Neuroprotective Effect of Smilacis chinae Rhizome on NMDA-Induced Neurotoxicity In Vitro and Focal Cerebral Ischemia In Vivo

Abstract

Abstract. Previous work has shown that the Smilacis chinae rhizome (SCR) markedly inhibits amyloid β protein (25-35)-induced neuronal cell damage in cultured rat cortical neurons. The present study was conducted to further verify the neuroprotective effect of SCR on excitotoxic and cerebral ischemic injury using both in vitro and in vivo studies. Exposure of cultured cortical neurons to 1 mM N-methyl-D-aspartate (NMDA) for 12 h induced neuronal cell death. SCR (10 and 50 µg / ml) inhibited NMDA-induced neuronal death, elevation of intracellular calcium ([Ca 2+ ] i ), and generation of reactive oxygen species (ROS) in primary cultures of rat cortical neurons. In vivo, SCR prevented cerebral ischemic injury induced by 3-h middle cerebral artery occlusion (MCAO) and 24-h reperfusion. The ischemic infarct was significantly reduced in rats that received SCR (30 and 50 mg / kg, orally), with a corresponding improvement in neurological function. Moreover, SCR treatment significantly decreased the histological changes observed following ischemia. Oxyresveratrol and resveratrol isolated from SCR also inhibited NMDAinduced neuronal death, increase in [Ca 2+ ] i , and ROS generation in cultured cortical neurons, suggesting that the neuroprotective effect of SCR may be attributable to these compounds. Taken together, these results suggest that the neuroprotective effect of SCR against focal cerebral ischemic injury is due to its anti-excitotoxic effects and that SCR may have a therapeutic role in neurodegenerative diseases such as stroke.

Neuroprotective Effect of Resveratrol Against Glutamate-Induced Excitotoxicity

“…Furthermore, some studies support that trans-Res inhibites the postsynaptic Glu receptors in hippocampal neurons, with NMDA receptors being more sensitive than AMPA receptors [17], which probably have an antioxidant effect that ameliorates ischemic brain injury. Res also inhibited NMDA-induced neuronal death, intracellular calcium increase and reactive oxygen species generation in rat cortical neurons, confirming the neuroprotective effect of Res [11,28]. However, other studies have shown that pretreatment with Res did not alter the magnitude of the hypothalamus-pituitary-adrenal axis response to NMDA [29].…”

Aralia cordata Protects Against Amyloid β Protein (25–35)–Induced Neurotoxicity in Cultured Neurons and Has Antidementia Activities in Mice

“…Primary cortical neuron cultures were prepared using embryonic day 15 -16 Sprague-Dawley rat fetuses, as described previously (24,25). Neurotoxicity experiments were performed on neurons after 3 -4 days in culture.…”

“…The final concentration of DMSO was ≤0.1%, which did not affect cell viability. For each experiment, A. cordata, oleanolic acid, N G -nitro-L-arginine methyl ester (L-NAME; Sigma), (5R,10S)-(+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine (MK-801; RBI, Natick, MA, USA), and verapamil (Sigma) were applied 15 min prior to treatment with 10 μM Aβ (25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35). They were also present in the medium during Aβ (25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35) incubation.…”

“…The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT, Sigma) assay and Hoechst 33342 (Molecular Probes, Eugene, OR, USA) staining were performed to measure neuronal death 36-h after exposure of cultured neurons to 10 μM Aβ(25-35), as previously described (24,25). Changes in [Ca 2+ ] i were measured with Fluo-4 AM (Molecular Probes), a calcium-sensitive fluorescent dye, using a laser scanning confocal microscope (TCS SP2 AOBS; Leica, Heidelberg GmbH, Germany) with a 488-nm excitation argon laser and 515-nm long-pass emission filters (24,25).…”

“…Also, α-tocopherol and anti-inflammatory agents such as indomethacin reportedly slow the progression of AD (13,14). Aβ (25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35), the core toxic fragment of Aβ , produces similar neurodegenerative properties as Aβ , including oxidative damage, inflammatory responses, and memory impairment (15,16). Aralia species belong to the family Araliaceae and have long been recognized in China, Japan, and Korea as therapeutic herbs with antinociceptive, antidiabetic, antioxidant, and anti-inflammatory activities.…”