title: Role of protein kinase C on the alteration of retinal endothelin-1 in streptozotocin-induced diabetic rats.
abstract: Activation of protein kinase C (PKC) has been implicated in the pathogenesis of diabetic retinopathy. The purpose of this study was to investigate the role of PKC on the alteration of retinal endothelin-1 in 2-week streptozotocin (STZ)-induced diabetic rats. The measurement of retinal PKC activities from membranous and cytosolic fractions was conducted by ELISA. Retinal tissues were analysed for the expression of endothelin-1 (ET-1), endothelin-3 (ET-3), endothelin-A (ET-A), and endothelin-B (ET-B) mRNA by means of semi-quantitative RT-PCR. Retinal vasculature isolated by trypsin digest technique was immunostained for ET-1. We followed the alteration of retinal ET-1 after intravitreal injection of a general PKC inhibitor, GF109203X, in 2-week diabetic rats. Retinal PKC specific activities were significantly increased by 37% (P=0.027) in the membranous fraction in diabetic rats compared with normal rats, whereas PKC specific activities in the cytosolic fraction were unchanged. The retina from the diabetic rats showed increased ET-1 mRNA expression after 2 weeks, while no changes were found for ET-3, ET-A and ET-B. ET-1 immunoreactivity was also increased in the retinal vasculature of diabetic rats. Retinal ET-1 expression was decreased after intravitreal injection of GF109203X (10(-5), 10(-6), 10(-7) M) in a dose-dependent manner. The results from this study showed that the enhanced ET-1 expression associated with the activation of PKC has occurred in early diabetes, and PKC inhibitor could reverse the up regulation of ET-1.
authors.affiliation: Department of Ophthalmology, Shanghai First People's Hospital, 85 Wu Jin Road, Shanghai 200080, People's Republic of China.
authors.forename: Qi
authors.initials: Q
authors.lastname: Zhu
authors.forename: Xun
authors.initials: X
authors.lastname: Xu
authors.forename: Xin
authors.initials: X
authors.lastname: Xia
authors.forename: Qing
authors.initials: Q
authors.lastname: Gu
authors.forename: Patrick C P
authors.initials: PC
authors.lastname: Ho
mesh_terms: D000818:Animals; D002462:Cell Membrane / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism*; D003930:Diabetic Retinopathy / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D019332:Endothelin-1 / Q000235:genetics / Q000378:metabolism*; D016232:Endothelins / Q000235:genetics / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects; D007211:Indoles / Q000494:pharmacology; D008297:Male; D008301:Maleimides / Q000494:pharmacology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000502:physiology*; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D012160:Retina / Q000378:metabolism*; D012171:Retinal Vessels / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D019332:Endothelin-1; D016232:Endothelins; D004791:Enzyme Inhibitors; D007211:Indoles; D008301:Maleimides; D012333:RNA, Messenger; D011493:Protein Kinase C; C070515:bisindolylmaleimide I