The development of water maze-learning ability in rats. (2) Effect of pretraining with the water-filled straight channel

To determine whether pretraining with the water-filled straight channel affects learning acquisition, we studied the water filled multiple T-maze learning ability in 8-weeks-old SPF Wistar-Imamichi rats. The performance time for the straight channel was markedly shortened at the 2nd and 3rd trial compared to the time at the 1st trial on the 1st day. But at subsequent trials on days 2 and 3 it was longer than at the 3rd trial on day 1. At the 1st trial on day 1, the performance time of the group unexperienced in the straight channel was more than three times that of the experienced group. In subsequent trials, however, both groups showed similar performance times. More errors were observed in the unexperienced group than in the experienced group at the 1st trial on day 1. No difference was found between the two groups in subsequent trials. These results indicate that the learning acquisition was largely influenced by pretraining in the straight channel at the 1st trial on day 1.     

百草枯对小鼠神经行为发育及学习记忆功能的影响

目的观察百草枯(PQ)对发育期C57BL/6J小鼠神经发育的毒性作用,并探讨百草枯对小鼠学习记忆的影响。方法 80只出生21日龄的仔鼠分为对照组(生理盐水)、1.25、2.5、5、10 mg/(kg·d)五组,灌胃染毒百草枯,每天一次,连续30 d。观察小鼠的一般生理和神经行为发育情况,并在染毒结束后进行Morris水迷宫实验和避暗实验,测试小鼠的学习记忆功能。神经行为学测试结束后取小鼠大脑,称重并进行病理检查,同时利用透射电镜观察各组小鼠中脑黑质部超微结构。结果染毒期间小鼠一般状况没有明显变化,染毒结束后各组体重没有统计学差异;在Morris水迷宫测试中,各组差异没有统计学意义,而避暗实验中与对照组相比,高剂量组的避暗潜伏期延长,差异有显著性(P<0.05);在病理切片和透射电镜观察中,在高剂量组分别观察到黑质细胞减少和神经元细胞凋亡。结论百草枯暴露对发育期小鼠成年后神经行为有影响,同时会使小鼠成年后出现脑组织的病理变化,发生器质性的病变。     

Comparative analysis of the learning ability in Morris water test in rats with the various rate of active acquisition of the avoidance conditioned reflex

Place learning in Morris place navigation task was studied in male rats of KHA (Koltushi High Avoidance) and KLA (Koltushi Low Avoidance) rat strains. These strains were selected for different rate of acquisition of active avoidance in a shuttle box. At the initial stages of learning and after changing the experimental conditions, the performance of KLA rats was significantly better than that of KHA. Analysis of individual escape latency showed that the latency of the platform finding in the first trial had a significant effect on successful performance in the second trial. This effect was different in KHA and KLA rats. As distinct from KLA, the KHA rats demonstrated more rigid strategy in spatial orientation, the clear-cut thigmotropism was characteristic for their behavior in water.     

Studies on the invasive ability of malarial merozoites (Plasmodium berghei).

Studies were performed to evaluate several methods for the artificial removal of Plasmodium berghei merozoites from infected mouse erythrocytes. These methods, many of which have been reported to yield free parasites capable of establishing a patent infection when injected into a suitable host, included NH4C1-mediated lysis, complement-mediated immune lysis, pressure filtration, and multiple-burst and continuous-flow sonication. Free parasites isolated from infected mouse blood were examined in vitro under conditions known to support merozoite invasion, and were found to be noninvasive, irrespective of the method used for their isolation. Although all methods tested achieved high degrees of lysis, none removed all intact parasitized erythrocytes. Using multiple-burst and continuous-flow sonication, the infective potential of free parasite preparations could be accounted for solely on the basis of the intact parasitized cells contaminating the free parasite preparations.     

Changes in the learning ability of epiphysectomized rats

The experiments on rats have shown changes in the learning ability of animals. The learning of locomotor reactions of escape and avoidance conditioned reflex was accelerated in animals after pinealectomy. Training of rats in U-shaped and 16-door mazes was significantly affected after pinealectomy. The index of reflex retention (1 and 7 days later) was not changed in the operated animals. Epithalamin (0.5 mg/kg for 5 days) selectively facilitated learning of visual and space discrimination.     

