In the present study, we have shown by histoblot that GIRK1, GIRK2 and GIRK3 are widely expressed in both the developing and adult brain, in agreement with previous in-situ hybridization studies (Chen et al., 1997; Karschin et al., 1996; Karschin & Karschin, 1997). In the hippocampus, we found similar temporal expression patterns for GIRK1, GIRK2 and GIRK3 in all hippocampal subfields and dendritic layers, increasing progressively during postnatal development to reach adult levels. In general, GIRK protein expression during development correlated well with the corresponding mRNA pattern (Karschin & Karschin, 1997; Chen et al., 1997), suggesting that transcriptional regulation is an important determinant of the density of GIRK channel subunits in hippocampal neurons.
