Molecular mechanisms for the antidepressant-like effects of a low-dose ketamine treatment in a DFP-based rat model for Gulf War Illness

Exposure to organophosphates (OP) during the First Gulf War is among one of the factors for Gulf War Illness (GWI) development in veterans and it has been challenging to treat GWI symptoms with existing therapies. Ketamine produces a rapid-onset and sustained antidepressant response, but there is no evidence whether ketamine treatment is effective for GWI depression. Repeated, low-dose exposure to diisopropyl fluorophosphate (DFP) mimic Gulf War related OP exposures and produces a chronic depressive state in rats. In this study, DFP-exposed rats treated with ketamine (10 mg/kg, i.p.) exhibited antidepressant-like effect on the Forced Swim Test at 1-h. This effect persisted at 24-h post ketamine, a time-point by which it is eliminated from the brain suggesting involvement of mechanisms that affect long-term synaptic plasticity. Western blot analysis showed significantly lower Brain-Derived Neurotrophic Factor (BDNF) levels in DFP rat brains. Ketamine produced a nonsignificant increase in BDNF expression at 1-h but produced a larger, significant (2.2-fold) increase at 24-h in DFP rats. We previously reported chronic hippocampal calcium elevations ([Ca²⁺]_i) in DFP rats. Ketamine-treated DFP rats exhibited significantly lower [Ca²⁺]_i at 1-h but not at 24-h. Interestingly, treatment with ANA-12, a TrkB-BDNF receptor antagonist, in DFP rats blunted ketamine’s antidepressant-like effect at 24-h but not at 1-h. These experiments suggest that in a rat model of DFP-induced depression, inhibition of the NMDAR-Ca²⁺ contributes to the rapid-onset antidepressant effects of ketamine while the antidepressant actions that persisted at 24-h post ketamine administration involve upregulation of BDNF signaling.     

Protective effects of melatonin and memantine in human retinal pigment epithelium (ARPE-19) cells against 2-ethylpyridine-induced oxidative stress: implications for age-related macular degeneration

Purpose: To investigate the possible protective effects of melatonin and memantine (MMT) against 2-ethylpyridine (2-EP)-induced oxidative stress and mitochondrial dysfunction in human RPE (ARPE-19) cells in vitro.

Materials and methods: The ARPE-19 cells were divided into seven groups. Oxidative stress was triggered by incubating the ARPE-19 cells with 30?μM of 2-EP for 24?h. Then, 200?μM of melatonin was administered over three days and 20?μM of MMT over six hours prior to the experiment. The effects of melatonin and MMT on the intracellular calcium release mechanism, reactive oxygen species production, caspase-3 and caspase-9 activities, as well as vascular endothelial growth factor levels were measured.

Results: Melatonin and MMT were found to significantly decrease apoptosis levels. The intracellular calcium release was regulated by both melatonin and MMT. Further, melatonin and MMT significantly decreased both caspase-3 and caspase-9 activities, as well as pro-caspase and poly(ADP-ribose) polymerase expression, in ARPE-19 cells. Moreover, melatonin significantly increased the protective effect of MMT. The combination of melatonin and MMT significantly decreased 2-EP-induced oxidative toxicity and apoptosis by inhibiting the intracellular reactive oxygen species production and mitochondrial depolarization levels.

Conclusions: These notable findings are the first to demonstrate the synergistic protective effects of melatonin and MMT against 2-EP-induced oxidative stress in ARPE-19 cells.     

五种治疗阿尔茨海默病药物分子结构与性质的密度泛函计算分析

目的：在模拟大脑油性环境下对五种抗阿尔茨海默病药物进行整体和局部性质计算比较分析。方法：采用密度泛函B3LYP/TZVP计算方法,对五种抗阿尔茨海默病药物的几何结构、电子结构、紫外光谱和概念密度泛函分析,利用环己烷模拟大脑油性环境。结果：共轭效应使得极性键键长缩短;静电势差异决定了分子间作用位点的不同,在酶反应中,与蛋白质构象的改变密切相关;溶剂效应对紫外光谱产生影响,其中溶剂的极性越大红移越大。由福井函数结合相对亲电指数与相对亲核指数,表明多奈哌齐和卡巴拉汀亲电、亲核能力都很强,加兰他敏亲核能力强,美金刚和石杉碱甲亲电、亲核能力均比较弱。结论：五种药物分子的结构差异、电性差异影响药物的理化性质并决定了药物不同的作用机制。四种抗胆碱酯酶抑制剂活性略有差异但明显高于N-甲基-D-天冬氨酸受体拮抗剂,其中多奈哌齐药理作用最强。     

Differentiation renders susceptibility to excitotoxicity in HT22 neurons

HT22 is an immortalized mouse hippocampal neuronal cell line that does not express cholinergic and glutamate receptors like mature hippocampal neurons in vivo.This in part prevents its use as a model for mature hippocampal neurons in memory-related studies.We now report that HT22 cells were appropriately induced to differentiate and possess properties similar to those of mature hippocampal neurons in vivo,such as becoming more glutamate-receptive and excitatory.Results showed that sensitivity of HT22 cells to glutamate-induced toxicity changed dramatically when comparing undifferentiated with differentiated cells,with the half-effective concentration for differentiated cells reducing approximately two orders of magnitude.Moreover,glutamate-induced toxicity in differentiated cells,but not undifferentiated cells,was inhibited by the N-methyl-Daspartate receptor antagonists MK-801 and memantine.Evidently,differentiated HT22 cells expressed N-methyl-D-aspartate receptors,while undifferentiated cells did not.Our experimental findings indicated that differentiation is important for immortalized cell lines to render post-mitotic neuronal properties,and that differentiated HT22 neurons represent a better model of hippocampal neurons than undifferentiated cells.     

盐酸美金刚胶囊人体药代动力学研究

目的：进行健康志愿者盐酸美金刚胶囊单次和多次口服的药代动力学研究。方法：采用高效液相色谱串联质谱法测定美金刚血浓度,以DAS2.0计算其药代动力学参数。结果：盐酸美金刚胶囊5、10和15 mg单次口服,美金刚药代动力学参数tmax为（5.6±1.2）、（5.2±2.0）和（4.9±1.1）h;Cmax为（4.4±0.9）、（8.9±1.6）和（16.5±2.8）ng/mL;t1/2为（47±10）、（47±9）和（51±9）h。10 mg多次口服,美金刚药代动力学参数tmax为（6.0±1.4）h,Cmax为（31.8±6.0）ng/mL,t1/2为（46±8）h。结论：美金刚单次给药,Cmax和AUC有良好剂量相关性;多次给药可发生蓄积。