IN-SITU HYBRIDIZATION ANALYSIS OF GIRK2 EXPRESSION IN THE DEVELOPING CENTRAL-NERVOUS-SYSTEM IN NORMAL AND WEAVER MICE

A mutation in the gene Girk2 that encodes an inwardly rectifying potas sium channel is the genetic defect causing the behavioral and patholog ic abnormalities of the weaver mutant mouse. Of the pathologic abnorma lities, the best studied is the neuronal degeneration that occurs in t he cerebellar cortex and in the midbrain dopaminergic neurons. A detai led characterization of the topographic and temporal expression of Gir k2 is fundamental to elucidate the mechanisms underlying neurodegenera tion in these mutant mice. In this study we utilized in situ hybridiza tion to determine the expression of Girk2 mRNA during prenatal and pos tnatal development in the murine central nervous system (CNS). Girk2 e xpression was seen in multiple regions of embryonic CNS including the cerebellum and midbrain. During postnatal development, the highest exp ression was seen in the cerebellum, midbrain and hippocampus. However, since the developing cerebellum undergoes significant neuronal loss d ue to the degeneration of granule cell precursors, Girk2 mRNA expressi on in this area decreases progressively.