Prodigiosin inhibits gp91phox and iNOS expression to protect mice against the oxidative/nitrosative brain injury induced by hypoxia–ischemia

This study aimed to explore the mechanisms by which prodigiosin protects against hypoxia-induced oxidative/nitrosative brain injury induced by middle cerebral artery occlusion/reperfusion (MCAo/r) injury in mice. Hypoxia in vitro was modeled using oxygen–glucose deprivation (OGD) followed by reoxygenation of BV-2 microglial cells. Our results showed that treatment of mice that have undergone MCAo/r injury with prodigiosin (10 and 100 μg/kg, i.v.) at 1 h after hypoxia ameliorated MCAo/r-induced oxidative/nitrosative stress, brain infarction, and neurological deficits in the mice, and enhanced their survival rate. MCAo/r induced a remarkable production in the mouse brains of reactive oxygen species (ROS) and a significant increase in protein nitrosylation; this primarily resulted from enhanced expression of NADPH oxidase 2 (gp91phox), inducible nitric oxide synthase (iNOS), and the infiltration of CD11b leukocytes due to breakdown of blood–brain barrier (BBB) by activation of nuclear factor-kappa B (NF-κB). All these changes were significantly diminished by prodigiosin. In BV-2 cells, OGD induced ROS and nitric oxide production by up-regulating gp91phox and iNOS via activation of the NF-κB pathway, and these changes were suppressed by prodigiosin. In conclusion, our results indicate that prodigiosin reduces gp91phox and iNOS expression possibly by impairing NF-κB activation. This compromises the activation of microglial and/or inflammatory cells, which then, in turn, mediates prodigiosin's protective effect in the MCAo/r mice.

► Prodigiosin ameliorated brain infarction and deficits.
► Prodigiosin protected against hypoxia/reperfusion-induced brain injury.
► Prodigiosin diminished oxidative/nitrosativestress and leukocytes infiltration.
► Prodigiosin reduced BBB breakdown.
► Prodigiosin down-regulated gp91phox and iNOS by inhibiting NF-κB activation.