Biphasic changes in the Ser-9 phosphorylation of glycogen synthase kinase-3β after electroconvulsive shock in the rat brain.

Abstract

Background: Glycogen synthase kinase-3β (GSK-3β) plays important roles in intracellular signaling pathways. Phosphorylation at Ser-9 reduces the activity of GSK-3β, while phosphorylation at Tyr-216 enhances its activity. Mood stabilizing agents increase the phosphorylation of GSK-3β at Ser-9, and hence inhibit its activity. This property has been considered to be related to the therapeutic action of these drugs. The effect of electroconvulsive shock (ECS), an effective mood stabilizing treatment, on the phosphorylation of GSK-3β is not known yet. Methods: In this study, the effect of ECS on the phosphorylation of GSK-3β was examined in the rat frontal cortex, hippocampus, and cerebellum by Western blot analysis using antibodies specific for Ser-9 or Tyr-216 phosphorylated GSK-3β. Results: In all regions, the phosphorylation of GSK-3β at Ser-9 was decreased immediately after ECS, but then increased above basal level within 10 min and maintained at an increased level for more than 30 min. Meanwhile, the phosphorylation at Tyr-216 of GSK-3β did not show any significant changes after ECS. Conclusions: These results showed that ECS could induce biphasic changes in the Ser-9 phosphorylation of GSK-3β in the rat brain, suggesting some similarities, as well as differences, in the actions of mood stabilizers and ECS in the signal transduction mechanisms of the brain.