Effect of selective muscarinic receptor agonists and antagonists on active-avoidance learning acquisition in rats

Effect of some selective muscarinic receptor agonists and antagonists was investigated on learning acquisition in an active-avoidance paradigm in rats which records an anticipatory conditioned avoidance apart from the classical conditioned avoidance response. The muscarinic M1 agonists, arecholine, pilocarpine and McN-A-343, facilitated learning acquisition, which was attenuated by the selective M1 antagonist, pirenzepine. On the other hand, M2 receptor agonist, carbachol, and physostigmine, induced a dose-related dual response, with lower doses retarding and higher doses facilitating the learning acquisition. The former effect was attenuated by gallamine, a muscarinic M2 antagonist, while the latter response was inhibited by pirenzepine, indicating that these putative M2 receptor agonist lose their receptor specificity on dose increment. The selective M2 receptor antagonists, gallamine and AF-DX 116, facilitated learning acquisition, which was inhibited by pirenzepine and the acetylcholine synthesis inhibitor hemicholinium. The results support the cholinergic hypothesis of learning and memory and indicate that M1 receptor agonists and M2 receptor antagonists are likely to prove beneficial in memory deficits. The data also indicates that the clinical dose of some drugs, like physostigmine, needs to be carefully established for optimum therapeutic benefit.     

Effect of ketamine on ERK expression in hippocampal neural cell and the ability of learning behavior in minor rats

To study the effects of ketamine on ERK expression in hippocampal neural cell and the ability of learning behavior in minor rats. Seventy-two Sprague–Dawley rats of 21 days old were randomly divided into nine groups. The Y-maze was used to test the ability of learning and spatial localization. At the end of training, all rats were killed and the expression levels of ERK1, ERK2 and p-ERK1/2 were tested by immunohistochemistry. The learning times and total reaction time (TRT) of group K2a, K2b, K2c and K3 have significant differences compared with T group (P < 0.05). Immunohistochemical staining showed that the level of ERK1, ERK2 and p-ERK1/2 in all rats which received light-electricity integrated training increased remarkably relative to the C group (P < 0.01). The expression levels of ERK1, ERK2 and p-ERK1/2 in hippocampal neural cell of group K2a, K2b and K3 significantly decreased when compared with T group (P < 0.05). Therefore, the results demonstrate that administration of over-anesthetic ketamine may impair learning ability of 21 days old rats within 24 h. ERK signal transduction pathway may be involved in the ability of learning and spatial localization. The inhibition of ERK signal transduction pathway may be one of the mechanisms of the impairment of learning and memory ability by ketamine.     

跑台运动促进幼龄大鼠学习能力

为了探讨跑台运动对幼龄大鼠学习能力的影响,实验采用5周龄Sprague-Dawley大鼠,随机分为安静对照组和跑台运动组,其中跑台运动组大鼠以低强度进行为期一周的跑台运动;然后使用Morris水迷宫,对两组大鼠的定位航行和空间探索能力进行分析。在定位航行实验中,运动组大鼠寻找到平台的潜伏期明显短于对照组（P〈0．05）;并且随着训练次数的增加,运动组大鼠的游泳速度明显高于对照组（P〈0．01）;另外,运动轨迹的弯曲度表明运动组大鼠还表现出了较强的寻找平台的动机以及对平台位置较为准确的空间定位能力。在空间探索实验中,两组大鼠的游泳速度并没有明显差异,从大鼠在各象限内穿越平台相应位置的次数来看,运动组大鼠在D象限穿越的次数高于对照组,但无统计学差异（P〉0．05）。上述结果提示,低强度的跑台运动在短时间内便可以明显提高幼龄大鼠的学习能力。     

Effect of dietary alpha-linolenate/linoleate balance on brain lipid compositions and learning ability of rats

