Curcumin attenuates doxorubicin-induced cardiotoxicity via suppressing oxidative Stress, preventing inflammation and apoptosis: Ultrastructural and computational approaches

Currently, doxorubicin (DOX) is one of the medications commonly used in chemotherapy to treat different types of tumors.Nonetheless, despite being effective in multiple tumors, yet its use is limited owing to its cytotoxic effects, the therapeutic use of DOX has been limited. This work aimed to explore whether curcumin (CMN) can prevents DOX-induced cardiotoxicity in rats. Four groups of rats were created, with the first functioning as a control, while the second group received CMN. DOX alone was administered to the third group, whereas CMN and DOX were administered to the fourth group. Lipid peroxidation assessed as Malondialdehyde (MDA), aspartate aminotransferase (AST), alanine aminotransferase (ALT), oxidative stress markers as catalase (CAT), superoxide dismutase (SOD), and inflammatory markers as tumor necrosis factor-alpha (TNF-α) in heart homogenates, each one was assessed. Heart specimens was investigated histologically and ultrastructurally. Increased, AST, and ALT serum levels, increased MDA levels, decreased SOD and CAT levels, and increased TNF-α concentrations in heart homogenates were all signs of DOX-induced myocardial injury. Histological and ultrastructural examinations revealed vacuoles and larger, swollen mitochondria in the cytoplasm. Furthermore, DOX caused significant changes in the myocardium, most notably nuclei disintegration, myofibrillar loss, and myocyte vacuolization. Using CMN with DOX reduced the harmful consequences of DOX on the myocardium by returning the increased AST and ALT levels to their original levels as compared to the control and reducing them. In cardiac tissue, CMN significantly increased the concentrations of SOD and CAT and significantly decreased the concentrations of MDA and TNF-α. Biochemical and histological studies have demonstrated that CMN has a heart-protective effect that might be related to its antioxidant and anti-inflammatory capabilities.

Therapeutic properties, biological effects, antiliver cancer, and anticolon cancer effects of some natural compounds: A biochemical approach

Natural compounds, such as carotenoids, flavonoids, anthocyanins, or terpenoids, are physiologically active components found in plants (pigments), often known as phytochemicals or phytonutrients. The in vitro cytotoxic and anticolon cancer effects of biologically bavachin, bavachinin, artepillin C, and aromadendrin compounds against SW48, SNU-C1, COLO 205, RKO, LS411N, and SW1417 cancer cell lines were assessed. Results of enzymes and antibacterial, antifungal were in level of micromolar that is good impacts. These natural compounds may be antidiabetic, anticancer, and antibacterial candidates for drug design. IC50 results were obtained between 14-19 and 5-119 µM for α-amylase and α-glucosidase, respectively. Good inhibitor Bavachinin was detected for both enzymes (IC50 for α-amylase: 14.37 µM and IC50 for α-glucosidase: 5.27 µM). The chemical activities of aromadendrin, artepillin C, bavachin, and bavachinin against pancreatic α-amylase and α-glucosidase were assessed by conducting the molecular docking study. The chemical activities of aromadendrin, artepillin C, bavachin, and bavachinin against some of the expressed surface receptor proteins (CD44, CD47, CXCR4, EGFR, folate receptor, HER2, and endothelin receptor) in the mentioned cell lines were investigated using the molecular docking calculations. The results illustrated the atomic-level properties and potential interactions. These chemicals have high binding affinities to the enzymes and proteins, according to the docking scores. In addition, the compounds formed strong contacts with the enzymes and receptors. Thus, these compounds could be potential inhibitors for enzymes and cancer cells.

The possible effects of α-tocopherol against amiodarone-treated lungs in rats: vimentin detection, lipid peroxidation assay, and histological and ultrastructural evaluations

