Person: GÜLHAN, REZZAN
Loading...
Email Address
Birth Date
Research Projects
Organizational Units
Job Title
Last Name
GÜLHAN
First Name
REZZAN
Name
13 results
Search Results
Now showing 1 - 10 of 13
Publication Metadata only The relationship between age-related development of spike-and-wave discharges and the resistance to amygdaloid kindling in rats with genetic absence epilepsy(ACADEMIC PRESS INC ELSEVIER SCIENCE, 2008) ONAT, FİLİZ; Carcak, Nihan; Aker, Rezzan Guelhan; Oezdemir, Osman; Demiralp, Tamer; Onat, Filiz YilmazGenetic Absence Epilepsy Rats from Strasbourg (GAERS) are resistant to amygdaloid kindling. Since in GAERS the characteristics of spike-and-wave discharges (SWDs) change with age, we have studied the relation between SWD maturation and the development of kindling resistance. Non-epileptic Wistar rats and GAERS were stimulated in basolateral amygdala with 400 mu A at 20 min intervals until they reached stage 5 seizures or for a maximum of 36 stimulations. All of the Wistar rats, the postnatal (PN) day 20 GAERS and the (kindling-prone) subgroups of GAERS at PN30 and PN60 reached stage 5 seizures; at PN20, PN30 and PN60 kindling rates were significantly slower in GAERS compared to Wistar rats. At PN30 and PN60, 41% and 69% of GAERS, respectively, showed no stage 3, 4 or 5 seizures after 36 stimulations (kindling-resistant subgroups). The SWD maturation involves changes in spectral patterns and correlate with age-related increases in kindling resistance in GAERS. (C) 2008 Elsevier Inc. All rights reserved.Publication Metadata only 6-Hidroksidopamin Uygulanan Wistar Ve Genetik Absans Epilepsili SıçanlarınRotasyonlarının Karşılaştırılması(2020-11-06) GÜLHAN, REZZAN; GÜLÇEBİ İDRİZ OĞLU, MEDİNE; TOPLU A., YAVUZ M., ÇULPAN Y., TURGAN AŞIK Z. N., GÜLHAN R., GÜLÇEBİ İDRİZ OĞLU M., ONAT F.GİRİŞ VE AMAÇ: 6-Hidroksidopamin (6-OHDA); nigro-striatal dopaminerjik nöronlar için toksik bir ajandır ve Parkinson hastalığının modellenmesinde kullanılır (1). Çalışmamızda, Strasbourg orijinli genetik absans epilepsili sıçanlarda (GAERS) ve Wistar sıçanlarda 6-OHDA toksisitesinin dopaminerjik hasar oluşturmasının göstergelerinden biri olan ve subkutan apomorfinle indüklenen rotasyon davranışını, 2 grup arasında kıyaslamak hedeflendi. YÖNTEM:Bu çalışmada, 30 günlük Wistar ve GAERS hayvanlar kendi içlerinde iki gruba ayrıldı. 6-OHDA (8 µg doz ve 4 µL/4dk hızında); GAERS-MFB (n=8) grubuna medial ön beyin demetine (MFB) (AP:-1,4; ML:1,6; V:7,1 mm) tek enjeksiyon, GAERS-Striatum (n=5) grubuna striatuma iki enjeksiyon (AP:-0,5/+0,5; ML:3,0; V:5,0 mm), Wistar-MFB (n=4) grubuna (AP:-1,4; ML:1,6; V:7,1 mm) tek enjeksiyon, Wistar-Striatum (n=2) grubuna da striatuma iki enjeksiyon (AP:-0,5/+0,5; ML:3,0; V:5,0 mm) olacak şekilde stereotaksik cerrahi yöntemle uygulandı.6-OHDA uygulamasından 21 gün sonra tüm hayvanlara apomorfin enjeksiyonu (0,05 mg/kg, subkutan) uygulandı. Apomorfin uygulanmasından sonra 30 dakika boyunca hayvanların 3600 sağa ve sola rotasyonları kaydedildi. Veriler ortalama±standart hata olarak ifade edildi. Tek yönlü ANOVA ve Tukey’in post-hoc testi kullanıldı (p<0,05 anlamlı olarak kabul edildi). BULGULAR:GAERS-MFB rotasyon sayısı dakikada ortalama 6,56±0,05 iken, GAERS-Striatum dakikada ortalama 6,19±1,72 oldu. Wistar-MFB rotasyon sayısı dakikada ortalama 4,74±2,33 iken, Wistar-Striatum rotasyon sayısı dakikada ortalama 3,27±1,40 olarak bulundu. Gruplar arasında istatistiksel olarak anlamlı bir fark bulunmadı. TARTIŞMA VE SONUÇ:Bulgular; gruplar arasında bir fark olmadığını göstermekle beraber, çalışmamızda grup sayılarının sınırlı olması nedeniyle, sayı arttırılarak çalışmanın devamı hedeflenmektedir. Çalışma