Isoflurane-Induced Neurotoxicity And Preconditioning Neuroprotection Of Ca²⁺ Mechanisms

Partâ… Effect of different concentration isoflurane exposure for different time on viability and intracellular calcium in rat primarycortical neuronsObjective This study examined and compared the viability effects of different concentration isoflurane exposure for different time on rat primary cortical neurons and their relationship with disruption of intracellular calcium homeostasis. Methods Primary rat cortical neurons were treated constantly with the equivalent of 0.5, 1 or 2 minimal alveolar concentration (MAC) of isoflurane exposure for 1,2,4,8,12,24 hours respectively. MTT reduction and LDH release assays were performed to evaluate cell viability. Changes of calcium concentration in cytosolic space ([Ca²⁺]i) were imaged using real-time confocal microscopy after exposing rat primary cortical neurons to different concentration isoflurane. Results Isoflurane at 0.5 MAC exposure for 24 hours increased cell viability in primary rat cortical neurons, which was associated with a elevation of peak [Ca²⁺]_i. Isoflurane at 1 MAC exposure for 12 or 24 hours and 2MAC exposure for 8,12, or 24 hours induced cytotoxicity in primary rat cortical neurons, which was also associated with a high and fast elevation of peak [Ca²⁺]_i. Conclusion Isoflurahe at 0.5MAC exposure within 24 hours did not induce neurotoxicity and elevations of [Ca²⁺]_i in primary cortical neurons of rat.This effects mybe induced by Ca²⁺ negative feedback . Isoflurane at 1MAC exposure for longer than 12 hours and 2MAC exposure for longer than 8 hours induced neurotoxicity and decreased cell viability in primary cortical neurons of rat. This cytotoxic effects of isoflurane mybe induced by calcium overload in primary cortical neurons of rat.Partâ…¡Isoflurane and sevoflurane induce cytotoxicity and change intracellular calcium concentration in rat primary cortical neuronsObjective This study examined and compared the cytotoxic effects of isoflurane and sevoflurane on rat primary cortical neurons and their relationship with disruption of intracellular calcium homeostasis .Methods Primary rat cortical neurons were treated with the equivalent of 1 minimal alveolar concentration (MAC) of isoflurane and sevoflurane for 12 hours. MTT reduction and LDH release assays were performed to evaluate cell viability. Changes of calcium concentration in the cytosolic space, [Ca²⁺]_i, were determined after exposing primary rat cortical neurons to isoflurane and sevoflurane. We also determined the effects of IP₃ receptor antagonist xestospongin C on isoflurane-induced cytotoxicity and calcium release from the ER in primary rat cortical neurons. Results Isoflurane at 1 MAC for 12 hours induced cytotoxicity in primary rat cortical neurons, which was also associated with a high and fast elevation of peak [Ca²⁺]_i. Xestospongin C significantly ameliorated isoflurane cytotoxicity in primary cortical neurons, as well as inhibited the calcium release from the ER in primary cortical neurons. Sevoflurane, at equivalent exposure to isoflurane, did not induce similar cytotoxicity or elevation of peak [Ca²⁺]_i in primary rat cortical neurons. Conclusion These results suggested that isoflurane induced elevation in [Ca²⁺]i, partially via elevated activity of IP3 receptors, which rendered cells vulnerable to isoflurane neurotoxicity. Sevoflurane, at an equivalent exposure to isoflurane, did not induce similar elevations of [Ca²⁺]_i or neurotoxicity in primary cortical neurons of rat.Partâ…¢Effect of isoflurane on apoptosis and intracellular calcium in Rat Pheochromocytoma Cells (PC12)Objective This study examined and compared the apoptosis effects of isoflurane on different types of rat pheochromocytoma neurosecretory cells (PC12) and their relationship with disruption of intracellular calcium homeostasis. Methods PC12 cells transfected with wild type (WT) or the Alzheimer's muted PS1 (L286V) were treated with equivalent of 1 MAC of isoflurane for 12 hr. LDH release assays were performed to evaluate cell viability. Changes of calcium concentration in cytosolic space ([Ca²⁺]_i) were imaged using real-time confocal microscopy after exposing different types of cells to isoflurane.We also determined the effects of IP3 receptor antagonist xestospongin C on isoflurane-induced apoptosis and calcium release from the ER in L286V PC12 cells. Results Isoflurane at 1 MAC for 12 hr induced apoptosis in L286V but not WT PC12 cells, which was also associated with greater and faster elevation of peak [Ca²⁺]_i in L286V than in the WT PC12 cells. Xestospongin C significantly ameliorated isoflurane cytotoxicity in both L286V cells , as well as inhibited the calcium release from the ER in L286V cells. Conclusion These results suggest that the Alzheimer's PS1 mutation augments the isoflurane-induced elevation in [Ca²⁺]i partially via elevated activity of IP3 receptors, which renders cells vulnerable to isoflurane neurotoxicity. Partâ…£Effects of isoflurane on Glutamate Induced apoptosii and Intracellular Calcium Change in rat primary cortical neuronsObjective To study the effects of isoflurane on glutamate induced apoptosis and intracellular calcium change in rat primary cortical neurons and its probable mechanism. Methods Rat primary cortical neurons were primarily cultured by using neonatal rat brains Primary rat cortical neurons were preconditioning with the equivalent of 1 MAC of isoflurane for 2 hours.Then low concentration glutamate induced neurons apoptosis . MTT reduction and LDH release assays were performed to evaluate cell viability. Using microfluorescent technique to detect the calcium signal and the effect of glutamate and sevoflurane on hippocampal neurons. We also determined the effects of IP3 receptor antagonist xestospongin C on isoflurane preconditioning in rat primary cortical neurons. Results Glutamate could increase apoptosis neurons and the intracellular free Ca concentration([Ca²⁺]_i) obviously. 1.0 MAC isoflurane preconditioning decreased apoptosis neurons and inhibited the increase [Ca²⁺]i induced by glutamate. Xestospongin C significantly ameliorated isoflurane neuroprotection in Rat primary cortical neurons, as well as inhibited the calcium release from the ER. Conclusion It is suggested that isoflurane preconditioning inhibites apoptosis and calcium overload induced by glutamate in rat primary cortical neurons.