VEGF-A and VEGF-B Coordinate the Arteriogenesis to Repair the Infarcted Heart with Vagus Nerve Stimulation.

BACKGROUND/AIMS: Vagus nerve stimulation (VNS) suppresses arrhythmic activity and minimizes cardiomyocyte injury. However, how VNS affects angiogenesis/arteriogenesis in infarcted hearts, is poorly understood. METHODS: Myocardial infarction (MI) was achieved by ligation of the left anterior descending coronary artery (LAD) in rats. 7 days after LAD, stainless-steel wires were looped around the left and right vagal nerve in the neck for vagus nerve stimulation (VNS). The vagal nerve was stimulated with regular pulses of 0.2ms duration at 20 Hz for 10 seconds every minute for 4 hours, and then ACh levels by ELISA in cardiac tissue and serum were evaluated for its release after VNS. Three and 14 days after VNS, Real-time PCR, immunostaining and western blot were respectively used to determine VEGF-A/B expressions and α-SMA- and CD31-postive vessels in VNS-hearts with pretreatment of α7-nAChR blocker mecamylamine (10 mg/kg, ip) or mACh-R blocker atropine (10 mg/kg, ip) for 1 hour. The coronary function and left ventricular performance were analyzed by Langendorff system and hemodynamic parameters in VNS-hearts with pretreatment of VEGF-A/B-knockdown or VEGFR blocker AMG706. Coronary arterial endothelial cells proliferation, migration and tube formation were evaluated for angiogenesis following the stimulation of VNS in coronary arterial smooth muscle cells (VSMCs). RESULTS: VNS has been shown to stimulate VEGF-A and VEGF-B expressions in coronary arterial smooth muscle cells (VSMCs) and endothelial cells (ECs) with an increase of α-SMA- and CD31-postive vessel number in infarcted hearts. The VNS-induced VEGF-A/B expressions and angiogenesis were abolished by m-AChR inhibitor atropine and α7-nAChR blocker mecamylamine in vivo. Interestingly, knockdown of VEGF-A by shRNA mainly reduced VNS-mediated formation of CD31+ microvessels. In contrast, knockdown of VEGF-B powerfully abrogated VNS-induced formation of α-SMA+ vessels. Consistently, VNS-induced VEGF-A showed a greater effect on EC tube formation as compared to VNS-induced VEGF-B. Moreover, VEGF-A promoted EC proliferation and VSMC migration while VEGF-B induced VSMC proliferation and EC migration in vitro. Mechanistically, vagal neurotransmitter acetylcholine stimulated VEGF-A/B expressions through m/nACh-R/PI3K/Akt/Sp1 pathway in EC. Functionally, VNS improved the coronary function and left ventricular performance. However, blockade of VEGF receptor by antagonist AMG706 or knockdown of VEGF-A or VEGF-B by shRNA significantly diminished the beneficial effects of VNS on ventricular performance. CONCLUSION: VNS promoted angiogenesis/arteriogenesis to repair the infracted heart through the synergistic effects of VEGF-A and VEGF-B.

Monosialoganglioside 1 may alleviate neurotoxicity induced by propofol combined with remifentanil in neural stem cells.

Monosialoganglioside 1 (GM1) is the main ganglioside subtype and has neuroprotective properties in the central nervous system. In this study, we aimed to determine whether GM1 alleviates neurotoxicity induced by moderate and high concentrations of propofol combined with remifentanil in the immature central nervous system. Hippocampal neural stem cells were isolated from newborn Sprague-Dawley rats and treated with remifentanil (5, 10, 20 ng/mL) and propofol (1.0, 2.5, 5.0 µg/mL), and/or GM1 (12.5, 25, 50 µg/mL). GM1 reversed combined propofol and remifentanil-induced decreases in the percentage of 5-bromodeoxyuridine(+) cells and also reversed the increase in apoptotic cell percentage during neural stem cell proliferation and differentiation. However, GM1 with combined propofol and remifentanil did not affect ß-tubulin(+) or glial fibrillary acidic protein(+) cell percentage during neural stem cell differentiation. In conclusion, we show that GM1 alleviates the damaging effects of propofol combined with remifentanil at moderate and high exposure concentrations in neural stem cells in vitro, and exerts protective effects on the immature central nervous system.