• Early axonal degeneration precedes cell body degeneration in Parkinson's disease, with initial lesions in the limbic system or olfactory bulb.
• Multiple signaling pathways contribute to axonal damage, including abnormal protein aggregation, mitochondrial dysfunction, ER stress, and inflammation.
• Repair pathways such as neurotrophic factors, cytoskeletal regulation, and axonal guidance can be activated to promote axonal repair.
• Combining inhibition of damage pathways and activation of repair pathways (e.g., via drugs or exercise) may offer novel therapeutic strategies.