Person: EYİGÖR, ÖZHAN
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EYİGÖR
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ÖZHAN
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Publication Glutamate receptor antagonist suppresses the activation of nesfatin-1 neurons following refeeding or glucose administration(Via Medica, 2022-01-01) Koçoğlu, S. Serter; Oy, C.; Halk, Z.; Çakır, C.; Minbay, Z.; Eyigör, O.; OY, CEREN; Halk, Z.; ÇAKIR, CİHAN; MİNBAY, FATMA ZEHRA; EYİGÖR, ÖZHAN; Tıp Fakültesi; Histoloji ve Embriyoloji Ana Bilim Dalı; 0000-0002-8332-7353; 0000-0003-3463-7483; ABQ-8779-2022; ABE-5128-2020; AAH-5249-2021; ABC-1475-2020Background: Nesfatin-1 is a newly identified satiety peptide that has regulatory effects on food intake and glucose metabolism, and is located in the hypothalamic nuclei, including the supraoptic nucleus (SON). In this study, we have investigated the hypothesis that nesfatin-1 neurons are activated by refeeding and intraperito-neal glucose injection and that the glutamatergic system has regulatory influences on nesfatin-1 neurons in the SON. Materials and methods: The first set of experiments analysed activation of nesfatin-1 neurons after refeeding as a physiological stimulus and the effective-ness of the glutamatergic system on this physiological stimulation. The subjects were randomly divided into three groups: fasting group, refeeding group and antagonist (CNQX + refeeding) group. The second set of experiments analysed activation of nesfatin-1 neurons by glucose injection as a metabolic stimulus and the effectiveness of the glutamatergic system on this metabolic stimulation. The subjects were randomly divided into three groups: saline group, glucose group and antagonist (CNQX + glucose) group. Results: Refeeding significantly increased the number of activated nesfatin-1 neurons by approximately 66%, and intraperitoneal glucose injection activated these neurons by about 55%, compared to the fasting and saline controls. The injections of glutamate antagonist (CNQX) greatly decreased the number of ac-tivated nesfatin-1 neurons. Conclusions: This study suggested that nesfatin-1 neurons were activated by peripheral and/or metabolic signals and that this effect was mediated through the glutamatergic system. (Folia Morphol 2022; 81, 2: 379-386)Publication Glutamatergic activation of A1 and A2 noradrenergic neurons in the rat brain stem(Medicinska Naklada, 2019-07-10) Gök-Yurtseven, Duygu; Kafa, İlker M.; Minbay, Zehra; Eyigör, Özhan; GÖK YURTSEVEN, DUYGU; KAFA, İLKER MUSTAFA; MİNBAY, FATMA ZEHRA; EYİGÖR, ÖZHAN; Fen Bilimleri Enstitüsü; Histoloji Bölümü ve Embriyoloji Bilim Dalı; 0000-0001-8309-0934; 0000-0003-3463-7483; AAW-4867-2021; AAG-7125-2021; ABE-5128-2020; ABC-1475-2020Aim To analyze the effects of glutamatergic agonists and antagonists on the activation of the A1 and A2 noradrenergic neurons localized in caudal ventrolateral medulla and nucleus tractus solitarii, respectively.Methods Rats were injected with glutamatergic agonists - kainic acid, alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA), or N-methyl-D-aspartic acid (NMDA), and the brain sections were prepared for immunohistochemistry. Before agonist injections, antagonists - 6-cyano-7-nitroquinoxaline-2,3-dione or dizocilpine were administered. The expression of c-Fos, as the neuronal activation marker, and tyrosine hydroxylase (TH), as the marker of noradrenergic neurons was assessed with dual immunohistochemistry. The percentage of c-Fos-positive noradrenergic neurons relative to all TH-positive neurons in the respective areas of the brain stem was calculated.Results All three glutamatergic agonists significantly increased the number of the c-Fos-positive noradrenergic neurons in both the A1 and A2 area when compared with control animals. Kainic acid injection activated about 57% of TH-positive neurons in A1 and 40% in A2, AMPA activated 26% in A1 and 38% in A2, and NMDA 77% in A1 and 22% in A2. The injections of appropriate glutamatergic antagonists greatly decreased the number of activated noradrenergic neurons.Conclusion Our results suggest that noradrenergic neurons are regulated and/or activated by glutamatergic system and that these neurons express functional glutamate receptors.Publication Expression of the ionotropic glutamate receptors on neuronostatin neurons in the periventricular nucleus of the hypothalamus(Via Medica, 2022-01-01) Kocoğlu, S. Serter; Çakir, Cihan; ÇAKIR, CİHAN; Eyigör, Özhan; MİNBAY, FATMA ZEHRA; EYİGÖR, ÖZHAN; Tıp Fakültesi; Histoloji ve Embriyoloji Ana Bilim Dalı; 0000-0002-8332-7353; 0000-0003-3463-7483; ABC-1475-2020; ABE-5128-2020; AAH-5249-2021; ABQ-8779-2022Background: Neuronostatin, a newly identified peptide, is accepted as an anorex- igenic peptide since it suppresses food intake when given intracerebroventricularly. Although the effect mechanisms of neuronostatin have been shown in different studies, there are no reports in the literature describing the mechanisms controlling neuronostatin neurons. In this study, we aimed to determine the presence of the ionotropic glutamate receptor subunits (iGluRs) in neuronostatin neurons in the periventricular nucleus of the hypothalamus. Materials and methods: The presence of glutamate receptors in neuronostatin neurons was investigated by dual immunohistochemistry. Immunohistochemistry was performed on 40 mu m thick coronal brain sections