TITLE:
Differential Effects of Voluntary Ethanol Consumption on Dopamine Output in the Nucleus Accumbens Shell of Roman High- and Low-Avoidance Rats: A Behavioral and Brain Microdialysis Study
AUTHORS:
Maria G. Corda, Giovanna Piras, Maria A. Piludu, Osvaldo Giorgi
KEYWORDS:
Roman High- and Low-Avoidance Rats, Voluntary Ethanol Consumption, Mesolimbic Dopaminergic System, Nucleus Accumbens Shell, Novelty-Seeking Behavior
JOURNAL NAME:
World Journal of Neuroscience,
Vol.4 No.3,
June
26,
2014
ABSTRACT: The Roman high(RHA)
and low-Avoidance (RLA) rats were selectively bred for rapid vs poor acquisition
of two-way active avoidance behavior. These lines differ in numerous behavioral
traits, with RLA rats being more fearful/anxious than RHA rats, and the latter
being novelty-seekers and showing larger intake of, and preference for,
addictive substances including ethanol (ETH). Moreover, several differences in
central dopaminergic, serotonergic, and GABAergic functions have been reported
in these two lines. Since those neural systems are involved in the regulation
of ETH consumption, it was considered of interest to investigate: 1) the
differences in ETH intake and preference between RHA and RLA rats, 2) the
effects of ETH on DA release in the shell of the nucleus accumbens (AcbSh) using brain microdialysis. ETH
solutions of increasing concentrations (2% - 10%) were presented on alternate
days in a free choice with water. To examine ETH intake and preference stability, animals were subsequently switched to
daily presentations of 10% ETH for 10 consecutive days. RHA rats consumed significantly larger
amounts of ETH and displayed higher ETH preference than did RLA rats throughout the acquisition and
maintenance phases. Following chronic exposure to ETH the animals were
habituated to a restricted access to ETH schedule (2% ETH, 2 h per day × 4
days) before surgical implantation of a dialysis probe in the AcbSh. Under
these experimental conditions, voluntary ETH intake (2%, 1 h, p.o.) produced a
significant increase in accumbal DA output in RHA rats but not in their RLA
counterparts. Finally, the i.p. administration of ETH (0.25 g/kg) to na?ve
Roman rats produced a significant increment in accumbal DA output only in RHA
rats. These results indicate that the mesolimbic dopaminergic system of RHA
rats is more responsive to the effects of ETH than that of RLA rats.