Juvenile hypocalcemia provokes persistent electroencephalographic change in renally compromised rats.

In view of the putative involvement of calcium in uremic encephalopathy and the critical importance of this element in juvenile development, we examined the effect of temporary restriction of dietary calcium intake on serum chemistry and the quantitative electroencephalogram (Q.EEG) in unilaterally 3/4 nephrectomized juvenile male Sprague-Dawley rats. Animals were renally infarcted at 22-26 days of age (50-74 g) and placed on one of two isocaloric dietary regimens: powdered normal rat diet (ND, n = 25) or low calcium diet (LCD, n = 8) for 30 days. At this time, ND animals showed normal serum chemistries, whereas LCD rats were hypocalcemic and azotemic with significantly elevated blood urea nitrogen (BUN) and serum creatinine concentrations and reduced renal creatinine clearance values. All animals thereafter received ND for 25-34 further days, during which time chronic Q.EEG electrodes were implanted. At the end of the common ND feeding period, serum chemistry values were equal and normal in both groups. The average theta/alpha ratio (TAR) of the overnight Q.EEG was assessed for 3 days. We found that the TAR of previously LCD animals was significantly elevated compared with ND rats. This indicates an encephalopathic slowing of the background rhythm of these animals. We conclude that, following restoration of a transient uremic and hypocalcemic episode induced by LCD feeding, the Q.EEG background frequency of juvenile renally impaired rats was abnormally slow after 30 days of ND feeding.     

Thiamin absorption is not compromised in folate-deficient rats

Thiamin absorption and excretion were assessed in rats with severe folate deficiency (FD) by determining the fate of oral 3H-labeled and intravenous 14C-labeled thiamin over a 6-h test period. Thiamin status was evaluated in these same rats by measuring transketolase activity levels of blood before (TKA) and after (TPPE) addition of thiamin pyrophosphate to the incubation mixture of the assay procedure. Two additional experiments assessed active transport of thiamin and the effect of dietary succinylsulfathiazole (SST) on TKA and TPPE in rats with moderate FD. Intestinal absorption in general and thiamin absorption in particular and thiamin status were unaltered in rats with severe FD. Inanition associated with severe FD may impair thiamin status. Thiamin absorption by active transport was not compromised in FD, and dietary succinylsulfathiazole did not affect thiamin status.     

Ethanol discrimination in Fawn-Hooded rats is compromised when compared to other strains

The drug discrimination paradigm was used to evaluate the behavioral differences in response to ethanol between three strains of rats, viz., Sprague-Dawley, N/Nih and Fawn-Hooded. This latter group is thought to have a genetically-transmitted diminished central serotonin function. Each group of rats was trained to discriminate between the stimulus properties of 600 mg/kg ethanol and its vehicle in a two-lever, food-motivated operant task. Results indicate that the Fawn-Hooded rats required a significantly longer time and a higher ethanol dose to reach criterion discrimination performance. Furthermore, the ED50 value of the Fawn-Hooded rats, once trained, was higher than the Sprague-Dawley or N/Nih rats. The possibility that a reciprocal relationship exists between lowered central serotonin concentrations and higher alcohol consumption is suggested and the hypothesis that the diminished ability to recognize the interoceptive stimuli produced by ethanol may result in larger amounts of ethanol being consumed is offered.     

Learned food-cue stimulates persistent feeding in sated rats

Cues that predict food can stimulate appetite and feeding independent of physiological hunger. How long such effects might last is currently unknown. Here we began to characterize long-term effects in a rodent model of cue-potentiated feeding. Rats were conditioned to associate a tone with food pellets distinct from their regular laboratory chow, and then were tested along with controls for food consumption following tone presentations. In Experiment 1, rats were tested under sated or food-deprived conditions to determine whether fasting would augment cue-driven feeding. Rats in the control group regulated intake based on physiological state, while conditioned rats consumed similar large amounts of food regardless. Experiment 2 tested the durability of cue-potentiated feeding to repeated testing in sated rats. We observed robust cue-potentiated feeding during the first two tests, while in the third and fourth tests both groups ate similar large amounts of pellets. In both experiments the conditioned tone-cue induced binge-like consumption of the cued food and persistent feeding for the duration of 4-h tests. Rats then failed to adjust daily chow consumption to account for their increased intake post-cue. In summary, brief cue priming stimulated substantial intake in sated states that was behaviorally uncompensated for by homeostatic mechanisms.     

