Neuroprotective effect of 2-(4-methoxyphenyl)ethyl-2-acetamido-2-deoxy-β-D-pyranoside against sodium nitroprusside-induced neurotoxicity in HT22 cells

Using RSM for Optimum of Optimum Production of Peptides from Edible Bird’s Nest By-Product and Characterization of Its Antioxidant’s Properties

In this research, the neutrase hydrolysis conditions of edible bird’s nest (EBN) by-products were optimized by response surface methodology (RSM). Antioxidant peptides were then isolated from the EBN by-products by ultrafiltration and chromatography taking the DPPH radical scavenging ability as an indicator. The antioxidant activity of the purified peptides was estimated by radical scavenging ability and sodium nitroprusside (SNP)-induced damage model in PC12 cells. When the enzyme concentration was10 kU/g-hydrolysis temperature was 45 °C, and hydrolysis time was 10.30 h, the degree of hydrolysis (DH) of EBN by-product hydrolysate (EBNH) was the highest. The purified peptide exerted strong scavenging ability with EC₅₀ values of 0.51, 1.31, and 0.65 mg/mL for DDPH, ABTS, and O₂⁻ radicals, respectively. In addition, the purified peptides could significantly reduce the SNP-induced oxidative damage of PC12 cells, and twelve peptides that were rich in leucine (Leu), valine (Val), and lysine (Lys) were identified by LC-MS/MS. These results suggested that EBN by-products have potential as new materials for natural antioxidant peptides.

Salidroside Reduces High-Glucose-Induced Podocyte Apoptosis and Oxidative Stress via Upregulating Heme Oxygenase-1 (HO-1) Expression

Background

Hyperglycemia is one of the most dangerous factors causing diabetic nephropathy. Salidroside is considered to have the effects of reducing oxidative stress damage and improving cell viability. This study was performed to investigate whether and how salidroside reduces high-glucose (HG)-induced apoptosis in mouse podocytes.

Material/Methods

We examined whether salidroside could decrease HG-induced podocyte oxidative stress and podocyte apoptosis in vitro. The potential signaling pathways were also investigated. Podocytes (immortalized mouse epithelial cells) were treated with normal glucose (5.5 mM) as control or HG (30 mM), and then exposed to salidroside treatment.

Results

HG enhanced the generation of intracellular reactive oxygen species (ROS) and apoptosis in podocytes. Salidroside reduced HG-induced apoptosis-related consequences via promoting HO-1 expression. Salidroside increased the expression level of phosphorylated Akt (p-Akt) and phosphorylated ILK (p-ILK), p-JNK, and p-ERK and localization of Nrf-2. JNK inhibitor and ILK inhibitor decreased HO-1 expression to different degrees. Moreover, specific siRNAs of ILK, Nrf-2, and HO-1, and inhibitors of HO-1 and ILK significantly increased ROS generation and Caspase9/3 expression in the presence of salidroside and HG.

Conclusions

The results suggest that salidroside reduces HG-induced ROS generation and apoptosis and improves podocytes viability by upregulating HO-1 expression. ILK/Akt, JNK, ERK1/2, p38 MAPK, and Nrf-2 are involved in salidroside-decreased podocyte apoptosis in HG condition.

Bax modulates neuronal survival while p53 is unaltered after Cytochrome C induced oxidative stress in the adult olfactory bulb in vivo

Background

The granule and periglomerular cells of the olfactory bulb migrate from the sub-ventricular zone (SVZ) as progenitor cell forming the neuronal stream of the rostral olfactory bulb. These cells are characterized by their ability to divide while expressing adult proteins; a phenomenon attributed to the prolonged cell cycle and the regulatory activities of proteins which modulates apoptosis and proliferation in the developing nervous system. Of interest are the proteins concerned with tumor suppression (p53) and cell cycle exit (Bax) and how they regulate survivability of these neurons in the adult system after an induced oxidative stress.

Purpose

This study sets to investigate the interplay between p53 and Bax in the adult olfactory bulb (periglomerular and granule cell layer), and how these proteins determine proliferation and neuronal survival after Cytochrome C induced-oxidative stress. Also, we demonstrate the effect of the induced-stress threshold on such regulation in vivo.

Methods

Adult Wistar rats were segregated into three groups. 10 and 20 mg/Kg BW of potassium cyanide (KCN) was administered to the treatment groups for 15 days while the control received normal saline for the same duration. The olfactory bulb was dissected and processed for general histology and immunohistochemistry of p53/Bax in the periglomerular and granule cell layers. Total (Histology) and immunopositive (p53 and Bax) cell count was done using Image J. Subsequently, we determined the analysis of variance with significance set at *P<0.05.

Results

We observed an increase in cell count for the 10 mg/KgBW treatment; this was characterized by a significant decrease in Bax expression and no change in p53 expression when this treatment group was compared to the control. However, no change was observed in the total cell count for 20 mg/Kg BW treatment for the same duration of exposure. Interestingly, there was also no significant change in Bax and p53 for this treatment when compared with the control.

Conclusion

Although p53 plays an important role in development of the olfactory bulb neurons, our findings suggests it has little contribution in neuronal cell viability and proliferation in the adult olfactory bulb. No significant change in p53 was observed irrespective of treatment dose and cell count while Bax expression was reduced at 10 mg/Kg BW treatment and was associated with an increased cell count. We conclude that regulation of survival of neurons in the adult olfactory bulb, following induced-oxidative stress was more dependent of the expression of Bax and the threshold of the induced stress rather than p53 expression.

Pretreatment with 2-(4-methoxyphenyl)ethyl-2-acetamido-2-deoxy-β-D-pyranoside attenuates cerebral ischemia/reperfusion-induced injury in vitro and in vivo

Salidroside, extracted from the root of Rhodiola rosea L, is known for its pharmacological properties, in particular its neuroprotective effects. 2-(4-Methoxyphenyl) ethyl-2-acetamido-2-deoxy-β-D-pyranoside (GlcNAc-Sal), an analog of salidroside, was recently synthesized and shown to possess neuroprotective properties. The purpose of the current study was to investigate the neuroprotective effects of GlcNAc-Sal against oxygen-glucose deprivation-reperfusion (OGD-R)-induced neurotoxicity in vitro and global cerebral ischemia-reperfusion (GCI-R) injury in vivo. Cell viability tests and Hoechst 33342 staining confirmed that GlcNAc-Sal pretreatment markedly attenuated OGD-R induced apoptotic cell death in immortalized mouse hippocampal HT22 cells. Western blot, immunofluorescence and PCR analyses revealed that GlcNAc-Sal pretreatment restored the balance of pro- and anti-apoptotic proteins and inhibited the activation of caspase-3 and PARP induced by OGD-R treatment. Further analyses showed that GlcNAc-Sal pretreatment antagonized reactive oxygen species (ROS) generation, iNOS-derived NO production and NO-related apoptotic cell death during OGD-R stimulation. GCI-R was induced by bilateral common carotid artery occlusion (BCCAO) and reperfusion in mice in vivo. Western blot analysis showed that GlcNAc-Sal pretreatment decreased the expression of caspase-3 and increased the expression of Bcl-2 (B-cell lymphoma 2)/Bax (Bcl-2-associated X protein) induced by GCI-R treatment. Our findings suggest that GlcNAc-Sal pretreatment prevents brain ischemia reperfusion injury by the direct or indirect suppression of cell apoptosis and GlcNAc-Sal could be developed as a broad-spectrum agent for the prevention and/or treatment of cerebral ischemic injury.