In this work, we used a combination of different techniques to reveal the temporal and spatial expression profile and subcellular localization of three GIRK channel subunits in the rodent brain during postnatal development. The results obtained with histoblot suggest that GIRK1, GIRK2 and GIRK3 are widely distributed in the adult brain and during the early stages of development, and display an overlapping and prominent expression pattern during development in multiple brain regions including the hippocampus, cerebellum, neocortex and thalamus. In addition, immunoelectron microscopy combined with quantitative analysis revealed that the subcellular distribution of GIRK channel subunits is differentially localized in a subunit- and time-dependent manner within the developing hippocampus. Specifically, we have provided evidence for the existence of a similar distribution pattern for GIRK1 and GIRK2, which is different from that for GIRK3. These data demonstrate that the three GIRK channel subunits are differentially regulated and their co-localization begins in the early stages of development.
