Telemetered heart rate responses of the rat during free and learned behavior

To assess the effect of recording on the heart rate and on the behavior of the free moving rat, the electrocardiogram was recorded with the aid of radiotelemetry or through wire leads attached to the animal in different behavioral situations. Adaptation of heart rate both within and across sessions in the home cage and in a novel environment (open-field) was observed in rats bearing a transmitter. No adaptation occurred in rats attached to wire leads. The pattern of heart rate changes appeared to be independent of the mode of recording during passive avoidance behavior and when the rats displayed various motor activities like walking, sniffing, rearing or grooming in the open-field. The heart rate of rats attached to wire leads, however, was always higher. These data indicate that radiotelemetry is preferable to the use of wire connections for recording cardiac activity during behavioral studies in the rat.     

Histochemical demonstration of copper in LEC rat liver

Livers of LEC rats were histochemically stained for copper according to the modified Timm's method, which includes trichloroacetic acid (TCA) treatment. TCA pretreatment was effective in removing zinc and iron, leaving copper as the major metal in the liver. Hepatocytes in 3-month-old rats were stained intensely by the modified Timm's method, both in frozen sections and in paraffin-embedded specimens. The centrilobular hepatocytes were usually stained, but positive cells were also randomly distributed in the hepatic lobes, showing a mosaic pattern. The staining was intensified in 8- compared to 3-month-old LEC rats. In contrast hepatocytes from LEA rats, the normal counterpart of LEC rats, were faintly stained for copper. Proliferating cholangioles found in older LEC rats were shown to lack copper deposition, and hepatocellular carcinoma showed less copper deposits than the hepatocytes surrounding the tumor. The copper staining was augmented in livers of LEC rats subjected to copper-loading, but was less intense in the livers treated with d-penicillamine. The staining intensity under the various experimental conditions showed good correlation with the copper concentration. Lysosomal deposition of copper in hepatocytes was demonstrated by electron microscopic analysis for copper. Thus the modified Timm's method was shown to produce valuable results in demonstrating copper in LEC rat livers, providing important information for an understanding of the mechanism of copper deposition and hepatic disease of the animal.     

Effect of dietary carbohydrates and copper status on blood pressure of rats

Copper deficiency was induced in rats by feeding diets containing either 62% starch, fructose or glucose deficient in copper for 6 weeks. All copper deficient rats, regardless of the dietary carbohydrate, exhibited decreased ceruloplasmin activity and decreased serum copper concentrations. Rats fed the fructose diet exhibited a more severe copper deficiency as compared to rats fed either starch or glucose. The increased severity of the deficiency was characterized by reduced body weight, serum copper concentration and hematocrit. In all rats fed the copper adequate diets, blood pressure was unaffected by the type of dietary carbohydrate. Significantly reduced systolic blood pressure was evident only in rats fed the fructose diet deficient in copper. When comparing the three carbohydrate diets, the physiological and biochemical lesions induced by copper deprivation could be magnified by feeding fructose.     

麻醉大鼠左心室插管新方法

目的：探索在0．014’’经皮冠状动脉（PTCA）指引导丝引导下行大鼠左心室插管的方法。方法：30只Wistar大鼠,先后在PTCA导丝引导经右侧颈外动脉,左侧颈外动脉插管至左心室并行血流动力学测定：结果：30只大鼠成功完成一次左心室重复插管,27只大鼠完成重复插管：结论：PTCA指引导丝引导下左心室插管安全并可重复操作。     

Effects of moderate copper deficiency on carbon tetrachloride-induced hepatotoxicity in rats.

Extreme copper deficiency has been shown to enhance CCl4-induced injury in rats. CCl4 hepatotoxicity was studied in rats with copper deficiency moderated by limiting deficiency periods to 5 or 6 weeks, using minimally adequate dietary zinc and including a marginal copper diet. Also, housing some rats in groups of six, rather than individually, was found to moderate the effects of low copper intake. Weanling male rats were fed copper at either 6, 2, or 0.2 mg/kg diet (adequate, marginal, deficient). Copper-zinc superoxide dismutase activity levels for singly and group-housed marginal rats were 80% and 93%, respectively, of adequate values. Values for deficient rats were 35% (singles) and 47% (group). In singly housed rats, a CCl4 dose of 400 microliters/kg intraperitoneally increased serum sorbitol dehydrogenase activities, indicators of cell membrane hepatotoxicity, in inverse proportion to dietary copper. A lower dose (100 microliters/kg) also produced smaller sorbitol dehydrogenase increases in adequate rats compared with deficients, but produced lowest increases in the marginals. The latter pattern also occurred in group-housed rats given the higher CCl4 dose, but the difference for adequate and marginal rats was not significant. The higher CCl4 dose, in singly housed rats, decreased liver glucose-6-phosphatase activities independently of copper intake. These activities are inversely proportional to microsomal lipid damage. In conclusion, moderate copper deficiency enhanced CCl4 hepatotoxicity, but the effect depended on injury criteria, CCl4 dose, and actual copper status as assessed by copper-zinc superoxide dismutase activities.     