The purpose of this study was to learn more about the pathogenesis of amiodarone (AD) on alveoli and also the possible preventive effect of α-tocopherol (α-T) against these hazards. Rats were divided into 4 groups, one of which acted as a control, the second received α-T, the third AD, and the fourth AD and α-T for 2 weeks. Light microscopy (LM), immunohistochemistry, transmission electron microscopy (TEM), and malondialdehyde (MDA) activity were analyzed in sections of lung tissue. Alveoli of lung tissue AD examined with LM showed dilatation of alveolar spaces, aggregation of red blood cells, and narrowing of alveolar septa. When stained with vimentin (VIM), alveoli showed a positive reaction in the majority and a moderate reaction in others. In the pneumocytes of the type II, some cytoplasmic vesicles had been deflated, whereas others contained lamellar bodies, a damaged nucleus, and vesicles in their heterochromatin. In the interstitial space, collagen fibers with aggregation of red blood cells and a disrupted blood-air barrier were detected. In rat lung alveoli treated with AD and α-T, the alveolar septum thickened and the alveolar spaces expanded as estimated. The alveoli of this group had more or less intact type I and II pneumocytes and a better appearance of the blood-air barrier. In the cells of the alveolar lining, the VIM staining leads to a diffuse positive response. Finally, lung parenchyma also improved, suggesting that α-T may help minimize the effects of AD.

The effectiveness of vitamin C on quinalphos ileal toxicity: a study of histological, ultrastructural, and oxidative stress markers

There is a significant hazard of human exposure to the organophosphates which is a constant threat, and they are responsible for numerous cases of poisoning and mammalian toxicity annually in non-target wildlife. The antioxidants, including the vitamin C (Vit C), have a protective effect on some organophosphorus compounds-induced organ damage. Quinalphos (QP) is one of these compounds. The investigation's objective is to see if there was any effect of QP on the rat ileum which could be rectified by using Vit C. Three groups of 24 animals were created. As a control, the first group was given pure water. Second group subjected to oral gavages of QPs. Third group rats were given oral gavages of Vit C plus QPs for 10 days. The reaction of ileal enterocytes to food-borne QPs was marked by poorly organized microvilli, numerous vacuoles within them, disrupted nuclei with chromatin margination, disoriented mitochondria, and an expanded intercellular space. The absorptive columnar cell illustrated many vacuoles inside with herniation of microvilli, and normal goblet cells were also seen. Many Paneth cells towards the lumen of intestinal gland contained secretory granules of different sizes and shapes. The histological architecture of the ileal mucosa in the QP plus Vit C group was found to be close to those of healthy controls. The outcomes of this study suggest that administering Vit C in rats treated with QPs protects them from ill dysfunction caused by QP.

Exendin-4 Protects Against Myocardial Ischemia-Reperfusion Injury by Upregulation of SIRT1 and SIRT3 and Activation of AMPK

This study evaluated if the cardioprotective effect of Exendin-4 against ischemia/reperfusion (I/R) injury in male rats involves modulation of AMPK and sirtuins. Adult male rats were divided into sham, sham + Exendin-4, I/R, I/R + Exendin-4, and I/R + Exendin-4 + EX-527, a sirt1 inhibitor. Exendin-4 reduced infarct size and preserved the function and structure of the left ventricles (LV) of I/R rats. It also inhibited oxidative stress and apoptosis and upregulated MnSOD and Bcl-2 in their infarcted myocardium. With no effect on SIRTs 2/6/7, Exendin-4 activated and upregulated mRNA and protein levels of SIRT1, increased levels of SIRT3 protein, activated AMPK, and reduced the acetylation of p53 and PGC-1α as well as the phosphorylation of FOXO-1. EX-527 completely abolished all beneficial effects of Exendin-4 in I/R-induced rats. In conclusion, Exendin-4 cardioprotective effect against I/R involves activation of SIRT1 and SIRT3. Graphical Abstract Exendin-4 could scavenge free radical directly, upregulate p53, and through upregulation of SIRT1 and stimulating SIRT1 nuclear accumulation. In addition, Exendin-4 also upregulates SIRT3 which plays an essential role in the upregulation of antioxidants, inhibition of reactive oxygen species (ROS) generation, and prevention of mitochondria damage. Accordingly, SIRT1 induces the deacetylation of PGC-1α and p53 and is able to bind p-FOXO-1. This results in inhibition of cardiomyocyte apoptosis through increasing Bcl-2 levels, activity, and levels of MnSOD; decreasing expression of Bax; decreasing cytochrome C release; and improving mitochondria biogenesis through upregulation of Mfn-2.

