Morroniside prevents H₂O₂ or Aβ_1-42-induced apoptosis via attenuating JNK and p38 MAPK phosphorylation

Area of Science:

• Neuroscience
• Pharmacology
• Biochemistry

Background:

• Alzheimer's disease (AD) is linked to amyloid-beta (Aβ) peptide toxicity, oxidative stress, and mitogen-activated protein kinase (MAPK) activation.
• Morroniside, derived from Cornus officinalis, exhibits known antioxidant properties.

Purpose of the Study:

• To investigate the protective effects of morroniside against H₂O₂ or Aβ₁₋₄₂-induced cytotoxicity in rat pheochromocytoma (PC12) cells.
• To elucidate the underlying mechanisms of morroniside's neuroprotective action, focusing on MAPK signaling pathways.

Main Methods:

• PC12 cells were exposed to hydrogen peroxide (H₂O₂) or Aβ₁₋₄₂.
• Cell viability, apoptosis-related protein expression (Bcl-2, Bax, cytochrome C, cleaved caspase-3), and MAPK phosphorylation (JNK, p38) were assessed.
• Cells were pretreated with varying concentrations of morroniside or specific MAPK inhibitors (SP600125, SB203580).

Main Results:

• H₂O₂ or Aβ₁₋₄₂ exposure induced significant PC12 cell death by altering apoptotic protein expression and increasing JNK and p38 MAPK phosphorylation.
• Morroniside pretreatment dose-dependently reversed these toxic effects.
• Morroniside inhibited both JNK and p38 MAPK phosphorylation, unlike selective MAPK inhibitors which affected only one pathway.

Conclusions:

• Morroniside demonstrates significant neuroprotective effects against Aβ and oxidative stress-induced apoptosis in neuronal cells.
• Morroniside's mechanism involves the simultaneous suppression of upstream JNK and p38 MAPK signaling pathways.
• Morroniside represents a potential therapeutic agent for Alzheimer's disease by targeting multiple key pathways in neurodegeneration.