White Rat Model Research Articles

The Effects of High Fat Diet on the Liver of the White Rat Model Obesity

BACKGROUND: Nonalcoholic fatty liver disease (NAFLD) is the most common form of chronic liver disease with the manifestation of over-accumulation of fat in the liver. AIM: The purpose of this study was to assess the degree of occurrence of steatosis in rats induced by a standard diet, a high-fat diet, and a modified high-fat diet. METHODS: This study used 18 white rats of the Wistar strain, divided into three groups, and fed for 9 weeks. Before feeding, all rats were measured their body weight, abdominal circumference, and body length. We measured body weight every week, while body length and waist circumference were measured every 2 weeks. After 9 weeks of diet, all rats were subjected to injection of Ketamine and examined for metabolic markers and histopathological examination of liver organs. RESULT: There was an increase in body weight of rats in the three groups with the average percentage increase in body weight in the three groups of rats before and after being fed a diet for 9 weeks found in Group 1 29.19% 1 (187−264.40 g), Group 2 by 19.12% (219.33−275 g), and Group 3 24.53% (213.33−275 g). Steatosis in Group 1 was 57.50% of hepatocytes containing macrovesicular fat droplets and called Grade 2 (moderate). In contrast, with a high-fat diet, steatosis occurred around 93.33%−95% of hepatocytes containing macrovesicular fat droplets and called steatosis Grade 3 (severe). CONCLUSION: The percentage of hepatocytes that had steatosis in obese rats induced by a high-fat diet was more significant than in obese models induced by a standard diet.

The Effect of Ethanol and Ethyl Acetate Fraction of Chayote fruit (Sechium edule Jacq. Swartz) on the Oxidative Stress and Insulin Resistance of Male White Rat Model Type 2 Diabetes Mellitus

BACKGROUND: Oxidative stress in type 2 diabetes mellitus (T2D) causes insulin resistance and disordered insulin secretion. Pathomechanisms of T2D consist of dysfunctional pancreatic β-cell and insulin resistance caused by free radical (reactive oxygen species and reactive nitrogen species) that produced from the glucose metabolism pathway. Insulin resistance can be measured using the homeostatic model assessment of insulin resistance (HOMA-IR). Oxidative stress can measure through the activities of malondialdehyde (MDA) and superoxide dismutase (SOD).
 AIM: This research aims to study the potential of chayote (Sechium edule Jacq. Swartz) to be used as antihyperglycemic in T2D.
 MATERIALS AND METHODS: This research was conducted with a post-test randomized controlled group design. Eleven groups with four male rats each were used. Normal untreated rats were treated under ad libitum feeding and drinking condition. Meanwhile, the rat models were induced with the combination of 45 mg/kg b.w. streptozotocin, 110 mg/kg b.w. nicotinamide, 40.5 mg/kg b.w. metformin, high-fat diet, and/or chayote extract. The chayote extract was orally administered to the rat in the form of ethanol extract and/or ethyl acetate fraction, with three dosages of 45 mg/kg b.w., 100 mg/kg b.w., and 150 mg/kg b.w. for each extract type. The body weight, glucose level, insulin level, MDA, and SOD activities were measured. The HOMA-IR was used.
 RESULTS: The lowest body weight of the rat model in week 0 was 145 ± 25.31, founded in Group H that was treated with ethyl acetate fraction of chayote extract (45 mg/kg b.w.). The lowest blood sugar level in the group with 2 h glucose load was 112.5 ± 27.00 on average, found in Group G that was treated with chayote ethanolic extract (150 mg/kg b.w.). The highest SOD in the group treated with chayote extract was 1.27 ± 0.20, founded in Group H treated with ethyl acetate 45 mg/kg b.w. The lowest level of MDA was 0.86 ± 0.70 in Group H treated with ethyl acetate 45 mg/kg b.w. The lowest fasting blood sugar spectrophotometer level was 150.54 ± 17.24 mg/dl in Group K with metformin treatment, followed by 155.16 ± 31.92 mg/dl in Group K treated 45 mg/kg b.w. ethanol treatment. The highest insulin level was 6.14 ± 0.71, founded in Group F that was treated with chayote ethanolic extract 100 mg/kg b.w. The lowest measurement of HOMA-IR was 0.16 ± 0.80 in Group E treated with ethanol extract of chayote 45 mg/kg b.w.
 CONCLUSION: Ethanol extract and fractionation of chayote work as an antioxidant and anti-insulin resistance.

