Person: YEGEN, BERRAK
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YEGEN
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BERRAK
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Publication Metadata only Melatonin supports alendronate in preserving bone matrix and prevents gastric inflammation in ovariectomized rats(WILEY, 2019) YEGEN, BERRAK; Gurler, Esra Bihter; Cilingir-Kaya, Ozlem Tugce; Eyuboglu, Irem Peker; Ercan, Feriha; Akkiprik, Mustafa; Reiter, Russell J.; Yegen, Berrak C.The anti-catabolic bisphosphonate alendronate is considered as the first-line medical treatment in post-menopausal osteoporosis; but several side effects, including gastric mucosal injury, are associated with its use. The aim was to elucidate whether combined treatment with melatonin plus alendronate would be more advantageous in the maintenance of bone and the prevention of gastric side effects. Under anaesthesia, female Sprague-Dawley rats underwent bilateral ovariectomy (OVX), while control group had sham surgery. Four weeks after the surgery, OVX rats were treated with saline, melatonin (25 mu g/mL/d), alendronate (70 mu g/kg/wk), melatonin + alendronate, melatonin + melatonin receptor antagonist (luzindole, 10 mu g/kg/d) or alendronate + melatonin + luzindole for 8 weeks. Rats were euthanized at the end of 12th week. Runx2 expression, apoptotic cells, and trabecular thickness were evaluated in tibiae, while gastric tissues were analysed for oxidative injury parameters. In all OVX groups, Runx2 expression was depressed. Saline-treated OVX group presented an extreme decrease in calcified area in opposition to melatonin- or alendronate-treated groups, while the bones in alendronate + melatonin-treated group were similar to those of the sham-operated group. Concomitant with the improvements examined histologically in bone tissues, quantitative TUNEL (+) cells were similarly lower in alendronate- or melatonin-treated groups. Oxidative gastric damage was increased in saline- or alendronate-treated groups, which were depressed in the presence of melatonin. Although melatonin and alendronate exerted similar supportive effects on the maintenance of bone mass, melatonin may have a more advantageous impact by protecting against OVX-induced gastric injury, which was aggravated by alendronate use. Highlights Our results demonstrate that alendronate and melatonin had similar supportive effects on the maintenance of bone mass, while melatonin prevented the gastric side effects of alendronate, making this combination an advisable therapeutic approach in the treatment of menopausal osteoporosis.Publication Metadata only The anti-inflammatory effect of leptin on experimental colitis: involvement of endogenous glucocorticoids(ELSEVIER SCIENCE INC, 2004) YEGEN, BERRAK; Cakir, B; Bozkurt, A; Ercan, F; Yegen, BCThe present study was designed to compare the effect of leptin on acute colonic inflammation with that of acute stress exposure, which acts via the hypothalamic-pituitary-adrenal (HPA) axis. Sprague-Dawley rats of both sexes were administered intrarectally with acetic acid. Either leptin (10 mug/kg; i.p.) or saline was injected immediately before and 6 h after the induction of colitis. A group of rats was exposed to water avoidance stress (WAS) for 30 min at the 6th h of colitis induction. RU-486 (2 mg/kg; i.p.), a glucocorticoid receptor antagonist, was injected intraperitoneally, at 12 and 1 h before the initial leptin injection, and at 1 h before the second leptin injection or exposure to WAS. Rats were decapitated at 24 h and the distal 8 cm of,the colon were removed for macroscopic and microscopic scoring, determination of tissue wet weight index (WI) and tissue myeloperoxidase activity (MPO). Acetic acid-induced colitis significantly increased macroscopic and microscopic damage scores, WI and MPO, compared to control group. Exposure to acute WAS or treatment with leptin reduced the elevations in damage scores, WI and MPO induced by colitis, but no additive inhibitory effect was observed when WAS and leptin were applied together. RU-486 treatment reversed the inhibitory effects of leptin or WAS on colonic inflammation. Our results demonstrate that exogenous leptin mimics the effects of HPA axis activation on colitis-induced inflammatory process. The results also suggest that the anti-inflammatory effect of leptin involves a tissue neutrophil-dependent mechanism and is dependent on the release of glucocorticoids. (C) 2003 Elsevier Inc. All rights reserved.Publication Open Access Neuropeptide W Exhibits Preventive and Therapeutic Effects on Acetic Acid-Induced Colitis via Modulation of the Cyclooxygenase Enzyme System(2023-01-01) ARABACI TAMER, SEVİL; ERCAN, FERİHA; YEGEN, BERRAK; ARABACI TAMER S., Akbulut S., Erdogan O., Cevik O., ERCAN F., YEGEN B.Background The novel peptide neuropeptide W (NPW) was originally shown to function in the control of feeding behavior and energy homeostasis. The aim of this study was to elucidate the putative preventive and therapeutic effects of NPW on colitis-associated oxidative injury and the underlying mechanisms for its action.Methods Sprague-Dawley rats in the acute