Role of dietary selenium in alleviating bisphenol A toxicity of liver albino rats: Histological, ultrastructural, and biomarker assessments

Bisphenol A (BPA) is used as a plasticizer in polycarbonate plastics. It has been used in consumer products and epoxy resins for decades as protective coatings and linings for food and beverage bottles. This can trigger human reactions to BPA which interferes with estrogen receptors. Our study explored the ameliorative effects of selenium (Se) in male rats on liver damage caused by BPA. Rats were divided into four groups at random: The first one obtained olive oil and acted as a control. Se (0.5 mg/kg diet) was given for the second group. The third one was treated with BPA (10 mg/kg body weight/day) orally. Concomitantly Se (0.5 mg/kg diet) and BPA (10 mg/kg body weight/day) were given orally in the fourth one. Liver specimens were prepared for light, electron microscopes and the serum samples were screened for biochemical markers. In the BPA received group, histological findings indicated apoptotic hepatic histological changes such as sinusoidal congestion, cytoplasmic vacuolation and leukocyte infiltration. Ultrastructurally, the same group had mitochondrial degeneration, rough endoplasmic reticulum swelling, and nuclear pyknosis, as well as fat droplet deposition and lysosome enhancement. Liver enzymes: In the BPA group, alanine aminotransferase (ALT) and aspartate aminotransferase (AST) have been substantially increased. Moreover, histological and ultrastructural improvements were seen in the rat population treated with BPA and Se, whereas ALT and AST levels were lowered and malondialdehyde (MDA), glutathione peroxidase (GPx), human C reactive protein (hCRP), and the serum levels of interleukin-6 (IL-6) were significantly modulated. PRACTICAL APPLICATIONS: Bisphenol A (BPA) is used in the manufacturing of polycarbonate plastic (e.g., water bottles, baby bottles) and epoxy resins (e.g., inner coating in metallic food cans). It is a non-polymer preservative for other plastics, one of the contaminants of the atmosphere and a common endocrine estrogenic disruptor. Our study explored the ameliorative effects of selenium (Se) in male rats on liver damage caused by BPA. Rats were divided into four groups at random: The first one obtained olive oil and acted as a control. Se (0.5 mg/kg diet) was given for the second group. The third one was treated with BPA (10 mg/kg body weight/day) orally. Concomitant Se (0.5 mg/kg diet) and BPA (10 mg/kg body weight/day) were given in the fourth one. Liver specimens were prepared for light, electron microscopes and the serum samples were screened for biochemical markers.

Grape seed extract protects against amiodarone - induced nephrotoxicity and ultrastructural alterations associated with the inhibition of biomarkers of inflammation and oxidative stress in rats

Amiodarone (AMD) is one of the highly effective antiarrhythmic agents used for treating refractory arrhythmias. It is well known to have long-term administration side effects such as nephrotoxicity. The possible ameliorative effects of antioxidant grape seed extract; on the extent of tissue damage in AMD-induced nephrotoxicity has not been investigated before. Twenty-four albino rats were used in this study and divided into four groups (n = 6). The 1^st group served as an untreated control group, under the same laboratory conditions, the 2^nd group received (100 mg/kg/day) of grape seed extract (GSE), the 3rd group, AMD-treated group, received AMD (40 mg/kg/day) and the 4th group received both AMD and GSE in the same doses as the previous groups. AMD-treated group showed abnormal glomerular capillaries with wrinkling basement membranes damaged mesangial cells and distorted proximal tubules with plenty of lysosomes. Ultrastructural alterations were also observed in this group. This was also associated with a significant increase in biomarkers of kidney injury (creatinine), oxidative stress ((Decreased SOD and increased MDA) and biomarkers of inflammation IL-6) in comparison to the control group. Supplementation of GSE to AMD group for eight weeks counteracted these effects. It caused an improvement in histological and t ultrastructure changes of the renal tissues associated with decreased creatinine and biomarkers of oxidative stress and inflammation in comparison to AMD-treated group. We conclude that GSE protects against AMD-induced kidney injuries in rats, which is associated with the inhibition of biomarkers of inflammation and oxidative stress.

Exendin-4 Attenuates Remodeling in the Remote Myocardium of Rats After an Acute Myocardial Infarction by Activating β-Arrestin-2, Protein Phosphatase 2A, and Glycogen Synthase Kinase-3 and Inhibiting β-Catenin

PURPOSE

This study tested if the protective anti-remodeling effect of GLP-1 agonist Exendin-4 after an acute myocardial infarction (MI) in rats involves inhibition of the Wnt1/β-catenin signaling pathway.

METHODS

Rats were divided into sham, sham + Exendin-4 (10 μg/day, i.p), MI, and MI + Exendin-4. MI was introduced to rats by permanent left anterior descending coronary artery (LAD) ligation.

