HMOX1 and neurodegenerative disease: A natural alkaloid, berberine, protected PC12 cells against 6-OHDA-induced neurotoxicity through activating the Nrf2/HO-1 signaling pathway and improved 6-OHDA-induced dopaminergic neuron loss and behavior movement deficiency in zebrafish, which supported the potency of berberine for the prevention and treatment of neurodegenerative diseases [21].