TÜBİTAK (218S653) tarafından desteklenmektedir.Publication Metadata only Evaluation of dendrite morphology in wistar and genetic absence epileptic (GAERS) rats(2022-07-09) ŞEHİRLİ, ÜMİT SÜLEYMAN; KİRAZLI, ÖZLEM; GÜLHAN, REZZAN; YAZI S., ŞEHİRLİ Ü. S., GÜLHAN R., ONAT F., KİRAZLI Ö.Aims The aim of the study is to examine the morphological features of dendrites and dendritic spines of pyramidal neurons in somatosensory cortex and hippocampus of Wistar and GAERS (Genetic Absence Epilepsy Rat from Strasbourg) rats. Methods GAERS (n=5) and Wistar (n=5) rats were sacrificed by transcardial perfusion method. Brain tissues were stained using the FD Rapid GolgiStain Kit. Coronal sections of 200 µm thickness were obtained with cryostat. Pyramidal neurons in deep layers of the somatosensory cortex and CA1 region of the hippocampus were examined using light microscope and Neurolucida 360 software. Branching and length of apical dendrite and basal dendrites, and types and densities of dendritic spines were analyzed. Results Statistically the total number of dendrite nodes (p=0.0053, p=0,0047), the total number of dendrite segments (dendritic arborization) (p=0.0036, p=0,0036), the total number of dendrite terminations (p=0.0033, p=0,0029), the total dendrite length (µm) (p=0.0002, p=0,0007) and the dendritic spine density (1/µm) (p=0.0168, p=0,0120) of the somatosensory cortex and the hippocampus were significantly higher in GAERS rats, respectively. When dendritic spine types were evaluated separately, stubby type dendritic spines in the hippocampus were found to be significantly higher in GAERS rats compared to Wistar rats (p=0.0204). Conclusions It was concluded that intense synaptic activation seen in postsynaptic cells in the somatosensory cortex and hippocampus in GAERS causes changes in the dendrite morphology of pyramidal neurons. This study was supported by Marmara University Scientifical Research Projects Commission (TYL-2021-10244).Publication Metadata only Genetik absans epilepsili ve epileptik olmayan sıçanlarda nigrostriatal yolak dejenerasyonunun kalretinin immunoreaktivitesi üzerine etkisi(2022-11-10) KİRAZLI, ÖZLEM; GÜLÇEBİ İDRİZ OĞLU, MEDİNE; ŞEHİRLİ, ÜMİT SÜLEYMAN; GÜLHAN, REZZAN; KİRAZLI Ö., Turgan Aşık Z. N., Çulpan Y., GÜLÇEBİ İDRİZ OĞLU M., ŞEHİRLİ Ü. S., GÜLHAN R., ONAT F.Amaç: Kalsiyum bağlayıcı proteinler, nöronal işlev ve nörogenezde önemli rol oynamaktadır. Kalretinin, dikensiz GABAerjik internöronlarda eksprese edilmekte ve gelen dopaminerjik afferentlerle ve glutamaterjik kortikostriatal afferentlerle sinaptik bağlantı kurmaktadır. Yaşla birlikte azalabilen kalretinin, ileri yaşlardaki motor fonksiyonda oluşacak kayıplardan sorumlu tutulabilmektedir. Parkinson modeli sıçanlarda nigro -striatal yolaktaki dopaminerjik nöron kaybı sonrasında striatumda bulunan kalretinin pozitif internöronlarda azalma meydana geldiği gösterilmiştir. Bu azalışa glutamat reseptörlerindeki aşırı aktivite ve dopaminin eksikliğinin neden olduğu iddia edilmiştir. Kalretinin pozitif internöronların temporal epilepsiye karşı hassas olduğu gösterilmiştir. Epileptogenez sürecinde kimyasal lezyon ile nigro-striatal yolağın devre dışı bırakılmasının kalretinin sentezleyen nöronlar üzerine etkisi incelenmiştir. Gereç ve Yöntem: Striatum, Substantia Nigra pars compacta ve pars reticulata da bulunan kalretinin içeren nöronların tespiti için medial ön beyin demetine 6-OHDA uygulanan Wistar (n=5) GAERS (n=5) Wistar kontrol (n=5) ve GAERS kontrol (n=5) 40µm’lik sıçan beyin kesitlerine immohistokimya yöntemi uygulanmıştır. Nöronların sayım işlemleri floresans boyanmış kesitler üzerinden yapılmıştır. İstatistiksel değerlendirme için GraphPad