Hsp70 Expression Profile in Preeclampsia Model of Pregnant Rat (Rattus norvegicus) after Giving the EVOO

Heat shock protein (Hsp) has long been known to protect cells from oxidative stress. In this case an increased expression is found on several cases of preeclampsia. One of the efforts to prevent preeclampsia is by giving antioxidants such as Extra Virgin Olive Oil (EVOO) or it’s better known as olive oil (Oleoa europaea), in the form of extra virgin known for its rich antioxidant content of tocopherols (vitamin E). The purpose of this study is to determine the expression levels of Hsp70 serum on pregnant white rat model of preeclampsia after being given EVOO. This type of research is true experiment; the subjects were female white rats and male virgin with Sprague Dawley, ± 8-11 weeks old, 180g BB s / d 200g, healthy and didn’t show any physical defects. Samples were 25 animals, divided into 5 groups, which consisted of different control and treatment given to T2 (rat model of preeclampsia), T3 (rat model of preeclampsia + EVOO 0.45g/bw/day), T4 (rat model of preeclampsia + EVOO 0.9g/bw/day) and T5 (rat model of preeclampsia + EVOO 1.8g/bw/day). The determination of each group was done by simple random sampling. Result on serum levels of Hsp70 that were tested by Elisa test in rats showed the average control was 14.64 mg / ml, group T2: 22:51 mg/ml, T3: 13.62 mg/ml, T4: 15.92 mg/ml, T5: 16:09 mg/ml. ANOVA test showed the P value was 0.001 <0.005, which meant there were significant differences on serum Hsp70 levels in the control and treatment pregnant rats group. It was known that there was a significant difference level of Hsp70 serum in group of control rats with T2 (P value <0.001) after LSD test was conducted, but not so with the group T3, T4, and T5, where the difference was not significant. There was a significant difference in the levels of Hsp70 serum on group T2 and T3 (P value 0.000), T4 (0004), T5 (0000). The gift of EVOO in the treatment group which was given EVOO with even low doses was able to control the induction of Hsp70 serum levels, which was not excessive, so the process of apoptosis did not occur excessively, especially in PE models. In this case, Hsp70 served as as an anti-apoptotic and it’s is suggested to further research to observe the relationship of Hsp70 and apoptotic index.

Effect of Low-Intensity Cardiac Rehabilitation on Cardiac Function and Degree of Fibrosis in a White Rat Acute Myocardial Infarction Model

The purpose of this study was to investigate the effects of low-intensity cardiac rehabilitation exercise on the cardiac function and the degree of fibrosis in an older white rat model. This study used male Sprague-Dawley white rats that were 50 weeks old. After the acute myocardial infarction induction, Twenty of the rats were randomly allocated into an experimental group and a control group, and each of the groups consisted of 8 rats. In the experimental group, the exercise was conducted for six weeks, 30 minutes a day, five days a week, using a Rotarod treadmill for animals. The degree of myocardial fibrosis was significantly repressed in the experimental group($13.69{\pm}1.90%$) and in the control group($15.67{\pm}1.54%$)(p<0.05). However, fractional shortening and ejection fraction did not show a significant difference. The results of this study suggest that cardiac rehabilitation with low intensity treadmill exercise repress the myocardial fibrosis.

Effect of Antiadhesion Barrier Solution and Fibrin on Capsular Formation After Silicone Implant Insertion in a White Rat Model.