colitis groups received NPW (0.5, 1 or 5 mu g/kg/day) injections prior to induction of colitis with acetic acid, while the chronic colitis groups were treated after the induction of colitis. In both acute and chronic colitis (CC) groups, treatments were continued for 5 days and the rats were decapitated at the 24th hour of the last injections and colon tissues were collected for assessments.Results NPW pretreatment given for 5 days before colitis induction, as well as treating rats with NPW during the 5-day course of CC, abolished colonic lipid peroxidation. NPW treatment prevented colitis-induced reduction in blood flow, diminished neutrophil infiltration, and pro-inflammatory cytokine responses. NPW pretreatment only at the higher dose reduced colonic edema and microscopic score and preserved colonic glutathione stores. Elevations in cyclooxygenase (COX) enzyme activity and COX-1 protein level during the acute phase of colitis as well as reduction in COX-2 were all reversed with NPW pretreatment. In contrast, NPW treatment was effective in reducing the elevated COX-2 concentration during the chronic phase.Conclusions NPW alleviates acetic acid-induced oxidative colonic injury in rats through the upregulation of colonic blood flow as well as the inhibition of COX-2 protein expression and pro-inflammatory cytokine production.Publication Metadata only Halofuginone, a Specific Inhibitor of Collagen Type 1 Synthesis, Ameliorates Oxidant Colonic Damage in Rats with Experimental Colitis(SPRINGER, 2010) YEGEN, BERRAK; Karakoyun, Berna; Yuksel, Meral; Ercan, Feriha; Salva, Emine; Isik, Isil; Yegen, Berrak C.To evaluate the effect of halofuginone on trinitrobenzene sulfonic acid (TNBS)-induced colonic injury, rats were given halofuginone (40 mu g/kg, intraperitoneally) or saline 1 h before the induction of colitis, and the injections were continued twice daily for 3 days until they were decapitated. High macroscopic and microscopic damage scores, elevated colonic wet weights, colonic myeloperoxidase activity, malondialdehyde and tissue collagen level, and luminol chemiluminescence values, and marked reduction in glutathione level of the saline-treated colitis group were all reversed by treatment with halofuginone. In conclusion, halofuginone exerts beneficial effects in TNBS-induced colonic inflammation in rats. The anti-inflammatory effects of halofuginone appear to involve suppression of neutrophil accumulation, preservation of endogenous glutathione, and inhibition of reactive oxidant generation. Halofuginone also shows antifibrotic effect via inhibition of tissue collagen production. The present data encourage possible use of the antifibrotic halofuginone as an anti-inflammatory agent in improving oxidative injury in colitis.Publication Metadata only Estrogen Alleviates Acetic Acid-Induced Gastric or Colonic Damage via Both ER alpha- and ER beta-Mediated and Direct Antioxidant Mechanisms in Rats(SPRINGER/PLENUM PUBLISHERS, 2014) YEGEN, BERRAK; Kumral, Zarife Nigar Ozdemir; Memi, Gulsun; Ercan, Feriha; Yegen, Berrak C.In order to demonstrate the possible protective effects of estrogen receptor (ER)-alpha and ER beta receptor subtypes in the pathogenesis of colonic and gastric oxidant damage, experimental ulcer and colitis were induced by acetic acid, and the animals were randomly divided as colitis, ulcer, and their corresponding non-ulcer and non-colitis control groups. Each group of rats was treated intramuscularly with the vehicle, selective ER alpha agonist propylpyrazole-triol (1 mg/kg), ER beta agonist diarylpropionitrile (1 mg/kg), non-selective ER agonist 17 beta estradiol (E2; 1 mg/kg), or E2 plus non-selective ER antagonist ICI-182780 (1 mg/kg). The results revealed that induction of ulcer or colitis resulted in systemic inflammation as assessed by increased levels of plasma TNF-alpha and IL-6 levels. In both tissues, the presence of oxidant damage was verified by histological analysis and elevated myleoperoxidase activity. In the colitis and ulcer groups, both ER agonists and the non-selective E2 reversed the oxidative damage in a similar manner. These findings indicate that estrogen acts via both ER alpha- and ER beta-mediated and direct antioxidant mechanisms, where both ER subtypes play equal and efficient roles in the anti-inflammatory action of estrogen, in limiting the migration of neutrophils to the inflamed tissue, reducing the release and activation of cytokines and thereby alleviating tissue damage.Publication Metadata only Nesfatin-1 ameliorates testicular injury and supports gonadal function in rats induced with testis torsion(ELSEVIER SCIENCE INC, 2018) YILDIRIM, ALPER; Tamer, Sevil Arabaci; Yildirim, Alper; Koroglu, M. Kutay; Cevik, Ozge; Ercan, Feriha; Yegen, Berrak C.Testicular torsion causes ischemia-reperfusion injury and an increased risk of infertility. Nesfatin-1 is a novel peptide with antioxidant, anti-inflammatory and anti-apoptotic properties. In the present study, we aimed to investigate the putative beneficial effects of nesfatin-1 on oxidative injury and impaired testicular function induced by testis torsion. Under anesthesia, male Sprague-Dawley rats (180-230 