The effect of aerobic exercise on dopamine release in periaqueductal gray region following the use of morphine in rat

Abstract

Background: Several studies have shown that exercise plays an important role in modifying addictive behaviors. Moreover, it seems that morphine exerts its effects on periaqueductal gray (PAG) region, which contains dopamine neurons, through the release of dopamine in this area. Therefore, in this study, we decided to evaluate the effect of aerobic exercise on the release of dopamine in the periaqueductal gray region following the use of morphine in rat. Methods: 28 male Wistar rats were selected and randomly divided into 4 groups of saline, morphine, saline + exercise, and morphine + exercise. Exercise groups ran on the treadmill apparatus during four weeks. Three doses of morphine (10, 20, and 40 mg/kg) were injected intraperitoneally in 9 days, and withdrawal symptoms were recorded. After preparing different specimens in 50 μl samples, the concentration of dopamine and 3,4-dihydroxyphenylacetic acid (DOPAC) were measured using high-performance liquid chromatography (HPLC). To compare the mean levels of dopamine and DOPAC, one-way ANOVA and Tukey's post hoc tests were used. Findings: The concentrations of dopamine and DOPAC were significantly higher in morphine, morphine + exercise, and saline + exercise compared to saline group (P < 0.050 for all). Conclusion: The results of this study show that aerobic exercise may have an important role in releasing dopamine and DOPAC into the periaqueductal gray region area, and it can be used for prevention and treatment of morphine addiction. © 2018, Isfahan University of Medical Sciences(IUMS). All rights reserved.