Expression of FP and EP Prostanoid Receptor Subtypes in DBA/2J Compared With C57/BL6 Mice

Abstract

Abstract: : Purpose: To investigate the expression of FP and EP prostanoid receptor subtypes in DBA/2J (pigmentary glaucomatous) and C57/BL6 (nonglaucomatous) mice at 1, 3, and 9 months of age. Methods: DBA/2J and C57/BL6 mice at different ages were obtained from The Jackson Lab (Bar Harbor, Maine). Mice were sacrificed and the eyes immediately were embedded in Tissue Freeze Medium and stored at –80⁰C for immunohistochemstry. After sectioning and fixing, primary antibodies of EP₁, EP₂, EP₃ and FP prostanoid receptors (Cayman Chemical, Ann Arbor, Michigan) were used to stain the ocular tissues. The receptor binding was visualized by using the secondary antibody linked to FITC and visualized under a fluorescence microscope (Nikon, Japan). Results: Compared with C57/BL6 mice at the same age, the expression of the EP₁ receptor was more in the corneal epithelial layers and the limbus of DBA/2J mice in all the age groups, and less in the retinal pigment epithelium, inner plexiform and retinal ganglion cell (RGC) layers at 9 months. EP₂ receptor was less expressed in inner plexiform and RGC layers at 9 months. EP₃ was less expressed in the cornea at 9 months while more expressed at the inner plexiform and RGC layers at 3 months. The expression of FP receptor was decreased in the ciliary body at 3 months, increased in the outer nuclear layer at 1 and 3 months while decreased at 9 months. Iris, ciliary and choroidal pigmentation were less in the DBA/2J mice in all the age groups compared to the C57/BL6 mice. Degeneration of the retina, especially the inner plexiform layer and ganglion cell layer, was visible in DBA/2J mice at 9 months of age. Conclusions: Our results demonstrate a wide distribution but differential expression of FP and EP prostanoid receptors subtypes in DBA/2J pigmentary glaucomatous mice. Decreased expression of FP and EP prostanoid receptor in the anterior segment and retina at a later stage in DBA/2J glaucomatous mice may contribute to the pathophysiology observed in this strain.

Keywords: immunohistochemistry • receptors: pharmacology/physiology • apoptosis/cell death