Immunolocalization of prostanoid EP receptor isotypes in human trabecular meshwork.

Purpose. To assess the localization of the EP-type prostanoid receptors in the human trabecular meshwork (TM) and to determine their spatial distribution in relation to the contractile α-smooth muscle actin fibres. Methods. Cryosections of human anterior segments were obtained from 17 different donors and immunostained with different EP receptor subtype specific antibodies. Double staining for the EP2 receptor and smooth muscle actin was carried out. Western blots of TM protein samples were studied. Results. No specific staining for the EP1 receptor was observed. The antibodies against the EP2 receptor revealed in all donors intense staining of human trabecular cells throughout the meshwork. EP3 receptor specific staining was not detected. EP4 immunostaining was confined to the corneo-scleral region near Schwalbe's line. On western blots, the EP2 receptor was detected. In the posterior TM, the EP2 receptor staining was associated with the dense network of actin fibres. Conclusions. These immunocytochemica...