The novel NADPH oxidase 4 inhibitor GLX351322 counteracts glucose intolerance in high-fat diet-treated C57BL/6 mice
Free radical research | 30 Jun 2015
E Anvari, P Wikström, E Walum and N Welsh
In Type 2 diabetes, it has been proposed that pancreatic beta-cell dysfunction is promoted by oxidative stress caused by NADPH oxidase (NOX) over-activity. Five different NOX enzymes (NOX1-5) have been characterized, among which NOX1 and NOX2 have been proposed to negatively affect beta-cells, but the putative role of NOX4 in type 2 diabetes-associated beta-cell dysfunction and glucose intolerance is largely unknown. Therefore, we presently investigated the importance of NOX4 for high-fat diet (HFD)-induced glucose intolerance using male C57BL/6 mice using the new NOX4 inhibitor GLX351322, which has relative NOX4 selectivity over NOX2. In HFD-treated male C57BL/6 mice a two-week treatment with GLX351322 counteracted non-fasting hyperglycemia and impaired glucose tolerance. This effect occurred without any change in peripheral insulin sensitivity. To ascertain that NOX4 also plays a role for the function of human beta-cells, we observed that glucose- and sodium palmitate-induced insulin release from human islets in vitro was increased in response to NOX4 inhibitors. In long-term experiments (1-3 days), high glucose-induced human islet cell ROS production and death were prevented by GLX351322. We propose that whilst short-term NOX4-generated ROS production is a physiological requirement for beta-cell function, persistent NOX4-activity, e.g. during conditions of high-fat feeding, promotes ROS-mediated beta-cell dysfunction. Thus, selective NOX-inhibition may be a therapeutic strategy in Type 2 diabetes.
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