Proton-gated ion channels in cultured mouse cortical neurons

Proton-gated ion channels in cultured mouse cortical neurons were characterized using the patch clamp technique. In voltage clamp, rapid shifts of the extracellular saline from pH 7.4 to <7.0 invariably triggered inward currents carried by sodium. The currents were inhibited by Amiloride (IC₅₀: 6.2 μM). In current clamp, acidic saline depolarized the neurons and triggered trains of action potentials. Concentration–response experiments revealed an extreme intercell variance as the EC₅₀-value for protons varied from pH 6.8 to 5.6, indicating heterogeneity in channel type expression from cell to cell. The possible involvement of acid sensing ion channels in ischemic neurodegeneration is discussed.     

Effect of cannabinoids on the turnover rate of acetylcholine in rat hippocampus,striatum and cortex

Summary The effects of ⁹-tetrahydrocannabinol, (⁹THC) the major psychoactive compound of marijuana, and cannabidiol (CBD), a non-psychoactive component, on the acetylcholine (ACh) concentration and the turnover rate of ACh (TR_ACh) have been studied in various regions of the rat brain. Neither ⁹THC doses from 0.2 to 10 mg/kg nor CBD (10 or 20 mg/kg) alter the ACh concentration in the brain areas examined 30 min, after the intravenous injection. However, ⁹-THC (doses from 0.2 to 10 mg/kg) causes a marked dose-related decrease in the TR_ACh in hippocampus whereas CBD is without effect in this brain region even when 20 mg/kg is given. Furthermore, high doses of ⁹-THC (5 mg/kg) and CBD (20 mg/kg) that produce a significant decrease in the TR_ACh of striatum fail to change the TR_ACh in parietal cortex. The low doses of ⁹-THC required to reduce hippocampal TR_ACh suggest that an action on these cholinergic mechanisms may play a role in the psychotomimetic activity of ⁹-THC.     

The transcortical nature of the late reflex responses in human small hand muscle to digital nerve stimulation

Summary The hypothesis that long-latency reflex activity in human small hand muscles in response to stimulation of digital nerves involves a transcortical pathway was tested by combining digital nerve stimulation and magnetic stimulation over the motor cortex in 12 studies on nine normal subjects. Postsynaptic events in human single first dorsal interosseous (FDI) motoneurones were derived from changes in the firing probability of voluntarily activated single motor units. Electromagnetic stimulation over the contralateral motor cortex resulted in a short-latency, brief facilitation of FDI motor units considered to be due to the activation of fast corticospinal neurones making monosynaptic projections to motoneurones. Stimulation of the digital nerves of the index finger produced a period of reduced firing probability (I1), a period of increased firing probability (E2) and a further period of reduced firing probability (I2) in FDI motor units. When the two stimuli were given separately and then together, timed so that the magnetic stimulus occurred at the predicted transit time of the E2 through the cortex, the facilitation of FDI motoneurones by the combined stimulation was often less than the algebraic sum of the facilitations from each stimulus alone. Thus, in contrast to the results of similar studies on the late response to muscle stretch, there is no confirmation that the E2 from digital nerve stimulation is due to a transcortical reflex.     

Excitatory and depressant effects of Δ 9-tetrahydrocannabinol and cannabidiol on cortical evoked responses in the conscious rat

The influences of ⁹-tetrahydrocannabinol (THC) and cannabidiol on electrically evoked cortical potentials of conscious rats with chronically implanted electrodes were investigated. Specifically, the cannabinoids' effects on a transcallosal evoked response were compared with those of ethosuximide, phenytoin, and pentylenetetrazol. THC produced dose-related opposite effects: Low doses increased the amplitude of the response, whereas higher doses reduced the response. Other drugs that can cause or exacerbate seizures, i. e., phenytoin and pentylenetetrazol, also increased the amplitude of the cortical response. In contrast, cannabidiol, over a wide dosage range, caused only depression. Ethosuximide, like cannabidiol, elicited a depressant effect. The data indicate that under the conditions of the present investigation, cannabidiol shares electrophysiological properties with ethosuximide but not with phenytoin, and that cannabidiol is a relatively selective, centrally acting drug. In addition, our findings support the suggestion that augmentation of neurotransmission in central pathways may contribute to the convulsant actions of THC, and the cannabinoids' depressant effects may, at least partially, account for their anticonvulsant actions.     

正交设计优选黄柏中小檗碱的提取工艺

目的：优选黄柏中小檗碱的提取工艺。方法：以小檗碱的含量为指标，应用正交试验设计筛选黄柏的最佳提取工艺条件。结果：最佳提取工艺为D2A2B3C2，即用7倍量的70%乙醇热回流提取2次，2h/次。结论：优选得到的工艺稳定可行。     

几种中药的化学振荡指纹图谱

应用振荡技术，采用KBrO3-MnSO4-H2SO4-丙酮振荡器，得到了解表药柴胡、葛根、连翘，祛风湿药木瓜、独活、五加皮和理血药鸡血藤、丹参、虎杖的振荡指纹图谱。结果表明，这些化学振荡指纹图谱可用于辨识中药。     

秦皮总香豆素致突变作用研究

目的评价秦皮总香豆素的致突变性。方法应用Ames试验、小鼠骨髓微核试验对秦皮总香豆素进行了致突变研究。结果秦皮总香豆素在受试剂量40～20000μg/皿范围内,各剂量组各菌株与阴性对照组比较均未见回变菌落数明显增加。秦皮总香豆素三个试验剂量组微核率均在正常范围内,经卡方检验与阴性对照组比较无显著性差异(P>0.05)。结论本实验条件下秦皮总香豆素无致突变作用。     

芫花根皮的生药学研究

描述了芫花根皮的药材性状、组织构造及粉末特征，为鉴别芫花根皮提供参考依据。     

中药“二黄”滴耳剂治疗急慢性化脓性中耳炎的临床观察(附1000例分析)

本文总结了“二黄”滴耳剂治疗急慢性中耳炎1000例，结果表明总有效率为89％，尤其对急性化脓性中耳炎效果更为明显，与其它抗生素相比具有很多优点。抗菌谱广，对革兰氏阳性菌及革兰氏阴性菌、病毒都有一定作用，低浓度抑菌，高浓度杀菌，不易产生抗药性及过敏反应，对第八对脑神经无毒性，价格低廉应用方便优于任何一种抗生素。     

An axotomy model for the induction of death of rat and mouse corticospinal neurons in vivo

To study trophic dependencies of rat and mouse corticospinal neurons (CSN), we established a lesion model for the induction of death of analogous populations of CSN in these rodent species. Before lesion, CSN were retrogradely labeled with Fast Blue (FB). A stereotaxic cut lesion through the entire internal capsule (ICL) was used to axotomize CSN. The extent of axotomy was determined by application of a control tracer. In both species, FB-labeled CSN were localized in three major areas: (1) the sensory motor cortex; (2) the supplementary motor and medial prefrontal cortex; and (3) the somatosensory cortex. ICL does not lead to complete axotomy of CSN of the rat and mouse somatosensory cortex. In rats, ICL results in complete axotomy of CSN of the sensory motor cortex and incomplete axotomy of the caudal portion of the supplementary motor and medial prefrontal cortex. In mice, the area of axotomized CSN extends significantly further frontally. In both species, axotomy-induced death of CSN is observed in the center of the sensory motor cortex. This lesion model is useful for investigations on the response of CSN of the sensory motor cortex to lesion and therapeutic drugs.