Comparison of copper status in rats when dietary fructose is replaced by either cornstarch or glucose

The purpose of this study was to determine what levels of starch or glucose replacement for fructose in the copper-deficient diet (copper) can minimize the fructose-copper interaction. Experimental diets contained either 100% fructose as the carbohydrate source, or the fructose was partially replaced with 50% starch, 50% glucose, 75% starch, or 75% glucose. Diets were either copper adequate (7-8 ppm) or inadequate (less than 1 ppm). Male weanling rats were fed their respective diet for 5 weeks and then fasted overnight. After decapitation, blood was collected and liver and heart were removed. Plasma copper was significantly reduced and ceruloplasmin was not detected in all copper-deficient groups. Copper deficiency increased plasma cholesterol, as well as heart and liver weight in the glucose groups, but not in the starch groups. Those organ weights were heavier in glucose-copper than starch-copper rats. Erythrocyte copper-zinc-superoxide dismutase activity was greater in starch-copper rats. Erythrocyte copper-zinc-superoxide dismutase activity was greater in starch-copper than glucose-copper rats regardless of carbohydrate amount. Hepatic copper concentration of the group fed starch-copper was twice levels observed in glucose-copper. The 50% glucose rats had lower hepatic copper than the 75% glucose rats. Hepatic copper-zinc-superoxide dismutase activity showed patterns similar to hepatic copper. Cardiac copper was greater in starch-copper than glucose-copper rats. Cardiac copper-zinc-superoxide dismutase activity was equally reduced in all copper-deficient groups. The 50% starch-replaced diet was more effective in minimizing copper deficiency than the 75% glucose-replaced diet. This poorer improvement of copper deficiency by glucose than starch may partially be due to a more severe reduction of food intake in glucose than in starch diets.     

Excessive hepatic copper accumulation in jaundiced rats fed a high-copper diet

The response of copper metabolism to dietary copper challenge was investigated in jaundiced rats with elevated plasma concentrations of conjugated bilirubin as a result of impaired canicular transport of bilirubin glucuronides. Control and jaundiced rats were fed purified diets with either normal (64 μmol Cu/kg) or high (640 μmol Cu/kg) concentration of added copper. Copper loading produced a greater increase in hepatic copper concentrations in the jaundiced than in control rats. The greater dietary-copper-induced increase in hepatic copper in the jaundiced rats can be explained by the observed smaller rise in biliary copper excretion and a greater efficiency of dietary copper absorption. In individual rats, there was a positive relationship between hepatic copper concentrations and biliary copper concentrations. It is suggested that not the transport of copper from liver cells to bile but that from plasma to bile is diminished in the jaundiced rats. The elevated plasma copper concentrations in the jaundiced rats may support this suggestion.     

Milk ceruloplasmin is a valuable source of nutrient copper ions for mammalian newborns

This research focuses on the role of milk ceruloplasmin (Cp), the main extracellular copper-containing protein of vertebrates, as a source of copper for newborns. In the first part of the study, Cp concentration and Cp-associated copper were measured in human skimmed milk at the 1st and the 5th days postpartum. It was shown that most of the copper was associated with Cp and that the decrease in copper concentration during lactation was related to the drop of Cp levels. The following in vivo experiments demonstrated that milk [(125)I]Cp per os administered to 6-day-old rats (embryonic-type copper metabolism) was transported into their bloodstream. The electrophoretic mobility and relative molecular weight of [(125)I]Cp transferred through the cellular barrier remained unaltered. However, 22-day-old rats (adult-type copper metabolism) digested the administered milk [(125)I]Cp completely. In the final part of the study, newborn rats were fed with baby formula for 8d. It was found that these rats switched their copper metabolism from embryonic type to adult type earlier than their littermates fed by dams. Activation of Cp gene expression in the liver, increased Cp and copper concentrations in the blood, and reduced copper content of the liver were observed in the rats fed with baby formula. In the brain, no copper concentration change was observed, but Cp and copper concentrations were dramatically increased in the cerebrospinal fluid. The role of milk Cp as a source of copper adapted to embryonic-type copper metabolism is discussed.     

