World glaucoma congress 参加報告
山梨大学 薬理学講座 濱田健太郎
先日開催された緑内障の国際学会であるW G Cにライフサイエンスコースのサポートのもと参加をさせていただいた。今回は初の国際学会であり、山梨大学眼科教室の教授である柏木先生に参加を推薦していただいたことでM DでもphDでもない身分で参加をさせていただくことが出来た。また海外の研究者、医師からもコメントをいただくことができ大変有意義であった。今後もこのような素晴らしい機会をサポートしていただいた全ての方に恥じないように一層精進したいと思う。
DEFICIENCY OF P2Y1 RECEPTOR INDUCES HYPERTENSIVE GLAUCOMA-LIKE PHENOTYPES IN MICE
K Hamada1, S Koizumi1, K Kashiwagi2, Y Shinozaki2, K Namekata3, T Harada3, T Segawa4,
1Department Neuropharmacol., Interdiscip. Grad. Sch. Medical, University Yamanashi, Yamanashi, 2Department of Ophthalmology, Interdisciplinary Graduate School of Medicine, University Yamanashi, Shimokato Chuo Yamanashi, 3Visual Research Project, Tokyo Metropolitan Institute of Medical Science, Tokyo, 4Center for Life Science Research, University Yamanashi, Shimokato Chuo Yamanashi, 5Department of Anatomy, Jichi Medical University, Tochigi, Japan
Glaucoma is leading cause of blindness which is characterized by degeneration of retinal ganglion cells (RGC).An elevated intraocular pressure (IOP) is a major risk factor for glau- coma, and the IOP reduction is a first-line therapy, which prevents or delays vision loss. Alt- hough several hypotensive drugs are currently used to reduce IOP, conventional drugs often fail to adequately reduce IOP because of drug resistance, ineffectiveness with a single drug, and side effects. Therefore, there is a need to identify a new molecular target for hypotensive drugs. As a potential target, we focused on purinergic receptors because it has been repor- ted that production/metabolism of extracellular ATP in aqueous humor is dysregulated in glaucoma patients. In the present study, we demonstrate the role of P2Y1 receptors on IOP reduction.
We used C57BL/6J (Wild type) and P2Y1KO mice. IOP was measured using a rebound type to- nometer. RGC damages were estimated by counting Brn3a- and Rbpms-positive cells. To es- timate the functional expression of P2Y1 receptors, we performed intracellular Ca2+ imaging ([Ca2+]i) of acutely isolated ocular tissues. To evaluate the expression of the P2Y1 receptor protein, we performed Western blotting and immunohistochemical analysis. Apoptotic cells were detected by TdT-mediated dUTP nick end labeling (TUNEL). Ultrastructural changes in optic nerve were analyzed using serial block face scanning electron microscopy (SBF-SEM). Ocular function was estimated by multifocal electro retinogram
Instillation of MRS2365(MRS), a selective agonist for P2Y1 receptors, significantly reduced IOP in WT mice but not in P2Y1KO mice. The hypotensive effects by MRS were transient and in a concentration-dependent manner. P2Y1 receptor was expressed in ciliary body, trabecular meshwork and Schlemm’s canal. P2Y1 receptor activation caused suppression and promoti- on of production and draining of aqueous humor, respectively. P2Y1KO mice showed chronic ocular hypertension regardless of their ages. At 3 months old, we found no RGC loss. At 12 months old, P2Y1KO mice showed significant RGC loss, increase in apoptotic RGCs, thinning of nerve fiber layer, optic nerve atrophy and impaired ocular function.
P2Y1 receptor activation reduces IOP, and the loss of P2Y1 receptor causes glaucoma-like pa- thologies, including chronic ocular hypertension, RGC degeneration, and ocular dysfuncti- on.