REPEATED EXPOSURE TO DELTA(9)-TETRAHYDROCANNABINOL REDUCES PREFRONTALCORTICAL DOPAMINE METABOLISM IN THE RAT

Long-term abuse of marijuana by humans can induce profound behavioral deficits characterized by cognitive and memory impairments. In particu lar, deficits on tasks dependent on frontal lobe function have been re ported in cannabis abusers. In the current study, we examined whether long-term exposure to Delta(9)-tetrahydrocannabinol, the active ingred ient in marijuana, altered the neurochemistry of the frontal cortex in rats. Two weeks administration of Delta(9)-tetrahydrocannabinol reduc ed dopamine transmission in the medial prefrontal cortex, while dopami ne metabolism in striatal regions was unaffected. These data are consi stent with earlier findings of dopaminergic regulation of frontal cort ical cognition. Thus, cognitive deficits in heavy abusers of cannabis may be subserved by drug-induced alterations in frontal cortical dopam ine transmission. (C) 1998 Elsevier Science Ireland Ltd.