Toxicological evaluation of Yulangsan polysaccharide in Wistar rats: A 26-week oral gavage study

Although numerous studies have proven the medicinal values of Yulangsan polysaccharide (YLSP), the toxicity of this active ingredient is unknown. In the acute toxicity study, a single oral administration of 24 g/kg YLSP caused neither toxicological symptoms nor mortality, and the LD₅₀ was estimated >24 g/kg. In the chronic toxicity study, we administered doses of 0, 0.6, 1.2 and 2.4 g/kg YLSP in rats by oral gavage for 26 weeks followed by a 3-week recovery period. There was no mortality or remarkable clinical signs observed during this 26-week study. Additionally, there were no toxic differences in the following parameters: body weight, food consumption, hematology, clinical biochemistry, organ weight, and macroscopic findings. There were no adverse effects on histopathology observed in males or female rats treated with YLSP. Based on the results, the no-observed-adverse-effect-level of YLSP in rats is greater than 2.4 g/kg when administered orally for 26 consecutive weeks.     

The long-term effect of pinealectomy on the crypts of the rat gastrointestinal tract

Abstract: Previously it has been found that rat small bowel crypt cell hyperplasia occurred several weeks after pinealectomy. To determine if this effect was longer-lasting (because of the possible role of the pineal in bowel malignancy) the crypt cell proliferation rate was determined in rat small bowel and colon 6 months after pinealectomy, using a stathmokinetic technique. Although the hyperproliferative effect of pinealectomy was well maintained in the small bowel crypts after 6 months, the hyper proliferative effect in the colonic crypts was much less marked. There is no obvious explanation for these findings, although it is possible that regional differences in levels of gut neuropeptides or melatonin are involved. The mechanism of the effect of pinealectomy on the crypts remains unexplained—in particular, why the effect is so prolonged.     

Age-related Changes in Excitability and Recurrent Inhibition in the Rat CA1 Hippocampal Region

In hippocampal slices from male Wistar rats aged 1–34 months, we recorded the synaptic field potential responses of the CA1 neurons to stimulation of Schaffer collaterals. Eight electrophysiological indexes were extracted from input/output curves and compared in 11 age groups from 1 to 30 months. Neuronal excitability presented a U-shaped curve of development with a minimum at ˜7–8 months of age. There was a significant continuous increase in neuronal excitability, i.e. a decrease in excitatory postsynaptic potential (EPSP) producing both the threshold and half-maximal population spike from middle age (8–10 months) to senescence (30 months). Synaptic efficiency also increased in old rats to reach a maximum during senescence, i.e. both the current for threshold EPSP and that for half-maximal EPSP reached a minimum in senescence, although the earlier developmental patterns of these two indexes were non-linear. The duration of the field EPSP elicited with maximal stimulation presented an abrupt decay after the first month. Aged animals presented a relatively small maximal population spike. Recurrent inhibition was most prominent on neuronal excitability rather than synaptic strength. Measured as the percentage change in the half-maximal EPSP and half-maximal population spike, recurrent inhibition was found to decrease during the first 7–10 months of life and remained small in later development.     

穹隆-海马伞切断对大鼠脑内TrkA表达的影响

①目的　探讨穹隆 海马伞切断对大鼠脑内不同部位神经生长因子受体TrkA表达的影响及临床意义。②方法　成年健康雌性Wistar大鼠 10只 ,随机分为穹隆 海马伞切断模型组和假手术组。两组大鼠均常规取海马CA1区、皮质区、杏仁复合体区、基底前脑Meynert核等部位脑组织与假手术组比较TrkA阳性细胞表达情况。③结果　假手术组大脑各观察区有基础水平的TrkA表达。模型组大脑海马CA1区、大脑皮质区、杏仁复合体区以及Meynert核区TrkA阳性细胞数明显减少 (t=3.94 4～ 8.4 4 2 ,P <0 .0 5 )。 ④结论　穹隆 海马伞切断可致大鼠脑内多部位TrkA表达减少 ,其可能是导致认知和情绪损伤的原因之一。     

断流和分流术后门脉高压性胃病大鼠Caspase-3 mRNA表达的变化

目的:研究断流术和分流术对门脉高压性胃病(PHG)大鼠胃粘膜细胞Caspase-3 mRNA表达的影响.方法:将48只Wistar雄性大鼠随机分成正常对照组、模型对照组、断流术组和分流术组.应用逆转录PCR(RT-PCR)测Caspase-3 mRNA表达.结果:正常对照组自由门脉压为(1.15±0.13)kPa,模型对照组升高至(2.68±0.16)kPa(P＜0.01),断流术组升高达(2.73±0.27)kPa,分流术组回降至(1.57±0.23)kPa,与模型对照组比较差异有统计学意义(P＜0.01).Caspase-3 mRNA表达有类似变化,正常对照组、模型对照组、断流术组和分流术组各组表达分别为0.48±0.02、0.96±0.04、1.04±0.06和0.65±0.03.结论:正常鼠胃粘膜上皮细胞凋亡基因Caspase-3 少量表达,PHG时Caspase-3 mRNA表达增加,断流术后Caspase-3 mRNA表达进一步上调,分流术后Caspase-3 mRNA表达有所下调.     

