ABSTRACT
Atrial natriuretic peptide(ANP) is a 28-amino acid hormone with potent natriuretic effect and diuretic one. ANP wag originally thought to be involved in the regulation of blood pressure and blood volume. However, recent studies have indicated that ANP has much wider physiologic roles, such as the regulation of mitoses, the secretion of thyroglobulin, the production of cerebrospinal fluid and aqueous fluid formation. This peptide hag been detected in the anterior uvea, retina and corneal endothelium. It was reported that ANP decreased intraocular pressure and aqueous humor formation. However the distribution of ANP in the eye was not clearly confirmed. This study was carried out to localize the immunoreactive ANP in the rat eye. The distribution of alpha-ANP in the rat eye was studied by immunohistochemistry using a polychnal antibody against synthetic rat alpha-ANP. Immunoreactive ANP was localized intensely in the epithelium of the ciliary body. ANP immunoreactivity was also strong in the corneal endothelium, iris and in the anterior epithelium of the lens. The immunoreactivity was observed in the nerve fiber layer, ganglion cell layer and inner plexiform layer in the retina. These data clearly confirm that ANP is widerly distributed and that it takes part in diverse functions in the rat eye.