Psychology, Department of
Date of this Version
2010
Citation
ACS Chem. Neurosci. (2010), 1, 265–278
Abstract
The discovery that delta-9-tetrahydrocannabinol
(Δ9-THC) is the primary psychoactive ingredient in
marijuana prompted research that helped elucidate
the endogenous cannabinoid system of the brain.
Δ9-THC and other cannabinoid ligands with agonist
action (CP 55,940, HU210, and WIN 55,212-2)
increase firing of dopamine neurons and increase
synaptic dopamine in brain regions associated with
reward and drug addiction. Such changes in cellular
processes have prompted investigators to examine
the conditioned rewarding effects of the cannabinoid
ligands using the place conditioning task with rats and
mice. As reviewed here, these cannabinoid ligands
can condition place preferences (evidence for rewarding
effects) and place aversions (evidence for aversive
qualities). Notably, the procedural details used
in these place conditioning studies have varied across
laboratories. Such variation includes differences
in apparatus type, existence of procedural biases,
dose, number of conditioning trials, injectionto-
placement intervals, and pretraining drug exposure.
Some differences in outcome across studies can
be explained by these procedural variables. For
example, low doses of Δ9-THC appear to have conditioned
rewarding effects, whereas higher doses
have aversive effects that either mask these rewarding
effects or condition a place aversion. Throughout
this review, we highlight key areas that need further
research.
Comments
Copyright 2010 American Chemical Society