大鼠心脏插管留置术的探讨

目的探讨大鼠右心房插管留置术实验方法。方法20只SD大鼠进行右心房导管置入术,术后随机分为2组（导管穿弹簧正内孔组、导管穿弹簧侧边入内孔组）,每组各10只。导管在体内固定后由颈背部引出,穿过弹簧,导管另一端固定于饲养笼外的支架上,导管外接三通管等。结果24 h对两组模型进行实验观察。（1）导管穿弹簧正内孔组：只有1只导管弹簧设备未完全破坏,另9只模型的导管被咬断或拉出了出来,10只模型都不能从导管抽取血液样本。（2）导管穿弹簧侧边入内孔组：导管和弹簧设备都完好,其中9只模型都能从导管抽取血液样本。结论导管穿弹簧侧边入内孔组模型方法是成功的,有一定的推广价值。     

Development of copper deficiency in rats fed fructose or starch: weekly measurements of copper indices in blood

Copper deficiency was induced in weanling rats fed diets whose sole source of carbohydrates was starch or fructose for 7 weeks. Conventional parameters of copper status, plasma copper concentrations, ceruloplasmin activity, and erythrocyte superoxide dismutase (SOD) activity were longitudinally monitored weekly to follow the development of the deficiency and to correlate these indices with the degree of severity of the deficiency. Although 30% of the rats fed a copper-deficient fructose diet died and no deaths occurred in rats fed the copper-deficient starch diet, plasma copper, ceruloplasmin, and SOD activities were reduced to a similar extent in all rats fed copper-deficient diets regardless of the type of dietary carbohydrate. Thus, none of the indices used accurately reflected the greater degree of deficiency or mortality in rats fed the fructose diet deficient in copper. The results of the present study underscore the need for more sensitive tests or alternative parameters to assess copper status in living animals.     

Suboptimal levels of dietary copper vary immunoresponsiveness in rats

The effects of severe, moderate, and mild copper deficiencies on cellular and humoral immunity were studied. Fifty male Sprague-Dawley rats, 5 wk of age, were fed diets containing 0.5, 2.0, 3.5, or 5.0 micrograms Cu/g for either 4 or 8 wk. Ten of the rats were fed the control diet, but were pair-fed with the 0.5-micrograms/g treatment group. All rats were immunized once with sheep red blood cells. Mean plasma-copper concentration reflected the dietary levels of copper, and ceruloplasmin activity correlated highly to plasma copper. Rats consuming suboptimal levels of copper responded differently to the deficiencies, so copper status varied among those animals. After 8 wk, cell proliferation, when stimulated by phytohemagglutinin, was dependent on the copper status of the animal. Severely deficient rats had consistently lower lymphocyte stimulation indexes for phytohemagglutinin and concanavalin A, but specific antibody response was not reduced. Immunoglobulin G (IgG) concentrations were variable for all rats, and immunoglobulin M (IgM) concentrations were lower for the severely deficient rats. Suboptimal dietary copper may alter immune function in rats, depending on the ensuing effect on copper status.     

Copper levels in cervical mucus of women with copper-bearing and noncopper-bearing intrauterine devices

The copper content of individual cervical mucus samples from 50 women using conventional plastic intrauterine devices (IUDs) and from 50 women using copper-bearing IUDs containing 200 sq. mm copper wire were determined. Both groups of women showed the same pattern of copper levels as normal controls with the lowerst level of copper at ovulation. The women using the copper-bearing IUDs showed a significantly higher copper content in all phases of the cycle. Prolonged use of the copper IUD (7 weeks - 2 years) was associated with a drop in copper levels of the cervical mucus to approximately the levels in women wearing a plastic IUD. It is concluded that changes in cervical mucus copper content are due to local effects of the devices on the reproductive tract.     

