Region-specific changes in expression and activity of calpains in the CNS of native rats.

Abstract

Introduction and Aim: It has been proposed that µ-calpain is responsible for neuronal survival, while m-calpain – for the degeneration. It can be assumed that the "susceptibility" to the damage factor for neurons in different CNS regions depends on the content/activity of calpain isoforms. We analyzed the mRNA levels and the activity of µ-and m-calpain in the different CNS structures of rats. Materials and Methods: After decapitation intact male Wistar rats the prefrontal cortex, striatum, hippocampus, midbrain, brainstem, cerebellum, and spinal cord were removed. Each structure was divided into two parts: casein zymography was performed to determine the activity and real-time RT–PCR - to determine the level of expression mRNA of µ-and m-calpains. Results: We have shown that m-calpain mRNA predominates in the striatum, midbrain and brainstem, while µ-calpain mRNA enrichment was noticed for the hippocampus and cerebellum. The highest µ-calpain activity was in the cervical spinal cord, the lowest - in the striatum. The m-calpain activity was relatively high in the midbrain, striatum, hippocampus and brainstem, while in the cervical spinal cord and cerebellum it was moderate. Conclusion: The selective neuronal death observed during neurodegeneration can be partially determined by the initial level of calpains expression and/or activity.