In Vitro Dose-Dependent Inhibition of the Intracellular Spontaneous Calcium Oscillations in Developing Hippocampal Neurons by Ketamine

Abstract

Spatial and temporal abnormalities in the frequency and amplitude of the cytosolic calcium oscillations can impact the normal physiological functions of neuronal cells. Recent studies have shown that ketamine can affect the growth and development and even induce the apoptotic death of neurons. This study used isolated developing hippocampal neurons as its study subjects to observe the effect of ketamine on the intracellular calcium oscillations in developing hippocampal neurons and to further explore its underlying mechanism using Fluo-4-loaded laser scanning confocal microscopy. Using a semi-quantitative method to analyze the spontaneous calcium oscillatory activities, a typical type of calcium oscillation was observed in developing hippocampal neurons. In addition, the administration of NMDA (N-Methyl-D-aspartate) at a concentration of 100 µM increased the calcium oscillation amplitude. The administration of MK801 at a concentration of 40 µM inhibited the amplitude and frequency of the calcium oscillations. Our results demonstrated that an increase in the ketamine concentration, starting from 30 µM, gradually decreased the neuronal calcium oscillation amplitude. The inhibition of the calcium oscillation frequency by 300 µM ketamine was statistically significant, and the neuronal calcium oscillations were completely eliminated with the administration of 3,000 µM Ketamine. The administration of 100, 300, and 1,000 µM NMDA to the 1 mM ketamine-pretreated hippocampal neurons restored the frequency and amplitude of the calcium oscillations in a dose-dependent manner. In fact, a concentration of 1,000 µM NMDA completely reversed the decrease in the calcium oscillation frequency and amplitude that was induced by 1 mM ketamine. This study revealed that ketamine can inhibit the frequency and amplitude of the calcium oscillations in developing hippocampal neurons though the NMDAR (NMDA receptor) in a dose-dependent manner, which might highlight a possible underlying mechanism of ketamine toxicity on the rat hippocampal neurons during development.

The role of TNF-α in regulating ketamine-induced hippocampal neurotoxicity

“…We used an organotypic hippocampal-slice culture model to introduce ketamine-related neurotoxicity in CA1 neurons in neonatal mice [ 10 ]. The in vitro hippocampal slices were initially cultured with or without 0.5 mM ketamine for 4 h, followed by wash and overnight incubation.…”

“…While the exact mechanisms of ketamine-induced hippocampal neurotoxicity remain elusive, a recent study demonstrated that blockage of the NMDA receptor by ketamine attenuated spontaneous Ca 2 + -dependent membrane potential oscillations in hippocampal neurons to induce apoptosis [ 10 ]. This interesting finding strongly suggested that ionic homeostasis of hippocampal neurons, especially through the modulation of glutamate receptors, may decisively affect the pathologic condition of apoptosis in the hippocampus.…”

Role of miR‐34c in ketamine‐induced neurotoxicity in neonatal mice hippocampus

“…Pharmacologically, the major mechanism of ketamine working as anesthetic is to inhibit the glutamate neuro-transmission through N-methyl-D-aspartate (NMDA) receptors (Ikonomidou et al, 1999Olney et al, 1991, and a ketamine overdose could severely affect the development of neonatal brain and induce cortical neurotoxicity in both animals and humans (McGowan and Davis, 2008;Brambrink et al, 2012 Dong andAnand, 2013). In hippocampus, the major component of brain associated with memory and learning, new evidence had revealed through both in vitro and in vivo animal models, that repetitive or high dose administration of ketamine suppressed neural excitability, induced apoptosis in hippocampus, thus significantly impair learning and memory functions (Huang et al, 2012Huang et al, 2013. Little is known about the underlying mechanisms or the associated signaling pathways during the process of hippocampal or memory neurodegeneration induced by anesthesia.…”

Mobilization and removing of cadmium from kidney by GMDTC utilizing renal glucose reabsorption pathway

“…After 12 h cultivation, cells were treated under different conditions and incubated with 5 μM Fluo-4 Am in Krebs-Ringer solution (145 mM NaCl, 4 mM KCl, 1.8 mM CaCl 2 , 1 mM MgCl 2 , 10 mM HEPES, and 10 M D-glucose). The fluorescence was excited with 488 nm by an argon ion laser and cells were scanned and images were taken using a confocal microscope (Huang et al, 2013). The average fluorescence intensity of 10 cells was calculated and used to represent the calcium concentration.…”