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ARABACI TAMER, SEVİL

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ARABACI TAMER

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SEVİL

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    PublicationOpen 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.
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    PublicationOpen Access
    High-fat Diet Enhances Gastric Contractility, but Abolishes Nesfatin-1-induced Inhibition of Gastric Emptying
    (KOREAN SOC NEUROGASTROENTEROLOGY & MOTILITY, 2021-04-30) YEGEN, BERRAK; Ozdemir-Kumral, Zarife N.; Koyuncuoglu, Turkan; Arabaci-Tamer, Sevil; Cilingir-Kaya, Ozlem T.; Koroglu, Ayca K.; Yuksel, Meral; Yegen, Berrak C.
    Neither HFD nor NES-1 changed methylcellulose emptying, but NES-1 delayed saline emptying in cannulated ND-rats. Inhibitory effect of NES-1 on gastric emptying in ND-rats was reversed by all antagonists, and abolished in HFD-rats. In HFD-rats, carbachol-induced contractility was enhanced in gastric, but inhibited in ileal strips. HFD increased body weight, while serum triglycerides, alanine transaminase, aspartate aminotransferase, glucose, and levels of malondialdehyde, glutathione, myeloperoxidase activity, and luminolchemiluminescence in hepatic, ileal, and adipose tissues were similar in ND- and HFD-rats, but only lucigenin-chemiluminescence was Background/Aims Gastrointestinal motility changes contribute to development and maintenance of obesity. Nesfatin-1 (NES-1) is involved in central appetite control. The aim is to elucidate effects of NES-1 and high-fat diet (HFD) on gastrointestinal motility and to explore myenteric neuron expressions of tyrosine hydroxylase (TH), vasoactive intestinal peptide (VIP), and neuronal nitric oxide synthase (nNOS) in HFDinduced oxidative injury. Methods Sprague-Dawley rats were fed with normal diet (ND) or HFD. Gastric emptying rate was measured following NES-1 (5 pmol/rat, intracerebroventricular) preceded by subcutaneous injections of glucagon-like peptide 1 (GLP-1), cholecystokinin 1 (CCK-1), and gastrin/CCK-2 receptor antagonists. In carbachol-contracted gastric and ileal strips, contractile changes were recorded by adding NES1 (0.3 nmol/L), GLP-1, CCK-1, and gastrin/CCK-2 antagonists. Results Neither HFD nor NES-1 changed methylcellulose emptying, but NES-1 delayed saline emptying in cannulated ND-rats. Inhibitory effect of NES-1 on gastric emptying in ND-rats was reversed by all antagonists, and abolished in HFD-rats. In HFD-rats, carbachol-induced contractility was enhanced in gastric, but inhibited in ileal strips. HFD increased body weight, while serum triglycerides, alanine transaminase, aspartate aminotransferase, glucose, and levels of malondialdehyde, glutathione, myeloperoxidase activity, and luminolchemiluminescence in hepatic, ileal, and adipose tissues were similar in ND-and HFD-rats, but only lucigenin-chemiluminescence was increased in HFD-rats. Vasoactive intestinal peptide (VIP) and TH immunoreactivities were depressed and nNOS immunoreactivity was increased in gastric tissues of HFD-rats, while VIP and TH were enhanced, but nNOS was reduced in their intestines. Conclusions HFD caused mild systemic inflammation, disrupted enteric innervation, enhanced gastric contractility, inhibited ileal contractility, and eliminated inhibitory effect of NES-1 on gastric motility. (J Neurogastroenterol Motil 2021;27:265-278)
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    PublicationOpen Access
    Nesfatin-1 ameliorates oxidative brain damage and memory impairment in rats induced with a single acute epileptic seizure
    (2022-04-01) ARABACI TAMER, SEVİL; KOYUNCUOĞLU, TÜRKAN; AKAKIN, DİLEK; YÜKSEL, MERAL; YEGEN, BERRAK; Arabacı Tamer S., Koyuncuoğlu T., Karagöz Köroğlu A., AKAKIN D., YÜKSEL M., YEGEN B.
    © 2022Aims: We aimed to investigate putative neuroprotective effects of nesfatin-1 on oxidative brain injury and memory dysfunction induced by a single epileptic seizure and to compare these effects with those of antiepileptic phenytoin. Main methods: Wistar albino rats were randomly divided into a control group and pentylenetetrazole (PTZ)-seizure groups pretreated intraperitoneally (ip) with saline or nesfatin-1 (NES-1; 0.3, 1 or 3 μg/kg/day) or phenytoin (PHE; 40 mg/kg/day) or PHE + NES-1 (0.3 μg/kg/day) at 30 min before the single-dose PTZ injection (45 mg/kg; ip). All treatments were repeated at the 24th and 48th h of the provoked epileptic seizure. Passive-avoidance test was performed to assess memory function. The rats were decapitated at the 72nd hour of seizures and brain tissues were analyzed for histopathological changes and for measuring levels of malondialdehyde, glutathione, myeloperoxidase activity and reactive oxygen/nitrogen species. Key findings: In parallel to the effects of phenytoin, NES-1 reduced seizure score, elevated antioxidant glutathione content, depressed generation of nitric oxide and protected against seizure-induced neuronal damage. Additionally, increased malondialdehyde levels and elevated glial fibrillary acidic protein immunoreactivity in the cortex and hippocampus were decreased and memory dysfunction was improved by NES-1. However, NES-1 had no impact on myeloperoxidase activity or production of reactive oxygen species in the brain. Significance: The findings of the present study demonstrate that nesfatin-1 treatment provides neuroprotection against seizure-induced oxidative damage and memory dysfunction by inhibiting reactive nitrogen species and upregulating antioxidant capacity, indicating its potential in alleviating memory deficits and increasing the effectiveness of conventional anti-convulsant therapies.