Swimming and L-arginine loaded chitosan nanoparticles ameliorates aging‐induced neuron atrophy, autophagy marker LC3, GABA and BDNF - TrkB pathway in the spinal cord of rats

Aging is associated with muscle atrophy, and erosion and destruction of neuronal pathways in the spinal cord. The study aim was to assess the effect of swimming training (Sw) and L-arginine loaded chitosan nanoparticles (LA-CNPs) on the sensory and motor neuron population, autophagy marker LC3, total oxidant status/total antioxidant capacity, behavioural test, GABA and BDNF -TrkB pathway in the spinal cord of aging rats. The rats were randomized to five groups: young (8-weeks) control (n = 7), old control (n = 7), old Sw (n = 7), old LA-CNPs (n = 7) and old Sw + LA-CNPs (n = 7). Groups under LA-CNPs supplementation received 500 mg/kg/day. Sw groups performed a swimming exercise programme 5 days per week for 6 weeks. Upon the completion of the interventions the rats were euthanized and the spinal cord was fixed and frozen for histological assessment, IHC, and gene expression analysis. The old group had more atrophy in the spinal cord with higher changes in LC3 as an indicator of autophagy in the spinal cord compared to the young group ( p < 0.0001). The old Sw + LA-CNPs group increased (improved) spinal cord GABA ( p = 0.0187), BDNF ( p = 0.0003), TrkB ( p < 0.0001) gene expression, decreased autophagy marker LC3 protein ( p < 0.0001), nerve atrophy and jumping/licking latency ( p < 0.0001), improved sciatic functional index score and total oxidant status/total antioxidant capacity compared to the old group ( p < 0.0001). In conclusion, swimming and LA-CNPs seems to ameliorate aging‐induced neuron atrophy, autophagy marker LC3, oxidant-antioxidant status, functional restoration, GABA and BDNF - TrkB pathway in the spinal cord of aging rats. Our study provides experimental evidence for a possible positive role of swimming and L-arginine loaded chitosan nanoparticles to decrease complications of aging.