Protective effects of a new glutamic acid derivative against stress after nNOS blockade

Abstract

We studied the effects of a new glutamic acid derivative, glufimet, on oxidative stress, activity of antioxidant enzymes, mitochondrial respiration, endothelial vasodilation and anti-platelet activity in female rats after exposure to 24-hour immobilization pain stress and 7-nitroindazole, a neuronal nitric oxide synthase (nNOS) inhibitor. A single dose administration of glufimet (29 mg/kg intraperitoneally) 10 minutes before stress exposure caused a decrease of NO metabolites in serum (by 27.2%) and heart homogenate (33.5% (p£0.05), respectively, compared with the control group. Administration of 7-nitroindazole with glufimet also decreased the studied parameters by 14.3% in the heart homogenate and by 30,3% in the brain (p£0.05) compared with stress exposed rats receiving only the nNOS inhibitor. Glufimet decreased the levels of primary and secondary products of lipid peroxidation (LPO), conjugated dienes by 20% (p£0.05) and 17.3% (p£0.05), ketodienes by 16% and 13.7%, malondialdehyde by 15% (p£0.05) and 26.6% (p£0.05) in the heart and brain mitochondria of stress exposed rats, respectively, compared with the control group. Glufimet administration also increased SOD activity (by 14.4% and 13.1%, respectively), catalase (by 19% and 26.8%, respectively) and glutathione peroxidase (GPx) activity (by 45.5% (p£0.05) and 7.3%, respectively). The antioxidant effect of glufimet may be also attributed to increased coupling between the processes of mitochondria respiration and oxidative phosphorylation. This was evidenced by an increase in the respiratory control ratio (RCR) (by 46.0% (p£0.05) for malate/glutamate and by 49,7% (p£0.05) for succinate) in the heart mitochondria. A statistically significant increase in RCR (by 37.3% (p£0.05)) was observed in stress exposed female rat brain mitochondria for succinate. RCRs differed significantly for succinate in the heart and brain of rats receiving glufimet after nNOS blockade. RCR increased by 62.3% (p£0.05) in the heart mitochondria and by 72.2% (p£0.05) in the brain mitochondria compared with the RCRs in stress exposed rats receiving 7-nitroindazole.

Effect of a new cyclic derivative of GABA, RGPU-207, on the functions of cardiac and cerebral mitochondria of stressed animals

“…When administered to the stressed animals, RGPU‐207 and the comparator drugs reduced LPO activity and enhanced antioxidant defence. Similar results have been obtained in a number of experiments involving GABA and its derivatives in different models: in ischaemia, β‐amyloid accumulation and age‐related changes, oxidative stress in lipopolysaccharide treated astrocyte cultures, alcohol intoxication in gastric mucosa of rats and in the culture of human gastric epitheliocytes GES‐1 . A decrease in the level of LPO products induced by piracetam and RGPU‐207 administration is likely to be due to higher fluidity of the damaged mitochondrial membranes, which improves the performance of the mitochondrial respiratory chain complexes, contributes to the decrease in the electron leakage and ROS production.…”

“…High concentrations of ROS have a cytotoxic effect, cause cell death due to apoptosis and necrosis . It was demonstrated that stress activates LPO processes and reduces ROS activity, which is likely to occur due to the developing oxidative stress, depletion of catalase, SOD and GP capacity, and decreased expression of their genes …”

“…We modelled stress by suspending the animals by their dorsal cervical skin fold for 24 h . The animals were divided into eight groups, with seven animals in each group: 1 – positive control group (unstressed rats receiving saline solution); 2 – negative control group (stressed male rats receiving saline solution); 3–5 – groups of unstressed animals receiving RGPU‐207 (the substance was developed at the Department of Organic Chemistry of Herzen State Pedagogical University (St Petersburg, Russia), comparator drugs – phenibut (HSPU, St Petersburg, Russia) and piracetam (OAO, Dalhimpharm, Russia) at a dose of 9.4, 25 and 400 mg/kg, respectively.…”

“…Groups 6–8: stressed animals receiving RGPU‐207, phenibut and piracetam in the concentrations listed above. The earlier experiments have demonstrated that when administered at the indicated doses, the investigated agents have the most pronounced pharmacological effects . RGPU‐207 compound, the comparator drugs and saline solution were administered intraperitoneally 30 min substituted before and immediately after the stress.…”

Activity of ROS-induced processes in the combined preconditioning with amtizol before and after cerebral ischemia in rats

“…The total activity of superoxide dismutase (SOD) was measured using the method for assessing a degree of inhibiting the quercetin oxidation reaction (Tyurenkov et al 2017). The SOD activity was determined based on a degree of quercetin oxidation inhibition (%) when constructing the calibration curve.…”