Barium enhances the excitability of a motoneurone from the cockroach (Periplaneta americana)

• 1.1. An isolated ganglion preparation was used to investigate the effects of barium ions (Ba²⁺) on excitability of the soma of the ‘fast’ coxal depressor motoneurone (D_f) from the cockroach Periplaneta americana.
• 2.2. Under current-clamp, short (50 ms) depolarising pulses applied to the soma of D_f elicited damped membrane oscillations in normal external solution. In the presence of 10 mM Ba²⁺, similar pulses produced all-or-none action potentials (n = 12).
• 3.3. Under voltage-clamp, addition of Ba²⁺ to the external solution suppressed the Ca-dependent K⁺ conductance (I_c) in D_f(n = 4).
• 4.4. Modulation of I_c may offer a means of altering the excitability, and therefore output, of motoneurone D_f.

     

The effects of chronic administration of ethosuximide on learning and memory: a behavioral and biochemical study on nonepileptic rats

Long-term use of antiepileptic drugs is common in the treatment of epilepsy. Clinical reports exist of cognitive impairment attributed to antiepileptic drugs. Hence, this study evaluates the effect of chronic administration of one antiepileptic drug, ethosuximide, on spatial and fear learning and memory in nonepileptic rats. High performance liquid chromatography with electrochemical detection was used for quantification of glutamate, glycine, taurine, gamma-aminobutyric acid, dopamine, and serotonin in the frontal cortex and hippocampus to elucidate the neurobiological basis of the effect of ethosuximide on learning and memory. We found that 21 days of ethosuximide treatment produced negative effects on fear memory (passive avoidance) at all doses (100, 200 and 250 mg/kg body weight), but had no effect on spatial learning (T-maze). Fear memory impairment was associated with decreased hippocampal dopamine levels. Ethosuximide (at all doses) had a minimal effect on the GABAergic and glutamatergic systems in all brain regions studied, with the exception of elevated levels of gamma-aminobutyric acid in the frontal cortex with the 250 mg/kg body weight dose. We have shown that long-term administration of ethosuximide adversely affects fear memory, but does not affect spatial learning and memory.     

Lethal and behavioral effects of chlordimeform in bobwhite

The 7-day LC50 of chlordimeform to bobwhite (Colinus virginianus) chicks was 2835 ppm (95% CI = 2169-3705 ppm). Bobwhite chicks fed 1000 ppm (approximately LC4) chlordimeform for 7 days ate less, weighed less, travelled farther from a fright stimulus in an avoidance test, and had significantly more groups make greater than or equal to 10 light beam interruptions in an open-field test at 8 days of age than bobwhite fed 0, 1, 10, or 100 ppm chlordimeform (P less than or equal to 0.05). Groups fed 100 ppm (P less than or equal to 0.05) and 1000 ppm (P = 0.11) for 7 days crossed more often from the shallow to deep side of a visual cliff at 8 days of age than birds fed lesser concentrations of chlordimeform. Bobwhites were retested at 15 days of age, after being fed untreated diets for 7 days following the chlordimeform diets. The 1000 ppm group still travelled greater distances in the avoidance test (P less than or equal to 0.05). But open-field and visual cliff performances were similar to controls and other treatment groups. Chlordimeform concentrations causing behavioral aberrations in bobwhite were appreciably higher than environmental concentrations following field applications of chlordimeform.     

Effects of cycloheximide and puromycin on learning and retention in the cockroach,P. americana

A new one-session T-maze training procedure for cockroaches, in which animals were trained to turn right or left to avoid shock, is described. This paradigm was utilized to investigate effects of protein synthesis inhibiting drugs on learning and retention. Cycloheximide (CXM), which inhibited protein synthesis by over 90% during the training period, did not impair acquisition and did not produce retention deficits at any interval up to 1 day after training. Puromycin (PURO), which inhibited protein synthesis by about 70% during the training period, produced amnesia 5 hr after training, while acquisition was not affected. Thus invertebrates, as well as vertebrates, are susceptible to amnesic effects of puromycin. Although PURO-injected animals showed retention deficits as measured by the number of correct turns, no retention deficit occurred for the behavioral modification consisting of an increase in runway time during the training period. Therefore, PURO appears to show specificity for the different types of longer-term memories that are formed in a training situation.     