Bone morphology,strength and density are compromised in iron-deficient rats and exacerbated by calcium restriction

Rats fed an iron-deficient diet develop decreased bone mass and increased fragility. This study documents that rats fed two minerals likely to be low in American diets, calcium and iron, had dramatic changes in bone density and morphometry. Weanling male Long-Evans rats were fed a diet that was either deficient in iron (5-8 mg/kg or 89-143 micro mol/kg diet), low in calcium (1.0 g/kg Ca or 0.025 mol/kg diet) or deficient in both minerals or a control diet with adequate iron and calcium. Eight rats in each of the four groups were fed their respective diets for 5 wk. Total femur and tibia widths were decreased in all experimental groups and iron-deficient rats had decreased medullary widths compared with the other three groups. Cortical width was decreased in all experimental groups, with either the calcium-restricted group or the iron-deficient + calcium-restricted group showing the greatest impact. Both calcium restriction and iron deficiency, either singly or in combination with one another, had reduced cortical bone area. Analysis by dual-energy X-ray absorptiometry revealed a pattern of significant reductions in bone density for iron-deficient, calcium-restricted and the combination of calcium-restricted+ iron-deficient rats, respectively, as compared with controls. These data suggest that a commonly deficient trace element in American diets, iron, has a negative impact upon bone health, and this impact is exacerbated by a calcium-restricted diet.     

慢性心房颤动患者心室率变化意义的探讨

目的分析探讨慢性心房颤动患者心室率变化的意义,为临床如何预防心房颤动患者出现脑栓塞、心功能降低等并发症提供理论依据。方法将入院或门诊就诊病程超过1年的慢性心房颤动患者分为脑栓塞组和非脑栓塞组,各30例,观察比较两组患者临床特征,动态心电图计数比较两组患者最大心室率、平均心室率及最小心室率变化,超声心动图测定两组患者左房内径大小、左室射血分数变化,血浆凝血酶原时间凝固法测定两组患者血浆凝血酶原时间国际标准化比值(I NR)变化。结果两组患者一般临床特征、左房内径大小、I NR值比较,差异无统计学意义。脑栓塞组最大心室率、平均心室率及最小心室率均明显快于非脑栓塞组,左室射血分数明显低于非脑栓塞组。结论慢性心房颤动患者降低心室率对预防脑栓塞、左心功能降低有重要意义。     

慢性心房颤动患者心室率变化意义的探讨

目的分析探讨慢性心房颤动患者心室率变化的意义，为临如何预防心房颤动患者出现脑栓塞、心功能降低等并发症提供理论依据。方法将入院或门诊就诊病程超过1年的慢性心房颤动患者分为脑栓塞组和非脑栓塞组，各30例，观察比较两组患者临床特征，动态心电图计数比较两组患者最大心室率、平均心室率及最小心室率变化，超声心动图测定两组患者左房内径大小、左室射血分数变化，血浆凝血酶原时间凝固法测定两组患者血浆凝血酶原时间国际标准化比值（INR）变化。结果两组患者一般临床特征、左房内径大小、INR值比较。差异无统计学意义。脑栓塞组最大心室率、平均心室率及最小心室率均明显快于非脑栓塞组，左室射血分数明显低于非脑栓塞组。结论慢性心房颤动患者降低心室率对预防脑栓塞、左心功能降低有重要意义。     

Early iron deficiency produces persistent damage to visual tracts in Wistar rats

Abstract

In this study, morphological changes in the optic nerve were determined by light microscopy in Wistar rats on an iron-deficient diet for 32 days or for 21 days followed by 10 days on an iron-recovery diet. The morphometric findings showed significantly fewer blood vessels and oligodendrocytes in the iron-deficient rats and iron-recovery rats than in the control group, as well as more astrocytes in the iron-recovery rats. Serum iron levels of the iron-deficient rats were significantly lower than those of the controls. On the other hand, iron-recovery rats had normal serum iron levels, but no change in the abnormal morphology of the myelinated axons and morphometric parameters. Our data indicate that iron is necessary for maintenance of the optic nerve cell structure, and morphological damage from iron-deficiency is not easily reverted by iron reposition.     

