The α1 adrenoceptors in ventrolateral orbital cortex contribute to the expression of morphine-induced behavioral sensitization in rats. (1st January 2016)

• Record Type: Journal Article
• Authors: Wei, Lai; Zhu, Yuan-Mei; Zhang, Yu-Xiang; Liang, Feng; Li, Teng; Gao, Hong-Yu; Huo, Fu-Quan; Yan, Chun-Xia
• Is Part Of: Neuroscience letters. Volume 610(2016)
• Page Start: 30
• Page End: 35
• Publication Date: 2016-01-01
• Subjects: α1-AR α1 adrenoceptor -- Beno benoxathian -- ERK extracellular signal-regulated kinase -- fmi forceps minor corpus callosum -- i.p. intraperitoneally -- m.i. microinjection -- min minute(s) -- Mor morphine -- NAc nucleus accumbens -- OFC orbitofrontal cortex -- p-ERK phosphorylated ERK -- PFC prefrontal cortex -- Sal saline -- VLO ventrolateral orbital cortex -- VTA ventral tegmental area; Morphine -- α1 adrenoceptor -- Ventrolateral orbital cortex -- Extracellular signal-regulated kinase -- Behavioral sensitization; Neurology -- Periodicals; Neurology -- Periodicals; Research -- Periodicals; Neurologie -- Périodiques; Neuroanatomie -- Périodiques; Neuropharmacologie -- Périodiques; Neurophysiologie -- Périodiques; Neurology; Periodicals; Electronic journals; 617.48
• DOI: 10.1016/j.neulet.2015.10.057
• Languages: English
• ISSNs: 0304-3940

Abstract

Highlights: The VLO is a novel anatomical substrate mediating morphine-induced behavioral sensitization. Blocking α1 adrenoceptors in the VLO suppressed the expression of morphine-induced behavioral sensitization. Morphine-induced behavioral sensitization may be associated with activated ERK in the VLO. Abstract: The aim of the present study was to investigate the effect of microinjection of benoxathian, selective α1 adrenoceptor antagonist, into the ventrolateral orbital cortex (VLO) on morphine-induced behavioral sensitization and its underlying molecular mechanism in rats. A single morphine treatment protocol was used in establishing the behavioral sensitization model. The effect of bilateral intra-VLO benoxathian injection on locomotor activity was examined and the protein expression levels of α1 adrenoceptors and activation of extracellular signal-regulated kinase (ERK) in the VLO were detected after locomotor test. The results showed that a single injection of morphine could induce behavioral sensitization by a low challenge dosage of morphine after a 7-days drug free period. Benoxathian significantly suppressed the expression but not the development of morphine-induced behavioral sensitization. Morphine treatment significantly elicited ERK phosphorylation and downregulated the expression level of α1 adrenoceptors in the VLO. In addition, intra-VLO benoxathian injection enhanced the expression levels of α1 adrenoceptors and phosphorylated ERK. These results suggest that α1 adrenoceptors in the VLO are involved in regulating the expression of morphine-induced behavioral sensitization. The effect of decreased locomotor activity by blocking α1 adrenoceptors might be associated with activation of ERK in the VLO.