Isozyme pattern of glycogen phosphorylase in the rat nervous system and rat astroglia-rich primary cultures: Electrophoretic and polymerase chain reaction studies

Of the three isozymes of glycogen phosphorylase (GP) known, the brain (B) a nd muscle (M) isoforms have been reported to occur in brain. We investigate d the regional and cellular occurence of the three isozymes in various part s of the rat nervous system, fetal brain and astroglia-rich primary culture s by means of electrophoresis of native proteins with subsequent activity s tain and by reverse transcriptase polymerase chain reaction. In the cortex, cerebellum, olfactory bulb, brainstem, spinal cord and dorsal root ganglia , both mRNA and enzyme protein were found for the B and M isozymes. In addi tion, the liver (L) isoform mRNA was detected in fetal brain and cultured a strocytes. Our studies indicate that there is no regional difference in dis tribution pattern between brain regions, spinal cord and dorsal root gangli a. In immature brain and cultured glial cells, the additional presence of t he L isozyme is possible. These results support the idea that astrocytes ex press two or even three GP isozymes simultaneously.