A specific harmaline-evoked increase in cerebellar 5′-nucleotidase activity

This study examines harmaline-induced changes in 5′-nucleotidase (5′-ND) activity in cerebellar fractions from rats with an intact inferior olive (IO) or prior destruction of the IO by 3-acetylpyridine (3-AP) intoxication. Harmaline markedly increased 5′-ND activity in the crude homogenate (P<0.05) and P2 fraction (P<0.001) of cerebella from rats with an intact IO. This increase was absent in the P1, P3 and S3 fractions and it was abolished by 3-AP olivectomy. It was also absent in basal ganglia P2 fractions. Since harmaline produces rhythmic complex spike discharges of Purkinje cells by activating IO neurons [4, 18], these data suggest that climbing fiber activation per se increases 5′-ND activity in the P2 fraction. This raises the possibility that a climbing fiber-induced local increase in 5′-ND activity at parallel fiber-Purkinje cell synapses results in a local increase in adenosine concentration. This may account for climbing fiber-evoked suppression of simple spike activity [12, 13, 28].     

Effects of unilateral stereotactic posterior striatotomy on harmaline‐induced tremor in rats

Although long known and the most prevalent movement disorder, pathophysiology of essential tremor (ET) remains controversial. The most accepted hypothesis is that it is caused by a dysfunction of the olivocerebellar system. Vilela Filho et al. [2001; Stereotact Funct Neurosurg 77:149–150], however, reported a patient with unilateral hand ET that was completely relieved after a stroke restricted to the contralateral posterior putamen and suggested that ET could be the clinical manifestation of posterior putamen hyperactivity. The present study was designed to evaluate this hypothesis in the most often used model of ET, harmaline‐induced tremor in rats. Fifty‐four male Wistar rats were randomly distributed into three groups: experimental (EG), surgical control (SCG), and pharmacological control (PCG) groups. EG animals underwent stereotactic unilateral posterior striatotomy. SCG rats underwent sham lesion at the same target. PCG served exclusively as controls for harmaline effects. All animals received, postoperatively, intraperitoneal harmaline, and the induced tremor was video‐recorded for later evaluation by a blind observer. Thirteen animals were excluded from the study. Limb tremor was reduced ipsilaterally to the operation in 20 of 21 rats of EG and in two of nine of SCG, being asymmetric in one of 10 of PCG rats. Comparisons between EG × SCG and EG × PCG were statistically significant, but not between SCG × PCG. Limb tremor reduction was greater in anterior than in posterior paws. Lateral lesions yielded better results than medial lesions. These results suggest that the posterior striatum is involved with harmaline‐induced tremor in rats and support the hypothesis presented. © 2013 Wiley Periodicals, Inc.     

骆驼蓬抗癌化学成分的分离鉴定和药理实验研究(附21例病人疗效观察)

在临床应用骆驼蓬制剂治疗消化道肿瘤等获得了一定效果的基础上,笔者从该植物种子内分离出两种生物硷单体。通过进行熔点、薄层、紫外、红外、核磁共振、质谱等方法测定,确认了其化学结构,即骆驼蓬硷(Harmaline)和去氢骆驼蓬硷(Harmine)。分别将这两种生物硷进行抗肿瘤试验,结果表明对小鼠肝癌、S—180、L_2等瘤株均有肯定的抑制作用。在体外用于处理人体宫颈癌(Hela)细胞,能明显地影响其生长。我们曾观察21例接受骆驼蓬总硷制剂(以上述两种生物硷为主要成分)治疗的恶性肿瘤病人,其有效率为85.7％。     

Neuropharmacological characterization of local ibogaine effects on dopamine release

