부산대학교 도서관

The aim of the present study was to investigate the effect of microinjection of benoxathian, selective α 1 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 α 1 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 α 1 adrenoceptors in the VLO. In addition, intra-VLO benoxathian injection enhanced the expression levels of α 1 adrenoceptors and phosphorylated ERK. These results suggest that α 1 adrenoceptors in the VLO are involved in regulating the expression of morphine-induced behavioral sensitization. The effect of decreased locomotor activity by blocking α 1 adrenoceptors might be associated with activation of ERK in the VLO. [ABSTRACT FROM AUTHOR]