RESULTS

On day 7 post-infraction, MI rats showed LV dysfunction with higher serum levels of cardiac markers. Their remote myocardia showed increased mRNA and protein levels of collagen I/III with higher levels of reactive oxygen species (ROS) and inflammatory cytokines, as well as protein levels of Wnt1, phospho-Akt, transforming growth factor (TGF-β1), Smad, phospho-Smad3, α-SMA, caspase-3, and Bax. They also showed higher protein levels of phospho-glycogen synthase kinase-3β (p-GSK3β), as well as total, phosphorylated, and nuclear β-catenin with a concomitant decrease in the levels of cyclic adenosine monophosphate (cAMP), mRNA of manganese superoxide dismutase (MnSOD), and protein levels of Bcl-2, β-arrestin-2, and protein phosphatase-2 (PP2A). Administration of Exendin-4 to MI rats reduced the infarct size and reversed the aforementioned signaling molecules without altering protein levels of TGF-1β and Wnt1 or Akt activation. Interestingly, Exendin-4 increased mRNA levels of MnSOD, protein levels of β-arrestin-2 and PP2A, and β-catenin phosphorylation but reduced the phosphorylation of GSK3β and Smad3, and total β-catenin levels in the LV of control rats.

CONCLUSION

Exendin-4 inhibits the remodeling in the remote myocardium of rats following acute MI by attenuating β-catenin activation and activating β-arrestin-2, PP2A, and GSK3β. Graphical Abstract A graphical abstract that illustrates the mechanisms by which Exendin-4 inhibits cardiac remodeling in remote myocardium of left ventricle MI-induced rats. Mechanisms are assumed to occur in the cardiomyocytes and/or other resident cells such as fibroblast. Β-catenin activation and nuclear translocation are associated with increased synthesis of inflammatory cytokines and transforming growth factor β-1 (TGF-β1). GSK3β is inhibited by phosphorylation at Ser⁹. Under normal conditions, β-catenin is degraded in the cytoplasm by the active GSK3β-dependent degradation complex (un-phosphorylated) which usually phosphorylates β-catenin at Ser^33/37/Thr⁴¹. After MI, TGF-β1, and Wnt 1 levels are significantly increased, the overproduction of Wnt1 induces β-catenin stabilization and nuclear translocation through increasing the phosphorylation of disheveled (DVL) protein which in turn phosphorylates and inhibits GSK3β. TGF-β1 stimulates the phosphorylation of Smad-3 and subsequent nuclear translocation to activate the transcription of collage 1/III and α-smooth muscle actin (α-SMA). Besides, TGF-β1 stabilizes cytoplasmic β-catenin levels indirectly by phosphorylation of Akt at Thr³⁰⁸-induced inhibition of GSK3β by increasing phosphorylation of Ser⁹. Exendin-4, and possibly through G protein-coupled receptors (GPCRs), increases levels of cAMP and upregulates β-arrestin-2 levels. Both can result in a positive inotropic effect. Besides, β-arrestin-2 can stimulate PP2A to dephosphorylation Smad3 (inhibition) and GSK3β (activation), thus reduces fibrosis and prevents the activation of β-catenin and collagen deposition.

Exendin-4 protects the hearts of rats from ischaemia/reperfusion injury by boosting antioxidant levels and inhibition of JNK/p66 Shc/NADPH axis

Exendin-4, a glucagon-like peptide-1 receptor agonist, was shown to protect against cardiac ischaemia/reperfusion (I/R) injury by suppressing oxidative stress. p⁶⁶ Shc, a pro-oxidant and an apoptotic protein, is activated in the infarcted left ventricles (LVs) after induction of I/R. This study investigated if the cardiac protective effect of Exendin-4 against I/R injury in rats involves inhibition of p⁶⁶ Shc and to determine the underlying mechanisms behind this. Adult male rats (n = 12/group) were divided into four groups as a sham, a sham + Exendin-4, an I/R, and an I/R + Exendin-4. Exendin-4 was administered to rats 7 days before the induction of I/R. Ischaemia was induced by ligating the left anterior descending (LAD) coronary artery for 40 minutes followed by reperfusion for 10 minutes. The infarct myocardium was used for further analysis. Exendin-4 significantly reduced infarct area (by 62%), preserved LV function and lowered serum levels of LDH and CK-MB in I/R-induced rats. Also, it significantly reduced LV levels of ROS and MDA and protein levels of cytochrome-c and cleaved caspase-3 but significantly increased levels of glutathione (GSH) and manganese superoxide dismutase (MnSOD) in LVs of I/R rats indicating antioxidant and anti-apoptotic effects. Furthermore, it inhibited JNK and p⁶⁶ Shc activation and downregulated protein levels of p⁶⁶ Shc and NADPH oxidase with no effect on protein levels/activity of p53 and PKCβII. Of note, Exendin-4 also increased GSH and MnSOD in LVs of control rats. In conclusion, Exendin-4 cardioprotective effect in I/R hearts is mediated mainly by antioxidant effect and inhibition of JNK/P⁶⁶ Shc/NADPH oxidase.