Neomycin has no persistent sparing effect on vitamin B-12 status in pectin-fed rats

In the present study, rats were depleted of vitamin B-12 with fiber-free or 5% pectin diets, with or without neomycin. Through use of this intestinal antibiotic reported to "spare" vitamin B-12, we sought to determine if bacterial fermentation of pectin might explain our previous observations of negative effects of pectin on vitamin B-12 status. However, neomycin did not lessen interference by pectin with vitamin B-12 metabolism. Pectin increased urinary methylmalonate and decreased propionate oxidation to a greater extent in the presence than in the absence of neomycin. Also, regardless of the presence of neomycin, the biologic half-life of injected [57Co]vitamin B-12 was 58 d for rats fed the fiber-free diets and only 38 d for rats fed 5% pectin diets. Neomycin delayed early fecal excretion of 57Co but had no persistent effect. Thus, neomycin-sensitive bacteria do not mediate the negative effects of pectin on vitamin B-12 status. Pectin may interfere directly with vitamin B-12 absorption or may stimulate vitamin B-12 uptake or propionate production by microbial species that have adapted to neomycin.     

去势雄性SD大鼠胰岛素敏感性的改变

目的 通过去势手术造成雄性SD大鼠低雄激素状态,并观察其胰岛素敏感性的改变.方法 将20只雄性SD大鼠随机分为对照组(n=10)及去势组(n=10).对去势组进行去势手术.手术8周后.观察各组动物体重改变、血清睾酮(T)、硫化去氢表雄酮(DHEAs)、空腹血糖(FBG)、空腹胰岛素(FIns)水平;并在第8周时进行高胰岛素正葡萄糖钳夹试验,以评价大鼠胰岛素敏感性.结果 去势组大鼠T水平明显下降(5.94±1.13降至0.11±0.02 nmol·L-1,P<0.01),DHEAs水平明显下降(12.49±3.17降至9.19±2.87 ng·ml-1,P<0.05),血清FIns水平(0.92±0.38 ng·dl-1)高于对照组(0.34±0.14 ng·dl-1)(P<0.01),葡萄糖清除率(GDR)(6.45±2.86 mg·kg-1·min-1)低于对照组(16.21±4.73 mg·kg-1·min-1),(P<0.01),FBG无明显差异.结论 雄性SD大鼠去势后,体内T、DHEAs降低,FIns升高,胰岛素敏感性明显下降.     

去势雄性SD大鼠胰岛素敏感性的改变

目的通过去势手术造成雄性SD大鼠低雄激素状态,并观察其胰岛素敏感性的改变。方法将20只雄性SD大鼠随机分为对照组（n=10）及去势组（n=10）。对去势组进行去势手术。手术8周后,观察各组动物体重改变、血清睾酮（T）、硫化去氢表雄酮（DHEAs）、空腹血糖（FBG）、空腹胰岛素（Fins）水平;并在第8周时进行高胰岛素正葡萄糖钳夹试验,以评价大鼠胰岛素敏感性。结果去势组大鼠T水平明显下降（5．94±1．13降至0．11±0．02nmol·L^-1,P〈0．01）,DHEAs水平明显下降（12．49±3．17降至9．19±2．87ng·ml^-1,P〈0．05）,血清Fins水平（0．92±0．38ng·dl^-1）高于对照组（0．34±0．14ng·dl^-1）（P〈0．01）,葡萄糖清除率（GDR）（6．45±2．86mg·kg^-1·min^-1）低于对照组（16．21±4．73mg·kg^-1·min^-1）．（P〈0．01）,FBG无明显差异。结论雄性SD大鼠去势后,体内T、DHEAs降低,Fins升高,胰岛素敏感性明显下降。     

Diurnal change in digestion and absorption of sucrose in vivo in rats

To clarify the physiological significance of circadian rhythmic changes in the activity of intestinal sucrase, the activity of digestion and absorption of sucrose in vivo were assessed during the daytime and the nighttime in rats fed ad libitum. When the jejunum was perfused at night with a solution containing sucrose in situ, the disappearance rate of sucrose from the lumen was higher than when perfused during the daytime, in parallel with the day/night difference in sucrase activity. The early response of plasma glucose to oral sucrose load in unanesthetized free-moving rats was also greater during the nighttime than the daytime. It was concluded that the digestion and absorption rate of sucrose shows circadian fluctuations under normal physiological conditions.     

