Postsynaptic calcium pathway contributes to synaptic plasticity between retinal cones and luminosity-type horizontal cells / 生理学报

It was previously found that the efficacy of synaptic transmission between retinal cone systems and luminosity-type horizontal cells (LHCs) was activity-dependent. Repetitive activation of red-cone pathway increased the LHCos hyperpolarizing response to red light, and the response enhancement was reversible. In this study, intracellular recording and pharmacological method were applied to investigate the mechanism(s) underlying red-flickering-induced response enhancement. Lowering intracellular Ca(2+) in the LHC by intracellular injection of Ca(2+) chelator EGTA prevented the development of red-flickering-induced response enhancement, which implicates the importance of postsynaptic calcium signal. The response enhancement could also be eliminated by a potent antagonist of Ca(2+)-permeable AMPA receptor (CP-AMPAR), which suggests the possibility that Ca(2+) influx via glutamate-gated calcium channels is related to the changes of [Ca(2+)](i). Furthermore, the administration of ryanodine or caffeine also attenuated the phenomenon, which gives evidence that the local calcium signal caused by intracellular calcium-induced calcium release (CICR) may be involved. Taken together, our data implicate that postsynaptic CICR and CP-AMPAR are related to the activity-dependent response enhancement.

Antiproliferation and induction differentiation of rosiglitazone in human gastric carcinoma transplanted into nude mice / 肿瘤研究与临床

Objective To investigate the antiproliferation and induction differentiation of human gas- tric carcinoma which human gastric lower-differentiation mucinous carcinoma MGC-803 cells transplanted in- to nude mice by using rosiglitazone(ROS),and to preliminarily explore the mechanism of differentiation. Methods The mice were randomly divided into five groups:model,ATRA,ROS 25 mg?kg~(-1),ROS 50 mg/kg, ROS 100 mg/kg.After that the volumes were measured and inhibition rates were calculated.The cell cycle was detected by FCM.The protein expression level of Mucin SAC was detected by immunohistochemistry. Results The volume of tumor decreased significantly in ROS treatment groups,the differences had statistical significance compared with model group(P0.05).The xenograft tumors of ROS groups demonstrated the characteristics of differentiation.Xenograft tumor cells were arrested in G_0/G_1 phase,and the cells in S phase decreased significantly,and up-regulated Mucin SAC gene expression.Conclusion ROS could inhibit the growth of tumor,and the effect were dose-dependent with ROS.ROS could induce the differentiation of Xenograft tumor cells of gastric cancer.Its mechanism might be related to the inhibit of transition from G_1 to S phase,degrade the activity of proliferation,regulate the expres- sion of Mucin 5AC.