Polydatin ameliorates hepatic ischemia-reperfusion injury by modulating macrophage polarization.

BACKGROUND: Polydatin, a glucoside of resveratrol, has been shown to have protective effects against various diseases. However, little is known about its effect on hepatic ischemia-reperfusion (I/R) injury. This study aimed to elucidate whether polydatin protects liver against I/R-induced injury and to explore the underlying mechanism. METHODS: After gavage feeding polydatin once daily for a week, mice underwent a partial hepatic I/R procedure. Serum alanine aminotransferase (ALT)/aspartate aminotransferase (AST), hematoxylin-eosin (H&E) and TdT-mediated dUTP nick-end labeling (TUNEL) staining were used to evaluate liver injury. The severity related to the inflammatory response and reactive oxygen species (ROS) production was also investigated. Furthermore, immunofluorescence and Western blotting were used to detect macrophage polarization and the NF-κB signaling pathway in macrophages. RESULTS: Compared with the I/R group, polydatin pretreatment significantly attenuated I/R-induced liver damage and apoptosis. The oxidative stress marker (dihydroethidium fluorescence, malondialdehyde, superoxide dismutase and glutathione peroxidase) and I/R related inflammatory cytokines (interleukin-1ß, interleukin-10 and tumor necrosis factor-α) were significantly suppressed after polydatin treatment. In addition, the result of immunofluorescence indicated that polydatin reduced the polarization of macrophages toward M1 macrophages both in vivo and in vitro. Western blotting showed that polydatin inhibited the pro-inflammatory function of RAW264.7 via down-regulating the NF-κB signaling pathway. CONCLUSIONS: Polydatin protects the liver from I/R injury by remodeling macrophage polarization via NF-κB signaling.

SIRT1 exerts anti-hypertensive effect via FOXO1 activation in the rostral ventrolateral medulla.

The rostral ventrolateral medulla (RVLM) is a pivotal region in the central regulation of blood pressure (BP). It has been documented that silent information regulator 2 homolog 1 (SIRT1), a nicotinamide adenine dinucleotide (NAD+)-dependent multifunctional transcription regulatory factor, has many cardiovascular protective effects. However, the role and significance of SIRT1 in the central regulation of cardiovascular activity, especially in RVLM, remains unknown. Therefore, the aim of this study was to explore the role and underlying mechanism of SIRT1 in the central regulation of cardiovascular activity in hypertension. Spontaneously hypertensive rats (SHRs) were given resveratrol (RSV) via intracerebroventricular (ICV) infusion or injected with SIRT1-overexpressing lentiviral vectors into the RVLM. In vitro experiments, angiotensin II (Ang II)-induced rat pheochromocytoma cell line (PC12 cells) were transfected with forkhead box protein O1 (FOXO1) small interfering RNA (siRNA) before treatment with RSV. Our results showed that SIRT1 activation with RSV or overexpression in the RVLM significantly decreased BP and sympathetic outflow of SHRs. Furthermore, SIRT1 overexpression in the RVLM significantly decreased reactive oxygen species (ROS) production and facilitated the forkhead box protein O1 (FOXO1) activation, accompanied by upregulation of the ROS-detoxifying enzyme superoxide dismutases 1 (SOD1) in the RVLM of SHRs. In PC12 cells, it was found that Ang II could induce oxidative stress and downregulate the SIRT1-FOXO1-SOD1 signaling pathway, which indicated that the suppressed expression of SIRT1 in the RVLM of SHRs might relate to the elevated central Ang II level. Furthermore, the enhanced oxidative stress and decreased SIRT1-FOXO1-SOD1 axis induced by Ang II were restored by treatment with RSV. However, these favorable effects mediated by SIRT1 activation were blocked by FOXO1 knockdown. Based on these findings, we concluded that SIRT1 activation or overexpression in the RVLM exerts anti-hypertensive effect through reducing oxidative stress via SIRT1-FOXO1-SOD1 signaling pathway, which providing a new target for the prevention and intervention of hypertension.

Proangiogenesis effects of compound danshen dripping pills in zebrafish.

BACKGROUND: The compound Danshen Dripping Pill (CDDP), which is a mixture of extracts from Radix Salviae and Panax notoginseng, is a patented traditional Chinese medicine that is widely used in multiple countries for relieving coronary heart disease (CHD), but its pharmacological mechanism has not been fully elucidated. In this study, we screened the key pharmacological pathways and targets of CDDP that act on CHD using a network pharmacology-based strategy, and the angiogenic activity of CDDP was directly visually investigated in zebrafish embryos in vivo. METHODS: The potential therapeutic targets and pathways were predicted through a bioinformatics analysis. The proangiogenic effects of CDDP were examined using vascular sprouting assays on subintestinal vessels (SIVs) and optic arteries (OAs) as well as injury assays on intersegmental vessels (ISVs). Pharmacological experiments were applied to confirm the pathway involved. RESULTS: Sixty-five potential therapeutic targets of CDDP on CHD were identified and enriched in the PI3K/AKT and VEGF/VEGFR pathways. An in vivo study revealed that CDDP promoted angiogenesis in SIVs and OAs in a dose-dependent manner and relieved the impairments in ISVs induced by lenvatinib, a VEGF receptor kinase inhibitor (VRI). In addition, Vegfaa and Kdrl expression were significantly upregulated after CDDP treatment. Furthermore, the proangiogenic effect of CDDP could be abolished by PI3K/AKT pathway inhibitors. CONCLUSIONS: CDDP has a proangiogenic effect, the mechanism of which involves the VEGF/VEGFR and PI3K/AKT signaling pathways. These results suggest a new insight into the cardiovascular protective effect of CDDP.