One of the most serious complications of breast reconstruction and augmentation using silicone implants is capsular contracture. Several preventive treatments, including vitamin E, steroids, antibiotics, and cysteinyl leukotriene inhibitors, have been studied, and their clinical effects have been reported. However, the problem of capsular contracture has not yet been completely resolved. This study was performed to compare anti-adhesion barrier solution (AABS) and fibrin in their ability to prevent fibrotic capsule formation and simultaneously evaluated their effect when used in combination by capsular thickness analysis and quantitative analysis of matrix metalloproteinases (MMPs), tissue inhibitors of metalloproteinases (TIMPs), and type I collagen within the fibrous capsule. This study used female six-week-old Sprague-Dawley rats. Eighty rats were equally subdivided into the four following groups: AABS-treated, fibrin-treated, AABS and fibrin combined-treated, and untreated control groups. Each rat received two silicone chips under the panniculus carnosus muscle layer. The test materials were applied around the silicon chips. Four weeks later, the implantation sites including the skin and muscle were excised to avoid the risk of losing the fibrous capsule around the implants. The capsular thickness was analyzed by Masson's trichrome stain. Quantitative analysis of type I collagen, MMPs, and TIMPs was performed by real-time PCR, Western blot, and zymography. The mean capsular thickness was 668.10 ± 275.12 μm in the control group, 356.97 ± 112.11 μm in the AABS-treated group, 525.96 ± 130.97 μm in the fibrin-treated group, and 389.24 ± 130.51 μm in the AABS and fibrin combined-treated group. Capsular thickness was significantly decreased in all experimental groups (p < 0.05). Capsular thickness was greater in the fibrin-treated group than in the AABS-treated group (p < 0.05). There was no statistically significant difference in capsular thickness between the AABS and fibrin combined-treated group and the AABS- or fibrin-treated group (p > 0.05). Compared to the control group, the experimental groups had significantly lower expressions of type I collagen and MMP-1 (p < 0.05), but there was no statistically significant difference in expressions of type I collagen and MMP-1 between the AABS-, fibrin-, and AABS and fibrin combined-treated groups (p > 0.05). The expressions of MMP-2 and TIMP-2 were not significantly different between the control and the experimental groups (p > 0.05). AABS is more effective in reducing capsular thickness compared with fibrin treatment in a white rat model.

Fabrication of hybrid scaffolds by polymer deposition system and its in-vivo evaluation with a rat tibial defect model

The purpose of this study was to investigate the bone regeneration ability of a polycaprolactone (PCL) tube scaffold fabricated by using a polymer deposition system with G-code and to evaluate the biocompatibility of bone graft material with Bio-C (HA (30%)/TCP (70%)), carboxymethyl cellulose (CMC), and bone morphogenetic protein-2(BMP-2). The fabrication of a rapid prototyping-based PCL tube scaffold requires a combination of several devices, including a heater, pressure dispenser, and motion controller, etc. This system can process polymer with high precision by a 200-μm nozzle. We used scanning electron microscopy to observe the surface of fabricated scaffold. Three groups considered in this study were PCL tube scaffold (Group A), BMP-2(0.1 mg)/Bio-C/CMC/PCL scaffold (Group B), and BMP-2(0.5 mg)/Bio-C/CMC/PCL scaffold (Group C). The functional recovery and bone regeneration potential were estimated by performing an in-vivo animal experiment with a white rat model. Then, the effect of the scaffold on tibial defects in rats was examined by observing an X-ray image at 4 or 8 weeks and by carrying out histological analysis. In this study, scaffolds fabricated by using the PDS (polymer deposition system), had a diameter of 4.0 mm and a height of 8.0 mm. Moreover, we confirmed that group C exhibited better biomedical characteristics for bone formation than the other scaffolds. The evaluation of in-vivo experimental results suggested that the co-fabrication of the PCL tube scaffold with group C resulted in sustained bone regeneration, which in turn improved the biocompatibility of the bone graft material.

The Effect of Montelukast and Antiadhesion Barrier Solution on the Capsule Formation after Insertion of Silicone Implants in a White Rat Model

Background and Purposes: Capsular contracture is one of the most severe complications that can occur in breast surgery following silicone implant insertion. The purpose of this study was to investigate the effect of montelukast and antiadhesion barrier solution (AABS) on reducing capsular formation and their possible synergism. Materials andMethods: This study was approved by the Animal Ethics Committee (Reference No. KNU 2012-33) and was conducted in accordance with the Kyungpook National University - Institutional Animal Care and Use Committee, Animal Ethics Committee. The experiments in this study were conducted in vivo in 4 groups of 24 rats. Following silicone implant insertion, the pocket was injected with different agents. Group I (control group) was given normal saline injections into the pocket and fed with pure water. Group II was given injections of AABS and fed with pure water. Group III was given injections of normal saline and the medication montelukast during the experimental period. Group IV was given injections of AABS and montelukast as postoperative medication. Peri-implant capsules were excised after 8 weeks and were evaluated for transparency, inflammatory cell content, capsule thickness, collagen pattern and TGF-β expression. Results: The capsules in the experimental groups (i.e., groups II-IV) were significantly more transparent than those in group I (controls; p < 0.05, Student's t test). The mean capsule thickness of the experimental groups II (296 ± 14.76 μm), III (280 ± 14.77 μm) and IV (276 ± 39.28 μm) was smaller than that of the control group I (361 ± 35.43 μm). Compared to the control group, the histologic findings in the experimental groups suggested a decreased inflammatory response occurring in the peri-implant capsules as they exhibited minor vascularization and a reduced number of mast cells and macrophages. The collagen patterns in the experimental groups were of a lower density than in the control group with the former showing a loose, tidy collagen pattern. The amounts of TGF-β and collagen I were higher in the control group than in the experimental groups. Group IV (the synergic effect group) had a more pronounced effect on all the parameters examined than that in groups II and III with separate drug administration. Conclusions: Montelukast and AABS reduced the thickness, the inflammatory cell infiltrate and the myofibroblast content of the peri-implant capsules around silicone implants in this white rat model. They lowered the expression of the fibrotic mediator, TGF-β, and inhibited the peri-implant capsular fibrosis. Therefore, montelukast and AABS are effective in the reduction of silicone-induced peri-implant capsular formation.

