Browsing by Author "Görgülü O."

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    The effect of resveratrol on the histologic characteristics of the cochlea in diabetic rats
    (John Wiley and Sons Inc., 2019) Erkan S.O.; Tuhanioğlu B.; Gürgen S.G.; Özdaş T.; Taştekin B.; Pelit A.; Görgülü O.
    Objectives/Hypothesis: The aim of this study was to investigate changes in the cochlea and the potential dose-dependent effects of resveratrol (RSV) against diabetes mellitus (DM) ototoxicity. Study Design: Animal model. Methods: Twenty-four male Wistar albino rats were divided into four groups. Baseline distortion product otoacoustic emission (DPOAE) measurements were evaluated. Group I was the control group, group II was made diabetic with single-dose streptozotocin, and groups III and IV were rendered diabetic as group II and administered 10 and 20 mg RSV, respectively, intraperitoneally for 4 weeks. All animals were sacrificed after repeated DPOAE measurement. Apoptosis was investigated using caspase-3, Bax (Bcl-associated X protein), and TUNEL (terminal deoxynucleotidyl transferase dUTP nick end labeling) staining. Results: The DPOAE values in the diabetic group were found to be significantly lower compared with the other groups at 5,714 Hz and 8,000 Hz (P <.05). No significant difference in otoacoustic emission was detected in the comparison of the RSV doses (P >.05). The histopathologic investigation using caspase-3, Bax, and TUNEL staining showed that the mean rank of the diabetic group was significantly higher compared with the RSV10, RSV20, and control groups (DM > RSV10 > RSV20 > control) (P <.05). Conclusions: These results imply that RSV administration offered statistically significant protection for the cochleas of rats against diabetes. This protective effect improved histologically with higher doses. Level of Evidence: NA Laryngoscope, 129:E1–E6, 2019. © 2018 The American Laryngological, Rhinological and Otological Society, Inc.
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    The effect of very low dose pulsed magnetic waves on cochlea; [Efeito de ondas magnéticas pulsadas de dosagem extremamente baixa na cóclea]
    (Elsevier Editora Ltda, 2019) Tuhanioğlu B.; Erkan S.O.; Gürgen S.G.; Özdaş T.; Görgülü O.; Çiçek F.; Günay İ.
    Introduction: In daily life biological systems are usually exposed to magnetic field forces at different intensities and frequencies, either directly or indirectly. Despite negative results, the therapeutic use of the low dose magnetic field has been found in recent studies. The effect of magnetic field forces on cochlear cells is not clear in the literature. Objective: In our study, we first applied in vivo pulsed magnetic fields to laboratory rats to investigate the effects on cochlea with distortion product otoacoustic emission test followed by histopathological examinations. Methods: Twelve rats were included in this study, separated into two groups as study group and control group. The rats in the study group were exposed to 40 Hz pulsed magnetic field for 1 h/day for 30 days; the hearing of the rats was controlled by otoacoustic emission test. Also, their cochleas were removed and histochemical examination was performed by Caspase-3, Caspase-9, and TUNEL methods. Results: A statistically significant difference was determined (p < 0.05) when the hearing thresholds of the groups obtained by using 5714 Hz and 8000 Hz stimuli were compared by Kruskal–Wallis test. A significant reaction was observed in the study group, especially in the outer ciliated cells during immunohistochemical examinations by using Caspase-3 and Caspase-9 methods. A significantly positive difference was determined in the study group, especially at the outer ciliated cells and the support cells of the corti organ, when compared to the control group (p < 0.05) by the TUNEL method. Conclusion: According to the results of our study, the very low dose magnetic field, which is considered to be used for therapeutic purposes recently, can cause both auditory function defects and histopathologic damage in cochlear cells. © 2018 Associação Brasileira de Otorrinolaringologia e Cirurgia Cérvico-Facial
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    Pterostilbene protects cochlea from ototoxicity in streptozotocin-induced diabetic rats by inhibiting apoptosis
    (Public Library of Science, 2020) Özdaş S.; Taştekin B.; Gürgen S.G.; Özdaş T.; Pelit A.; Erkan S.O.; Tuhanioğlu B.; Gülnar B.; Görgülü O.
    Diabetes mellitus (DM) causes ototoxicity by inducing oxidative stress, microangiopathy, and apoptosis in the cochlear sensory hair cells. The natural anti-oxidant pterostilbene (PTS) (trans-3,5-dimethoxy-4-hydroxystylbene) has been reported to relieve oxidative stress and apoptosis in DM, but its role in diabetic-induced ototoxicity is unclear. This study aimed to investigate the effects of dose-dependent PTS on the cochlear cells of streptozotocin (STZ)-induced diabetic rats. The study included 30 albino male Wistar rats that were randomized into five groups: non-diabetic control (Control), diabetic control (DM), and diabetic rats treated with intraperitoneal PTS at 10, 20, or 40 mg/kg/day during the four-week experimental period (DM + PTS10, DM + PTS20, and DM + PTS40). Distortion product otoacoustic emission (DPOAE) tests were performed at the beginning and end of the study. At the end of the experimental period, apoptosis in the rat cochlea was investigated using caspase-8, cytochrome-c, and terminal deoxyribonucleotidyl transferase-mediated dUTP-biotin end labeling (TUNEL). Quantitative real-time polymerase chain reaction was used to assess the mRNA expression levels of the following genes: CASP-3, BCL-associated X protein (BAX), and BCL-2. Body weight, blood glucose, serum insulin, and malondialdehyde (MDA) levels in the rat groups were evaluated. The mean DPOAE amplitude in the DM group was significantly lower than the means of the other groups (0.9–8 kHz; P < 0.001 for all). A dose-dependent increase of the mean DPOAE amplitudes was observed with PTS treatment (P < 0.05 for all). The Caspase-8 and Cytochrome-c protein expressions and the number of TUNEL-positive cells in the hair cells of the Corti organs of the DM rat group were significantly higher than those of the PTS treatment and control groups (DM > DM + PTS10 > DM + PTS20 > DM + PTS40 > Control; P < 0.05 for all). PTS treatment also reduced cell apoptosis in a dose-dependent manner by increasing the mRNA expression of the anti-apoptosis BCL2 gene and by decreasing the mRNA expressions of both the pro-apoptosis BAX gene and its effector CASP-3 and the ratio of BAX/BCL-2 in a dose-dependent manner (P < 0.05 compared to DM for all). PTS treatment significantly improved the metabolic parameters of the diabetic rats, such as body weight, blood glucose, serum insulin, and MDA levels, consistent with our other findings (P < 0.05 compared to DM for all). PTS decreased the cochlear damage caused by diabetes, as confirmed by DPOAE, biochemical, histopathological, immunohistochemical, and molecular findings. This study reports the first in vivo findings to suggest that PTS may be a protective therapeutic agent against diabetes-induced ototoxicity. © 2020 Özdaş et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.