title: Nitric oxide generation and poly(ADP ribose) polymerase activation precede beta-cell death in rats with a single high-dose injection of streptozotocin.
abstract: Streptozotocin (STZ) is widely used for the induction of diabetes in animals by causing destruction of pancreatic beta cells. This experiment was designed to elucidate the sequential process of beta-cell destruction in rats with a single high-dose injection of STZ. At 0, 2, 5, 8 and 24 h after injection, rats were perfused with Krebs-Ringer buffer with dichlorofluorescein diacetate (DCF-DA), a marker for free radicals, and the pancreata were pathologically analyzed. Injection of STZ rapidly elicited an increase in fluorescence of DCF-DA in beta cells at 2 h after the injection. The fluorescence was diminished by carboxy-PTIO, a specific scavenger of nitric oxide (NO), but not by L-NAME, an inhibitor of NO synthase. During this process, an inducible form of NO synthase was not detected. Thereafter, upregulated expression of poly(ADP ribose) polymerase (PARP) and massive beta-cell death were detected at 5-8 h after injection. Migration of macrophages into the islet was conspicuous at 24 h, clearing up the debris of destroyed beta cells. Nicotinamide, a PARP inhibitor, significantly inhibited beta-cell death without apparent suppression of NO generation at 2 h. The current study documented serial processes of STZ-induced beta-cell death, starting with NO generation and PARP activation followed by a clearance with macrophages, where the activation of PARP plays a central role in beta-cell death.
authors.affiliation: Department of Pathology, Hirosaki University School of Medicine, 5 Zaifu-cho, 036-8562, Hirosaki, Japan. ryuichi@cc.hirosaki-u.ac.jp
authors.forename: Ryuichi
authors.initials: R
authors.lastname: Wada
authors.forename: Soroku
authors.initials: S
authors.lastname: Yagihashi
mesh_terms: D000818:Animals; D002465:Cell Movement; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism*; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005609:Free Radicals; D007150:Immunohistochemistry; D020287:In Situ Nick-End Labeling; D007515:Islets of Langerhans / Q000187:drug effects / Q000378:metabolism / Q000473:pathology*; D008264:Macrophages / Q000378:metabolism; D008297:Male; D009569:Nitric Oxide / Q000096:biosynthesis*; D011065:Poly(ADP-ribose) Polymerases / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D013311:Streptozocin / Q000633:toxicity; D013997:Time Factors
chemical_list: D004791:Enzyme Inhibitors; D005609:Free Radicals; D009569:Nitric Oxide; D013311:Streptozocin; D011065:Poly(ADP-ribose) Polymerases