Prism Tek yönlü ANOVA ve gruplar arasındaki karşılaştırma kullanılmıştır. Bulgular: Çalışmamızda (6 –OHDA) enjekte edilen Wistar ve GAERS sıçanlarda kontrol gruplarına göre kalretinin pozitif hücre sayısında azalma gözlenmiştir. Bu azalma Striatum için istatistiksel olarak anlamlı bulunmazken, Substantia Nigra pars compacta (p<0,05) ve pars reticulata (p<0,05) için anlamlıdır. Sonuç: Literatürde (6 –OHDA) enjekte edilen sıçanlarda nigrostriatal yolakta sağlam kalan dopaminerjik nöronların kalretinin eksprese ettiği gözlemlenmiştir. Bu sonuçlar sonrasında, kalretininin nöroprotektif etkisinden dolayı dopaminerjik nöronları koruyabildiği ileri sürülebilir.Publication Metadata only GABA(A) receptor mediated transmission in the thalamic reticular nucleus of rats with genetic absence epilepsy shows regional differences: Functional implications(ELSEVIER SCIENCE BV, 2006) ONAT, FİLİZ; Aker, Rezzan Gulhan; Ozyurt, Hazan B.; Yananli, Hasan R.; Cakmak, Yusuf Ozgur; Ozkaynakci, Aydan E.; Sehirli, Umit; Saka, Erdinc; Cavdar, Safiye; Onat, Filiz YimazThe aim of the present study was to investigate the effect of local injections of the GABA(A) receptor antagonist, bicuculline, into the rostral and caudal parts of the thalamic reticular nucleus (TRN), on the generation of spike-and-wave discharges in Genetic Absence Epilepsy Rats from Strasbourg (GAERS). Spike-and-wave discharges are important in the pathophysiology of absence epilepsy and generated by the cortico-thalamo-cortical pathway, where GABA has a significant role, particularly in the TRN. Artificial cerebrospinal fluid or bicuculline was administered to rostral or caudal parts of TRN of GAERS through a stereotaxically placed guide cannula. Administration of bicuculline produced opposite effects according to the injection site. Administration into the caudal TRN produced statistically significant increases in the duration of spike-and-wave discharges, whereas injections into the rostral TRN produced significant decreases. Correspondingly, distinct patterns of afferent connections have been demonstrated with the wheat-germ-agglutinin horseradish peroxidase (WGA-HRP) retrograde tracing method in control non-epileptic rats and GAERS for the rostral and caudal parts of the TRN. Injection of WGA-HRP tracer showed no detectable difference regarding the rostral and caudal connections between GAERS and Wistar animals. Rostral parts of TRN have thalamic and cortical connections that are primarily motor and limbic whereas for the caudal parts these connections are primarily sensory. Further, the rostral parts receive inputs from the substantia nigra pars reticularis and the ventral pallidum that the caudal part lacks. The extent to which these connectional differences may be responsible for the functional differences demonstrated by the bicucculine injections remains to be explored. (c) 2006 Elsevier B.V. All rights reserved.Publication Metadata only Changes in intracellular protein expression in cortex., thalamus and hippocampus in a genetic rat model of absence epilepsy(PERGAMON-ELSEVIER SCIENCE LTD, 2011) OGAN, AYŞE; Danis, Ozkan; Demir, Serap; Gunel, Aslihan; Aker, Rezzan Gulhan; Gulcebi, Medine; Onat, Filiz; Ogan, AyseEpilepsy is a chronic disorder characterized by repeated seizures resulting from abnormal activation of neurons in the brain. Although mutations in genes related to Na+, K+, Ca2+ channels have been defined, few studies show intracellular protein changes. We have used proteomics to investigate the expression of soluble proteins in a genetic rat model of absence epilepsy Genetic Absence Epilepsy Rats from Strasbourg (GAERS). The advantage of this technique is its