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BAHAR, ASLI NUR

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BAHAR

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ASLI NUR

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  • PublicationOpen Access
    Signaling pathways in liver fibrosis
    (2023-01-01) BAHAR, ASLI NUR; BAHAR A. N., AKBULUT K. G.
    Liver fibrosis is a disease characterized by activation of hepatic stellate cells (HSCs) and excessive accumulation of extracellular matrix (ECM) components that destroy the physiological structure of the liver. Liver fibrosis contributes to the increasing prevalence and severity of chronic liver diseases. If liver fibrosis, which is of great clinical importance, is not treated, it ends with cirrhosis, which is characterized by fatal and intense complications. Cirrhosis can progress to hepatocellular carcinoma. Although fibrosis was previously thought to be an irreversible process, studies have shown that because of the liver\"s high regenerative ability, regression and return to normal architecture is higher than in other tissues, even in advanced disease.Targeting signaling pathways that cause fibrosis and anti-fibrotic therapies are needed to prevent the progression of liver disease and the development of hepatocellular carcinoma (HCC). Activation of HSCs and transforming growth factor beta (TGF-beta), Wnt/beta-catenin signaling pathways and interactions play an important role in the pathogenesis of the disease. Sirtuins (SIRT) belong to the sirtuin family of Nicotinamide Adenine Dinucleotide, (NAD+) dependent protein deacetylases and are involved in many important cellular biological processes, including the inflammatory response, oxidative stress, and fibrosis. Sirtuin family has been shown to be involved in the regulation of fibrosis signaling pathways and in the cellular and molecular mechanisms of liver fibrosis. In this review, we aimed to summarize current knowledge about the signaling pathways that trigger differentiation, profibrotic activation of myofibroblasts and cause liver fibrosis that can be modulated by sirtuins.
  • Publication
    Effect of SIRT2 Inhibition on Developing Fibrosis in D-Galactose-Induced Aging Model
    (2023-01-05) BAHAR, ASLI NUR; Bahar A. N., Keskin Aktan A., Sonugür F. G., Akarca Dı̇zakar. S. Ö., Akbulut K. G.
    AIM: Aging is a risk factor for fibrosis and liver injury. SIRT2 inhibition has been shown to have a protective effect on the mechanism of renal interstitial fibrosis. In our study, it was aimed to determine the effect of SIRT2 inhibition by AGK-2 on liver functions and its role in the fibrosis process in the aging model caused by D-galactose (D-GAL).METHODS: A total of 32 3-month-old Sprague Dawley rats were used in the study. Rats were divided into 4 groups as Control, D-GAL, Solvent+D-GAL, D-GAL+AGK2+Solvent. D-galactose (150 mg/ kg/day), AGK-2 (10μM/bw) as a specific SIRT2 inhibitor, 4%DMSO+PBS as a solvent were applied to the experimental groups and physiological saline was applied to the control group for 10 weeks. Biochemical parameters (ALT, AST, platelet count, LDH, HDL, VLDL, total cholesterol, triglyceride) were measured in plasma.AST-ALT Ratio, AST-Platelet Ratio Index (APRI), liver index (liver weight/body weight) were calculated. SIRT2 levels in liver tissues were determined by western blot (WB) and immunohistochemical (IHC) analysis.The expression level of TGF β, β catenin, PDGFBB genes was determined by real-time-polymerase chain reaction. Histopathological scoring was performed to detect tissue damage.For statistical analysis, the data obtained from the study were presented as \"mean±standard deviation\".One-way ANOVA (post-hoc LSD) test was used to determine the intergroup differences, and Pearson correlation test was used to determine the relationshipsbetween the variables(p<0.05). RESULTS: D-Galactose administration increased AST, AST-ALT ratio, APRI, SIRT2 protein expression, TGF β, β catenin mRNA levels in liver tissue. AGK-2 application decreased all theseparameters. SIRT2 expression (WB) is positively correlated with AST,APRI index, TGF β1, β-catenin mRNA expression. SIRT2(IHC) is positively correlated with AST/ALT and APRI index.CONCLUSION: It is thought that SIRT2 inhibition may be effective in improving aging-related fibrotic changes in the liver and preventing aging-related loss of function.Keywords:D-Galactose, Fibrosis, SIRT2 inhibition, TGFβ, β catenin,Liver.
  • PublicationOpen Access
    Cerebellum and oxidative stress in natural and accelerated aging model
    (2023-01-05) BAHAR, ASLI NUR; Kavak H., Bahar A. N., Keskin Aktan A., Akbulut K. G.
    AIM: Intracerebroventricular administration of galactose causes motor coordination deficiency by decreasing glutathione (GSH) level in the cerebellum. It has been shown that aging increases oxidative stress and Sirtuin 2 (Sirt2) expression in rat cerebellum tissue and Sirt2 inhibition has a protective effect in aging. In our study, we aimed to investigate the effect of AGK-2 administration, a specific Sirt2 inhibitor, on oxidative stress in an accelerated aging model with natural and D-galactose (D-GAL) administration.METHODS: In the study, 7 groups were formed using 48 male rats of Wistar (W) and Sprague-Dawley (SD) species;1) Young-Control (3 months, n=6), 2) Young-AGK-2 (3 months, n=6), 3) Old-Control (22 months, n=6), 4) Old-AGK-2 (22 months, n=6), 5) D-GAL (3 months, n=9), 6) Solvent+D-GAL (3 months, n=8), 7) Solvent+D-GAL+AGK-2 (3 months, n=7). Control groups were given 4% DMSO+PBS, and experimental groups were given AGK-2 (10 μM/bw) subcutaneously (SC). For the accelerated aging model, D-galactose (150 mg/kg/day, SC) was administered for 10 weeks. Malondialdehyde (MDA) and GSH levels in cerebellum tissue were measured by spectrophotometric method.In the statistical analysis, one-way ANOVA (post-hoc LSD) was used to determine the differences between groups. The statistical significance level was set at p<0.05.RESULTS: The D-GAL administration increased the cerebellum MDA level significantly compared to the young control group (p<0.001). In the D-GAL group, AGK-2 administration decreased the MDA levels and increased the GSH levels (p=0.003; p=0.006). D-GAL administration increased MDA levels more and decreased GSH levels significantly compared to aged rats (p=0.006; p<0.001). AGK-2 administration in natural aging was found to be more effective in increasing GSH levels compared to the accelerated aging model (p<0.001).CONCLUSION: Both models compared increased oxidant stress in the cerebellum. AGK-2 application was found to be more effective than D-GAL on oxidant stress in natural aging.Keywords:AGK-2, Accelerated aging, Cerebellum, D-galactose, Natural aging, Oxidative Stress