Spontaneously hypertensive rats (SHR) and normotensive control, Wistar/Kyoto (WKY) rats through two generations were fed a semipurified diet supplemented either with safflower oil (rich in linoleate) or with perilla oil (rich in alpha-linolenate). The cerebral lipid contents and phospholipid compositions did not differ between the two dietary groups of SHR rats. There were also no differences in the unsaturated/saturated ratios of individual phospholipids or the proportions of plasma-logens. However, the proportions of (n-3) and (n-6) fatty acids were significantly different. Decreases in the proportions of docosahexaenoate [22:6 (n-3)] in phosphatidylethanolamine and phosphatidylserine in the safflower oil group were compensated for with increases in the proportions of docosatetraenoic [22:4 (n-6)] and docosapentaenoic [22:5 (n-6)] acids as compared with the perilla oil group. These differences in phospholipid acyl chains were much smaller than the difference in the proportions of linoleate and alpha-linolenate of the diets. In a brightness-discrimination learning test, the total number of responses to the positive and negative stimuli were less in the groups fed perilla oil. However, the alpha-linolenate-deficient group took longer to decrease the frequency of R- responses and therefore longer to learn the discrimination. Consequently, the correct response ratios were higher in the perilla oil groups than in the safflower oil groups. Thus, the dietary alpha-linolenate/linoleate balance influenced the (n-3)/(n-6) balance of polyenoic fatty acids differently among brain phospholipids.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of luteolin on learning acquisition in rats: involvement of the central cholinergic system

The study was conducted to investigate the ameliorating effects of luteolin on memory acquisition in rats. The effects of luteolin on scopolamine-induced impairment of passive avoidance response were evaluated primarily, as well as the role of the central nervous system through the use of central neurotoxins and central nervous antagonists. Luteolin was not reversed by scopolamine N-methylbromide (M-SCOP) but blocked the impairment of learning acquisition induced by cholinergic neurotoxin (ethylcholine aziridinium, AF64A) and muscarinic (scopolamine hydrobromide, SCOP) and nicotinic (mecamylamine, MECA) receptor antagonists. However, it did not block dopaminergic neurotoxin (6-hydroxydopamine, 6-OHDA)-induced and serotonergic neurotoxin (5,7-dihydroxytryptamine, 5,7-DHT)-induced impairments. From these results, we suggest that the attenuating effect of luteolin (10 mg/kg, i.p.) on the deficits of passive avoidance performance induced by SCOP may be related to the increases in the activities of central muscarinic and nicotinic receptors.     

Effect of etimizol on instrumental learning in rats

The action of etimizol on the acquisition of the conditioned reflexes with different complexity and biological significance of reinforcement was studied. The acquisition was performed in a shuttle box and U-shaped maze using food and footshock stimuli. The time interval between administration of etimizol (3 mg/kg) and the onset of learning varied between 0.5 and 3 h in the several series. Etimizol did not facilitate the learning in rats whatever the time of administration and biological modality of reinforcement. It is suggested that the positive effect of etimizol on the memory is related to its influence on the consolidation stage.     

小檗碱对血管性认知功能障碍模型大鼠学习记忆能力的影响*

目的:观察小檗碱(berberine)对血管性认知功能障碍(VCI)大鼠学习记忆的影响。 方法:68只Wistar大鼠随机分为:正常组10只、 假手术组10只、造模组48只。造模组大鼠行双侧颈动脉结扎术制备血管性认知功能障碍模型,造模后大鼠又随机分为血管性认知功能障模型组、小檗碱低剂量(20 mg/kg)组、中剂量(40 mg/kg)组和高剂量(60 mg/kg)组(每组大鼠10只)。治疗组腹腔注射不同剂量的小檗碱,其余组腹腔注射生理盐水,每天1次,共34 d。给药28 d后,Morris水迷宫检测大鼠学习记忆能力;水迷宫实验后,检测超氧化物歧化酶(SOD)活性和谷胱甘肽(GSH)、丙二醛(MDA)以及前脑皮层TNF-α、IL-1β、5-HT的含量与单胺氧化酶(MAO)的含量。 结果:与假手术组比较,模型组大鼠逃避潜伏期显著延长(P＜0.01),通过平台次数显著减少(P＜0.01),海马或前脑皮层SOD、GSH和5-HT水平明显降低(P＜0.01),MDA、TNF-α、IL-1β和MAO水平明显升高(P＜0.01);与模型组相比,小檗碱各治疗组逃避潜伏期显著缩短(P＜0.01,P＜0.05),通过平台的次数显著增加(P＜0.01,P＜0.05),海马或前脑皮层SOD、GSH 和5-HT水平明显升高(P＜0.01),MDA、TNF-α、IL-1β和MAO水平明显降低(P＜0.01)。结论:小檗碱显著提高血管性认知功能障碍模型大鼠的空间学习记忆能力,其机制可能与小檗碱调节大鼠的海马抗氧化应激、抗炎性反应和前脑皮层单胺类神经递质系统的作用有关。小檗碱60 mg/kg组作用较好。     