Microelectrode Guided Implantation of Electrodes into the Subthalamic Nucleus of Rats for Long-term Deep Brain Stimulation

Deep brain stimulation (DBS) is a widely used and effective therapy for several neurologic disorders, such as idiopathic Parkinson’s disease, dystonia or tremor. DBS is based on the delivery of electrical stimuli to specific deep anatomic structures of the central nervous system. However, the mechanisms underlying the effect of DBS remain enigmatic. This has led to an interest in investigating the impact of DBS in animal models, especially in rats. As DBS is a long-term therapy, research should be focused on molecular-genetic changes of neural circuits that occur several weeks after DBS. Long-term DBS in rats is challenging because the rats move around in their cage, which causes problems in keeping in place the wire leading from the head of the animal to the stimulator. Furthermore, target structures for stimulation in the rat brain are small and therefore electrodes cannot easily be placed at the required position. Thus, a set-up for long-lasting stimulation of rats using platinum/iridium electrodes with an impedance of about 1 MΩ was developed for this study. An electrode with these specifications allows for not only adequate stimulation but also recording of deep brain structures to identify the target area for DBS. In our set-up, an electrode with a plug for the wire was embedded in dental cement with four anchoring screws secured onto the skull. The wire from the plug to the stimulator was protected by a stainless-steel spring. A swivel was connected to the circuit to prevent the wire from becoming tangled. Overall, this stimulation set-up offers a high degree of free mobility for the rat and enables the head plug, as well as the wire connection between the plug and the stimulator, to retain long-lasting strength.     

Effects of copper metabolism on neurological functions in Wistar and Wilson's disease model rats

Behavioral functions of Wistar and Long-Evans Cinnamon (LEC) rats, Wilson's disease animal model, were compared by measuring the open-field, acoustic startle reflex and prepulse inhibition (PPI), and shuttle-box avoidance learning tests with or without oral supplementation with copper or D-penicillamine, copper chelator. All of the LEC rats, irrespective of the treatment, exhibited higher locomotor activity, a decreased habituation to startle response or a lower PPI, compared with Wistar rats. The copper content of all brain regions examined, except for the medulla oblongata of LEC rats, was significantly lower than those in Wistar rats. Besides, in the region of the striatum and the nucleus accumbens of the LEC rats, lower content of norepinephrine, and higher content of dopamine and serotonin were observed compared with Wistar rats. Although copper supplementation did not affect the brain copper content, it reduced the PPI in both Wistar and LEC rats. In contrast, D-penicillamine supplementation decreased both the brain copper content and locomotor activity, and enhanced the startle amplitude only in Wistar rats. These findings suggest that an imbalance in copper homeostasis affects monoamine metabolism and behavioral functions.     

鼠类扩散种子的几种标签标记法的比较

以四川省都江堰市亚热带常绿阔叶林内的优势鼠种——小泡巨鼠为实验动物,通过半自然状态围栏控制实验,检验了几种种子标签法对鼠类扩散植物种子的影响。结果表明:鱼线和细钢丝两种标记线在跟踪扩散种子命运上都是很有效的,但考虑到鱼线有时会被实验鼠咬断,细钢丝是更值得推广应用的一种标记线。3种标记牌(大塑料牌、小塑料牌和金属牌)在跟踪扩散种子命运上没有显著差异,但由于较大的尺寸和较强的可见度,大塑料牌更适合作为标签应用于野外种子扩散标记。     

Effects of acute prednisolone administration on plasma and liver copper in rats with adjuvant arthritis

Several studies in animals and humans have shown that copper metabolism could be affected by inflammation or by corticosteroids. The relative importance of these two factors, often imbedded in clinical practice, was assessed by investigating the effects of acute prednisolone administration (30 mg/kg, ip) on healthy and adjuvant arthritis rats. Plasma copper levels were significantly higher in arthritic rats compared to healthy animals, whereas there was a slight, but nonsignificant increase in liver copper. Acute prednisolone administration in healthy rats resulted in a significant increase in plasma copper (10–15%) as early as 4 h after corticosteroid administration, which was maintained for 12 h. In arthritic rats, the response was much higher (25–40%), but somewhat delayed and shorter. Liver copper was not clearly modified by prednisolone treatment in both groups. This time-controlled study showed that acute prednisolone administration increased plasma copper in both healthy and arthritic rats, but in different ways, indicating that inflammation and corticosteroids may act synergistically.     

