Diazoxide preconditioning alleviates apoptosis of hippocampal neurons induced by anoxia-reoxygenation in vitro through up-regulation of Bcl-2/Bax protein ratio / 生理学报

Activating mitochondrial ATP-sensitive potassium (mitoK(ATP)) channels is a critical event of pharmacological preconditioning, which can enhance neuronal ability against various insults. mitoK(ATP) channels are abundant in neurons and can be selectively opened by diazoxide (DZ). The aim of this study was to determine whether DZ could restrain neuronal apoptosis induced by anoxia-reoxygenation and to reveal the effect of DZ preconditioning on the expressions of Bcl-2 and Bax proteins in cultured hippocampal neurons. Cultured for 9~10 d in vitro, the hippocampal neurons of Sprague-Dawley rats were assigned to the following 5 groups randomly: Control, DZ 0 mumol/L, DZ 30 mumol/L, DZ 100 mumol/L, DZ 100 mumol/L+5-hydroxydecanoate (5-HD, a selective mitoK(ATP) channel blocker) 100 mumol/L. Prior to oxygen deprivation, the hippocampal neurons except those in the control group were treated with DZ or DZ+5-HD for 1 h per day and this treatment persisted for 3 d. Thereafter, neurons were subjected to anoxia for 4 h and followed by reoxygenation. At 24 h of reoxygenation the neuronal survival rates were measured by MTT method, while the apoptotic rates were assayed by annexin V-FITC staining. The expressions of Bcl-2 and Bax proteins were detected with immunocytochemistry and evaluated by Western blot. Anoxia-reoxygenation injury reduced the survival rates and increased apoptotic rates significantly. In comparison with those in other groups, the survival rate in DZ 100 mumol/L group was increased by about 15%, whereas the apoptotic rate was decreased by almost 12% simultaneously. 5-HD could abolish the neuroprotection afforded by 100 mumol/L DZ. Bcl-2 and Bax proteins in the control normoxic neurons were both expressed slightly, while anoxia-reoxygenation led to high expression of Bax protein. The administration of 100 mumol/L DZ enhanced the expression of Bcl-2 protein by nearly 60%, whereas Bax protein was reduced by approximately 30%. Lower concentrations of DZ had no detectable effects on the expressions of Bcl-2 and Bax proteins. However, beneficial effects of DZ on the expressions of Bcl-2 and Bax proteins were reversed after the co-treatment with 5-HD. In conclusion, 100 mumol/L DZ prevented cultured hippocampal neurons from apoptosis induced by anoxia-reoxygenation possibly through up-regulating the expression of Bcl-2 protein and down-regulating the expression of Bax protein.

Diazoxide preconditioning plus subsequent hypothermia increased resistance of rat cultured hippocampal neurons against hypoxia-reoxygenation injury / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Cerebral ischemia-reperfusion/hypoxia-reoxygenation insult triggers lots of pathophysiological and biochemical events that separately affect the evolution of cerebral damage. Accordingly, all known effective neuroprotective measures should be taken to get the optimal efficacy of therapy. This study was undertaken to investigate whether diazoxide (DZ) preconditioning combined with the following hypothermia could contribute to synergistic neuroprotection compared with either hypothermia or DZ preconditioning alone.</p><p><b>METHODS</b>Cultured for 9-10 days in vitro, the hippocampal neurons of SD rats were preconditioned with DZ 0 micromol/L or DZ 250 micromol/L for 1 hour per day and this treatment lasted for 3 days. Subsequently, neurons were subjected to deprivation of oxygen for 4 hours at 37 degrees C, 34 degrees C, 30 degrees C and 22 degrees C, respectively. This experiment consisted of 8 groups (4 temperature groups and 4 combination groups) and each group contained 12-well or 2-dish cells. Survival rate, expression of Bcl-2, fluorescence magnitude of intracellular calcium, and concentration of malondialdehyde (MDA) were determined at 24 hours after reoxygenation.</p><p><b>RESULTS</b>The survival rate and expression of Bcl-2 were both increased in individually hypothermic conditions compared with those at 37 degrees C (P < 0.05), whereas intracellular calcium and MDA did the opposite exhibition simultaneously (P < 0.05). 22 degrees C contributed to a higher survival rate and greater expression of Bcl-2 in comparison with other hypothermia (P < 0.05). Preceding administration of 250 micromol/L DZ took the similar effects on the neurons like hypothermia. Moreover, compared with individual hypothermia or DZ preconditioning, the neuronal survival rate and expression of Bcl-2 in the combination group were increased significantly (P < 0.05), whereas the calcium fluorescence density and concentration of MDA were reduced further (P < 0.05). 250 micromol/L DZ preconditioning combined with 22 degrees C provided a maximal neuroprotection.</p><p><b>CONCLUSIONS</b>Compared with either individual hypothermia or DZ preconditioning, the combination of both treatments conferred synergistic protection for cultured hippocampal neurons in vitro against hypoxia-reoxygenation insult.</p>

Quantitative study on depth of ketamine anesthesia for preschoolers / 实用儿科临床杂志

Objective To compare and quantify the determinants in quantitative electroencephalogram(q-EEG) and heart rate variability power spectrum analysis(HRV-PSA) of ketamme(KTM) anesthesia for preschoolers. Methods Seventy four cases were selected and assigned into 3 groups named A(4-5 years), B(5-6 years), C(6-7 years), 22,28,24 cases in every group respectively. All cases were induced with KTM 5 mg /kg intramuscularly and changes of determinants were recorded continuously. If body movement happened, KTM would be injected with 1 mg/kg. Results On pre- anesthesia, BIS in group A was the least among 3 groups, while LF/HF and HRVI were the largest(P