Neuroprotective Effect And Mechanisms Of (-)clausenamide On Cerebral Ischemic Injury And APP Transgenic Mice

Part I. The effect of clau on calcium signaling in primary cultured rat cortical neuronsOur previous studies found clau could elevate cytosolic free calcium concentration ([Ca²⁺]_i). For further understanding the mechanism by which clau play its actions, we investigated the effect of clau on calcium signaling by using laser confocal microscopy in the primary cultured rat cortical neurons.Clau triggered a calcium transient in a concentration-dependent manner. The mean amplitude of clau (1 μM) induced calcium transient was similar in extracellular solution with or without calcium; and clau failed to trigger calcium transient after treatment with endoplasmic reticulum (ER) calcium-pumps inhibitor BHQ. This result suggested that the primary source of clau induced [Ca²⁺]_i elevation was from ER entracellular stores.Application of IP₃ receptor inhibitor MgCl₂ and PLC-y inhibitor U73122 suppressed clau induced calcium transient, whereas 100 μM ryanoding almost had no inffluence on the action of clau, indicating that lack of involement of ryanodine receptor pathway in clau induced calcium transient. This result further support the conclusion that the major source of clau induced calcium transient was from IP₃ receptor pathway.With fluorescence bleacher Mn²⁺ which can enter through capacitative calcium channels in the extracellular solution, clau evoked only a small calcium transient, suggested that clau could dinduce extracellular calcium entry through capacitative calcium channels.Mitochondria involved in clau triggered calcium transient indirectly.Clau induced calcium transient decayed slowly in the extracellular solution without Na⁺, which inhibit the plasmamembrane Na⁺-Ca²⁺ exchanger, indicated that Na⁺-Ca²⁺ exchanger played an important role in the Ca²⁺ extrusion of clau induced calcium transient.Neurons showed no responses to high K⁺ stimulus when clau triggered a larger [Ca²⁺]_i elevation, whereas smaller calcium transient followed by an overt response.Part II. The protective effect of clau in MCA occlusion of ratsSection 1. Neuroprotective effect of clau in transient focal cerebral ischemia of ratswithin one weekTwenty-four hours following MCA occlusion/reperfusion, rats were assessed for...