Publication: Glutamic acid decarboxylase ımmunoreactivity in the mossy fiber terminals of the hippocampus of genetic absence epileptic rats
Abstract
AMAÇ: Genetik absans epilepsili sıçanlar (GAERS, genetic absence epilepsy rats from Strasbourg) absans epilepsi modeli olarak deneysel çalışmalarda kullanılmaktadır. Talamo-kortiko-talamik döngüde artmış GABA aracılı mekanizmaların absans epilepside rol oynadığı gösterilmiş olmasına rağmen, son zamanlarda yapılan çalışmalarda hipokampustaki nöronal ağ dikkati çekmektedir. Yapılan çalışmalarda hipokampus mossy lif terminallerindeki (MLT) glutamik asit dekarboksilazın (GAD) konvülzif nöbetlerden sonra artış gösterdiği saptanmıştır. Bu çalışmanın amacı, konvülzif nöbetlerde görülen GAD enzimi seviyesindeki değişikliklerin genetik absans epilepsili sıçanlarda da görülüp görülmediğini araştırmaktır. YÖNTEM ve GEREÇLER: Hipokampal CA3 ve dentat girus (DG) bölgelerinden alınan dokular elektron mikroskopik işlemler için hazırlandı. İnce kesitler anti-GAD 65/67 primer antikoru ile inkübe edildi. Niceliksel analiz için “NIH Image Analysis” görüntü analiz programı kullanıldı. BULGULAR: Her iki grup hipokampusunda CA3 ve DG MLT’de GAD 65/67 immünreaktivitesinin pozitif olduğu gözlendi. Kontrol ve GAERS hipokampusunun her iki bölgesinde veziküler GAD 65/67 immün-işaretlenme yoğunlukları arasında istatistiksel olarak anlamlı fark bulunmadı. SONUÇ: Bu çalışmada GAERS ve Wistar MLT’de GABA sentezleyen enzim olan GAD’ın varlığı gösterilmiş ve konvülzif nöbetlerden farklı olarak, MLT’deki bu enzimin absans epilepside artış göstermediği sonucuna varılmıştır.
AIm: Genetic absence epilepsy rats from Strasbourg (GAERS) provide a model of absence epilepsy. Although excessive GABA mediation within the thalamo-cortico-thalamic circuit has been shown to play a role in absence epilepsy, neuronal networks of hippocampus have recently received attention. Glutamic acid decarboxylase (GAD) was previously shown to be increased after convulsive seizures in the mossy fiber terminals (MFTs) of hippocampus. The aim of the present study was to investigate whether the change in the level of this enzyme in convulsive seizures is also observed in rats having genetic absence epilepsy. Ma terIal and Methods: Hippocampal CA3 and dentate regions were processed for transmission electron microscopic evaluations. Thin sections were incubated with anti-GAD65/67 antibody. The NIH Image Analysis program was used for the quantitative analysis. Results: It was observed that GAD65/67 immunoreactivity was positive in CA3 and dentate gyrus MFTs of both groups and the difference in the density of immunolabeling between the groups was not statistically significant. ConclusIon: The present study demonstrated that GABA synthesizing enzyme, GAD, is found in MFTs of Wistar and GAERS hippocampus and this enzyme does not show an increase in these terminals in absence epilepsy, in contrast to convulsive seizures.
AIm: Genetic absence epilepsy rats from Strasbourg (GAERS) provide a model of absence epilepsy. Although excessive GABA mediation within the thalamo-cortico-thalamic circuit has been shown to play a role in absence epilepsy, neuronal networks of hippocampus have recently received attention. Glutamic acid decarboxylase (GAD) was previously shown to be increased after convulsive seizures in the mossy fiber terminals (MFTs) of hippocampus. The aim of the present study was to investigate whether the change in the level of this enzyme in convulsive seizures is also observed in rats having genetic absence epilepsy. Ma terIal and Methods: Hippocampal CA3 and dentate regions were processed for transmission electron microscopic evaluations. Thin sections were incubated with anti-GAD65/67 antibody. The NIH Image Analysis program was used for the quantitative analysis. Results: It was observed that GAD65/67 immunoreactivity was positive in CA3 and dentate gyrus MFTs of both groups and the difference in the density of immunolabeling between the groups was not statistically significant. ConclusIon: The present study demonstrated that GABA synthesizing enzyme, GAD, is found in MFTs of Wistar and GAERS hippocampus and this enzyme does not show an increase in these terminals in absence epilepsy, in contrast to convulsive seizures.