Notoginsenoside R1 attenuates sevoflurane-induced neurotoxicity

Background Sevoflurane, a volatile anesthetic, is known to induce widespread neuronal degeneration and apoptosis. Recently, the stress-inducible protein sestrin 2 and adenosine monophosphate-activated protein kinase (AMPK) have been found to regulate the levels of intracellular reactive oxygen species (ROS) and suppress oxidative stress. Notoginsenoside R1 (NGR1), a saponin isolated from Panax notoginseng, has been shown to exert neuroprotective effects. The effects of NGR1 against neurotoxicity induced by sevoflurane were assessed. Methods Sprague-Dawley rat pups on postnatal day 7 (PD7) were exposed to sevoflurane (3%) anesthesia for 6 h. NGR1 at doses of 12.5, 25, or 50 mg/kg body weight was orally administered to pups from PD2 to PD7. Results Pretreatment with NGR1 attenuated sevoflurane-induced generation of ROS and reduced apoptotic cell counts. Western blotting revealed decreased cleaved caspase 3 and Bad and Bax pro-apoptotic protein expression. NGR1 substantially upregulated nuclear factor erythroid 2-related factor 2 (Nrf2) expression along with increased heme oxygenase-1 (HO-1) and NAD(P)H quinone oxidoreductase-1 levels, suggesting Nrf2 signaling activation. Enhanced sestrin-2 and phosphorylated AMPK expression were noticed following NGR1 pretreatment. Conclusion This study revealed the neuroprotective effects of NGR1 through effective suppression of apoptosis and ROS via regulation of apoptotic proteins and activation of Nrf2/HO-1 and sestrin 2/AMPK signaling cascades.