Aerobic exercise mitigates hippocampal neuronal apoptosis by regulating DAPK1/CDKN2A/REDD1/FoXO1/FasL signaling pathway in D-galactose-induced aging mice

Aerobic exercise modulates RIPK1-mediated MAP3K5/JNK and NF-κB pathways to suppress microglia activation and neuroinflammation in the hippocampus of D-gal-induced accelerated aging mice

Microglia activation-induced neuroinflammation is a risk factor for cognitive dysfunction in the hippocampus during the early stages of neurodegenerative diseases. Exercise is an intrinsic remedy that plays a crucial role in enhancing the survival of neurons and reducing neuroinflammation in the brain. Among these theories, alterations in intracellular signaling pathways associated with neuronal growth and inflammation have been emphasized. Based on these observations and recent evidence demonstrating the beneficial effects of exercise on suppressing brain inflammation in the elderly, we examined cellular signaling pathways in the hippocampal formation of D-galactose-induced accelerated aging mice that underwent 8 weeks of treadmill exercise. To accomplish this, we utilized immunohistochemistry and Western blotting to detect the expression of hippocampal proteins, and qPCR to detect the expression of mRNA. We found that aerobic exercise significantly promoted the survival of hippocampal neurons, inhibited microglia activation, and decreased the expression of inflammatory cytokines TNF-α, IL-1α, IL-1β, and chemokines CXCL-1, CXCR-2 in D-galactose model mice. Furthermore, exercise contributed to decreasing the microglia activation marker Iba1-positive cell count and average optical density and increasing the number of NeuN-immunopositive cells. Exercise also reduced RIPK1 and MAP3K5 expression in the hippocampus. Surprisingly, aerobic exercise significantly decreased the expression ratios of p-p65/p65, p-IκBα/IκBα, and p-JNK/JNK. Therefore, we hypothesized that exercise has an anti-inflammatory effect on the hippocampus of mice in the D-galactose-induced aging model. This effect may be attributed to the ability of aerobic exercise to down-regulate the RIPK1-mediated NF-κB and JNK pathways.

miR-34a/TAN1/CREB Axis Engages in Alleviating Oligodendrocyte Trophic Factor-Induced Myelin Repair Function and Astrocyte-Dependent Neuroinflammation in the Early Stages of Alzheimer's Disease: The Anti-Neurodegenerative Effect of Treadmill Exercise

Reduced myelin stability observed in the early stages of Alzheimer's disease leads to spatial learning and memory impairment. Exercise has been shown to protect nerves, reduce the risk of Alzheimer's disease, and strengthen synaptic connectivity. However, the underlying mechanisms of how exercise can promote myelin repair and coordinate inflammation and proliferation are still uncertain. In this study, we conducted histological and biochemical assays of cortical lysates after behavioral testing to detect pathological changes, myelin sheath thickness, and mRNA and protein levels. It is notable that D-galactose model mice exhibited elevated miRNA-34a levels, overactive astrocytes, decreased myelin staining scores, increased apoptosis, and decreased synaptic plasticity in the brain. Significantly, after eight weeks of exercise, we observed improvements in LFB scores, NeuN( +) neuron counts, and myelin basic protein (MBP) expression. Additionally, exercise promoted the expression of oligodendrocyte markers Olig2 and PDFGR-α associated with brain proliferation, and improved spatial cognitive function. Furthermore, it decreased the inflammation caused by astrocyte secretions (TNF-α, Cox-2, CXCL2). Interestingly, we also observed downregulation of miR-34a and activation of the TAN1/PI3K/CREB signaling pathway. Our data shed light on a previously unsuspected mechanism by which exercise reduces miR-34a levels and protects neuronal function and survival by preventing excessive demyelination and inflammatory infiltration in the CNS.