Roles of the Nucleus Accumbens and Amygdala in the Acquisition and Expression of Ethanol-Conditioned Behavior in Mice
The Journal of Neuroscience, January 30, 2008, 28(5):1076-1084
Although progress has been made identifying the neural areas
underlying the primary reinforcing effects of ethanol, few studies
have examined the neural areas mediating ethanol-induced conditioned
Previous work using the conditioned place preference
(CPP) procedure implicates the ventral tegmental area (VTA)
(Bechtholt and Cunningham, 2005), but the downstream neural
areas modulating the conditioned rewarding effects of ethanol
have not been identified. Although the nucleus accumbens (Acb)
and the amygdala (Amy), which both receive dopamine innervation
from the VTA, have been implicated in the primary reinforcing
effects of ethanol, the roles these areas play in ethanol-conditioned
behaviors are unknown.
In the present set of experiments, we
use the CPP procedure along with selective electrolytic lesions
to examine the neural areas underlying the acquisition and expression
of ethanol conditioned behavior.
In the acquisition experiment,
male DBA/2J mice received bilateral lesions of the Acb or Amy
before CPP training. In the expression experiments, mice received
bilateral lesions of the Acb, Acb shell, Acb core, and Amy,
or unilateral lesions of the Amy after training but before testing.
Lesions of the Acb and Amy before training disrupted acquisition
and expression of ethanol CPP.
However, when given after training,
only lesions of the Amy disrupted expression, whereas lesions
of the Acb core facilitated loss of responding, of ethanol CPP.
For the first time, these results demonstrate the role of the
Acb and Amy in the acquisition and expression of ethanol-induced
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