title: Transient inactivation of the nucleus accumbens reduces both the expression and acquisition of morphine-induced conditioned place preference in rats.
abstract: In the present study, the effects of transient inhibition of the shell and core parts of the nucleus accumbens by lidocaine on the expression and acquisition of morphine-induced conditioned place preference in male Wistar rats were investigated. In addition, the number of bouts of sniffing, rearing, and compartment crossing was scored. Lidocaine hydrochloride was injected into different parts of the nucleus accumbens 5 min before each morphine session for the transient inhibition of particular anatomical regions. Subcutaneous (s.c.) injection of morphine (2.5 and 5mg/kg) induced place preference. Transient inhibition of the left and/or right side of the shell part of nucleus accumbens reduced morphine place conditioning. However, when both sides of the nucleus were inhibited, inhibition was weaker when compared to the results when only one side was inhibited. Also, the number of compartment crossings in these animals reduced significantly. Nevertheless, the number of rearing occurrences was reduced only when both sides of the shell part of the nucleus accumbens were inhibited. In contrast, the number of sniffing bouts increased in all three groups. The results for the core part of the nucleus accumbens also indicated that place preference was inhibited after transient inhibition of the left, right, and both sides. However, although the number of total compartment crossings was reduced in all experimental groups, the reduction was not statistically significant. The data obtained was similar to the number of rearings, yet the number of sniffing bouts increased in the experimental groups compared to the control. In conclusion, these results confirmed the involvement of the left and right sides and core and shell parts of the nucleus accumbens in morphine place conditioning.
authors.affiliation: Department of Physiology, School of Medicine, Qazvin University of Medical Sciences, Qazvin, Iran.
authors.forename: Mohammad-Hossein
authors.initials: MH
authors.lastname: Esmaeili
authors.forename: Hedayat
authors.initials: H
authors.lastname: Sahraei
authors.forename: Hengameh
authors.initials: H
authors.lastname: Ali-Beig
authors.forename: Mojgan
authors.initials: M
authors.lastname: Ardehari-Ghaleh
authors.forename: Zahra
authors.initials: Z
authors.lastname: Mohammadian
authors.forename: Homeira
authors.initials: H
authors.lastname: Zardooz
authors.forename: Seyed Hassan
authors.initials: SH
authors.lastname: Salimi
authors.forename: Jamal
authors.initials: J
authors.lastname: Shams
authors.forename: Ali
authors.initials: A
authors.lastname: Noroozzadeh
mesh_terms: D000818:Animals; D003216:Conditioning, Operant; D004305:Dose-Response Relationship, Drug; D008297:Male; D009020:Morphine / Q000494:pharmacology*; D009714:Nucleus Accumbens / Q000187:drug effects*; D051381:Rats; D017208:Rats, Wistar
chemical_list: D009020:Morphine