Distribution of histamine recepter in the gerbil retina

In the central nervous system, histamine is known to act on three major types of G-protein-coupled receptors; histamine receptor 1 (HR1), histamine receptor 2 (HR2) and histamine receptor 3 (HR3). HR1 has been characterized in mammalian retinas. HR2 typically activated the signaling pathway. Histamine increased a GABA-mediated chloride current in amacrine cells from rat retinal slices via protein kinase A. Histamine via HR3 inhibited electrically-evoked dopamine release from the pig retina. Through electron microscopic technique and immunocytochemical staining methods, the localization of HR3, mGluR6 and GABA became apparent in ON-bipolar cell dendrites of the macaque retina, while HR1 and TH were localized in dopaminergic amacrine cells in the rat retina (Matthew et al., 2006).The gerbil is the animal which is characteristic to the central retinal artery. We have examined the localization of the histamine receptors in the gerbil retina using immunocytochemical method. The gerbils were perfused intracardially with a mixture of 4% paraformaldehyde in 0.1M sodium phosphate buffer. After the removed eyeballs were frozen with the rapid liquid nitrogen, they were cut with section of 10 μm using a cryostat. Experiments were performed to identify the targets of histaminergic retinopetal axons. We report the localization of histamine receptors in gerbil retinas by using light microscopic immunolabeling techniques. [J Physiol Sci. 2007;57 Suppl:S110]