慢性砷中毒大鼠肝脏血清酶活性变化分析

目的 探讨慢性砷中毒大鼠肝脏和肝线粒体损伤相关血清酶活性的变化,为揭示砷对机体毒性作用的机制及选择慢性砷中毒早期诊断酶学指标提供资料。方法 选用Wistar大鼠,经饮水给予75 mg/L三氧化二砷6个月。处死动物6个月,用差速离心法提取大鼠肝脏线粒体,用分光光度法测定肝脏线粒体呼吸酶及血清酶活性。结果 砷中毒大鼠肝脏线粒体细胞色素C氧化酶和三磷酸腺苷(ATP)酶活性下降;血清谷氨酸脱氢酶、鸟氨酸氨基甲酰转移酶、精氨酸酶、腺苷脱氨酶、谷胱甘肽硫转酶活性升高。结论 慢性砷中毒能够导致肝线粒体细胞色素C氧化酶和ATP酶的活性下降。血清中与肝细胞及线粒体功能有关的血清酶活性升高,进一步证实了砷中毒对肝细胞及其线粒体的损害作用。上述5种血清酶的测定,对于慢性砷中毒的辅助诊断可能具有一定的价值。     

Stress-induced change in tissue levels of ascorbic acid and histamine in rats

Effects of acute immobilization stress on the metabolism of ascorbic acid and histamine were studied in rats by determining changes in the tissue levels of these substances. Stress provoked a significant rise in the histamine levels of blood, stomach, kidney, lung and skin. The serum ascorbic acid level increased rapidly, whereas the amount of the vitamin in the lung and skin was reduced by stress. The hepatic ascorbic acid levels were modulated biphasically; there was a decrease within 15 minutes after the onset of the stress regimen, followed by an increase occurring during the next 15 minutes. There was a gradual decrease in the amount of ascorbic acid in the adrenal glands with a marked transient accumulation of corticosterone in the tissues. Administration of histamine caused an increase in the serum level of ascorbic acid, while it led to a transitory decrease in the hepatic level of the vitamin. These results suggest that the metabolism of ascorbic acid is modulated in rats suffering from stress. These changes in ascorbic acid metabolism seem to be closely associated with the stress-induced alteration of histamine metabolism.     

Time-course of the change in blood pressure level in magnesium-deficient Wistar rats

The aim of the present study was to determine whether a severely Mg-deficient diet can modify blood pressure in rats and whether these alterations in blood pressure are associated with a change in in vivo cardiovascular reactivity, alteration in plasma lipids and modification of the production of hormones involved in blood pressure regulation. Weanling male Wistar rats were pair-fed for 40 weeks with control (960 mg Mg/kg) and Mg-deficient (80 mg Mg/kg) diets. At 2 weeks, blood pressure was lower in Mg-deficient rats, while heart rate was greater than in controls. Mg-deficiency-induced hypotension was transitory and the administration of antihistamine agents inhibited the appearance of this hypotensive phase, suggesting that histamine may play a role in lowering blood pressure. Until 15 weeks, blood pressures were similar for control and Mg-deficient rats. Thereafter, blood pressure rose gradually until the end of the experiment in Mg-deficient rats. Heart rate remained higher in hypertensive Mg-deficient rats. After 21 weeks, in vivo cardiovascular reactivity to noradrenaline was lower and reactivity to angiotensin II was unchanged in hypertensive Mg-deficient rats. At 2 and 21 weeks, hypomagnesaemia was accompanied by higher plasma levels of Ca, triacylglycerols and cholesterol. Plasma renin activity was higher at week 2, whereas levels of plasma angiotensin converting enzyme were lower at 2 and 21 weeks in Mg-deficient rats. The plasma aldosterone level was higher at 2 and 21 weeks while the vasopressin level did not change. Plasma corticosterone levels were lower at 2 weeks and higher at 21 weeks. It is concluded that Mg deficiency induced a transitory hypotension followed by a sustained hypertension in rats. The release of vasodilator inflammatory agents may contribute to the early hypotension. The hypertensive phase may be explained by the increased sympathetic nervous activity induced by Mg deficiency even though the contribution of several hormonal systems implicated in blood pressure regulation remains to be elucidated.     

Acquisition of texture-cued fasting-anticipatory meal-size change in rats with adequate energy intake

To determine if an increase in intake at a meal before a long fast can be conditioned to food texture cues, male Sprague-Dawley rats were given a high- or low-fat diet in one texture (powder or pellet) for 1 h prior to a 12.5-h fast and in the other texture before a 3-h fast. Each group (N = 9) went through a pseudorandom sequence of four duplicates of each texture-fast pairing over 4 experimental days in each of three training trials, followed by one 4-day trial under extinction, i.e. without the difference in fast lengths between textures. Neither the high-fat group nor the low-fat group as a whole gave a clear indication of a learnt texture-cued increase in meal size before the longer fast relative to the shorter fast. However, the rats trained on the high-fat diet that had the highest intakes on the first 4 days of training showed a relative increase in the amount eaten of the texture predicting the longer fast during the third training trial, and this effect also approached statistical significance in the extinction test. These results provide some support for the conclusion that anticipatory hunger/satiety can be differentially conditioned to dietary texture cues, but only if sufficient food is eaten before a short fast to prevent the rise in hunger during longer fasts that reinforces the discriminative increase in meal size.     