Enhancement in Tonically Active Glutamatergic Inputs to the Rostral Ventrolateral Medulla Contributes to Neuropathic Pain-Induced High Blood Pressure.

Neuropathic pain increases the risk of cardiovascular diseases including hypertension with the characteristic of sympathetic overactivity. The enhanced tonically active glutamatergic input to the rostral ventrolateral medulla (RVLM) contributes to sympathetic overactivity and blood pressure (BP) in cardiovascular diseases. We hypothesize that neuropathic pain enhances tonically active glutamatergic inputs to the RVLM, which contributes to high level of BP and sympathetic outflow. Animal model with the trigeminal neuropathic pain was induced by the infraorbital nerve-chronic constriction injury (ION-CCI). A significant increase in BP and renal sympathetic nerve activity (RSNA) was found in rats with ION-CCI (BP, n = 5, RSNA, n = 7, p < 0.05). The concentration of glutamate in the RVLM was significantly increased in the ION-CCI group (n = 4, p < 0.05). Blockade of glutamate receptors by injection of kynurenic acid into the RVLM significantly decreased BP and RSNA in the ION-CCI group (n = 5, p < 0.05). In two major sources (the paraventricular nucleus and periaqueductal gray) for glutamatergic inputs to the RVLM, the ION-CCI group (n = 5, p < 0.05) showed an increase in glutamate content and expression of glutaminase 2, vesicular glutamate transporter 2 proteins, and c-fos. Our results suggest that enhancement in tonically active glutamatergic inputs to the RVLM contributes to neuropathic pain-induced high blood pressure.

Exercise Training Improves the Altered Renin-Angiotensin System in the Rostral Ventrolateral Medulla of Hypertensive Rats.

The imbalance between angiotensin II (Ang II) and angiotensin 1-7 (Ang 1-7) in the brain has been reported to contribute to cardiovascular dysfunction in hypertension. Exercise training (ExT) is beneficial to hypertension and the mechanism is unclear. This study was aimed to determine if ExT improves hypertension via adjusting renin angiotensin system in cardiovascular centers including the rostral ventrolateral medulla (RVLM). Spontaneously hypertensive rats (SHR, 8 weeks old) were subjected to low-intensity ExT or kept sedentary (Sed) for 12 weeks. Blood pressure elevation coupled with increase in age was significantly decreased in SHR received ExT compared with Sed. The results in vivo showed that ExT significantly reduced or increased the cardiovascular responses to central application of sarthran (antagonist of Ang II) or A779 (antagonist of Ang 1-7), respectively. The protein expression of the Ang II acting receptor AT1R and the Ang 1-7 acting receptor Mas in the RVLM was significantly reduced and elevated in SHR following ExT, respectively. Moreover, production of reactive oxygen species in the RVLM was significantly decreased in SHR following ExT. The current data suggest that ExT improves hypertension via improving the balance of Ang II and Ang 1-7 and antioxidative stress at the level of RVLM.

The PI3K signaling-mediated nitric oxide contributes to cardiovascular effects of angiotensin-(1-7) in the nucleus tractus solitarii of rats.

Angiotensin-1-7 [Ang-(1-7)], acting via the Mas receptor in the central nervous system, is involved in the regulation of cardiovascular activity. Nitric oxide (NO) is implicated as an important modulator in the nucleus tractus solitarii (NTS), a key region involved in control of cardiovascular activity. The aim of the present study was to determine the role of phosphatidylinositol 3-kinase (PI3K) signaling in mediating the effect of Ang-(1-7) on NO generation in the NTS. In Sprague-Dawley rats, acute injection of Ang-(1-7) into the NTS significantly increased NO generation and neuronal/endothelial NO synthase (n/eNOS) activity, which were abolished by the selective Mas receptor antagonist d-Alanine-[Ang-(1-7)] (A-779), the PI3K inhibitor LY294002, or the Akt inhibitor triciribine (TCN). Western blotting analysis further demonstrated that Ang-(1-7) significantly increased levels of Akt/NOS phosphorylation in the NTS, and Ang-(1-7)-induced e/nNOS phosphorylation was antagonized by LY294002 or TCN. Furthermore, gene knockdown of PI3K by lentivirus containing small hairpin RNA in the NTS prevented the Ang-(1-7)-induced increases in NOS/Akt phosphorylation and NO production. The physiological (in vivo) experiments showed that pretreatment with the NOS inhibitor l-NAME, LY294002, or TCN abolished the decreases in blood pressure, heart rate, and renal sympathetic nerve activity induced by Ang-(1-7) injected into the NTS. Our findings suggest that nitric oxide release meditated by the Mas-PI3K-NOS signaling pathway is involved in the cardiovascular effects of Ang-(1-7) in the NTS.