g; n = 24) had sham-operation or they underwent testicular torsion by rotating the left testis 720 degrees and fixing it for 2 h, followed by a 2-h detorsion. Rats in each group were treated intraperitoneally with either nesfatin-1 (0.3 mu g/kg) or saline prior to the torsion or sham-torsion. At the end of the 4-h experimental period, tissue samples were removed for evaluation of spermatozoa, molecular and histochemical analyses. In saline-treated torsion/detorsion group, a high percentage of abnormal spermatozoa with head defects was observed, which was abolished in nesfatin-1 -treated torsion/detorsion group. The levels of 8-OHdG, tumor necrosis factor (TNF)-alpha, interleukin (IL)-6, caspase-3 were increased in the saline-treated torsion/detorsion group as compared to sham-operated group, while nesfatin-1 pre-treatment significantly decreased the expressions of the pro-inflammatory cytokines, depressed apoptosis, and also reduced the tubular degeneration. In addition, nesfatin-1 in torsion/detorsion group elevated expressions of transforming growth factor (TGF)-beta and reduced expressions of protein kinase B (AKT) and cAMP response element binding protein (CREB) in the testis tissue. The present findings show that nesfatin-1, by regulating AKT and CREB signaling pathways and pro-inflammatory/anti-inflammatory cytokine balance, preserves the spermatogenic cells and ameliorates torsion-detorsion-induced tubular degeneration.Publication Metadata only Leptin ameliorates burn-induced multiple organ damage and modulates postburn immune response in rats(ELSEVIER, 2005) YEGEN, BERRAK; Cakir, B; Cevik, H; Contuk, G; Ercan, F; Eksioglu-Demiralp, E; Yegen, BCThe present study was designed to determine whether exogenous leptin reduces remote organ injury in the rats with thermal burn trauma. Leptin (10 mug/kg) or saline was administered intraperitoneally after burn injury, and the rats were decapitated at either 6 or 24 h. Plasma samples of 24-h burn group were assayed for the determination of monocyte and neutrophil apoptosis. Thermal injury increased tissue-associated myeloperoxidase (MPO) activity and microscopic damage scores in the lung, liver, stomach, colon and kidney of both 6- and 24-h burn groups. In the 6-h burn group, leptin reduced microscopic damage score in the liver and kidney only, while damage scores in the 24-h burn group were reduced in all the tissues except the lung. Also, in both burn groups, leptin reduced elevated MPO activity in all tissues except the lung. The percentage of mononuclear cells was significantly reduced at the 24 h of burn injury, while the granulocyte percentage was increased. Leptin treatment, however, had no significant effect on burn-induced reversal of white blood cell ratios. On the other hand, burn-induced increase in the death of mononuclear cells and granulocytes was significantly reduced in leptin-treated rats. The results of the present study suggest that leptin may provide a therapeutic benefit in diminishing burn-induced inflammation and associated multiple organ failure. (C) 2004 Elsevier B.V. All rights reserved.Publication Metadata only beta-glucan ameliorates methotrexate-induced oxidative organ injury via its antioxidant and immunomodulatory effects(ELSEVIER, 2006) YEGEN, BERRAK; Sener, Goksel; Eksioglu-Demiralp, Emel; Cetiner, Mustafa; Ercan, Feriha; Yegen, Berrak C.Methotrexate is an antifolate that is widely used in the treatment of rheumatic disorders and malignant tumors. The efficacy of methotrexate is often limited by severe side effects and toxic sequelae, where oxidative stress is noticeable. In the present study, the possible protective effect of beta-glucan in methotrexate-induced toxicity was investigated. Following a single dose of methotrexate injection (20 mg/kg), either saline or beta-glucan (50 mg/kg; orally) was administered for 5 days. After decapitation of the rats, trunk blood was obtained and the ileum, liver and kidney were removed to measure tissue malondialdehyde (NMA) and glutathione (GSH) levels, myeloperoxidase (MPO) activity and collagen content, as well as histological examination. Methotrexate caused a significant decrease in GSH levels, while MDA levels, WO activity and collagen content were increased in all the tissues (P < 0.05-0.001). On the other hand, administration of IS-glucan following methotrexate abolished the depletion of GSH and inhibited the increases in MDA, MPO activity and collagen content, while the histological analysis revealed that beta-glucan attenuated the tissue damage. Stimulation index, an indicator of oxidative burst in the neutrophils, was decreased by methotrexate (P < 0.001), while beta-glucan abolished this effect. Furthermore, increased leukocyte apoptosis and cell death in methotrexate-treated animals were inhibited by beta-glucan (P < 0.05). Thus, the findings of the present study suggest that beta-glucan, through its antioxidant and immunoregulatory effects, may be of therapeutic value in alleviating the leukocyte apoptosis, oxidative tissue injury and thereby the intestinal and hepatorenal side effects of methotrexate treatment. (c) 2006 Elsevier B.V. All rights reserved.