high throughput quantitative and qualitative detection of all proteins with their post-translational modifications at a given time. The parietal cortex and thalamus, which are the regions responsible for the generation of absence seizures, and the hippocampus, which is not involved in this activity, were dissected from GAERS and from non-epileptic control rat brains. Proteins from each tissue sample were isolated and separated by two-dimensional gel electrophoresis. Spots that showed significantly different levels of expression between controls and GAERS were identified by nano LC-ESI-MS/MS. Identified proteins were: ATP synthase subunit delta and the 14-3-3 zeta isoform in parietal cortex; myelin basic protein and macrophage migration inhibitory factor in thalamus; and macrophage migration inhibitory factor and 0-beta 2 globulin in hippocampus. All protein expressions were up-regulated in GAERS except 0-beta globulin. These soluble proteins are related to energy generation, signal transduction, inflammatory processes and membrane conductance. These results indicate that not only membrane proteins but also cytoplasmic proteins may take place in the pathophysiology and can be therapeutic targets in absence epilepsy. (C) 2011 Elsevier Inc. All rights reserved.Publication Metadata only Perirhinal cortical kindling in rats with genetic absence epilepsy(ELSEVIER IRELAND LTD, 2010) ONAT, FİLİZ; Akman, Ozlem; Karson, Ayse; Aker, Rezzan Gulhan; Ates, Nurbay; Onat, Filiz YilmazTwo genetic models of absence epilepsy, GAERS and WAG/Rij rat strains, are resistant to progression of partial seizures induced by amygdaloid or hippocampal kindling. Perirhinal cortex is one of the crucial areas for the secondary generalization of partial seizures. Therefore we focused on perirhinal cortical kindling in both epileptic rat strains and examined whether the resistance to limbic epilepsy is restricted to the amygdala and hippocampus or whether it can also occur with perirhinal cortical kindling. The mean afterdischarge (AD) thresholds were significantly higher in WAG/Rij and GAERS compared to the Wistar rats. Analysis of the rate of perirhinal cortical kindling for the 3 strains indicated highly significant differences. The mean number of stimulations for the development of the first stage 2, 3, 4 or 5 seizures was significantly higher in WAG/Rij and GAERS groups than in Wistar rats. Further, the cumulative total duration and number of SWDs increased during the first epoch of the post-stimulation period at the first stage 2 and 4/5 seizures in the WAG/Rij and GAERS rats compared to the pre-stimulation period. The higher AD threshold and delays to all stages of kindling in WAG/Rij and GAERS indicate that the perirhinal cortex is a part of the circuits involved in the kindling resistance in genetic models of absence epilepsy. (C) 2010 Elsevier Ireland Ltd. All rights reserved.Publication Metadata only Absans epilepsinin epileptogenez sürecinde nigro-striatal dopaminerjik yolağın rolünün araştırılması(2021-05-27) YANANLI, HASAN RACİ; GÜLHAN, REZZAN; GÜLÇEBİ İDRİZ OĞLU, MEDİNE; TOPLU A., YAVUZ M., ÇULPAN Y., TURGAN AŞIK Z. N., YANANLI H. R., GÜLHAN R., GÜLÇEBİ İDRİZ OĞLU M., ONAT F.Epilepsinin ve epileptogenezin patogenezinde rol alan nöronal mekanizmaların ortaya konması güncel hedeflerden bir tanesidir. Bu çalışmada non-konvülsif nöbetlerle karakterize absans epilepsisinin epileptogenez döneminde nigro-striatal dopaminerjik yolağın rolünün ortaya konması hedeflenmiştir. Bu amaçla Strasbourg kökenli genetik absans epilepsili sıçanların (GAERS) ve kontrol grubunu oluşturan Wistar sıçanların mediyal önbeyin demetine (MFB) 6-Hidroksidopamin (6-OHDA) verilmesi ile ortaya çıkan sonuçlar kıyaslanmıştır. Yöntemler: Deneylerde 30 günlük GAERS(n=5) ve Wistar sıçanlar(n=2) kullanıldı. Stereotaksik cerrahiyle 6-OHDA (8 µg/4µL/4dk hızında) MFB’ye (AP:-1,4; ML:1,6; V:7,1) enjekte edildi. Gruplarda 21 gün sonra adımlama, silindir ve rotasyon testleri yapıldı. Silindir testi için pleksiglas silindire alınan hayvanların sağ ve sol ön pençeleriyle silindire değme sayısı gözlendi. Adımlama testi için 50 cm parkurda tek ön pençesiyle ilerlemesi sağlanarak (diğer pençeler tutularak) adım sayısı hesaplandı. Rotasyon testi öncesi tüm hayvanlara apomorfin (0,05 mg/kg, subkutan) enjeksiyonu yapılarak 30 dakika boyunca hayvanların 3600 sola dönüşleri kaydedildi. Veriler ortalama±standart hata olarak belirtildi. Spearman korelasyon testi ile istatistiksel değerlendirme yapıldı. Bulgular: GAERS grubu için rotasyon sayısı 257,8±39,98; adımlama testinde adım sayısı sol 10±4,25, sağ 11,8±3,21 idi. Silindire değme testinde ön pençe değme sayısı sol 8,2±2,39, sağ 9,4±2,37 idi. Wistar grubu için rotasyon sayısı 245±89; adımlama testinde adım sayısı sol 0, sağ 5±4 idi. Silindire değme testinde ön pençe değme sayısı sol 7,5±1,5, sağ 11±3 idi. Gruplar arasında anlamlı bir korelasyon bulunmadı. Sonuçlar: 6-OHDA enjekte edilen sıçanların rotasyon testi ile adımlama ve silindir testleri arasında anlamlı bir korelasyon bulunamadı. Çalışmamızda grup sayılarının sınırlılığı nedeniyle, sayı arttırılarak çalışmanın devamı hedeflenmektedir. Çalışma TÜBİTAK (218S653) tarafından desteklenmektedir. Anahtar Kelimeler: GAERS, absans epilepsisi, rotasyon, adımlama, silindir testi Objective: One of the aims in the neuroscience is to define the neuronal mechanisms involved in the pathogenesis of epilepsy and epileptogenesis. In this study, we examined the role of the nigrostriatal dopaminergic pathway in the epileptogenesis of absence epilepsy characterized by non-convulsive seizures. We compared the findings of injection of 6-Hydroxydopamine (6-OHDA) to the medial forebrain bundle (MFB) of the Strasbourg genetic absence epilepsy rats (GAERS) with the control Wistar rats. Methods: The MFB (AP:-1.4; ML:1.6; V:7.1) of 30-days-old GAERS(n=5) and Wistar(n=2) animals were targeted and injected with 6-OHDA(8 µg/4µL/4min) by stereotaxic surgery. After 21 days, cylinder, stepping and rotation tests were performed. For the cylinder test, the number of right and left front paw touch to the plexiglass cylinder were counted separately from the animals which were observed for 20 min. For the stepping test, the number of steps taken was calculated by driving the animals on a single front paw (right and left front paws were calculated separately). Afterwards, all animals received an injection of apomorphine (0.05 mg/kg), and the rotation(3600) of animals were recorded for 30 min. Data were expressed as mean±standart error. Spearman correlation was performed. Results: In GAERS group, number of rotations were 257.8±40.0. In the stepping test, the left steps were 10±4.25; while the right were 11.8±3.21.In the cylinder test, the number of front paw touches with left paw were 8.2±2.39; and the right were 9.4±2.37. For the Wistar group, number of rotations were 245±89. In the stepping test, the left steps were 0; the right were 5±4. And the number of front paw touches left were 7.5±1.5; the right were 11±3 with no significant correlation between the groups. Conclusions: No significant correlation was found between rotation behavior and the stepping-cylinder test of animals. In the study, group numbers are planned to be increased. The study is supported by TUBITAK (218S653).Publication Metadata only Ultrastructural GABA