Preferencje help
Polish version English version Język
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 3

Liczba wyników na stronie
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 1 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników

Wyniki wyszukiwania

help Sortuj według:

help Ogranicz wyniki do:
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 1 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
1

Tetrabromobisphenol A directly interferes with activity of NMDA isolated cortical membranes

100%
Diamandakis D., Zieminska E., Salinska E., Lazarewicz J. W.
Acta Neurobiologiae Experimentalis
|
2015
|
tom 75
|
nr Supl.
BACKGROUND AND AIMS: The results of early studies suggested a role of glutamate receptors in the mechanism of increases in intracellular Ca2+ concentration ([Ca2+]i ) and cytotoxicity induced by the brominated flame retardant, tetrabromobisphenol-A (TBBPA). Although now interest has focused mainly on TBBPA-induced Ca2+ release from intracellular stores, here we revisited the former issue and tested the involvement of NMDA receptors (NMDARs) in Ca2+ imbalance in neurons induced by TBBPA. METHODS: These effects were examined in primary cultures of rat cerebellar granule cells (CGC), and then, using isolated cortical membranes we checked whether TBBPA directly interacts with the agonist and modulatory sites of the NMDAR complex. On the 7th day in vitro CGC were treated with TBBPA at low µM concentrations. 45Ca uptake was detected and changes in [Ca2+]i , and plasma membrane potential were measured using fluorescent probes fluo-3 and oxonol VI, respectively. Moreover effects of TBBPA on specific binding of [3 H]MK-801, [3 H]glutamate and [3 H]glycine to isolated fraction of the rat brain cortex membranes were studied. RESULTS: The results demonstrated that TBBPA concentrationdependently increased 45Ca uptake and [Ca2+]i in CGC, and the increase was partially inhibited by NMDARs antagonist, MK-801. This effect was additive to glutamate-induced Ca2+ transients. TBBPA increased oxonol VI fluorescence in CGC reflecting depolarization of the cultured neurons. The binding assays demonstrated potentiation by TBBPA binding of [ 3 H]MK-801 in the presence of NMDA and glycine, with maximum at 20 µM TBBPA, which was inhibited by spermidine and antagonists of the polyamines’ site; inhibition by TBBPA of [ 3 H]glutamate binding, and no significant effect on [3 H]glycine binding. CONCLUSIONS: TBBPA directly enhances the activity of NMDARs in neuronal membranes by interfering with their modulatory sites, and by inducing depolarization of neurons. Supported by the NCN grant 2012/05/B/NZ7/03225
2

Dysregulation of calcium homeostasis and oxidative stress: interrelated mediators of tetrabromobisphenol a toxicity in primary cultures of rat cerebellar granule cells

88%
Lazarewicz J. W., Zieminska E., Lenart J., Diamandakis D., Salinska E.
Acta Neurobiologiae Experimentalis
|
2017
|
tom 77
|
nr Suppl.1
There are alarming reports on cytotoxicity of the brominated flame retardant tetrabromobisphenol A (TBBPA) in the in vitro cellular models, that seem to be mediated by increases in the intracellular calcium concentration ([Ca2+] i) and oxidative stress. Still, the mechanisms of both these phenomena, their mutual cause‑and‑effect relationships and implication in the TBBPA-induced neuronal death are not clear. In our experiments the primary cultures of rat cerebellar granule cells (CGC) were acutely challenged with TBBPA. Such induced rises of [Ca2+]i appeared to result independently from the intracellular Ca2+ release via ryanodine receptors transformed into dysfunctional leak channels, and from Ca2+ influx mediated by NMDA receptors. These receptors seem to be activated indirectly, due to depolarization of neurons by TBBPA, which is mediated by the voltage-gated sodium channels and ionotropic glutamate receptors. TBBPA induced oxidative stress as evidenced by ROS production and decrease in GSH content and catalase activity. The pharmacological preventing of the TBBPA-induced rises in [Ca2+]i also entirely prevented oxidative stress induced by 10 µM TBBPA, while the effects of 25 µM TBBPA were only partially reduced. Application of free radical scavengers significantly reduced TBBPA‑induced oxidative stress, but did not interfere with rises in [Ca2+]i. This indicates that TBBPA-induced increase in [Ca2+]i is a primary and major event triggering oxidative stress, however at higher µM concentrations a Ca2+‑independent portion of oxidative stress emerges, and this effect seems to be directly induced by TBBPA. Furthermore, the separate application of inhibitors of TBBPA-induced Ca2+ transients and free radical scavengers, both provided a strong but incomplete cytoprotection, whereas combination of these substances completely prevented the death of neurons, showing that Ca2+ imbalance and oxidative stress are the triggers of acute TBBPA toxicity in CGC. FINANCIAL SUPPORT: This study was supported by the Polish National Science Centre grant no. 2012/05/B/ NZ7/03225.
3

Glutamate, glutamine and GABA levels in the rat hippocampus in the pharmacological models of autism: a microdialysis study

76%
Diamandakis D., Zieminska E., Hilgier W., Filipkowski R. K., Polowy R., Toczylowska B., Lazarewicz J. W.
Acta Neurobiologiae Experimentalis
|
2017
|
tom 77
|
nr Suppl.1
INTRODUCTION: The disorders of the glutamatergic neurotransmission have been implicated in the pathogenesis of autism, but data on brain content of glutamate (Glu) in patients and animal models are inconsistent. AIM(S): Aim of this study is to evaluate changes in the brain content of Glu, glutamine (Gln) and GABA in the rat models of pharmacologically-induced autism. METHOD(S): The rat females at the 11th day of gestation were given orally 800 mg/kg b.w. of valproic acid (VPA) or 500 mg/kg b.w. of thalidomide (THAL). The pups at PND 9 were submitted to ultrasonic vocalization (USV) test, and at PND 30, under anesthesia, to in vivo unilateral microdi alysis of the hippocampus with a calcium-containing medium. The samples of dialysate representing the basal level followed by a 40 min pulse of 100 mM KCl were collected. The contralateral hippocampi were prepared and homogenized. After derivatization of the amino acids with o-phtalaldehyde, the samples were submitted to HPLC analysis with a fluorescence detection. RESULTS: The results of USV tests showed that the pups prenatally treated with VPA, and to a greater extent with THAL, less frequently produced USV calls, which is regarded as impairment in social communication, a symptom characteristic of autism. In the male rats of the VPA and THAL groups, a total content of Glu increased to 143% and 158%, respectively, and also Gln and GABA contents were significantly elevated. All these values remained unchanged in the female rats. Basal levels of Glu, Gln and GABA in the dialysates of the hippocampi in the experimental groups did not differ from controls, however in VPA‑treated male rats during application of 100 mM KCl a reduction by 59% of Gln concentration and tendency to increase GABA level were found. CONCLUSIONS: The results demonstrate increased content of glutamate in the hippocampus of rats in two chemical models of autism, support a hypothesis on the role of the glutamatergic disturbances in the pathogenesis of autism. FINANCIAL SUPPORT: This study was supported by the Polish National Science Centre, grant no. 2014/15/B/ NZ4/04490.
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 1 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.