Chronic consumption of a high-fat diet rich in corn oil activates intrinsic cell death pathway and induces several ultrastructural changes in the atria of healthy and type 1 diabetic rat

This study investigates the effect of chronic consumption of a high-fat diet rich in corn oil (CO-HFD) on atrial cells ultrastructure, antioxidant levels and markers of intrinsic cell death of both control and type 1 diabetes mellitus (T1DM)-induced rats. Adult male rats (10 rats/group) were divided into four groups: control fed standard diet (STD) (3.82 kcal/g, 9.4% fat), CO-HFD (5.4 kcal/g, 40% fat), T1DM fed STD, and T1DM + CO-HFD. CO-HFD and T1DM alone or in combination impaired systolic and diastolic functions of rats and significantly reduced levels of GSH and the activity of SOD, enhanced lipid peroxidation, increased protein levels of P53, Bax, cleaved caspase-3, and ANF and decreased levels of Bcl-2 in their atria. Concomitantly, atrial cells exhibited fragmentation of the myofibrils, disorganized mitochondria, decreased number of atrionatriuretic factor (ANF) granules, and loss of gap junctions accompanied by changes in capillary walls. Among all treatments, the severity of all these findings was more severe in T1DM and most profound in the atria of T1DM + CO-HFD. In conclusion, chronic consumption of CO-HFD by T1DM-induced rats elicits significant biochemical and ultrastructural damage to rat atrial cells accompanied by elevated oxidative stress and mitochondria-mediated cell death.

A high-fat diet rich in corn oil induces cardiac fibrosis in rats by activating JAK2/STAT3 and subsequent activation of ANG II/TGF-1β/Smad3 pathway: The role of ROS and IL-6 trans-signaling

This study compared the effect of low-fat diet (LFD) and high-fat diet rich in corn oil (HFD-CO) on left ventricular (LV) fibrosis in rats and examined their effect of angiotensin II (ANG II), JAK/STAT, and TGF-1β/smad3 pathways. As compared to LFD which didn't affect any of the measured parameters, HFD-CO-induced type 2 diabetes phenotype and increased LV collagen synthesis. Mechanistically, it increased LV levels of ROS, ANG II, ACE, IL-6, s-IL-6Rα, TGF-β1, Smad-3, and activities of JAK1/2 and STAT1/3. AG490, a JAK2 inhibitor, partially ameliorated these effect while Losartan, an AT1 inhibitor completely abolished collagen synthesis. However, with both treatments, levels of ANG II, IL-6, and s-IL-6Rα, and activity of JAK1/STAT3 remained high, all of which were normalized by co-administration of NAC or IL-6 neutralizing antibody. In conclusion: HFD-CO enhances LV collage synthesis by activation of JAK1/STAT3/ANG II/TGF-1β/smad3 pathway. PRACTICAL APPLICATIONS: We report that chronic consumption of a high-fat diet rich in corn oil (HFD-CO) induces diabetes mellitus phenotype 2 associated with left ventricular (LV) cardiac fibrosis in rats. The findings of this study show that HFD-CO, and through the increasing generation of ROS and IL-6 levels and shedding, could activate LV JAK1/2-STAT1/3  and  renin-angiotensin system (RAS) signaling pathways, thus creating a positive feedback between the two which ultimately leads to activation of TGF-1β/Smad3 fibrotic pathway. Herein, we also report a beneficial effect of the antioxidant, NAC, or IL-6 neutralizing antibody in preventing such adverse effects of such HFD-CO. However, this presents a warning message to the current sudden increase in idiopathic cardiac disorders, especially with the big shift in our diets toward n-6 PUFA.