Summary Local perfusion with ibogaine (10^–6M—10^–3M) via microdialysis probes in the nucleus accumbens or striatum of rats produced a biphasic dose-response effect on extracellular dopamine levels. Lower doses (10^–6M—10^–4M) produced a decrease while higher doses (5 × 10^–4M—10^–3M) produced an increase in dopamine levels. Dihydroxyphenylacetic acid (DOPAC) levels were not effected. Naloxone (10^–6M) and norbinaltorphimine (10^–6M—10^–5M) did not affect dopamine levels, but when co-administered with ibogaine (10^–4M) blocked the decrease in dopamine levels produced by ibogaine. Ibogaine (10^–3M) stimulation of dopamine levels in the striatum was calcium independent and not blocked by tetrodotoxin (10^–5M). Pretreatment with cocaine (15mg/kg), reserpine (5mg/kg) or alpha-methyl-paratyrosine (250mg/kg) given intraperitoneally significantly reduced ibogaine (10^–3M) stimulation of striatal dopamine levels. In striatal synaptosomes, both ibogaine and harmaline (10^–7—10^–4M) produced dose-dependent inhibition of [³H]-dopamine uptake. These findings suggest that ibogaine has both inhibitory and stimulatory effects on dopamine release at the level of the nerve terminal. It is suggested that the inhibitory effect is mediated by kappa opiate receptors while the stimulatory effect is mediated by interaction with the dopamine uptake transporter.     

Harmaline-induced activation of the olivo-cerebellar system in young rabbits: Further evidence for a transient multiinnervation of purkinje cells by climbing fibres

Ontogenetic evolution of behavioural and electrophysiological responses to harmaline was studied in the maturing rabbit. As regards behavioural effects, harmaline-induced tremor could not be elicited before the second post-natal week, but as soon as it appeared, no significant difference was seen in its intensity compared with the adult animal. Electrophysiological studies of cerebellar Purkinje cell activity revealed a similar age-dependence since no rhythmic firing of climbing fibre responses was found before the 8th post-natal day. In addition, harmaline activation revealed a transient multiple innervation of Purkinje cells by climbing fibres. It is suggested that the presence of serotonergic fibres is critical for the effects of harmaline to develop.     

复方木尼孜其颗粒中骆驼蓬子质量控制方法研究

目的研究复方木尼孜其颗粒中骆驼蓬子的质量控制方法。方法分别以骆驼蓬碱(HAL)和去氢骆驼蓬碱(HAR)为对照,建立复方木尼孜其颗粒中骆驼蓬子的薄层色谱鉴别及HPLC含量测定方法。薄层色谱:以硅胶HSGF254为薄层板,乙酸乙酯-甲醇-氨水(10∶1.5∶0.5)为展开剂;HPLC条件:采用反相HPLC色谱柱,以乙腈-醋酸铵缓冲盐(22∶78)为流动相,流速1.0 ml/min,柱温为30℃,检测波长为330 nm。结果复方木尼孜其颗粒的薄层色谱中HAL、HAR分离度良好,可以用于鉴别复方木尼孜其颗粒中的骆驼蓬子。含量测定方法学研究结果表明,HAL和HAR分别在0.33~104.10 mg/L和0.13~40.91 mg/L范围内呈良好的线性关系,方法平均回收率分别为97.04%和101.83%,RSD分别为2.02%和2.32%,方法的日内和日间精密度RSD均小于3%。15批复方木尼孜其颗粒样品的测定结果表明,HAL含量范围为1.62~5.04 mg/袋,平均为(2.87±0.95)mg/袋;HAR含量范围为0.87~2.22 mg/袋,平均为(1.51±0.41)mg/袋;总碱(HAL+HAR)含量范围为(2.49~7.14)mg/袋,平均为(4.38±1.33)mg/袋。结论建立的复方木尼孜其颗粒中骆驼蓬子质量控制方法灵敏、准确、重现性好、精密度高、专属性强,适用于复方木尼孜其颗粒中骆驼蓬子的质量控制。     

5种生物碱胃癌多药耐药逆转剂的筛选及机制研究

目的研究骆驼蓬碱、去氢骆驼蓬碱、贝母素甲、贝母素乙和氧化苦参碱对肿瘤细胞多药耐药性(MDR)的逆转作用及机制。方法以胃癌亲本细胞系SGC-7901和MDR细胞系SGC-7901/VCR为细胞模型,采用MTT法检测上述5种生物碱的细胞毒活性及对MDR的逆转效果;用流式细胞仪检测MDR逆转效果最好的贝母素乙对肿瘤细胞内阿霉素(ADR)蓄积的影响;Western blotting法检测P-糖蛋白(P-gp)的表达;Hoechst荧光染色和细胞免疫荧光法检测贝母素乙诱导SGC-7901/VCR细胞凋亡情况。结果骆驼蓬碱、去氢骆驼蓬碱、贝母素甲、贝母素乙和氧化苦参碱均能不同程度地抑制SGC-7901和SGC-7901/VCR细胞的增殖,在非毒剂量下贝母素乙能够显著提高SGC-7901/VCR细胞对ADR的敏感性及细胞内ADR的浓度,降低P-gp表达。贝母素乙联合5-氟尿嘧啶(5-FU)给药可诱导SGC-7901/VCR细胞凋亡,凋亡细胞cleaved caspase-3呈高表达。结论贝母素乙具有作为胃癌MDR逆转剂的潜力,其逆转耐药的机制可能与下调P-gp表达和诱导细胞凋亡有关。     

