The effect of different exercise training modes on dentate gyrus neurodegeneration and synaptic plasticity in morphine-dependent rats

Abstract

Various impacts of exercise on brain performance following the induction of morphine dependence have been documented; however, the underlying neuronal mechanisms are still unclear. The present research was done to investigate the impact of different exercise training modes on apoptosis, neuronal maturation, and synaptic plasticity in the perforant pathway (PP)-dentate gyrus (DG) synapses in the morphine-dependent rats. Five groups, including a control group (Con, ten healthy rats) and forty morphine-dependent rats were considered as follows (n = 10/group): 1) sedentary-dependent (Sed-D); 2) endurance exercise-dependent (En-D); 3) strength exercise-dependent (St-D); and 4) concurrent exercise-dependent (Co-D). The exercise training groups were subjected to endurance, strength, and concurrent training five days a week for ten weeks. After training sessions, the field excitatory postsynaptic potential (fEPSP) slope and population spike (PS) amplitude in the DG were determined in response to high-frequency stimulation (HFS) of the PP. For assessing neurogenesis and apoptosis, NeuroD and Caspase-3 expression levels were evaluated after all experiments. Concurrent training increased PS amplitude and EPSP compared to the control group. NeuroD in the morphine-dependent rats significantly decreased, but concurrent training returned the NeuroD to its levels in healthy rats. Furthermore, Caspase-3 expression levels in morphine-dependent rats remarkably increased and concurrent training significantly reduced Caspase-3 expression levels compared to the Sed-D group. Concurrent training can ameliorate synaptic plasticity impairment in morphine-dependent rats through neurogenesis promotion and apoptosis reduction. According to the results, concurrent training can be an appropriate novel candidate for treating opioid addiction.