Ghrelin prevents cardiac cell apoptosis during cardiac remodelling post experimentally induced myocardial infarction in rats via activation of Raf-MEK1/2-ERK1/2 signalling

CONTEXT

Mechanisms by which ghrelin affords its cardioprotection in mammals remained unclear.

OBJECTIVE

To examine if ghrelin confers cardio-protection during cardiac remodelling post-MI by modulating the RAF-1-MEK1/2-ERK1/2 signalling pathway.

MATERIALS AND METHODS

Rats were divided into control, sham, sham + ghrelin, myocardial infarction (MI), and MI + ghrelin groups. Ghrelin (100 µg/kg) was administered for 21 days, starting one-day post-MI.

RESULTS

Ghrelin enhanced cardiac contractility and the activities of antioxidant enzymes, lowered serum levels of enzyme markers of cardiac dysfunction, and lowered inflammatory mediator levels. Ghrelin increased levels of phospho-Raf-1 (Ser³³⁸), phospho-MEK1/2 (Ser^217/221), phospho-ERK1/2 (Thr²⁰²/Tyr²⁰⁴), and of their downstream target p-BAD (Ser¹¹²) and inhibited the cleavage of caspase-3. Concomitantly, ghrelin prevented the increases in the levels of fibrotic markers, including α-smooth muscle actin (α-SMA), metalloproteinase-9 (MPP-9), and type III collagen.

CONCLUSION

Post-MI in rats, ghrelin stimulated Raf-1-MEK1/2-ERK1/2-BAD signalling in the LV infarct areas, accounting for its anti-apoptotic effect, enhancing cardiac function, and inhibiting cardiac fibrosis during cardiac remodelling.

Fas/FasL-mediated cell death in rat's diabetic hearts involves activation of calcineurin/NFAT4 and is potentiated by a high-fat diet rich in corn oil

This study investigated if calcineurin/nuclear factor of activated T cells (NFAT) axis mediates the cardiac apoptosis in rats with type 1 diabetes mellitus (T1DM)-induced rats or administered chronically high-fat diet rich in corn oil (CO-HFD). Also, it investigated the impact of chronic administration of CO-HFD on Fas/Fas ligand (Fas/FasL)-induced apoptosis in the hearts of T1DM-induced rats. Adult male Wistar rats (140-160 g) were classified as control: (10% fat) CO-HFD: (40% fat), T1DM, and T1DM + CO-HFD (n=20/each). In vitro, cardiomyocytes were cultured in either low glucose (LG) or high glucose (HG) media in the presence or absence of linoleic acid (LA) and other inhibitors. Compared to the control, increased reactive oxygen species (ROS), protein levels of cytochrome C, cleaved caspase-8 and caspase-3, myocardial damage and impeded left ventricular (LV) function were observed in the hearts of all treated groups and maximally in T1DM + CO-HFD-treated rats. mRNA of all NFAT members (NFAT1-4) were not affected by any treatment. CO-HFD or LA significantly up-regulated Fas levels in both LVs and cultured cardiomyocytes in a ROS dependent mechanism and independent of modulating intracellular Ca²⁺ levels or calcineurin activity. T1DM or hyperglycemia significant up-regulated mRNA and protein levels of Fas and FasL by activating Ca²⁺/calcineurin/NFAT-4 axis. Furthermore, Fas/FasL cell death induced by recombinant FasL (rFasL) or HG media was enhanced by pre-incubating the cells with LA. In conclusion, activation of the Ca²⁺/calcineurin/NFAT4 axis is indispensable for hyperglycemia-induced Fas/FasL cell death in the cardiomyocytes and CO-HFD sensitizes this by up-regulation of Fas.

Acylated ghrelin protects aorta damage post-MI via activation of eNOS and inhibition of angiotensin-converting enzyme induced activation of NAD(P)H-dependent oxidase

