Jujuboside A (JuA) is a main component of jujubogenin extracted from the seed of Ziziphus jujuba Mill var spinosa (Bunge) Hu ex H F Chou (Ziziphus), which is widely used in Chinese traditional medicine for the treatment of insomnia and anxiety. Previously, we reported the inhibitory effects of JuA on hippocampal formation in vivo and in vitro, the present study was carried out to examine the effects of JuA on glutamate (Glu)-mediated excitatory signal pathway in hippocampus. Microdialysis coupled with high-performance liquid chromatography (HPLC) was used to monitor the changes of Glu levels in the hippocampus induced by penicillin sodium, or a mixture of penicillin sodium and JuA. The results showed that penicillin increased the hippocampal Glu concentration (p < 0.01) and a high dose of JuA (0.1 g/L) significantly blocked penicillin-induced Glu release (p < 0.05). Moreover, the effect of JuA on intracellular Ca2+ changes after the stimulation by Glu was studied in cultured hippocampal neurons with confocal laser scanning microscope (CLSM). It was found that Glu (0.5 mM) induced an intracellular [Ca2+]i increase (p < 0.01), and JuA significantly inhibited the Glu-induced Ca2+ increase. The calmodulin (CaM) antagonist trifluoperazine (TFP) showed a similar inhibitory effect as JuA. These observations suggested that JuA has inhibitory effects on Glu-mediated excitatory signal pathway in hippocampus and probably acts through its anti-calmodulin action.
Our recent studies have displayed the protective functions of aspirin against heat stress (HS) in chicken myocardial cells, and it may be associated with heat shock proteins (HSPs). In this study, we further investigated the potential role of HSPs in the aspirin-induced heat stress resistance. Four of the most important HSPs including HspB1 (Hsp27), Hsp60, Hsp70, and Hsp90 were induced by aspirin pretreatment and were suppressed by BAPTA-AM. When HSPs were induced by aspirin, much slighter HS injury was detected. But more serious damages were observed when HSPs were suppressed by BAPTA-AM than those cells exposed to HS without BAPTA-AM, even the myocardial cells have been treated with aspirin in prior. Comparing to other HSPs, HspB1 presented the largest increase after aspirin treatments, 86-fold higher than the baseline (the level before HS). These findings suggested that multiple HSPs participated in aspirin's anti-heat stress function but HspB1 may contribute the most. Interestingly, during the experiments, we also found that apoptosis rate as well as the oxidative stress indicators (T-SOD and MDA) was not consistently responding to heat stress injury as expected. By selecting from a series of candidates, myocardial cell damage-related enzymes (CK-MB and LDH), cytopathological tests, and necrosis rate (measured by flow cytometry assays) are believed to be reliable indicators to evaluate heat stress injury in chicken's myocardial cells and they will be used in our further investigations.
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