Increased activities of Na +/K +-ATPase and Ca 2+/Mg 2+-ATPase in the frontal cortex and cerebellum of autistic individuals

Abstract

Aims Na +/K +-ATPase and Ca 2+/Mg 2+-ATPase are enzymes known to maintain intracellular gradients of ions that are essential for signal transduction. The aim of this study was to compare the activities of Na +/K +-ATPase and Ca 2+/Mg 2+-ATPase in postmortem brain samples from the cerebellum and frontal, temporal, parietal, and occipital cortices from autistic and age-matched control subjects. Main methods The frozen postmortem tissues from different brain regions of autistic and control subjects were homogenized. The activities of Na +/K +-ATPase and Ca 2+/Mg 2+-ATPase were assessed in the brain homogenates by measuring inorganic phosphorus released by the action of Na +/K +- and Ca 2+/Mg 2+-dependent hydrolysis of ATP. Key findings In the cerebellum, the activities of both Na +/K +-ATPase and Ca 2+/Mg 2+-ATPase were significantly increased in the autistic samples compared with their age-matched controls. The activity of Na +/K +-ATPase but not Ca 2+/Mg 2+-ATPase was also significantly increased in the frontal cortex of the autistic samples as compared to the age-matched controls. In contrast, in other regions, i.e., the temporal, parietal and occipital cortices, the activities of these enzymes were similar in autism and control groups. Significance The results of this study suggest brain-region specific increases in the activities of Na +/K +-ATPase and Ca 2+/Mg 2+-ATPase in autism. Increased activity of these enzymes in the frontal cortex and cerebellum may be due to compensatory responses to increased intracellular calcium concentration in autism. We suggest that altered activities of these enzymes may contribute to abnormal neuronal circuit functioning in autism.