Decreased PKG transcription mediated by PI3K/Akt/FoxO1 pathway is involved in the development of nitroglycerin tolerance

Resveratrol Reverses Myogenic Induction Suppression Caused by High Glucose Through Activating the SIRT1/AKT/FOXO1 Pathway

Background

Differentiated bone marrow mesenchymal stem cells (BMSCs) may be a therapeutic strategy to treat sarcopenia caused by high glucose. The effects of resveratrol in the myogenic induction of BMSCs under high glucose are unknown. We evaluated the effects and possible mechanisms of high glucose and resveratrol on myogenic induction of rat BMSCs.

Methods

Primary rat BMSCs were isolated and purified from Sprague-Dawley rats aged between 3 and 4 weeks. Rat BMSCs were differentiated into myogenic cells using conditioned medium and treated with glucose and/or resveratrol along with EX527 (a specific silent information regulator 1 [SIRT1] inhibitor). The expressions of MyoD1 and Myogenin were measured. The reactive oxygen species (ROS) level, superoxide dismutase (SOD) activity, and the expressions of FOXO1 and p-AKT/AKT during myogenic induction were also examined.

Results

High glucose decreased cell viability, cell proliferation, and SOD activity, increased intracellular ROS levels, and inhibited the AKT/FOXO1. Resveratrol reversed myogenic induction suppression caused by high glucose, partly through restoring cell proliferation and viability, reducing peroxidative damage, and activating the AKT/FOXO1 pathway; this effect was eliminated by EX527.

Conclusion

Our results indicate that resveratrol promoted myogenic induction and partially reversed the suppression of myogenic induction caused by high glucose through activating the SIRT1/AKT/FOXO1 pathway.

The Effect of Blood Flow-Restricted Low Resistance Training on Microvascular Circulation of Myocardium in Spontaneously Hypertensive Rats

Objective: The purpose of this study was to explore the effect of blood flow-restricted low resistance training on microvascular rarefaction in the myocardium of spontaneously hypertensive rats (SHRs).

Methods: Four-week-old male SHRs were randomly divided into the following groups: Wistar-Kyoto (WKY), SHR control (SHR-SED), high-intensity resistance training (HIRT), low-intensity resistance training (LIRT), and blood flow-restricted low resistance training (BFRT). The exercise groups began to receive exercise intervention for 8 weeks at the age of 7 weeks. Blood pressure (BP), heart rate (HR), cardiac function, capillary density, and Vascular endothelial growth factor -Phosphatidylinositol 3-kinase-Protein kinase B-Endothelial nitric oxide synthetase (VEGF-Pi3k-Akt-eNOS) were assessed.

Results: 1) BP and HR of BFRT decreased significantly, Ejection fraction (EF) and Fraction shortening (FS) increased, and the effect of BFRT on lowering BP and HR was better than that of other groups (p < 0.05); 2) The expression of VEGF, VEGFR2, p-VEGFR2, Pi3k, Akt, p-Akt, eNOS and p-eNOS in the myocardium of the BFRT was significantly upregulated, and eNOS expression was significantly higher than other groups (p < 0 05); 3) the expression of VEGF in the blood of the BFRT was significantly upregulated, higher than SHR-SED, lower than HIRT (p < 0.05), and there was no significant difference between BFRT and LIRT(p > 0.05); 4) the capillary density in the myocardium of BFRT was significantly higher than other exercise groups (p < 0 05).

Conclusion: Blood flow-restricted low resistance training can activate the VEGF-Pi3k-Akt-eNOS pathway, upregulate the expression of VEGF in blood, improve microvascular rarefaction, and promote myocardial microvascular circulation, thereby improving cardiac function and lowering blood pressure, achieving the preventive effect of early hypertension.

Glucocorticoids induce osteonecrosis of the femoral head in rats via PI3K/AKT/FOXO1 signaling pathway

Background

Steroid-induced osteonecrosis of the femoral head (SONFH) is a disorder that causes severe disability in patients and has a high incidence worldwide. Although glucocorticoid (GC)-induced apoptosis of osteoblasts is an important cytological basis of SONFH, the detailed mechanism underlying SONFH pathogenesis remains elusive. PI3K/AKT signaling pathway was reported to involve in cell survival and apoptosis.

Objective

We explored the role of PI3K/AKT/FOXO1 signaling pathway and its downstream targets during glucocorticoid -induced osteonecrosis of the femoral head.

Methods

We obtained gene expression profile of osteoblasts subjected to dexamethasone (Dex) treatment from the Gene Expression Omnibus (GEO) database. Differentially expressed genes (DEGs) were screened out and functional enrichment analysis were conducted by bioinformatics analysis. In vitro, we analyzed Dex-induced apoptosis in MC3T3-E1 cells and explored the role of PI3K/AKT/FOXO1 signaling pathway in this phenomenon by employing siRNA-FOXO1 and IGF-1(PI3K/AKT agonist). Finally, we verified our results in a rat model of SONFH.

Results

In Dex-treated osteoblasts, DEGs were mainly enriched in the FOXO signaling pathway. Dex inhibited MC3T3-E1 cell viability in a dose-dependent effect and induced apoptosis by increasing the expression levels of FOXO1, Bax, cleaved-Caspase-3, and cleaved-Caspase-9, while reducing the expression of Bcl-2. Notably, these results were reversed by siRNA-FOXO1 treatment. Dex inhibited PI3K/AKT signaling pathway, upregulated FOXO1 expression and increased FOXO1 nuclear translocation, which were reversed by IGF-1. Compared to normal rats, the femoral head of SONFH showed increased expression of FOXO1, increased number of apoptotic cells, and empty osteocytic lacunas, as well as decreased bone tissue content and femoral head integrity. Significantly, the effects of GC-induced SONFH were alleviated following IGF-1 treatment.

