Animal models have historically played a critical role in the exploration and characterization of disease pathophysiology and target identification and in the evaluation of novel therapeutic agents and treatments in vivo. Diabetes mellitus disease, commonly known as diabetes, is a group of metabolic disorders characterized by high blood glucose levels for a prolonged time. To avoid late complications of diabetes and related costs, primary prevention and early treatment are therefore necessary. Due to its chronic symptoms, new treatment strategies need to be developed, because of the limited effectiveness of the current therapies. We overviewed the pathophysiological features of diabetes in relation to its complications in type 1 and type 2 mice along with rat models, including Zucker Diabetic Fatty (ZDF) rats, BB rats, LEW 1AR1/-iddm rats, Goto-Kakizaki rats, chemically induced diabetic models, and Nonobese Diabetic mouse, and Akita mice model. The advantages and disadvantages that these models comprise were also addressed in this review. This paper briefly reviews the wide pathophysiological and molecular mechanisms associated with type 1 and type 2 diabetes, particularly focusing on the challenges associated with the evaluation and predictive validation of these models as ideal animal models for preclinical assessments and discovering new drugs and therapeutic agents for translational application in humans.

Objective: Gastrointestinal methane generation has been demonstrated in various stress conditions, but it is not known whether nonasphyxiating amounts have any impact on the mammalian pathophysiology. We set out to characterize the effects of exogenous methane administration on the process of inflammatory events arising after reoxygenation in a large animal model of ischemia–reperfusion. Design: A randomized, controlled in vivo animal study. Setting: A university research laboratory. Subjects: Inbred beagle dogs (12.7 6 2 kg). Interventions: Sodium pentobarbital-anesthetized animals were randomly assigned to sham-operated or ischemia–reperfusion groups, where superior mesenteric artery occlusion was maintained for 1 hr and the subsequent reperfusion was monitored for 3 hrs. For 5 mins before reperfusion, the animals were mechanically ventilated with normoxic artificial air with or without 2.5% methane. Biological responses to methane–oxygen respirations were defined in pilot rat studies and assay systems were used with xanthine oxidase and activated canine granulocytes to test the in vitro bioactivity potential of different gas concentrations. Measurements and Main Results: The macrohemodynamics and small intestinal pCO₂ gap changes were recorded and peripheral blood samples were taken for plasma nitrite/nitrate and myeloperoxidase analyses. Tissue superoxide and nitrotyrosine levels and myeloperoxidase activity changes were determined in intestinal biopsy samples; structural mucosal damage was measured by hematoxylin and eosin staining. Methane inhalation did not influence the macrohemodynamics but significantly reduced the magnitude of the tissue damage and the intestinal pCO₂ gap changes after reperfusion. Furthermore, the plasma and mucosal myeloperoxidase activity and the intestinal superoxide and nitrotyrosine levels were reduced, whereas the plasma nitrite/nitrate concentrations were increased. Additionally, methane effectively and specifically inhibited leukocyte activation in vitro. Conclusions: These data demonstrate the anti-inflammatory profile of methane. The study provides evidence that exogenous methane modulates leukocyte activation and affects key events of ischemia–reperfusion-induced oxidative and nitrosative stress and is therefore of potential therapeutic interest in inflammatory pathologies. (Crit Care Med 2012; 40:–1278)

The aim of the present study was to investigate if hyperlipidemia interferes with the infarct size-limiting effect of postconditioning and to study the involvement of peroxynitrite in this phenomenon. Rats were fed a 2% cholesterol-enriched or normal diet for 12 wk. Infarct size by triphenyltetrazolium chloride staining was measured in hearts isolated from both groups and subjected to 30 min coronary occlusion followed by 120 min reperfusion with or without the postconditioning protocol induced by six cycles of 10 s coronary occlusion and 10 s reperfusion at the onset of the reperfusion. Postconditioning significantly decreased infarct size in the normolipidemic but not in the hyperlipidemic group. Postconditioning increased cardiac 3-nitrotyrosine concentration (a marker for peroxynitrite formation) in the normal but not in the cholesterol-fed group when measured at the 5th min of reperfusion. Next, we tested if the postconditioning-induced acute increase in peroxynitrite is involved in the cardioprotection in normolipidemic animals in separate experiments. Postconditioning failed to decrease infarct size in the presence of the peroxynitrite decomposition catalyst 5,10,15,20-tetrakis-[4-sulfonatophenyl]-porphyrinato-iron [III] (20 mg/l) in normolipidemic animals. We conclude that an early increase in peroxynitrite after postconditioning plays a role in cardioprotection. Furthermore, hyperlipidemia blocks the cardioprotective effect of postconditioning at least in part via deterioration of the postconditioning-induced early increase in peroxynitrite formation.