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I n t e r n a t i o n a l C o n f e r e n c e o n
Neurological Disorders,
Stroke and CNS
October 22-23 , 2018
Athens , Greece
Journal of Neurology and Neuroscience
ISSN: 2171-6625
Stroke and CNS 2018
T
he nucleus accumbens (NAc) and the ventral tegmental area (VTA) are two major areas for the mesolimbic dopaminergic
system which are strongly involved in the development of behavioral sensitization. In the present study, we investigated the
role of D1/D2 dopaminergic receptors within the NAc or VTA in response to sensitization to morphine by the tail-flick test as
a model of acute pain. Sensitization was induced by subcutaneous (SC) injection of morphine (5 mg/kg), once daily for three
days followed by 5 days free of drug. After the sensitization period, antinociceptive responses induced by an ineffective dose of
morphine (1 mg/kg; SC) were obtained by the tail-flick test, and represented as maximal possible effect (%MPE). In experimental
groups, D1 and D2 receptor antagonists, SCH-23390 and sulpiride (0.25, 1 and 4 µg/rat), were separately microinjected into the
NAc or VTA, 10 min before morphine administration during the sensitization period, respectively. Results showed that injection
of morphine during the sensitization period (development of sensitization) increased %MPE of the ineffective dose of morphine
from 2.43±1.4% in naive to 47.75±4.01% in sensitized animals (P<0.001). Unilateral microinjections of different doses of the D1/
D2 receptor antagonists, SCH-23390 and sulpiride, into the NAc dose-dependently decreased %MPEs in morphine-sensitized
animals. Nonetheless, %MPEs were only affected by intra-VTA administration of SCH-23390 in morphine-sensitized animals
(P<0.05). Our findings suggest that both the D1/D2 dopamine receptors in the NAc and the D1 receptors in the VTA may be of
more important in the development of sensitization to in rats.
leilazarepour1@yahoo.comInvolvement of D1/D2 dopamine receptors within
the nucleus accumbens and ventral tegmental
area in the development of sensitization to
antinociceptive effect of morphine
Leila Zarepour
Iran University of Medical Sciences, Iran
J Neurol Neurosci 2018, Volume: 9
DOI: 10.21767/2171-6625-C3-015