饮食诱导雄性肥胖大鼠生长激素轴变化

目的　探讨饮食诱导雄性肥胖大鼠生长激素 (GH)轴〔GH/胰岛素样生长因子 -I(IGF -I)〕的轴性变化。方法　建立高脂饮食诱导肥胖的大鼠模型 ,实验 12周末处死大鼠 ,采用放射免疫分析方法检测大鼠血清GH、IGF -I、胰岛素水平 ,用免疫组化方法检测肝脏IGF -I的含量。结果　饮食诱导肥胖后高脂组大鼠血清GH水平下降 (P <0 0 5 ) ;游离IGF -I水平升高 (P <0 0 1) ;血清胰岛素水平升高 (P <0 0 5 ) ;肝脏IGF -I的积分光密度值和阳性面积百分比均显著低于对照组 (P <0 0 1) ,肝脏的IGF -I合成分泌下降。结论　在饮食诱导肥胖的雄性大鼠体内 ,可能并不存在真正意义上的GH/IGF -I轴性变化损伤。     

糖尿病大鼠心肌Cx43的变化及相关性研究

目的 研究糖尿病大鼠心肌连接蛋白(Connexin43)的变化.方法 使用链脲佐菌素(STZ)建立糖尿病大鼠模型.经右颈总动脉插管采用电生理记录仪及超声心动图检测心功能的变化,应用免疫组化及图像分析技术观察心肌细胞CX43的改变.结果 糖尿病组大鼠心肌细胞Cx43表达明显减少,以24周组更明显(P均<0.01),12周及24周组的最大舒张期压力变化速率(-dp/dtmax)、最大收缩期压力变化速率(+dp/dtmax)均显著下降(P<0.01),左室射血分数(LVEF)亦明显降低(12周P<0.05;24周P<0.01),Cx43与-dp/dtmax(r=0.564,P<0.01)、+dp/dtmax、LVEF(r=0.426,0.414,P<0.05)呈正相关.结论 糖尿病大鼠心肌Cx43表达明显减少,心功能减低,两者具有明显相关性.     

胰岛素不同时机给药对脓毒症大鼠炎性反应的影响

目的:通过注射内毒素(LPS)建立的大鼠脓毒症模型,观察胰岛素不同时机给药对血清和肝细胞因子表达的影响。方法:将81只大鼠分为九组,即A组腹腔注射等渗盐水;B组腹腔注射LPS;C、D、E、F、G、H、I组分别在腹腔注射LPS前30 min和注射后0、1、3、6、12、24 h给予胰岛素治疗。观察各组大鼠LPS注射后24和48h血清白细胞介素-1β(IL-1β)、IL-6、肿瘤坏死因子α(TNF-α)和IL-10的变化,以及LPS注射48 h后肝组织IL-1β、IL-6、TNF-α和IL-10的变化。结果:注射LPS后24和48 h,大鼠血IL-1β、IL-6、TNF-α和IL-10均显著增加。LPS注射48 h后,肝组织中IL-1β、TNF-α、IL-6和IL-10蛋白水平也明显增加。在注射LPS前30 min或注射后6 h内给予胰岛素,能明显降低注射后24和48 h血清中的IL-1β、TNF-α和IL-6水平(P0.05);而IL-10水平则仅在注射LPS前或注射同时给予胰岛素,才较LPS组明显增加(P0.05)。在LPS注射前30 min或注射后6 h内给予胰岛素,注射后48 h肝内的IL-1β和TNF-α水平较LPS组明显降低(P0.05);而肝的IL-6水平仅在LPS注射前30min或与同时给予胰岛素时,才较LPS组明显降低(P0.05)。结论:胰岛素对脓毒症大鼠有抑制炎性细胞因子,增加抗炎介质释放等保护作用。在注射LPS 6 h内给予胰岛素可发挥良好的抗炎保护作用,而在注射LPS 6 h后给予胰岛素治疗其抗炎保护作用明显减弱。