美洲大蠊提取物对小鼠真皮成纤维细胞迁移影响的初步研究

目的:考察美洲大蠊提取物对小鼠真皮成纤维细胞迁移的影响,探讨其在创面修复中的作用机制。方法:采用酶消化法体外分离培养小鼠真皮成纤维细胞,建立体外细胞划痕创伤模型,加入0,1,5,20mg生药.mL-1提取物,培养24,48h,观察细胞迁移。结果:培养24h后,0,1,5,20mg生药.mL-1提取物各组细胞迁移率分别为:42.31%±4.41%、87.29±9.23%、72.22±6.59%、32.18±3.45%,1,5mg生药.mL-1提取物可明显促进细胞迁移(P0.01)。结论:美洲大蠊提取物可促进创面的愈合,其机制与促进参与创面修复的成纤维细胞迁移有关。     

Effects of pre-training administration of scopolamine on learning and retention in the cockroach,P. americana

The muscarinic cholinergic blocker, scopolamine, has no effect on acquisition or retention of the choice behavior of the cockroach, P. americana trained to turn right or left to avoid shoch in a T-maze. Scopolamine does, however, prevent runaway habituation during training, suggesting that such habituation may be dependent on central cholinergic synapses as there are no known peripheral cholinergic receptors in cockroaches. Previous work demonstrating that no effect of scopolamine on such retention, suggests that puromycin does not produce its amnesic effect on choice behavior by interferring with central cholinergic synaptic processes.     

静态强磁场影响大鼠学习记忆能力的行为学和电生理研究

目的探讨3 T静态强磁场对大鼠的学习、记忆功能的影响。方法将80只大鼠随机分为4组,分别为照射组、照射后恢复组、假照射组、假照射后恢复组。照射组和照射后恢复组大鼠经3 T静态强磁场照射。假照射组、假照射后恢复组在无静态强磁场的相似环境中模拟。然后,各组大鼠再随机数字表法分为2组,分别进行水迷宫行为学实验和在体长时程增强(LTP)电生理实验。结果 1定位航行实验的第1~3天,3 T静态强磁场照射组大鼠寻找水下平台的逃避潜伏期与假照射组及照射后恢复组相比均明显延长。2静态强磁场照射未影响大鼠海马LTP。结论静态强磁场可能会影响大鼠的空间学习记忆能力,也可能会导致大鼠前庭功能障碍,但这种影响和损伤是暂时而且可逆的。     

美洲大蠊醇提物对小鼠急性肝损伤的保护作用

目的 研究美洲大蠊醇提物对四氯化碳(CCl4)和刀豆蛋白A(Con A)所致小鼠肝损伤的保护作用.方法 采用ip 0.1%cch以及尾iv 20 mg,mg/kg Con A造成小鼠急性肝损伤,检测血清中ALT、AST和肝组织中SOD、MDA的水平.将肝大叶HE染色,观察美洲大蠊醇提物对小鼠肝脏组织病理学的影响.结果 ...     

Pyrethroid toxicology: Protective effects of diazepam and phenobarbital in the mouse and the cockroach

Diazepam delayed the onset of action of deltamethrin and fenvalerate (pyrethroids producing the Type II syndrome) but not of permethrin and allethrin (pyrethroids producing the Type I syndrome) in both the mouse and cockroach. Phenobarbital was less potent as an anticonvulsant and also less selective since it delayed the onset of signs for both deltamethrin and permethrin in each animal. In vivo extracellular nerve recordings in the cockroach showed differences between deltamethrin and permethrin in the nerves responding, the types of response, and the protective effect of diazepam. A 3 mg/kg ip dose of diazepam protected the mouse against mortality due to a subsequent intracerebroventricular dose of either deltamethrin or permethrin, increasing their LD₅₀ values by six- to ninefold. Possible mechanisms for the Type II pyrethroid syndrome include an action at the GABA receptor complex or a closely linked class of neuroreceptor, or through depolarization of nerve terminals.     

Synthesis of proctolin analogues and their cardioexcitatory effect on cockroach,Periplaneta americana L., and yellow mealworm,Tenebrio molitor L.

