Neuropharmacology and NeurotoxicityCannabinoids excite dopamine neurons in the ventral tegmentum and substantia nigraFrench, Edward D.1,2; Dillon, Kathryn1; Wu, Xiaofang1Author Information 1Department of Pharmacology, College of Medicine, University of Arizona, Tucson, AZ 85724, USA 2Corresponding Author: Edward D. French ACKNOWLEDGEMENT: This work is supported through Grant DA 09025 from the National Institute on Drug Abuse. Received 30 August 1996; accepted 17 October 1996 NeuroReport: February 10, 1997 - Volume 8 - Issue 3 - p 649-652 Buy Abstract EXTRACELLULAR recordings were used to determine the effects of cannabinoids on the activity of dopamine neurons within the ventral tegmental area (VTA) and substantia nigra pars compacta (SNC). Systemic administration of the natural psychoactive cannabinoid Δ9-tetrahydrocannabinol (Δ9-THC) and the synthetic cannabimimetic aminoalkylindole WIN 55,212-2 produced dose-dependent increases in firing rate and burst firing in both neuronal populations. These effects appear to be specific as the non-psychoactive cannabidiol and the inactive enantiomer WIN 55,212-3 failed to alter either parameter of neuronal excitability. Furthermore, dopamine neurons in the VTA were more sensitive than those in the SNC to the stimulatory actions of Δ9-THC. These results may provide a mechanism by which psychoactive cannabinoids increase extracellular dopa-mine levels in mesolimbic and striatal tissues, and thereby contribute to the reinforcing effects of marijuana. © Lippincott-Raven Publishers.