title: Endothelin expression in ocular tissues of diabetic and insulin-treated rats.
abstract: OBJECTIVE
  The endothelins are potent vasoactive peptides that are widely distributed in ocular tissues. There is evidence linking the endothelins to vascular dysfunction in diabetic microangiopathy. Thus, the synthesis and distribution of endothelin-1 (ET-1) and endothelin-3 (ET-3) were studied in the retinas of diabetic and nondiabetic animals.
  
  
  METHODS
  Levels of ET-1 and ET-3 were determined by radioimmunoassay in ocular tissues of normal rats, and in rats with streptozotocin-induced diabetes of 6 and 12 weeks' duration, insulin-treated and untreated. In a separate cohort of similarly treated animals, retinal vascular trypsin digest preparations were immunostained, using antibodies raised against ET-1 and ET-3.
  
  
  RESULTS
  Ocular ET-1 levels were elevated twofold in diabetic animals that received insulin treatment for 7 days when compared with levels in normal rats. Insulin treatment for 10 days before death caused a fourfold elevation of ET-1 in ocular tissues. Endothelin-1 was also increased in 12-week-old diabetic animals and in those maintained on insulin throughout their period of diabetes. Immunofluorescence to anti-ET-1 within the capillary bed and veins of the retina in diabetic insulin-treated animals was elevated when compared with digests from normal litter-matched control animals. Ocular tissue ET-3 levels were unaffected by diabetes.
  
  
  CONCLUSIONS
  Overall ocular and retinal tissue levels of ET-1 were selectively elevated by diabetes and insulin treatment, suggesting that the endothelins may be involved in the pathogenesis of diabetic retinal microangiopathy.
authors.affiliation: Department of Ophthalmology, Queen's University of Belfast, Northern Ireland, UK.
authors.forename: U
authors.initials: U
authors.lastname: Chakravarthy
authors.forename: R G
authors.initials: RG
authors.lastname: Hayes
authors.forename: A W
authors.initials: AW
authors.lastname: Stitt
authors.forename: A
authors.initials: A
authors.lastname: Douglas
mesh_terms: D000818:Animals; D002851:Chromatography, High Pressure Liquid; D003921:Diabetes Mellitus, Experimental / Q000188:drug therapy / Q000378:metabolism*; D003930:Diabetic Retinopathy / Q000188:drug therapy / Q000378:metabolism*; D019332:Endothelin-1 / Q000378:metabolism*; D019334:Endothelin-3 / Q000378:metabolism*; D007328:Insulin / Q000627:therapeutic use*; D007421:Intestine, Small / Q000378:metabolism; D007668:Kidney / Q000378:metabolism; D008297:Male; D011863:Radioimmunoassay; D051381:Rats; D017208:Rats, Wistar; D012160:Retina / Q000378:metabolism*; D012171:Retinal Vessels / Q000378:metabolism
chemical_list: D019332:Endothelin-1; D019334:Endothelin-3; D007328:Insulin