Increased Activities of Brain Na+-K+-ATPase and Ca2+-Mg2+-ATPase in Frontal Cortex and Cerebellum from Autism

Background: The enzymes Na⁺-K⁺-ATPase and Ca²⁺-Mg²⁺-ATPase are ubiquitously present and they maintain intracellular gradients of ions that are essential for signal transduction. 

Objectives: To compare the activities of Na⁺-K⁺-ATPase and Ca²⁺-Mg²⁺-ATPase in brain homogenates from frontal, temporal, parietal, and occipital cortex and cerebellum from autism subjects with an age range of 4 to 39 yrs (N = 7 to 10 for different regions) and age-matched control subjects (N = 9 to 10). 

Methods: Na⁺-K⁺-ATPase and Ca²⁺-Mg²⁺-ATPase hydrolyze the ATP into ADP and inorganic phosphorus.  Inorganic phosphorus thus released was assayed by measuring the inorganic phosphorus.

Results: The activities of both Na⁺-K⁺-ATPase (p < 0.05) and Ca²⁺-Mg²⁺-ATPase (p < 0.001) were significantly increased in the cerebellum in the autism samples as compared to age-matched controls. The activity of Na⁺-K⁺-ATPase (p < 0.05) but not Ca²⁺-Mg²⁺-ATPase was increased in the frontal cortex in the autism samples as compared to age-matched controls.  In contrast, the activities of these enzymes were not different between autism and control groups in other regions of brains, i.e., temporal, parietal and occipital cortex.  
Conclusions: We propose that increased activities of Na⁺-K⁺-ATPase and Ca²⁺-Mg²⁺-ATPase in frontal cortex and cerebellum may contribute, in part, to altered neocortical circuit functions in autism.