Multiple recording of electromyograms in a chronic experiment

The authors describe electromyographic electrodes (EMG electrodes) for recording the activity of several muscles in chronic experiments on cats. An EMG electrode is a loop made of a silver wire 200 micron in diameter and 1.5-2 cm long, to which a flexible copper wire insulated with teflon 300 micron in diameter is soldered. The soldering site is insulated with biologically indifferent material. The EMG electrodes turned out fairly good in numerous experiments.     

High arsenic intake raises kidney copper and lowers plasma copper concentrations in rats

The effect of high arsenic intake on copper metabolism was investigated. Male rats aged 6 wk had free access to purified diets containing either 0 or 100 mg As/kg diet and demineralized water for a period of 2 wk. Arsenic was added to the diet in the form of NaAsO₂. The high-arsenic diet decreased feed and water intake and body weight gain, but significantly increased liver weight. Kidney weight was not affected. Arsenic feeding drastically elevated kidney copper concentration, but significantly reduced copper concentration in plasma. Both true absorption and biliary excretion of copper were decreased significantly in rats fed the high-arsenic diet. True copper absorption was lowered essentially through the lower copper intake in the rats fed arsenic. It is speculated that arsenic feeding primarily leads to copper accumulation in the kidney, followed by a decrease in feed intake and thus in true, absolute copper absorption, a decrease in plasma copper concentration, and a decrease in biliary copper excretion.     

Effect of Silver Ions on Copper Metabolism during Mammalian Ontogenesis

Copper metabolism was studied in laboratory rats that received silver ions with food (Ag diet) from birth for 5, 20, 40, and 180 days. Parameters of the copper status in the blood serum were determined, and data on the distribution of silver ions in the body were obtained. A comparative histological analysis of brain, liver, kidney, and spleen sections of adult rats kept on the Ag diet for 30 or 180 days was performed. Copper and silver content, expression levels of the genes of copper transport proteins, and the activity of copper enzymes were determined in the cells of the liver, the central organ responsible for copper metabolism in mammals. In adult rats kept on the Ag diet for 30 days, copper status parameters dropped to near-zero values. In contrast, these parameters were decreased only twofold in rats that had been kept on the Ag diet for 6 months from birth. At the same time, the expression of genes involved in copper homeostatis was downregulated. The expression of genes that encode copper enzymes was unchanged. The activity of ceruloplasmin, the main copper-containing protein of the blood, was decreased, while the activity of SOD1, a cellular copper enzyme, was unchanged. The pathways by which silver can interfere with copper metabolism and the mechanisms that compensate these effects are discussed. The data obtained may help assess the potential consequences of growing environmental exposure to silver due to increasing use of silver nanoparticles in different areas of human activity.     

Regional distribution of metallothionein, zinc, and copper in the brain of different strains of rats

The regional brain distribution of metallothionein (MT), zinc, and copper in the brain was determined in nine anatomical regions (olfactory bulb, cortex, corpus striatum, hippocampus, thalamus plus hypothalamus, pons plus medulla oblongata, cerebellum, midbrain, and white matter) and was compared between two different strains of rat (Sprague-Dawley [SD] and Lewis). No significant difference was observed in the whole-brain MT level between the two strains (17.8 ± 3.4 μg/g in SD rats and 20.3 ± 2.3 μg/g in Lewis rats). In SD rats, however, MT was more highly expressed in the white matter than in the other regions studied. In contrast, MT concentration was highest in the cortex and lowest in the olfactory bulb in Lewis rats. The MT levels in the cortex, corpus striatum, hippocampus, and thalamus plus hypothalamus were significantly lower in SD rats than in Lewis rats. In both strains, the olfactory bulb contained markedly higher levels of both zinc and copper than the other regions (27.9 ±6.8 μg/g zinc in SD rats and 27.6 ± 6.9 μg/g zinc in Lewis rats, and 5.2 ± 1.5 μg/g copper in SD rats and 11.1 ± 4.8 μg/g copper in Lewis rats). The next high-est zinc levels were seen in the hippocampus, whereas the next highest copper levels were in the corpus striatum in both SD and Lewis rats. The high levels of zinc and copper in the olfactory bulb were not accompanied by concomitant high MT concentrations. These results indicate that the strain of rat as well as the anatomical brain region should be taken into account in MT and metal distribution studies. However, the highest concentrations of zinc and copper in olfactory bulb were common to both SD and Lewis rats. The discrepancy between MT and the metal levels in olfactory bulb suggests a role for other proteins in addition to MT in the homeostatic control of zinc and copper.