Physical activity alleviates anxiety but not hippocampal BDNF deficits in morphine abstinent rats

The long history of morphine consumption causes anxiety and behavioral disorders. Sport activities can have positive effects, especially via brain-derived neurotrophic factor (BDNF) on the brain. The purpose of this study was to investigate the effects of voluntary and compulsory exercise on anxiety-like behaviors and BDNF levels in hippocampus in morphine-dependent rats.
Rats were injected with bi-daily doses (10 mg/kg, at 12 hr intervals) of morphine for 10 days. Following, the rats in voluntary exercise were allowed to freely exercise in a running wheel for 10 days. The rats in the treadmill exercise groups were forced to run on a motorized treadmill for 30 min once a day for 10 days. Then, anxiety profile was tested using elevated plus maze (EPM) and light-dark box (L/D), and hippocampal BDNF was measured.
Morphine abstinent rats showed increased anxiety in both EPM and L/D box and reduced hippocampal BDNF. Enhanced anxiety, but not a decline in hippocampal BDNF was alleviated by both exercise regimens. Moreover, both exercises increased hippocampal BNDF and reduced anxiety in none-morphine treated rats.
This study showed that physical acivity could allivate the anxiety deficits in morphine abstienet rats probably through mechanisms that do not involve hippocampal BDNF. This suggests that physical acivity could be a potential therpeautic method to reduce anxiety disorders during abstience perioid.