immunocytochemistry in the mossy fiber terminals of Wistar and genetic absence epileptic rats receiving amygdaloid kindling stimulations(ELSEVIER, 2011) AKAKIN, DİLEK; Akakin, Dilek; Sirvanci, Serap; Gurbanova, Ayten; Aker, Rezzan; Onat, Filiz; San, TangulThe existence of absence epilepsy and temporal lobe epilepsy in the same patient is not common in clinical practice. The reason why both types of seizures are rarely seen in the same patient is not well understood. Therefore, we aimed to investigate kindling in a well known model of human absence epilepsy, genetic absence epilepsy rats from Strasbourg (GAERS). In the present study, we analyzed whether the GABA content of GAERS that received kindling stimulations was altered in the hippocampal mossy fiber terminals compared to non-epileptic control (NEC) Wistar rats. For this purpose, we used an immunocytochemical technique at the ultrastructural level. Ultrathin sections were immunolabeled with anti-GABA antibody and transmission electron microscopy was used for the ultrastructural examination. The number of gold particles per nerve terminal was counted and the area of the nerve terminal was determined using NIH image analysis program. The GABA density was found to be higher in sham-operated GAERS than sham-operated Wistar rats. The density was increased in kindling Wistar group compared to sham-operated Wistar and kindling GAERS groups. No statistical difference was observed between sham-operated GAERS and kindling GAERS groups. The increase in GABA levels in stimulated Wistar rats may be a result of a protective mechanism. Furthermore, there may be strain differences between Wistar rats and GAERS and our findings addressing different epileptogenesis mechanisms in these strains might be a basis for future experimental studies. (C) 2010 Elsevier B.V. All rights reserved.Publication Metadata only Hippocampal kindling in rats with absence epilepsy resembles amygdaloid kindling(ELSEVIER, 2008) ONAT, FİLİZ; Akman, Ozlem; Karson, Ayse; Aker, Rezzan Gulhan; Ates, Nurbay; Onat, Filiz YilmazPurpose: WAG/Rij and GAERS rats show delays or resistance to secondary generalization of limbic seizures during amygdaloid kindling. In this study, we aimed to evaluate the kindling from a different limbic site, hippocampus, and to compare its effects on spike-and-wave discharges (SWDs) with that of amygdaloid kindling. Methods: Recording electrodes were implanted epidurally and a stimulation/recording electrode was implanted into the ventral hippocampus in the WAG/Rij, GAERS and Wistar rats. Animals received kindling stimulation twice daily at their afterdischarge thresholds until they reached stage 5 seizures, or the maximum number of stimulations (50) had been delivered. The EEG was recorded to analyze SWDs and afterdischarge durations. Results: All Wistar rats reached stage 5 by the 34th stimulation. 4 of 8 WAG/Rij rats and 3 of 6 GAERS rats displayed stage 4/5 seizures (kindling-prone rats); the rest stayed at stage 2 seizures (kindling-resistant rats) even after 50th stimulations. The cumulative duration and number of SWDs decreased in the post-stimulation period after the first stage 2 seizures, whereas these parameters increased after the first stage 3 seizures in the kindling-prone WAG/Rij and GAERS. The peak frequency of SWDs and its harmonics decreased significantly only in the GAERS group after stage 4 seizures. Conclusion: Hippocampal kindling resembles amygdaloid kindling in showing a delay of or resistance to secondary seizure generalization, which supported the interaction of thalamo-cortical and limbic circuitry in GAERS and WAG/Rij. (C) 2008 Elsevier B.V. All rights reserved.