with antibodies against AMPA (GluA1-4), kainate (GluK1/2/3, and GluK5), and NMDA (GluN1 and GluN2A) receptor subunits. Results: The results showed that the neuronostatin neurons expressed most of the NMDA and non-NMDA receptor subunits. The neuronostatin neurons in the anterior hypothalamic periventricular nucleus were particularly immunopositive for GluA1, GluA4, GluK1/2/3, GluK5 and GluN1 antibodies. No expression was observed for GluA2, GluA3 and GluN2A antibodies. Conclusions: For the first time in the literature, our study demonstrated that the neuronostatin neurons express glutamate receptor subunits which may form homomeric or heteromeric functional receptor complexes. Taken together, these results suggest that multiple subunits of iGluRs are responsible for glutamate transmission on neuronostatin neurons in the anterior hypothalamic periventricular nucleus.Publication Immunohistochemical determination of the excitatory and inhibitory axonal endings contacting nucb2/nesfatin-1 neurons(Elsevier, 2023-12-28) GÖK YURTSEVEN, DUYGU; Aghayeva, Aynura; HASANOĞLU AKBULUT, NURSEL; Akbulut, Nursel Hasanoglu; Eyigör, Özhan; EYİGÖR, ÖZHAN; Tıp Fakültesi; Histoloji ve Embriyoloji Ana Bilim DalıNesfatin-1 is an anorexigenic peptide suppressing food intake and is synthesized and secreted by neurons located in the hypothalamus. Our study was aimed to demonstrate the effect of excitatory and inhibitory neurotransmitters on NUCB2/nesfatin-1 neurons. In this context, dual peroxidase immunohistochemistry staining was performed using NUCB2/nesfatin-1 primary antibody with each of the primary antibodies of vesicular transporter proteins applied as markers for neurons using glutamate, acetylcholine, and GABA as neurotransmitters. In double labeling applied on floating sections, the NUCB2/nesfatin-1 reaction was determined in brown color with diaminobenzidine, while vesicular carrier proteins were marked in black. Slides were analyzed to determine the ratio of nesfatin-1 neurons in the three hypothalamic nucleus in contact with a relevant vesicular carrier protein. The ratios of NUCB2/nesfatin-1 neurons with the innervation were compared among neurotransmitters. In addition, possible gender differences between males and females were examined. The difference in the number of VGLUT2-contacting NUCB2/nesfatin-1 neurons was significantly higher in males when compared to females. When both genders were compared in different nuclei, it was seen that there was no statistical significance in terms of the percentage of NUCB2/nesfatin-1 neuron apposition with VGLUT3. The statistical evaluation showed that number of NUCB2/nesfatin-1 neurons receiving GABAergic innervation is higher in males when compared to females (*p <= 0.05; p = 0.045). When the axonal contact of vesicular neurotransmitter transporter proteins was compared between the neurotransmitters, it was determined that the most prominent innervation is GABAergic. In the supraoptic region, no contacts of VAChT-containing axons were found on NUCB2/nesfatin-1 neurons in both female and male subjects. In conclusion, it is understood that both excitatory and inhibitory neurons can innervate the NUCB2/nesfatin-1 neurons and the glutamatergic system is effective in the excitatory innervation while the GABAergic system plays a role in the inhibitory mechanism.Publication The localization of R-spondin1 and R-spondin 3 peptides in rat hypothalamus: An immunohistochemical study(Soc Chilena Anatomia, 2023-12-01) Gök, D. Yurtseven; Coşkan, N.; Topal, G.; Akbulut, N. Hasanoğlu; Eyigör, O.; GÖK YURTSEVEN, DUYGU; Coşkan, N.; Topal, G.; HASANOĞLU AKBULUT, NURSEL; EYİGÖR, ÖZHAN; Tıp Fakültesi; Histoloji ve Embriyoloji Ana Bilim Dalı; JYE-8429-2024; JYM-2286-2024; ECI-5570-2022; JXZ-3834-2024; JYE-8338-2024The R-spondin protein family is a group of proteins that enhance Wnt/b-catenin signaling and have pleiotropic functions in stem cell growth and development. In the literature reviews, there is no histomorphological study showing the localization and distribution of R-spondins in different hypothalamic nuclei. For this reason, the purpose of this study was to determine the localization, distribution characteristics, and densities in the hypothalamic nuclei of neurons expressing Rspo1 and Rspo3 proteins. The free-floating brain sections of the male rats who were not exposed to any treatment were stained with the indirect immunoperoxidase method using the relevant antibodies. As a result of the immunohistochemical studies, it was determined that neurons expressing the Rspo1 protein were found in large numbers in the supraoptic nucleus (SON), the suprachiasmatic nucleus (SCh), anterior paraventricular nucleus, periventricular hypothalamic nucleus (PeV), anterior hypothalamic area, magnocellular preoptic nucleus (MCPO) and the lateral hypothalamic area (LH) from the hypothalamic nuclei, while they were localized in fewer numbers in the arcuate nucleus (ARC). Rspo3 protein expression was found in neurons localized in the hypothalamic nuclei SON, paraventricular nucleus (PVN), PeV, ARC, ventromedial nucleus (VMH), LH, anterior parvicellular nucleus, and zona inserta (ZI). In addition, neurons synthesizing both peptides were found in the cortex and hippocampus regions (H). Rspo1 and 3 proteins are expressed in hypothalamic energy homeostatic areas, thus these proteins may be involved in the regulation of food intake.