mt¦1 melatonin receptor localization in the human and guinea pig retina

grantor: University of TorontoIt has been postulated that melatonin regulates dark adaptation of the retina through direct interactions with the rod pathway and dopaminergic neurons through the mt1 receptor. Western blot analysis confirms the presence of a specific 37-kDa band representing the expected size of the mt1 receptor in the retina of both species. Double immunocytochemistry with the mt1 antibody and anti-calretinin, an AII amacrine cell marker, showed that in the human, approximately 20% of AII amacrine cells express the mt1 receptor both centrally and peripherally, but in guinea pig, only 1% expression was found. Colocalization of the mt1 receptor with antibodies to tyrosine hydroxylase (TH), a dopamine cell marker, was found in a subset of amacrine cells both in human and guinea pig retina. Horizontal cell markers anti-parvalbumin and anti-calbindin demonstrated that the mt1 receptor is expressed in approximately 20% of horizontal cells throughout the human retina, predominantly on the H1 subtype.M.Sc