Conclusion

Dex induces osteoblast apoptosis via the PI3K/AKT/FOXO1 signaling pathway. Our research offers new insights into the underlying molecular mechanisms of glucocorticoid-induced osteonecrosis in SONFH and proposes FOXO1 as a therapeutic target for this disease.

Moringa oleifera leaf extracts protect BMSC osteogenic induction following peroxidative damage by activating the PI3K/Akt/Foxo1 pathway

Objective

We aimed to investigate the therapeutic effects of Moringa oleifera leaf extracts on osteogenic induction of rat bone marrow mesenchymal stem cells (BMSCs) following peroxidative damage and to explore the underlying mechanisms.

Methods

Conditioned medium was used to induce osteogenic differentiation of BMSCs, which were treated with H₂O₂, Moringa oleifera leaf extracts-containing serum, or the phosphatidyl inositol-3 kinase (PI3K) inhibitor wortmannin, alone or in combination. Cell viability was measured using the MTT assay. Cell cycle was assayed using flow cytometry. Expression levels of Akt, phosphorylated (p)Akt, Foxo1, and cleaved caspase-3 were analyzed using western blot analysis. The mRNA levels of osteogenesis-associated genes, including alkaline phosphatase (ALP), collagen І, osteopontin (OPN), and Runx2, were detected using qRT-PCR. Reactive oxygen species (ROS) and malondialdehyde (MDA) levels, as well as superoxide dismutase (SOD), glutathione peroxidase (GSH-PX), and ALP activity were detected using commercially available kits. Osteogenic differentiation capability was determined using alizarin red staining.

Results

During osteogenic induction of rat BMSCs, H₂O₂ reduced cell viability and proliferation, inhibited osteogenesis, increased ROS and MDA levels, and decreased SOD and GSH-PX activity. H₂O₂ significantly reduced pAkt and Foxo1 expression, and increased cleaved caspase-3 levels in BMSCs. Additional treatments with Moringa oleifera leaf extracts partially reversed the H₂O₂-induced changes. Wortmannin partially attenuated the effects of Moringa oleifera leaf extracts on protein expression of Foxo1, pAkt, and cleaved caspase-3, as well as mRNA levels of osteogenesis-associated genes.

Conclusion

Moringa oleifera leaf extracts ameliorate peroxidative damage and enhance osteogenic induction of rat BMSCs by activating the PI3K/Akt/Foxo1 pathway.

Thioredoxin mitigates H2 O2 -induced inhibition of myogenic differentiation of rat bone marrow mesenchymal stem cells by enhancing AKT activation

Thioredoxin (Trx) is a hydrogen acceptor of ribonucleotide reductase and a regulator of some enzymes and receptors. It has been previously shown that significantly elevated levels of Trx expression are associated with the osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs), but it is not clear how Trx regulates the effects of hydrogen peroxide (H₂O₂) on myogenic differentiation of BMSCs. Here, we report that rat BMSCs treated with a high dose (150 µm) of H₂O₂ exhibited a significant reduction in viability, cell cycling, and superoxide dismutase and glutathione peroxidase levels, and an increase in reactive oxygen species and malondialdehyde levels, which was accompanied by reductions in protein kinase B activation and forkhead Box O1, myogenic differentiation 1 and myogenin expression during myogenic differentiation. Furthermore, treatment with recombinant human Trx significantly mitigated the effects of H₂O₂ on the myogenic differentiation of BMSCs, and this was abrogated by cotreatment with wortmannin [a specific phosphatidylinositol 3‐kinase inhibitor]. In summary, our results suggest that treatment with recombinant human Trx mitigates H₂O₂‐induced oxidative stress and may promote myogenic differentiation of rat BMSCs by enhancing phosphatidylinositol 3‐kinase/protein kinase B/forkhead Box O1 signaling.

Antihypertensive potential of cis-[Ru(bpy)2(ImN)(NO)]3+, a ruthenium-based nitric oxide donor

The aim of this study was to investigate the antihypertensive properties of cis-[Ru(bpy)₂ImN(NO)]³⁺ (FOR0811) in normotensive and in N^ω-nitro-L-arginine methyl ester (L-NAME)-induced hypertensive rats. Vasorelaxant effects were analyzed by performing concentration response curve to FOR0811 in rat aortic rings in the absence or presence of 1H-[1,2,4]-oxadiazolo-[4,3,-a]quinoxalin-1-one (ODQ), L-cysteine or hydroxocobalamin. Normotensive and L-NAME-hypertensive rats were treated with FOR0811 and the effects in blood pressure and heart rate variability in the frequency domain (HRV) were followed. FOR0811 induced relaxation in rat aortic rings. Neither endothelium removal nor L-cysteine altered the FOR0811 effects. However, the incubation with ODQ and hydroxocobalamin completely blunted FOR0811 effects. FOR0811 administered intravenously by bolus infusion (0.01-1 mg/bolus) or chronically by using subcutaneous implanted osmotic pumps significantly reduced the mean arterial blood pressure. The effect was long lasting and did not induce reflex tachycardia. FOR0811 prevented both LF and VLF increases in L-NAME hypertensive rats and has antihypertensive properties. This new ruthenium complex compound might be a promising nitric oxide donor to treat cardiovascular diseases.