Neuroprotective effect of long-term resistance physical exercise against memory damage elicited by a lipopolysaccharide-induced neuroinflammation model in male rats

Resistance exercise training (RET) is considered an excellent tool for preventing diseases with an inflammatory background. Its neuroprotective, antioxidant, and anti-inflammatory properties are responsible for positively modulating cholinergic and oxidative systems, promoting neurogenesis, and improving memory. However, the mechanisms behind these actions are largely unknown. In order to investigate the pathways related to these effects of exercise, we conducted a 12-week long-term exercise training protocol and used lipopolysaccharide (LPS) to induce damage to the cortex and hippocampus of male Wistar rats. The cholinergic system, oxidative stress, and histochemical parameters were analyzed in the cerebral cortex and hippocampus, and memory tests were also performed. It was observed that LPS: (1) caused memory loss in the novel object recognition (NOR) test; (2) increased the activity of acetylcholinesterase (AChE) and Iba1 protein density; (3) reduced the protein density of brain-derived neurotrophic factor (BDNF) and muscarinic acetylcholine receptor M1 (CHRM1); (4) elevated the levels of lipid peroxidation (TBARS) and reactive species (RS); and (5) caused inflammatory damage to the dentate gyrus. RET, on the other hand, was able to prevent all alterations induced by LPS, as well as increase per se the protein density of the alpha-7 nicotinic acetylcholine receptor (nAChRα7) and Nestin, and the levels of protein thiols (T-SH). Overall, our study elucidates some mechanisms that support resistance physical exercise as a valuable approach against LPS-induced neuroinflammation and memory loss.