Real-time measurement of Caflux in hippocampal slice with non-invasive micro-test technique / 生理学报

ABSTRACT

The deposition of amyloid-β protein (Aβ) in the brain is the most important pathological feature of Alzheimer's disease (AD). The mechanism of Aβ neurotoxicity may be closely related to the disturbance of intracellular Cahomeostasis. Non-invasive micro-test technique (NMT) is a novel technique developed in recent years, which can be used to directly record transmembrane ion influx and efflux in a non-contact way by detecting the diffusion potentials outside of the membrane. The present study examined the effects of Aβpretreatment on glutamate (Glu)-induced Cainflux and low [Ca] solution-induced Caefflux in the hippocampal slices of C57BL/6 mice using NMT. The results showed that (1) acute administration of Glu (2.5, 5, 10 mmol/L) evoked a persistent transmembrane Cainflux in hippocampal CA1 neurons, with a rapid onset and subsequent decay; (2) pretreatment with Aβ dose-dependently increased the average rate of Cainflux induced by Glu during the initial 5 min, which was blocked by NMDA receptor antagonist D-APV; (3) perfusion with low [Ca] artificial cerebrospinal fluid (aCSF) induced a continuous Caefflux, which was mostly blocked by KB-R7943, a specific antagonist of Na/Caexchanger; (4) Aβpretreatment partially inhibited the low [Ca] aCSF-induced Caefflux. These results indicate that Aβ not only facilitates Cainflux but also inhibits Caefflux, which jointly contribute to the Aβ-induced intracellular Caoverload; the potentiation of Aβ on Glu excitotoxicity is mainly mediated by NMDA receptors, while the target for Aβ to affect Caefflux was mainly Na/Caexchanger. NMT showed multiple advantages in detecting transmembrane Caflux in brain slices, such as non-invasiveness to target cells, fast, convenient and real-time acquisition of Caflux. Therefore, this study provided new experimental evidence for Aβ-induced Caoverload, as well as a novel application for NMT in measuring transmembrane Caflux of neurons in the brain.