Cellular and subcellular distributions of β1- and β2-Adrenoceptors in the CA1 and CA3 regions of the rat hippocampus

β-Adrenoceptors (ARs) in the hippocampus play an important role in regulating synaptic plasticity and memory consolidation. However, little is known about the distributions of β-ARs in the hippocampus, especially in the cornu ammonis (CA)1 and CA3 regions of Sprague-Dawley rats. Here, we report that β1- and β2-ARs in the CA1 and CA3 regions have differential subcellular distributions. Using double immunofluorescence labeling and confocal laser scanning microscopy, we found that almost all of the neuronal nuclei positive cells express β1- and β2-ARs, while few glial fibrillary acidic protein positive cells express them. Interestingly, β1-ARs are predominantly distributed in the cell membrane and cytoplasm, whereas β2-ARs are predominantly distributed not only in the membrane and cytoplasm, but also in the nucleus. The differential subcellular distribution of β1- and β2-ARs may have functional significance.