In situ hybridization histochemistry has been used to analyze the regional expression of a class of voltage-dependent K+ channel that is sensitive to two polypeptide toxins (MCD peptide and dendrotoxin I) that produce spectacular effects on brain function. A heterogeneous expression of this K+ channel was observed throughout the brain. High naRNA contents were observed in the granule cells of the gyrus dentatus as well as in pyramidal cells of the Ammon hom (CA3 > CA1) and in the cerebellum. Conversely, low levels of expression were found in basal ganglia (caudate putamen, globus pallidus, and ventral pallidum).
