miR-133b-3p Mitigates D-galactose-Induced Hippocampal Neuron Aging through Autophagy Regulation via the MAPK/ERK Signaling Pathway

While remarkable progress has been achieved in contemporary medical research, effective drugs or prophylactic approaches targeting neurodegenerative diseases associated with aging are still limited. Increasing evidence suggests that microRNAs (miRNAs) are closely associated with age-related neurological diseases, positioning them as novel therapeutic targets. During aging, autophagy in neurons participates in the renewal of damaged or aged endoplasmic reticulum, mitochondria, other organelles, and aggregated proteins. This study evaluated the anti-aging mechanism of miR-133b-3p in D-galactose (D-gal)-induced hippocampal neurons. A mouse aging model was established by long-term D-gal injection and compared with 18-month-old naturally aged mice to verify and confirm the successful establishment of the aging model, providing a more reliable experimental basis for exploring the changes in mechanisms during aging. Compared with young mice, both the D-gal group and the 18M group showed decreased learning and memory abilities, altered neuronal structures, down-regulated miR-133b-3p expression, and inhibited MAPK/ERK signaling pathway and autophagy. Additionally, in the D-galactose-induced HT22 cell senescence model, autophagy was inhibited, and the expression of the age-related protein p53 was down-regulated. We also found that overexpression of miR-133b-3p under aging conditions can activate autophagy via the MAPK/ERK signaling pathway and exerting neuroprotection in hippocampal neurons. However, the effect of miR-133b-3p in reducing cellular aging damage was weakened when the MAPK/ERK signaling pathway was blocked or autophagy was inhibited. This research brought to light the significant mechanism whereby miR-133b-3p protects hippocampal neurons in aging mice. MiR-133b-3p alleviates D-gal-induced cellular aging damage by activating autophagy through the MAPK/ERK signaling pathway.