Piceatannol protects against cerebral ischemia/reperfusion-induced apoptosis and oxidative stress via the Sirt1/FoxO1 signaling pathway

Reperfusion is a critical therapeutic intervention used following acute ischemic stroke; however, it may cause cerebral ischemia/reperfusion injury (CIRI) and aggravate brain damage. Piceatannol (Pic), a hydroxylated analog of resveratrol, has been reported to exhibit anti-inflammatory effects. However, the detailed molecular mechanisms and its effects on CIRI have not been sufficiently assessed, and, to the best of our knowledge, current methods of prevention of CIRI are limited. The aim of the present study was to investigate the effects of Pic on improving neurological function in a mouse model of CIRI. For the animal experiments, 8-week-old C57BL/6 mice were raised and randomly grouped, and an in vivo model of CIRI was established. Mice were administered a low (10 mg/kg/day) or high-dose (20 mg/kg/d) of Pic 1 h after CIRI orally and once daily for the next 6 days. Neurological dysfunction was assessed using a modified neurological severity score and a rotarod test 1 week after CIRI establishment, and the cognitive status of the mice was assessed using a Morris water maze. Hematoxylin and eosin staining was used to evaluate the histopathological changes. The expression levels of sirtuin 1 (Sirt1), FoxO1, cleaved caspase-3 (CC-3), Bax and Bcl-2 were measured using western blotting. Intracellular reactive oxygen species (ROS) generation, antioxidant enzymes [superoxide dismutase, glutathione (GSH) peroxidase and catalase] and non-enzymatic antioxidants (GSH) were also detected using spectrophotometry. After inhibition of the Sirt1/FoxO1 pathway, a TUNEL assay was used for the detection of apoptotic cells in vitro and in vivo. The co-localization of neuron-specific nuclear protein and CC-3 was assessing using immunofluorescent staining. Pic improved neurological functions and ameliorated hippocampal neuronal pathology following CIRI. In addition, the expression levels of CC-3 and Bax and intracellular ROS levels were increased, while levels of antioxidant and non-enzymatic enzymes were decreased in the mouse model of CIRI. Low and high doses of Pic significantly decreased ROS production and the expression levels of apoptosis-related proteins, but increased antioxidant enzyme levels. However, a high-dose of Pic did not result in increased levels of non-enzymatic enzymes. Furthermore, low and high doses of Pic treatment significantly activated the Sirt1/FoxO1 pathway. Following inhibition of the Sirt1/FoxO1 pathway, the percentage of TUNEL-positive cells and expression of CC-3 were increased, and CC-3 was enriched in neurons. The antioxidant effects of Pic were blocked by inhibition of Sirt1 in vitro and in vivo. In conclusion, these results suggested that Pic may exert a neuroprotective effect against in hippocampal neurons via the Sirt1/FoxO1 pathway.