-induced behavioural sensitization or the expression of cocaine-induced conditioned locomotion. Only MAGL inhibition attenuated the expression of an already acquired cocaine-induced behavioural sensitization. These results suggest that pharmacological inhibition of endocannabinoid degradation might exert a negative feedback on D2/D3 receptor-mediated hyperactivity. This finding might be relevant for therapeutic approaches for either psychomotor disorders (dyskinesia, corea) or disorganized behaviours associated with dopamine-mediated hyperactivity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Benzamides / pharmacology
  • Carbamates / pharmacology
  • Dopamine Agonists / toxicity*
  • Endocannabinoids / antagonists & inhibitors*
  • Endocannabinoids / metabolism
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Psychomotor Agitation / metabolism
  • Psychomotor Agitation / prevention & control*
  • Quinpirole / toxicity*
  • Receptors, Dopamine D2 / agonists*
  • Receptors, Dopamine D2 / metabolism
  • Receptors, Dopamine D3 / agonists*
  • Receptors, Dopamine D3 / metabolism
  • Stereotyped Behavior / drug effects
  • Stereotyped Behavior / physiology

Substances

  • Benzamides
  • Carbamates
  • Dopamine Agonists
  • Endocannabinoids
  • Receptors, Dopamine D2
  • Receptors, Dopamine D3
  • cyclohexyl carbamic acid 3'-carbamoylbiphenyl-3-yl ester
  • Quinpirole