NAD(P)H dependent oxidase derived-reactive oxygen species (ROS) due to activation of the renin-angiotensin-aldosterone system (RAAS) in blood vessels postmyocardial infarction MI or during the HF leads to endothelium dysfunction and enhanced apoptosis. Acylated ghrelin (AG) is a well-reported cardioprotective and antiapoptotic agent for the heart. AG receptors are widely distributed in most of blood vessels, suggesting a role in the regulation of endothelial function and survival. This study investigated if AG can protect aorta of rats' postmyocardial infarction (MI)-induced damage and endothelial dysfunction. Adult male rats were divided into four groups of (1) Sham, (2) Sham + AG, (3) MI, and (4) MI + AG. Vehicle (normal saline) or AG (100 µ/kg) was administered to rats for 21 consecutive days, after which, numerous biochemical markers were detected by blot. Both histological and electron microscope studies were carried on aortic samples from MI-induced rats. AG increased protein levels of both total and phosphorylated forms of endothelial nitric oxide synthase (eNOS and p-eNOS, respectively). Only in MI-treated rats, AG prevented the decreases in the levels of reduced glutathione (GSH) and superoxide dismutase (SOD) and lowered levels of malondialdehyde (MDA) and glutathione disulfide (GSSG). Concomitantly, it lowered the increased protein levels of angiotensin-converting enzyme (ACE), p22phox and cleaved caspase-3 and prevented the aorta histological and ultrustructural abnormalities induced by MI.

Cardioprotective effect of ghrelin against myocardial infarction-induced left ventricular injury via inhibition of SOCS3 and activation of JAK2/STAT3 signaling

The molecular mechanisms through which ghrelin exerts its cardioprotective effects during cardiac remodeling post-myocardial infarction (MI) are poorly understood. The aim of this study was to investigate whether the cardioprotection mechanisms are mediated by modulation of JAK/STAT signaling and what triggers this modulation. Rats were divided into six groups (n = 12/group): control, sham, sham + ghrelin (100 µg/kg, s.c., daily, starting 1 day post-MI), MI, MI+ ghrelin, and MI+ ghrelin+ AG490, a potent JAK2 inhibitor (5 mg/kg, i.p., daily). All treatments were administered for 3 weeks. Administration of ghrelin to MI rats improved left ventricle (LV) architecture and restored cardiac contraction. In remote non-infarcted areas of MI rats, ghrelin reduced cardiac inflammation and lipid peroxidation and enhanced antioxidant enzymatic activity. In addition, independent of the growth factor/insulin growth factor-1 (GF/IGF-1) axis, ghrelin significantly increased the phosphorylation of JAK2 and Tyr702 and Ser727 residues of STAT3 and inhibited the phosphorylation of JAK1 and Tyr701 and Ser727 residues of STAT1, simultaneously increasing the expression of BCL-2 and decreasing in the expression of BAX, cleaved CASP3, and FAS. This effect coincided with decreased expression of SOCS3. All these beneficial effects of ghrelin, except its inhibitory action on IL-6 expression, were partially and significantly abolished by the co-administration of AG490. In conclusion, the cardioprotective effect of ghrelin against MI-induced LV injury is exerted via activation of JAK2/STAT3 signaling and inhibition of STAT1 signaling. These effects were independent of the GF/IGF-1 axis and could be partially mediated via inhibition of cardiac IL-6.

Effect of dehydroepiandrosterone (DHEA) on memory and brain derived neurotrophic factor (BDNF) in a rat model of vascular dementia

The effect of dehydroepiandrosterone (DHEA) on memory and cognition in experimental animals is well known, but its efficacy in clinical dementia is unproven. So, the aim of the present study was to investigate the effect of DHEA on learning and memory activities in a rat model of vascular dementia (VD). Forty-eight male rats that positively passed the holeboard memory test were chosen for the study before bilateral permanent occlusion of the common carotid artery. They were divided into four groups (n=12, each) as follows (i) untreated control, (ii) rats exposed to surgical permanent bilateral occlusion of the common carotid arteries (BCCAO) leading to chronic cerebral hypoperfusion, (iii) rats exposed to BCCAO then received DHEA (BCCAO + DHEA) and (i.v.) rats exposed to BCCAO then received donepezil (BCCAO + DON). Holeboard memory test was used to assess the time, latency, working memory and reference memory. Central level of acetylcholine, norepinephrine and dopamine in the hippocampus were measured. Furthermore, the expression of brain derived neurotrophic factor (BDNF) in the hippocampus was determined. Histopathological studies of the cerebral cortex and transmission electron microscope of the hippocampus were performed. BCCAO decreased the learning and memory activities in the holeboard memory. Also, it decreased the expression of BDNF as well as the central level of acetylcholine, noradrenaline and dopamine as compared to control rats. Treatment with DHEA and donepezil increased the working and reference memories, BDNF expression as well as the central acetylcholine in the hippocampus as compared to BCCAO rats. DHEA produced neuroprotective effects through increasing the expression of BDNF as well as increasing the central level of acetylcholine and catecholamines which are non-comparable to donepezil effects.