Neuroprotective effects of carnosic acid on neuronal cells under ischemic and hypoxic stress

Abstract

Ischemia/hypoxia induces oxidative stress which is associated with neurodegenerative diseases. The present study investigated protective mechanism of carnosic acid (CA) on ischemia/reperfusion and hypoxia-induced neuronal cell injury. The results showed that CA reduced 52% of the infarct volume from brains under ischemia/reperfusion in vivo and protected the PC12 cells from hypoxic injury in vitro. CA (1.0 µM) enhanced cell viability, prevented lactic dehydrogenase (LDH) release, scavenged reactive oxygen species (ROS), increased superoxide dismutase activity, and attenuated Ca²⁺ release, lipid peroxidation, and prostaglandin E₂ production in hypoxic PC12 cells. In addition, CA also reduced nitric oxide (NO) and interleukine (IL)-1 and IL-6 production from activated BV-2 microglia. Furthermore, its effect on hypoxia-induced mitogen-activated protein kinases (MAPKs) signaling pathway and caspase-3 was examined. Extracellular signal-regulated protein kinases, c-jun NH₂-terminal kinase, and p38 MAPK were activated during hypoxia. CA inhibited MAPKs, caspase-3, and COX-2 activation and correlated well with the diminished LDH release and apoptosis (TUNEL) in PC12 cells under hypoxia. Taken together, CA protected neuronal cells under ischemia/hypoxia through scavenging or reducing of ROS and NO, inhibiting COX-2 and MAPK pathways by anti-inflammatory and anti-oxidative properties.

Keywords:

• Carnosic acid
• Hypoxia
• ROS
• NO
• Cytokine
• MAPKs
• Caspase-3
• COX-2

Acknowledgments

This study was supported by a grant TCVGH-997310C from Taichung Veterans General Hospital.