cytochrome-c-t and efaroxan

Interleukin (IL)-1beta-treated rat islets of Langerhans were exposed in vitro either to the imidazoline compound, Efaroxan, or to the selective inducible nitric oxide synthase (iNOS) inhibitor, 1400W, in a medium containing a high concentration of glucose (16.7 mmol/L). Our data have evidenced the following: (i) addition of Efaroxan to islet cultures inhibited IL-1beta activation of ICE (cysteine protease IL-1beta converting enzyme) while addition of 1400W did not; (ii) Efaroxan completely inhibited IL-1beta-induced suppression of insulin secretion and induction of iNOS mRNA transcripts, and, in addition, counteracted islet beta-cell protein profile alterations, Bax-cytochrome c translocation, caspase activation, and apoptosis; (iii) 1400W inhibited IL-1beta induction of iNOS, but failed to completely counteract the other cytotoxic effects; (iv) the two compounds, moreover, exerted different effects on manganese superoxide dismutase (MnSOD), in fact, while Efaroxan inhibited the early stimulatory effect of IL-1beta on MnSOD, 1400W did not. Thus, Efaroxan completely protected islet beta cells from damage caused by IL-1beta-induced toxicity, while compound 1400W only inhibited NO radical production without altering the cytokine's cytotoxicity. Our observations have evidenced that suppression of ICE activation is required to counteract IL-1beta-mediated islet beta cell toxicity, and that IL-1beta-induced apoptosis is NO-independent and involves the cytochrome c-mitochondrial pathway.

Topics: Aconitate Hydratase; Adrenergic alpha-Antagonists; Amidines; Animals; bcl-2-Associated X Protein; Benzofurans; Benzylamines; Caspases; Cell Death; Cells, Cultured; Cytochromes c; Drug Interactions; Enzyme Inhibitors; Gene Expression Profiling; Imidazoles; Insulin; Interleukin-1; Islets of Langerhans; Mitochondria; Nitrates; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Nitrites; Proto-Oncogene Proteins c-bcl-2; Rats; Rats, Wistar; RNA, Messenger; Superoxide Dismutase