Crebanine attenuates copper neurotoxicity via PACS-2 upregulation and TXNIP/TRPV1 axis suppression

Continuous copper (Cu) deposition in the brain induces endoplasmic reticulum (ER) stress by activating p38-MAPK, which triggers the p-PERK-ATF4-CHOP cascade. Besides, Cu provokes oxidative stress, stimulating the TXNIP/TRPV1 to promote chronic neuroinflammation. Instead, PACS-2 serves as a reductive anti-inflammatory protein in regulating mitochondrial-ER communication during cellular homeostasis; however, its involvement in mitigating Cu neurotoxicity is still obscure. Amazingly, crebanine (Creb), an alkaloid with antioxidant and anti-inflammatory properties, was hypothesized to disturb p38-MAPK signal, hence counteracting Cu-induced neuroinflammation, enhancing PACS-2 expression, and suppressing TXNIP/TRPV1 activation. Molecular docking research showed that Creb showed a high direct affinity towards PACS-2, TXNIP and TRPV1. To explore this, male Wistar rats were fed orally (100 mg Cu/kg/day, 6 weeks) and intraperitoneally (25 or 50 mg Creb/kg, 7 days). The object recognition, plus maze, open-field, and climbing pole tests were used to assess behavioral performance. Western blotting, ELISA, RT-qPCR, immunofluorescence, and histopathological analyses were conducted to study ER stress, oxidative stress, inflammasome activation, and glial reactivity. Cu exposure induced cognitive impairment, p38-MAPK activation, p-PERK-ATF4-CHOP stimulation, oxidative dysregulation, and TXNIP/TRPV1 propagation, culminating in NLRP3/caspase-1/GSDMD-mediated pyroptosis and STAT3/GFAP-driven astrogliosis. Conversely, Creb upregulated PACS-2 and PGC-1α, augmented Nrf2/HO-1 antioxidant signals, and inhibited the TXNIP/TRPV1, as well as inflammatory cytokine release. This effect was clarified at a 50 mg/kg dose. Regarding this, the data suggests that Creb facilitates neuroprotection by restoring PACS-2-induced mitochondrial-ER homeostasis, thereby inhibiting p38-MAPK-induced ER stress and oxidative stress, as well as altering TXNIP/TRPV1-neuroinflammatory signaling. The axis symbolizes a possible therapeutic strategy for copper-related neurodegenerative disorders.