Naoluo Xintong capsule ameliorates apoptosis induced by endoplasmic reticulum stress in rats with cerebral ischemia/ reperfusion injury

Abstract

Naoluo Xintong (NLXT) capsuleis a newly developed drug recorded in the Chinese Pharmacopoeia. It is derived from traditional Chinese medicine (TCM) NLXT decoction, and has been widely used to treat cerebrovascular diseases in clinic. However, it is currently unknown whether it improve cerebral ischemia reperfusion (I/R) injury. The effect of NLXT on regional cerebral blood flow (rCBF) was examined using Laser Doppler flower. The Terminal deoxyribonucleotide transferase-mediated Nick end labeling (Tunel) assay was performed to determine the effects of NLXT on apoptosis. Subsequently, cerebral water content and TTC staining were measured to assess cerebral edema and infarct volume, respectively. The protein expression levels were analyzed with Immunofluorescence and western blot assays. The results indicated that NLXT ameliorated MCAO-induced cerebral I/R injury by decreasing infract volume, inhibition of apoptosis, and upregulation rCBF. In addition, it decreased the expression of key protein involved endoplasmic reticulum (ER)-stress, including glucose-regulated protein 78 (GRP78), C/EBP-homologous protein (CHOP) and Caspase-12 at 24 h following reperfusion. This was accompanied reduced degradation level of TRPC6 and increased phosphorylation of cAMP/Ca2+ response elementbinding protein (p-CREB), and decreased calpain-specific αII-spectrin breakdown product (SBDP145) activity. Interestingly, inhibition of mitogen-activated protein kinase (MEK) activity abolished the effect of NLXT on CREB activity. Collectively, the results indicated that NLXT can improve I/R injury therapy by activating TRPC6/MEK/CREB signaling pathway to attenuate ER-stress related neuronal apoptosis.