Effect of GABA mimetic phenibut on oxidoreductase activity in the brain compartment of adult and juvenile scorpionfish Scorpaena porcus Linnaeus, 1758
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Abstract
An increase in GABA levels serves to the survival of neurons during hypoxia/anoxia. During ontogenesis, GABA is capable of transforming its mediator function from excitatory to inhibitory. The oxidoreductase activity (MDH, 1.1.1.37; LDH, 1.1.1.27; catalase, 1.11.1.6) was studied in the brain compartments - the medulla oblongata (MB) and the forebrain, diencephalon, midbrain (AB) - in juvenile and adult Black scorpionfish Scorpaena porcus on the background of injection of GABA mimetic phenibut (400 mg/kg i.p.). AB structures of juvenile scorpionfish were characterized by an intensity of aerobic metabolism comparable to that of adults. At the same time, an elevated LDH activity in juvenile MB and AB was observed, which may serve to increase survivorship at low environmental PO2. Catalase activity in both age groups was somewhat higher in MB, which may be related to the intensity of oxidative phosphorylation as well as to MB tolerance to injures during hypoxia. Moreover, catalase activity in the brain of juveniles (especially in AB) was somewhat lower than that of adults. Phenibut simultaneously increased MDH and LDH activity in the brain compartments of adult scorpionfish, which may be associated with the activation of the malate-aspartate shunt, with an opposite trend towards the restriction of anaerobic glycolysis in the juvenile brain, being, especially, pronounced in AB (p<0.05). Simultaneously, phenibut contributed to an increase in catalase activity in all brain compartments, regardless of the age of scorpionfish (p<0.05). It was supposed that catalase-controlled H2O2 level translates the changes in cellular metabolism into a meaningful physiological response by influencing H2O2-sensitive ion channels that determine neuronal excitability and modulates GABAergic transmission. Such a mechanism may be involved in the brain maturation, to maintain brain resistance to hypoxia, and to ensure adaptive processes in juvenile and adult scorpionfish.