利用植物悬浮细胞体系对骆驼蓬碱进行生物转化

目的:利用植物悬浮细胞培养体系对骆驼蓬碱进行生物转化。方法:利用长春花、一叶萩、烟草和金银花植物悬浮细胞培养体系转化骆驼蓬碱,应用薄层色谱法和质谱法对转化结果进行检识。结果:4种植物悬浮细胞培养体系中均检测到新的转化产物,该转化产物采用碘化铋钾溶液在薄层色谱上显色,在正离子模式下,准分子离子为213.0,二级碎片为198.1、170.2,初步推测为去氢骆驼蓬碱。结论:利用植物悬浮细胞培养体系生物转化的方法可以将骆驼蓬碱转化成去氢骆驼蓬碱。     

Serotonin Modulation of Inferior Olivary Oscillations and Synchronicity: A Multiple-electrode Study in the Rat Cerebellum

Simultaneous recording of complex spikes from multiple Purkinje cells (up to 44) in the rat cerebellum was used to examine the effects of 5-hydroxytryptamine (serotonin, 5-HT) on olivocerebellar function. Microinjection into the inferior olive was found to increase the average firing rate of inferior olivary neurons while slowing their oscillation frequency and increasing the coherence of their oscillations. Indeed, while the normal rostrocaudal band of synchronous activity remained unchanged, the degree of synchrony between Purkinje cell complex spikes within this band was enhanced following the 5-HT injections. Multiple-electrode recordings obtained from crus Ha and vermal lobule Vlb yielded qualitatively similar results; however, the effects on vermal activity were more pronounced. The effects of the 5-HT microinjection decayed with a time course of 75 min. The half-maximum effective concentration of 5-HT was between 10 and 100 μM. Injections of various 5-HT agonists and antagonists demonstrated that a 5-HT type-2A (5-HT_2A) receptor is the main mediator for the 5-HT effect, which was very similar to the effect produced by injections of harmaline. However, 5-HT and harmaline appear to have independent mechanisms since the action of harmaline was not blocked by the 5-HT_2A antagonist LY53857. A possible role for 5-HT, as a physiological enhancer of the timing of motor function of the olivocerebellar system, is discussed.     

CaV3.1 is a tremor rhythm pacemaker in the inferior olive

The rhythmic motor pathway activation by pacemaker neurons or circuits in the brain has been proposed as the mechanism for the timing of motor coordination, and the abnormal potentiation of this mechanism may lead to a pathological tremor. Here, we show that the potentiation of Ca_V3.1 T-type Ca²⁺ channels in the inferior olive contributes to the onset of the tremor in a pharmacological model of essential tremor. After administration of harmaline, 4- to 10-Hz synchronous neuronal activities arose from the IO and then propagated to cerebellar motor circuits in wild-type mice, but those rhythmic activities were absent in mice lacking Ca_V3.1 gene. Intracellular recordings in brain-stem slices revealed that the Ca_V3.1-deficient inferior olive neurons lacked the subthreshold oscillation of membrane potentials and failed to trigger 4- to 10-Hz rhythmic burst discharges in the presence of harmaline. In addition, the selective knockdown of Ca_V3.1 gene in the inferior olive by shRNA efficiently suppressed the harmaline-induced tremor in wild-type mice. A mathematical model constructed based on data obtained from patch-clamping experiments indicated that harmaline could efficiently potentiate Ca_V3.1 channels by changing voltage-dependent responsiveness in the hyperpolarizing direction. Thus, Ca_V3.1 is a molecular pacemaker substrate for intrinsic neuronal oscillations of inferior olive neurons, and the potentiation of this mechanism can be considered as a pathological cause of essential tremor.