Oxymatrine Ameliorates Memory Impairment in Diabetic Rats by Regulating Oxidative Stress and Apoptosis: Involvement of NOX2/NOX4

Abstract

Oxymatrine (OMT) is the major quinolizidine alkaloid extracted from the root of Sophora flavescens Ait and has been shown to exhibit a diverse range of pharmacological properties. The aim of the present study was to investigate the role of OMT in diabetic brain injury in vivo and in vitro. Diabetic rats were induced by intraperitoneal injection of a single dose of 65 mg/kg streptozotocin (STZ) and fed a high-fat and high-cholesterol diet. Memory function was assessed using a Morris water maze test. A SH-SY5Y cell injury model was induced by incubation with glucose (30 mM/l) to simulate damage in vitro. The serum fasting blood glucose, insulin, serum S100B, malondialdehyde (MDA), and superoxide dismutase (SOD) levels were analyzed using commercial kits. Morphological changes were observed using Nissl staining and electron microscopy. Cell apoptosis was assessed using Hoechst staining and TUNEL staining. NADPH oxidase (NOX) and caspase-3 activities were determined. The effects of NOX2 and NOX4 knockdown were assessed using small interfering RNA. The expression levels of NOX1, NOX2, and NOX4 were detected using reverse transcription-quantitative PCR and western blotting, and the levels of caspase-3 were detected using western blotting. The diabetic rats exhibited significantly increased plasma glucose, insulin, reactive oxygen species (ROS), S-100B, and MDA levels and decreased SOD levels. Memory function was determined by assessing the percentage of time spent in the target quadrant, the number of times the platform was crossed, escape latency, and mean path length and was found to be significantly reduced in the diabetic rats. Hyperglycemia resulted in notable brain injury, including histological changes and apoptosis in the cortex and hippocampus. The expression levels of NOX2 and NOX4 were significantly upregulated at the protein and mRNA levels, and NOX1 expression was not altered in the diabetic rats. NOX and caspase-3 activities were increased, and caspase-3 expression was upregulated in the brain tissue of diabetic rats. OMT treatment dose-dependently reversed behavioral, biochemical, and molecular changes in the diabetic rats. In vitro, high glucose resulted in increases in reactive oxygen species (ROS), MDA levels, apoptosis, and the expressions of NOX2, NOX4, and caspase-3. siRNA-mediated knockdown of NOX2 and NOX4 decreased NOX2 and NOX4 expression levels, respectively, and reduced ROS levels and apoptosis. The results of the present study suggest that OMT alleviates diabetes-associated cognitive decline, oxidative stress, and apoptosis via NOX2 and NOX4 inhibition.

The Effect of Induced Diabetes Mellitus on the Cerebellar Cortex of Adult Male Rat and the Possible Protective Role of Oxymatrine: A Histological, Immunohistochemical and Biochemical Study

“…In addition, it was documented that oxymatrine had a regulatory role in DM and succeeded in reducing glucose blood level in diabetic rats (Huang et al, 2020). A previous work also showed that oxymatrine preserved the structure of the pancreatic islets, enhanced insulin production and sensitivity and reduced both hyperglycemia and hyperlipidemia in streptozotocin-induced diabetic rats (Zuo et al, 2019).…”

“…Also, another study proved that oxymatrine protected the brain against hypoxic-ischemic brain injury by minimizing apoptosis in neonatal rats (Liu et al, 2020). Moreover, oxymatrine prevented neuronal cells from apoptosis that occurs in the rat brain after cerebral hemorrhage (Huang et al, 2012) and also inhibited apoptosis of neuronal cells in diabetic rats through reduction of both expression and activity of cleaved caspase-3 protein (Huang et al, 2020).…”

“…Moreover, in their study on rats' brain following intracerebral hemorrhage, Huang et al (2020) illustrated that oxymatrine prevented brain's oxidative injury through reducing production of 12/15-LOX proteins which play an essential role in developing oxidative damage in the brain tissues. In addition, Huang et al (Huang et al, 2020) reported that oxymatrine improved hippocampal histological structure and cognitive brain function in diabetic rats through suppression of the oxidative stress through reduced expression and activity of NOX2 and NOX4 which are considered main sources of ROS in brain tissue that play a role in neuronal damage. Other studies also demonstrated that oxymatrine increased activity of SOD and decreased synthesis and release of lipid peroxides and malondialdehyde, contributing to its antioxidant activities (Hong-li et al, 2008;Zhao et al, 2008).…”

Oxymatrine Attenuates Osteoclastogenesis via Modulation of ROS-Mediated SREBP2 Signaling and Counteracts Ovariectomy-Induced Osteoporosis

“…Oxymatrine (OMT) is a quinazine alkaloid extracted from Sophora flavescens which has been reported to exhibit various therapeutic effects, such as immunomodulation, anti-inflammation, anti-oxidation, anti-tumor, anti-virus, and hepatoprotection ( Lean et al, 2003 ; Lee et al, 2005 ; Jung et al, 2008 ; Huang et al, 2020 ; Li et al, 2020a , b ; Wang et al, 2020 ; Xiang et al, 2020 ). However, there is no report on the treatment of osteoporosis with OMT.…”

Obesity increases neuropathic pain via the AMPK-ERK-NOX4 pathway in rats

“…These results suggest that the ERK inhibitor protects DRG neurons from damage caused by high fat. Considering the close relationship between NOX4 and inflammation, oxidative stress and apoptosis [ 16 – 19 ], the protective effect of the ERK inhibitor may be related to the reduction of NOX4.…”