Spinal cord restitution following compression injuries in rats

Spinal cord compression injuries were produced in rats by applying weights to a plate 2.2 x 50 mm in size, placed on the exposed midthoracic dura covering the spinal cord. The influence of force and duration of compression was studied by using 3 different weights, 20, 35 and 50 g, applied for 1, 5 and 10 min. Postoperative neurological function was tested by the inclined plane method and the rats were observed for 3 weeks. Neurological impairment increased with force and duration of compression. It is therefore reasonable to conclude that patients suffering from spinal cord injury should be investigated immediately for signs of persistent cord compression. If this is present, early decompression might be of value, although nothing is known in man concerning the limits of force and duration of compression permitting postoperative neurological recovery.     

交链孢酚单甲醚在大鼠小鼠体内的分布

对食管癌高发区粮食中分离的互隔交链孢霉的毒素交链孢酚单甲醚(AME)在大鼠、小鼠体内的分布进行研究。给动物腹腔内注射氚标记的交链孢酚单甲醚(~3H-AME),然后在不同时间测各脏器的放射性。结果表明:在所测9个脏器中,2h肝脏含量最高,食管下段在大小鼠分别居第四和第三。但大小鼠分别在72、24h则以食管下段最高,说明AME及其代谢物在此清除较慢,即对其有较高的亲和力。     

大鼠肺微血管和肺泡铸型的扫描电镜观察

用扫描电镜观察以甲基丙烯酸甲酯灌注鼠的肺微血管和肺泡。胸膜下毛细血管较稀疏,网孔粗大。毛细血管部分成锐角折返,亦可见毛细血管盲端。肺泡隔毛细血管均成扁平状膨大,且相互吻合成单层密集网。肺泡铸型为大小不等、不规则的多面体,表面可见肺泡Ⅱ型细胞核之压迹。两肺泡之间可见呈桥式连接的肺泡孔,亦可见部分呈三通管样相连。     

中枢去甲肾上腺素能神经元在脑水肿发生过程中的作用实验研究

为探讨中枢去甲肾上腺素（ＮＥ）能神经元兴奋对脑水肿的影响，作者观察了刺激或损毁大鼠右侧蓝斑后，同侧大脑半球脑水含量的变化．结果，ＮＥ能神经元兴奋时，同侧半球脑皮质神经元也处于兴奋状态，脑内ＮＥ，肾上腺素（Ｅ）含量分别达正常组的３０７．４６％和２９９．４１％，脑水含量（７９．２１±０．２８％）也较正常组（７８．４６±０．４２％）明显增高（Ｐ＜０．０１）．损毁蓝斑后，同侧半球脑内ＮＥ，Ｅ含量仅为正常组的１２．８０％和３２．３１％，脑水含量稍有下降，无统计学意义．提示中枢ＮＥ能神经元兴奋可能是脑水肿发生过程中的重要环节之一．     

Intrahippocampal Injection of Endothelin-1: A New Model of Ischemia-induced Seizures in Immature Rats

Summary:  The goal of this study was to develop a new model of ischemia-induced seizures in immature rats using injection of vasoconstrictor Endothelin-1 (ET-1) into the brain. ET-1 (10, 20, or 40 pmol) was infused into the left dorsal hippocampus of freely moving Wistar rats 12 (P12) and 25 (P25) days old. Animals were then video/EEG-monitored for 100 min and monitoring was repeated 22 h later. Parameters of electrographic seizures (frequency and mean duration) as well as pattern of their behavioral correlates were evaluated. The pattern of behavioral seizures was used to develop model-specific scoring system. Cresyl violet and Fluoro Jade-B-staining were used to evaluate brain damage. Extension of the lesion was correlated with seizure severity. After ET-1-injection, seizures occurred in 83–100% animals of all age-and-dose groups and persisted for 24 h except P12 rats with 10 pmol. There were no differences in average seizure duration (18–40 s) or seizure frequency (3–7 seizures/100 min) among individual dose-groups. Between the 1st and 2nd observation period, total seizure duration decreased in 71% of P12 and 47% of P25 rats. Electrographic seizure activity was most frequently accompanied by clonus, incidence of more severe convulsions (barrel rolling or generalized clonic seizures) increased with dose of ET-1. Morphologic examination did not reveal any dose-related difference in damage severity, hippocampal damage was however more extensive in P12 compared to P25 animals. Seizure severity correlated positively with severity of the damage in both age groups. Our study presents focal injection of ET-1 into the brain as a new and practical model of ischemia-induced seizures in immature rats.     

