TGF-β2/Smad3 Signaling Pathway Activation Through Enhancing VEGF and CD34 Ameliorates Cerebral Ischemia/Reperfusion Injury After Isoflurane Post-conditioning in Rats

Evidence has shown the therapeutic potential of isoflurane (ISO) in cerebral stroke. The present study investigated the mechanism of ISO on vascular endothelial growth factor (VEGF) and CD34 expression in a rat model of stroke. Transient focal cerebral ischemia was established by middle cerebral artery occlusion (MCAO) for 1 h followed by reperfusion for 24 h in rats. ISO was administered for 1.5 h when the reperfusion was initiated. Neurologic deficit scores, infarct volumes, HE staining, Nissl staining, and TUNEL staining were evaluated at 24 h after reperfusion. The levels of transforming growth factor (TGF)-beta 2, Smad3, p-Smad3, VEGF, and CD34 proteins were detected by immunofluorescence (IF) staining and Western blot assay. Administration of ISO significantly reduced the neurologic deficit scores, infarct volumes, and damaged and apoptotic cells after cerebral ischemia/reperfusion (I/R) injury (P < 0.05). Meanwhile, ISO post-conditioning significantly increased the expression levels of TGF-beta 2, p-Smad3, VEGF, and CD34 (P < 0.05), whereas the expression of Smad3 showed no difference (P > 0.05). However, Pirfenidone, a TGF-beta 2 inhibitor, decreased the expression levels of TGF-beta 2, p-Smad3, VEGF, and CD34 (P < 0.05). Moreover, the protective effects of ISO post-conditioning were negated by the inhibitor. The present study indicated that ISO attenuates brain damage by activating the TGF-beta 2/Smad3 signaling pathway and increasing the protein expression of VEGF and CD34 in the rat MCAO model.