Measurement of biological activity of somatotropin in hypophysectomized rats

目的：建立测定生长激素（ＧＨ）在体生物活性的方法．方法：以去垂体大鼠体重增长（ＢＷＧ）和胫骨骺软骨板宽度（ＴＥＷ）为指标，观察动物性别、给药途径、次数和周期不同对效应的影响；同时进行４ｄＢＷＧ，６ｄＢＷＧ和６ｄＴＥＷ法，测定ＧＨ的效价（平行线３×３设计）．结果：♀和♂ｓｃ和ｉｍ给药以及每日给药１次和２次的ＢＷＧ和ＴＥＷ差异无显著意义．给药６ｄ比给药４ｄ引起较大的ＢＷＧ和ＴＥＷ（Ｐ＜００５）．４ｄＢＷＧ法和６ｄＢＷＧ法在００２０－０５００ＩＵ·ｄ－１有较好的λ值（００６６０和０１７４７）和ｒ值（０９０００和０９２３７）；４ｄＢＷＧ，６ｄＢＷＧ和６ｄＴＥＷ法测得ｒｈＧＨ的效价为４６１３２，３９８２９和４８０２３ＩＵ／ａｍｐ．６ｄＢＷＧ法有较小的λ值和较低的ＡＲＦＬ值．结论：可在同一组去垂体大鼠体内同时用４ｄＢＷＧ，６ｄＢＷＧ和６ｄＴＥＷ法测ＧＨ活性，以６ｄＢＷＧ法较好．     

Catecholamines in the adrenals of August and Wistar rats with acute emotional stress

Acute emotional stress caused by immobilization and cutaneous electrical stimulation increases the relative weight of adrenals in Wistar rats and decreases it in August rats. The epinephrine and norepinephrine contents of the adrenals in control and stressed August rats are higher than in Wistar rats. Acute stress lowers the levels of these biogenic amines in the adrenals of both strains, particularly in Wistar rats. The left adrenal gland of control and stressed August rats, but not of Wistar rats, has a higher content of biogenic amines than the right, and both adrenals of stressed August rats contained higher dopamine concentrations than those of stressed Wistar rats. Presumably, epinephrine and norepinephrine are resynthesized in the adrenals of stressed August rats at higher rates than they are released from these glands, while the adrenals of Wistar rats respond to stress by rapidly releasing these catecholamines and resynthesizing them at a slow rate. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 123, No. 6, pp. 645–648, June, 1997     

骨质疏松对骨的粘弹性性质影响的实验研究

目的研究正常大鼠股骨和维甲酸所致大鼠骨质疏松股骨的压缩粘弹性性质,为临床提供生物粘弹性力学参数。方法选用175～245g,6月龄Wistar大鼠30只,随机分为正常对照组15只,模型组15只。对模型组大鼠每日灌服维甲酸(70mg·kg-1·d-1),实验动物于第12周末处死。取股骨进行压缩应力松弛、蠕变实验。结果得出了正常对照组和模型组股骨应力松弛,蠕变数据和曲线。对应力松弛蠕变实验数据进行归一化处理,得出归一化应力松弛函数、蠕变函数及曲线。结论模型组的7200s应力松弛、蠕变量指标显著低于正常对照组(P<0.05)。     

全反式维甲酸对培养的大鼠动脉平滑肌细胞迁移的影响

目的 :研究全反式维甲酸 (ATRA)对培养的大鼠动脉平滑肌细胞 (VSMCs)迁移的影响。方法 :血管平滑肌细胞采用组织贴块法培养 ,ATRA(2 .5× 10 -6mol/L)分别作用经PDGF -BB(2 0ng/ml)和 10 0 %FCS趋化作用下的VSMCs,采用改良的Boydenchamber方法检测VSMCs的迁移活性。结果 :ATRA作用的VSMCs对PDGF -BB和 10 0 %FCS的化学趋化活性明显减弱。结论 :ATRA具有抑制VSMCs迁移的作用。     

格列齐特对糖尿病大鼠血液流变学的影响

目的　研究格列齐特对四氧嘧啶糖尿病大鼠血液流变学的影响。方法　用四氧嘧啶造成 Wistar大鼠糖尿病模型 ,于造模后 4周开始用格列齐特灌胃 8周。比较给药前后的血液流变学变化。结果　造模后的大鼠给予格列齐特后血液流变学的各项指标与治疗前相比均有显著性差异 (P<0 .0 5 )。结论　格列齐特可明显改善糖尿病大鼠的血液流变学。