低氧分压对大鼠勃起功能的影响

目的探讨低氧分压对大鼠勃起功能障碍（ED）的影响。方法48只成年白色雄性SD大鼠随机分为对照组和实验组，每组按照实验时间（2周、6周、10周）分为3个亚组，每个亚组8只。实验组置于密闭低氧舱中饲养，对照组在正常环境中饲养，其他条件相同。分别观察其勃起功能，采用免疫组化SP法检测神经源性一氧化氮合成酶（nNOS）阳性神经纤维的数量、内皮源性一氧化氮合成酶（eNOS）的表达。结果实验组与对照组比较：（1）大鼠勃起次数明显降低（P〈0．001）；（2）nNOS阳性神经纤维数量、eNOS蛋白的表达均有显著性差异（P〈0．01）。实验组间比较：勃起次数6周组明显低于2周组，10周组稍高于6周组；nNOS阳性神经纤维数量有显著性差异（P〈0．01）；eNOS的表达6周组最低，10周组有所回升。结论低氧分压致大鼠勃起功能受损和nNOS、eNOS的表达下降。nNOS染色阳性神经纤维数量的减少、eNOS表达的下降，可能是低氧分压环境中大鼠ED发生的原因之一。     

Time course of vascular prostanoid production in the fructose‐hypertensive rat

1 There is a relationship between hypertension, insulin resistance and an altered plasmatic lipid profile known as ‘metabolic syndrome’. Fructose (F) overload induces in the rat a mild hypertension associated with metabolic alterations such as hyperglycemia, hypertriglyceridemia and insulin resistance, resembling such syndrome. 2 Prostanoids (PR), metabolites of arachidonic acid, include vasoactive substances synthesized and released by the vessel wall. An altered pattern of PR release has been previously found in mesenteric vessels of experimental diabetic rats. 3 This study analyzed the effects of F‐overload during different periods (4, 9, 15 and 22 weeks) on PR release in aorta (A) and mesenteric vascular beds (MVB). Animals received tap water (control) or F solution (10% w/v) to drink. 4 Rats with F overload showed significantly higher systolic blood pressure, glycemia and triglyceridemia than controls; but no differences in this parameters were found among periods of treatment either in controls or experimental animals. 5 In A, prostacyclin was decreased at 9, 15 and 22 weeks of treatment when compared to 4 weeks and controls. In MVB, prostacyclin showed different patterns of release in the studied periods of F overload. Prostaglandin (PG) E₂ diminish in MVB at the same extent in all periods. No changes were observed in A. The vasoconstrictor thromboxane was elevated in the MVB at 9 weeks. PGF₂α, also a vasoconstrictor, remains unchanged. 6 In conclusion, F overload provokes in the rat a decrease in the vascular production of vasodilator PR and, in one of the studied periods, an increase in the release of the vasoconstrictor thromboxane, leading to a negative imbalance in the prostacylin/thromboxane ratio. This could be involved in the blood pressure alterations found in this experimental model of metabolic syndrome.     

神经病理性疼痛老年大鼠海马CA1区突触长时程增强的变化

目的观察神经病理性疼痛老年大鼠海马CA1区突触长时程增强(LTP)的变化。方法老年雄性Wistar大鼠15只,随机均分为三组。模型组,结扎左侧L4/L5脊神经;D-2-氨基-5-磷酸戊酸(AP5)组,侧脑室输注AP5,余同模型组;假手术组,操作同模型组,但不结扎。观察大鼠行为变化,连续3周测定大鼠电痛阈值,1次/周;记录海马CA1区树突层兴奋性突触后膜电位(EPSP)、输入/输出曲线及LTP的变化。结果模型组与AP5组大鼠术后行为异常,术后各时点电痛阈值低于术前值及假手术组相应时点值(P<0.05);三组基础EPSP幅值稳定,最大基础EPSP幅值的50%组间比较差异无统计学意义;模型组LTP高于其他两组(P<0.05)。结论结扎老年大鼠L4/L5脊神经所致的神经病理性疼痛,不干扰海马CA1区突触及锥体细胞兴奋性,但可易化该区突触LTP。     

运动对大鼠腓肠肌一氧化氮含量和铁转运蛋白表达的影响

目的观察游泳运动后大鼠腓肠肌一氧化氮(NO)含量及铁转运相关蛋白表达的变化,探讨运动对骨骼肌铁代谢的调节机制。方法20只雌性SD大鼠随机分为对照组和运动组(每天游泳1.5小时,6次/周),每组10只。实验10周后分别采用试剂盒测定两组大鼠腓肠肌和血清一氧化氮合酶(NOS)活性及NO含量,免疫组织化学方法测定腓肠肌二价金属离子转运体1(DMT1)、膜铁转运蛋白1(FP1)和转铁蛋白受体1(TfR1)的表达,分析其平均光密度变化。结果(1)运动组大鼠血清和腓肠肌NO含量和NOS活性均显著高于对照组(P<0.05);(2)运动组大鼠腓肠肌DMT1(IRE)和TfR1表达较对照组显著增加,FP1表达显著减少(P<0.05),而DMT1(non-IRE)表达无明显变化。结果提示运动可能通过增加NOS活性刺激NO合成增加,进而调节腓肠肌铁转运蛋白的表达,提高腓肠肌摄铁能力,以满足运动中机体对铁的需求。