Studies on the earthy-musty odours in natural water (IV). Mechanism of earthy-musty odour production of actinomycetes

Many reservoirs for water supply have been troubled with earthy-musty odour compounds--2-metylisoborneol (2-MIB) and geosmin. Both of these compounds are terpenoid and related to the metabolite of L-methionine. An experiment using [CD3]methionine and [14CH3]methionine showed that the C-2 methyl group in 2-MIB originate from L-methionine. In the incubation experiment with 10-1000 mg/l of L-methionine, 2-MIB and geosmin appeared in the earlier stages, in greater amounts than in the control. The maximum production of 2-MIB and geosmin increased considerably in the experiments with 10 and 100 mg/l of L-methionine. The effective time for L-methionine addition was after 1 d. Additions after 3 and 5 d were similar to the control. In the incubation experiment with 10-1000 mg/l of folic acid, 2-MIB and geosmin increased only during the 1000 mg/l addition. There seems to be little doubt that L-methionine takes part in the metabolism of 2-MIB and geosmin.     

Studies on the earthy-musty odours in natural water (IV). Mechanism of earthy-musty odour production of actinomycetes

Many reservoirs for water supply have been troubled with earthy-musty odour compounds—2-methylisoborneol (2-MIB) and geosmin. Both of these compounds are terpenoid and related to the metabolite of l-methionine. An experiment using [CD₃]methionine and [¹⁴CH₃]methionine showed that the C-2 methyl group in 2-MIB originate from l-methionine. In the incubation experiment with 10–1000 mg/l of l-methionine, 2-MIB and geosmin appeared in the earlier stages, in greater amounts than in the control. The maximum production of 2-MIB and geosmin increased considerably in the experiments with 10 and 100 mg/l of l-methionine. The effective time for l-methionine addition was after 1 d. Additions after 3 and 5 d were similar to the control. In the incubation experiment with 10–1000 mg/l of folic acid, 2-MIB and geosmin increased only during the 1000 mg/l addition. There seems to be little doubt that l-methionine takes part in the metabolism of 2-MIB and geosmin.     

Studies on the (pro) insulin biosynthesis of islets of Langerhans of sand rats (Psammomys obesus).

By feeding a regular laboratory chow, sand rats (Psammomys obesus) from our breeding colony gained different body weights, though they received approximately the same quantity of calories. Sand rats, reaching a body weight above 160 g (group B) showed significantly increased blood glucose values in contrast to the animals with a body weight under 160 g (group A). Isolated pancreatic islets of these two groups of sand rats were incubated with [3H]-leucine to study the incorporation of this amino acid into proinsulin and insulin. The incorporation into proteins of pancreatic islets of sand rats of group B was stimulated by 0.45 mg and 3.0 mg/ml glucose. In group A there was no further stimulation from 0.45 mg to 3.0 mg/ml glucose. Insulin secretion could be stimulated by glucose in both groups, but the stimulation was stronger in group B than in group A.     

苹果多酚对高尿酸血症大鼠抗氧化能力的影响

目的:高尿酸血症与许多现代慢性疾病关系密切,本文旨在研究苹果多酚对高尿酸血症大鼠体内抗氧化能力的影响.方法:采用对Wistar大鼠灌胃酵母膏及氧嗪酸钾的方法,制作高尿酸血症大鼠模型,再给其灌胃不同剂量苹果多酚.通过测定大鼠血清总抗氧化能力,脂质过氧化产物含量,超氧化物歧化酶、过氧化氢酶和谷胱甘肽过氧化物酶活力,探讨苹果多酚对高尿酸血症大鼠机体抗氧化能力的影响.结果:服用苹果多酚的高尿酸血症大鼠的血清总抗氧化能力显著升高,脂质过氧化产物水平相对降低;超氧化物歧化酶是受高尿酸血症和苹果多酚摄入影响最大的抗氧化酶,模型组酶活显著升高,而苹果多酚可以抑制该酶活力因大量尿酸生成引发的升高现象.结论:苹果多酚在适当剂量水平可以显著提高高尿酸血症大鼠的总抗氧化能力,抑制脂质过氧化,同时抑制因大量尿酸生成而引发的超氧化物歧化酶活升高,维护机体氧化还原平衡.