Protection of neuronal cells from excitotoxicity by disrupting nNOS-PSD95 interaction with a small molecule SCR-4026.

Stroke is a major public health problem leading to high rates of death and disability in adults. Coupling of postsynaptic density protein-95 (PSD-95) and neuronal nitric oxide synthase (nNOS) plays an important part in neuronal damage caused by stroke. Recent studies suggest the possibility of alleviating post ischemia neuron damage by blocking ischemia-induced nNOS-PSD-95 association. Here, we report a small-molecular inhibitor of nNOS-PSD-95 interaction, SCR-4026, which exhibits neuroprotective activities in NMDA-induced or Oxygen and glucose deprivation (OGD)-induced neuronal damage in primary cortical neurons cultures, and ameliorated focal cerebral ischemic damage in rats subjected to middle cerebral artery occlusion (MCAO) and reperfusion. Furthermore, we found that SCR-4026 was also able to promote neural stem cells to differentiate into neurons-like cells, which is potentially of great significance for neural protection. Taken together, SCR-4026 is identified as a novel small molecule that shows great potential in treating stroke.

The synergetic effect of edaravone and borneol in the rat model of ischemic stroke.

Free radical production contributes to the early ischemic response and the neuroinflammatory response to injury initiates the second wave of cell death following ischemic stroke. Edaravone is a free radical scavenger, and borneol has shown anti-inflammatory effect. We investigated the synergistic effect of these two drugs in the rat model of transient cerebral ischemia. Edaravone scavenged OH, NO and ONOO─ concentration-dependently, and borneol inhibited ischemia/reperfusion-induced tumor necrosis factor-α (TNF-α), inducible nitric oxide synthase (iNOS), interleukin-1ß (IL-1ß) and cyclooxygenase-2 (COX-2) expressions. In the rat model of transient cerebral ischemia and reperfusion, the combination of edaravone and borneol significantly ameliorated ischemic damage with an optimal proportion of 4:1. Emax (% inhibition) of edaravone, borneol and two drugs in combination was 55.7%, 65.8% and 74.3% respectively. ED50 of edaravone and borneol was 7.17 and 0.36 mg/kg respectively. When two drugs in combination, ED50 was 0.484 mg/kg, in which edaravone was 0.387 mg/kg (ineffective dose) and borneol was 0.097 mg/kg (ineffective dose). Combination index (CI)<1 among effects observed in experiments, suggesting a significant synergistic effect. Reduced levels of pro-inflammatory mediators and free radicals were probably associated with the synergistic effect of edaravone and borneol. The combination exhibited a therapeutic time window of 6h in ischemia/reperfusion model, and significantly ameliorated damages in permanent ischemia model. Moreover, two drugs in combination promoted long-term effect, including improved elemental vital signs, sensorimotor functions and spatial cognition. Our results suggest that the combination of edaravone and borneol have a synergistic effect for treating ischemic stroke.

Intracellular GSH and ROS levels may be related to galactose-mediated human lens epithelial cell apoptosis: role of recombinant hirudin variant III.

Oxidative processes in the lenses are the most commonly found damaging factor for the development of cataracts. Hirudin, a most potent inhibitor of thrombin as an antithrombic drug, also have potential use in cataracts. In order to investigate the mechanisms of hirudin against galactose-induced cataract at the cellular level. We used recombinant hirudin variant III (rHV3) to study the protective effect of hirudin on galactose-mediated human lens epithelial cells injury. The human lens epithelial cells (hLECs) were cultured in D/F(12)-10% FBS medium containing 125 mM D-galactose with or without rHV3. Cell viability was assessed by methylthiazol tetrazolium (MTT) assay and propidium iodide (PI) staining in situ. Cell apoptosis was elevated with comet assay (single cell gel electrophoresis, SCGE), AO/EB double staining and Annexin-V/PI double staining assay. Reactive oxygen species (ROS) were quantified with 2',7'-dichlorofluorescein (DCF), and free glutathione (GSH) levels were measured with a commercial GSH quantification kit. Decreased viability and increased apoptosis of the hLECs were observed when incubated with 125 mM galactose. These hLECs also demonstrated the increased presence of ROS, whereas GSH was reduced. rHV3 blocked the induction of cell death, apoptosis and oxidative stress in hLECs. One mechanism may be through regulating intracellular ROS and GSH levels to inhibit apoptosis of the human lens epithelial cells.

Potential use of hirudin in diabetic cataract: a study of galactose mediated human lens epithelial cells injury.

Osmotic stress, together with weakened antioxidant defense mechanisms, is attributed to the changes observed in human diabetic cataract. The use of hirudin, an antithrombic agent, in the pathogenesis of human cataracts has not been studied so far. Since the epithelium is the metabolic unit of the lens, the effect of recombinant hirudin variant III (rHV3) on galactose-induced morphological changes and antioxidant status of human lens epithelial line SRA01/04 in culture was evaluated in this study. The human lens epithelial cells (hLECs) were cultured in D/F(12) medium (normal group), D/F(12) medium + 50 mM D-galactose (control group) or D/F(12) medium + 50 mM D-galactose+rHV3 (test group) for 24 or 72 h. The cells were observed under the light, fluorescence and transmission electron microscope for any morphological changes, while the cell viability was assessed by methylthiazol tetrazolium (MTT) assay. The cells in flasks were harvested for the estimation of various antioxidant parameters. Cell morphology, viability, malondialdeyde, glutathione and antioxidant enzymes were significantly altered in the control group as compared with the normal group. Administration of rHV3 confers significant protection against these changes in the human lens epithelial cells. These results demonstrated that rHV3 could effectively protect galactose-induced hLEC injury and suggested that it could have potential use in diabetic cataracts.