Five proctolin analogues modified in position 2 of the peptide chain by (4-NH₂)- ( I ), (4-NO₂)- ( II ), (4-NMe₂)- ( III ), (4-OMe)-L-phenylalanine ( IV ) and β-(cyclohexyl-4-OMe)-L-alanine ( V ) were synthesized by conventional liquid phase method. Biological activity of the obtained peptides was investigated in cardioexcitatory test on two insect species, cockroach, Periplaneta americana L., and yellow mealworm, Tenebrio molitor L. Peptides I–IV exhibited higher activity than proctolin itself.     

Working memory, executive processes and the effects of alcohol on Go/No-Go learning: testing a model of behavioral regulation and impulsivity

Rationale: Impulsivity is associated with increased risk for alcoholism. Alcohol also may increase impulsive behavior, although little is known about the processes underlying this effect. Objectives: This study tested a model proposing that the executive processes of working memory (WM) and conditional associative learning (CAL) modulate behavioral inhibition. Subjects had either a positive (FHP) or a negative (FHN) family history of alcoholism. Hypotheses were that alcohol would increase Go/No-Go impulsive responding but only in subjects with low working memory capacity (low-WM), low-CAL ability, or FHP for alcoholism. The model also predicted that WM and CAL modulate inhibitory responses to contingency reversal on a Go/No-Go task. Methods: A Go/No-Go learning task with a midway contingency reversal was administered to 71 FHP and 78 FHN subjects when sober and after drinking one of two moderate doses of alcohol. WM (digits backward) and CAL (conditional spatial association task) were also assessed when sober. Results: Alcohol resulted in more false alarms but only in low-WM subjects. Both WM and CAL modulated learning to inhibit behavior after contingency reversal, suggesting separate modulation mechanisms for WM and CAL. Subjects with low- capacity WM and subjects with low-capacity CAL ability had more difficulty learning response inhibition after contingency reversal. FHPs and FHNs did not differ in their response to alcohol. Conclusions: The results support our model of the modulatory role of WM and CAL in the ongoing regulation of behavioral inhibitory systems. The results also suggest that individuals with low capacity WM are more susceptible to alcohol’s effect of increasing impulsive behavior, suggesting that alcohol reduces the capacity of working memory to modulate response inhibition. Received: 3 March 1999 / Final version: 28 May 1999     

GABA-ergic drugs: effects on conditioning, memory and learning

In order to study the role of GABA in behaviour, various GABA-mimetic and GABA-blocking drugs were tested for their effects on a conditioned avoidance response (CAR). Sodium valproate slowed the acquisition of CAR and failed to affect the latency of a well-learned CAR, but interestingly, showed a marked anti-conflict effect similar to that of benzodiazepine-derivatives. The similarity of effects of drugs such as benzodiazepines and sodium valproate, which are postulated to potentiate GABA-ergic transmission, suggests that GABA plays a role in conditioning, memory and learning.     

The effects of single-dose lorazepam on memory and behavioural learning

To assess the influence of lorazepam on memory and behavioural learning, a non-clinical sample of undergraduate psychology students (n = 24), received lorazepam (2.5 mg) or placebo orally. Pre-drug and post-drug neuropsychological assessment comprised the Rey auditory verbal learning test, verbal fluency test, digit span and word stem completion. Relative to placebo, lorazepam induced a marked deficit in delayed free-recall, perceptual priming, and written word fluency, with preservation of digit span. Behavioural learning was assessed on a computer-aided vicarious exposure treatment for obsessive-compulsive disorder, administered post-drug, and repeated 1 week later, drug free. Compared to placebo, lorazepam treated participants enacted 51% less exposure activity on the behavioural learning task post-drug. Whilst both groups enacted increased exposure at the drug-free session, exposure activity was 49% less in the lorazepam group, indicating a carryover effect of the impaired learning under drug 1 week before. There were no significant differences between lorazepam and placebo on indices of overall activity on the program. These results suggest lorazepam-induced impairment in the ability to learn behavioural strategies, possibly due to impaired acquisition of information into long-term episodic memory. These findings suggest caution in the co-prescribing of benzodiazepines in people undergoing behavioural therapies in clinical populations.     

The effects of anti-hypertensive medication on learning and memory.

1. The aim of the study was to investigate whether there were differential effects of three different anti-hypertensive medications (cilazapril, atenolol, nifedipine) on cognitive function. 2. A sub-group of patients participating in a large clinical trial of these three drugs, randomly allocated between the three drug conditions, received cognitive assessment at two points before the commencement of treatment and then after 12 and 24 weeks of treatment. Seventy-six patients began treatment, and 55 completed the full course. 3. Tests of learning and memory were designed specially for the study, with a different but comparable version administered on each assessment occasion, in a fixed order. 4. No significant differences between drug groups were found in any index of learning or memory, at any testing occasion. The results were the same whether or not treatment non-completers were included in the analysis.     

