The effect of aerobic exercise and crocin consumption on the gene expression of BDNF, TrkB, dopamine, and serotonin in the cerebral cortex of rats induced with methamphetamine

Abstract

Background and Purpose: In this study, the effect of aerobic exercise and crocin on the gene expression of BDNF, TrKB, dopamine, and serotonin in the cerebral cortex of rats induced with methamphetamine was investigated. Materials and Methods: In this research, 40 female Wistar rats (age, eight weeks; weight 140-160 grams) were divided into five groups including healthy control, methamphetamine, methamphetamine+aerobic exercise, methamphetamine+crocin, methamphetamine+crocin+aerobic exercise. 15 mg of methamphetamine was given to the subjects every 12 hours for four days. Moreover, the dose of crocin was 80 mg per kilogram of body weight, which was mixed intraperitoneally with distilled water and injected over five days. The aerobic exercise program included running on a treadmill with a 0% incline until the third week and a 5% incline from the fourth to the eighth week, which was performed three days a week for eight weeks. The duration of the aerobic exercise protocol increased from 20 min in the first sessions to 30 min in the final sessions. Furthermore, the speed of running increased from 20 meters per minute in the first weeks to 25 meters per minute in the final weeks. After anesthesia, an autopsy was performed and samples of cerebral cortex tissue were taken. The gene expression of BDNF, TrkB, dopamine and serotonin in the cerebral cortex was measured by the real-time technique with the rotor gene Q device. Y-maze tests were also used to evaluate the behavioral data. The data were analyzed by using one-way analysis of variance and Tukey's post hoc-test at the significance level of P≤0.05. Results: The results showed that the mean expression of BDNF, TrkB, dopamine and, serotonin genes in the cerebral cortex in rats induced with methamphetamine were significantly lower than the control group (P=0.001). The average expression of BDNF, TrkB, dopamine and, serotonin genes in the methamphetamine+aerobic exercise, methamphetamine+crocin and methamphetamine+crocin+aerobic exercise groups were significantly higher than the methamphetamine group (P=0.001). However, methamphetamine+crocin+aerobic exercise group had a significantly higher average expression of BDNF, TrkB, dopamine and, serotonin genes compared to methamphetamine+aerobic exercise and methamphetamine+crocin groups (P=0.001). The results in the model validation section by examining the behavioral data, showed no significant differences in the average total number of arms entering and the average non-repetitive frequency among the different groups (P<0.05). However, the comparison between before and after methamphetamine induction shows a significant decrease in the average total number of arms entering and the average of non-repetitive frequency (P<0.0001). Conclusion: The results of the present research showed that methamphetamine was associated with a decrease in the expression of the genes of neural factors in the cerebral cortex tissue. In addition, eight weeks of aerobic training, consumption of crocin, and aerobic exercise plus crocin supplementation can have a neuroprotective effect in rats induced with methamphetamine, and lead to increases in the expression of BDNF, TrkB, dopamine and serotonin genes in the cerebral cortex in rats.

Keywords

• methamphetamine
• aerobic exercise
• crocin
• dopamine
• serotonin