Treadmill exercise improves LPS-induced memory impairments via endocannabinoid receptors and cyclooxygenase enzymes

Abstract

Endocannabinoid system and cyclooxygenase enzymes are implicated in neuroinflammation-induced cognitive impairment. It is believed that non-pharmacological treatments such as physical exercise affect neural systems that control behavioral responses. This research examined the effects of treadmill aerobic exercise on the expression of cannabinoid receptors and cyclooxygenases against LPS-induced cognitive disorders in the hippocampus tissue of rats. For this purpose, rats received intraperitoneal injection of 0.25mg/kg LPS or saline for 9 continuous days before exercise training. They again received a single i.p. injection with 0.5mg/kg LPS or saline on days 20 and 41 after the beginning of exercise. The exercise groups were forced to run on a motorized treadmill 5 days per week for 8 weeks. After the last exercise training session, the water maze test was conducted to measure cognitive function. Finally, the hippocampus tissue samples of rats were removed and used to determine the levels of gene expression using the Real-Time PCR method. Data showed that the LPS-treated rats had longer escape distance and longer escape latency to reach the hidden platform and they spent less time than the other groups in the target quadrant, but exercise training improved them in the LPS+Exe (LPS+exercise) group. Exercise increased the expression of CB1 receptor in the Sal+Exe (saline+exercise) group and reduced the expression of CB2 receptor, COX-2 and mPGES-1 in the LPS+Exe group compared to the Sal+LPS group. The findings indicate that treadmill exercise may be beneficial for improvement of cognitive function by modulating the neuroinflammatory processes.