The toxic effects of dieldrin in rats: a reevalution of data obtained in a two-year feeding study.

Tumor data from a 2-year feeding trial with dieldrin (HEOD) in rats has been subjected to histological review and further statistical analysis utilizing and actuarial method where tumor incidence is related to the live population of animals at risk. The revised tumor data are presented with lifetables and the relative risk analyses, the results of which support the previously reported conclusion that there was not a treatment-related increase in tumor incidence.     

The central actions of lidocaine and a pesticide, chlordimeform

The injection of 300–1000 μg of lidocaine or chlordimeform (CDM) into the lateral ventricles of rats lightly anaesthetized with urethane produced similar dose-dependent pressor (or depressor) responses. Stimulation of the dorsal raphe nucleus caused suppression of the spontaneous EEG recorded from bipolar electrodes implanted in the amygdala. Intraventricular lidocaine and CDM blocked the raphe-mediated suppression of the amygdala EEG activity.

Higher doses (3–4 mg) of intraventricular lidocaine or CDM resulted in clonic limb movements, spikes in the amygdala EEG and blood pressure oscillation. All seizure manifestations could be blocked by intense raphe stimulation or by intravenous diazepam (1 mg/kg).

These studies indicate a central origin for the secondary pressor response that is observed with higher intravenous doses (10–50 mg/kg) of lidocaine or CDM.     

高血压大鼠学习记忆障碍及降压药物疗效

目的：观察高血压大鼠学习记忆功能的损害并评价比较降压药物的治疗效果。方法：自发性高血压大鼠（ＳＨＲ，１６ｗｋ）分３组（ｎ＝６），其中两组分别使用尼群地平、卡托普利，另一组为对照组；肾血管性高血压Ｗｉｓｔａｒ－Ｋｙｏｔｏ（ＷＫＹ）大鼠（ＲＨＲ，１６ｗｋ）共６组（ｎ＝６），其中５组分别使用卡托普利、美多洛尔、普萘洛尔、硝苯地平、哌唑嗪，另一组不用药。再设一正常对照ＷＫＹ（１６ｗｋ，ｎ＝６）组。治疗８ｗｋ后，连续５ｄ进行跳台试验，每天１０次。结果：两种未经治疗的高血压大鼠ｄ５的主动回避反应计分均有不同程度的下降（ＳＨＲ：０．９±１．１，ＲＨＲ：４．２±１．２ｖｓ，ＷＫＹ：８．７±１．８，Ｐ均＜０．０１）；用药ＳＨＲ两组与对照ＳＨＲ组相比（３．６±１６，４．３±１．８ｖｓ０．９±１．１，Ｐ＜０．０５），记分明显改善；ＲＨＲ美多洛尔７．７±１．６，ＲＨＲ普萘洛尔８．３±１．９，ＲＨＲ卡托普利８．０±２．０，ＲＨＲ硝苯地平７．２±１．７，ＲＨＲ哌唑嗪７．３±１．７，与ＲＨＲ对照（４．２±１．２）比较，Ｐ均＜０．０１；主动回避反应计分有显著提高。进一步比较不同药物治疗组，当降压程度相似时，各组主动回避反应计分无明显差别。?     

创面灵抗过敏止痒作用及毒理学试验研究

目的：观察创面灵的抗过敏、止痒作用及其对皮肤的刺激性和皮肤用药急性毒性。方法：2,4-二硝基氯苯(DNCB)所致迟发型皮肤过敏反应观察其抗过敏作用,采用豚鼠皮肤过敏试验评分法研究其皮肤过敏作用,磷酸组织胺致痒法观察其止痒作用。结果：创面灵不同剂量均对DNCB所致小鼠迟发型过敏反应有一定抑制作用,并可显著提高磷酸组织胺致痒阈;外用后豚鼠皮肤无红斑及水肿发生,对皮肤刺激强度分值显著低于刺激强度评价标准;体外给药未见毒副反应。结论：创面灵具有抗过敏、止痒作用,对皮肤无过敏反应、无刺激性,体外使用无毒副作用。