Effect of Amniotic Fluid Stem Cells and Amniotic Fluid Cells on the Wound Healing Process in a White Rat Model

BackgroundAmniotic-fluid-derived stem cells and amniocytes have recently been determined to have wound healing effects, but their mechanism is not yet clearly understood. In this study, the effects of amniotic fluid stem cells and amniocytes on wound healing were investigated through animal experiments.MethodsOn the back of Sprague-Dawley rats, four circular full-thickness skin wounds 2 cm in diameter were created. The wounds were classified into the following four types: a control group using Tegaderm disc wound dressings and experimental groups using collagen discs, amniotic fluid stem cell discs, and amniocyte discs. The wounds were assessed through macroscopic histological examination and immunohistochemistry over a period of time.ResultsThe amniotic fluid stem cell and amniocyte groups showed higher wound healing rates compared with the control group; histologically, the inflammatory cell invasion disappeared more quickly in these groups, and there was more significant angiogenesis. In particular, these groups had significant promotion of epithelial cell reproduction, collagen fiber formation, and angiogenesis during the initial 10 days of the wound healing process. The potency of transforming growth factor-β and fibronectin in the experimental group was much greater than that in the control group in the early stage of the wound healing process. In later stages, however, no significant difference was observed.ConclusionsThe amniotic fluid stem cells and amniocytes were confirmed to have accelerated the inflammatory stage to contribute to an enhanced cure rate and shortened wound healing period. Therefore, they hold promise as wound treatment agents.

Kangaroo rat bone compared to white rat bone after short-term disuse and exercise.

Kangaroo rats (Dipodomys ordii) were used to study the effects of confinement on mechanical properties of bone with a long range objective of proposing an alternative to the white rat model for the study of disuse osteoporosis. Kangaroo rats exhibit bipedal locomotion, which subjects their limbs to substantial accelerative forces in addition to the normal stress of weight bearing. We subjected groups of kangaroo rats and white rats (Rattus norvegicus) to one of two confinement treatments or to an exercise regime; animals were exercised at a rate calculated to replicate their (respective) daily exercise patterns. White laboratory rats were used as the comparison because they are currently the accepted model used in the study of disuse osteoporosis. After 6 weeks of treatment, rats were killed and the long bones of their hind limbs were tested mechanically and examined for histomorphometric changes. We found that kangaroo rats held in confinement had less ash content in their hind limbs than exercised kangaroo rats. In general, treated kangaroo rats showed morphometric and mechanical bone deterioration compared to controls and exercised kangaroo rats appeared to have slightly "stronger" bones than confined animals. White rats exhibited no significant differences between treatments. These preliminary results suggest that kangaroo rats may be an effective model in the study of disuse osteoporosis.

Characterization of a model of malaria in the pregnant host: Plasmodium berghei in the white rat.

This study characterizes a Plasmodium berghei white rat model of P. falciparum malaria in the pregnant human. Seventy-day-old and 114-day-old female rats, given an infecting inoculum at time of mating, had higher parasitemias and a more severe anemia than age- and sex-matched controls. Under these experimental conditions, the parasitemia went to crisis in all animals and there were no fatal infections. In contrast, all animals died when the infection was initiated 7 days after conception, a timing that brought a coincidence of peak parasitemia and term. Pregnancy during the post-crisis subpatent period did not cause recrudescence. At the time of delivery, the parasitemia was consistently higher in the placental (crush smear) blood than in the peripheral (tail) blood. This difference was greatest in animals giving birth shortly before or 1-2 days after the parasitemic crisis. Very young, compact parasite forms predominated in the placental blood, whereas trophozoites predominated in the peripheral blood.