Abstract
Objective: Mechanism of high fat diet-induced obesity is analyzed and serum tumor necrosis factor, malondialdehyde and glutathione levels of obesity resistant rats are effectively analyzed. Methods: 120 male SD rats were grouped into obesity group and control group, each group with 60 rats. Obese rats were fed with high fat diet, while control rats were fed with ordinary fodder. After six months of feeding, growth degree of two groups of rats is observed , and the rats are divided into obesity group and obesity resistant group based on extent of growth. Then glutathione, tumor necrosis factor-α and MDA content in bat serum are detected with enzyme-linked immunosorbent assay. Results: The content of tumor necrosis factor α in obese rats and obesity resistant rats is far higher than that in control group (P < 0.05), there exists no statistical significance (P > 0.05) in tumor necrosis factor α in obesity group and obesity resistant group, glutathione level of obesity group rats and obesity resistant group rats is significantly increased (P < 0.05) compared with that of control group, and also serum MDA level of the two groups has statistical significance compared with that of normal control group (P < 0.05). Conclusion: Among rats fed with high fat diet, in comparison with weight of obesity resistant rats and control group rats, there is no statistically significant difference, (P > 0.05). However, high fat diet will impact mechanisms in vivo in rats, which then induces oxidative stress response and inflammatory response in rats.
Keywords: High-fat diets, Obesity, Obesity resistant rats, Serum TNF-α, MDA, Glutathione
1. Introduction
At the end of the last century, the World Health Organization introduced relevant provisions on obesity, regarding that obesity is a disease. In recent years, with the continuous improvement of people’s living standards and change in dietary structure, incidence of obesity has shown an increasing trend and obesity has become a serious health killer. Relevant research shows that obesity is often accompanied with chronic inflammation and emergence of oxidative stress in patients. Tumor necrosis factor-α is the major protein associated with obesity, which plays a very important role in regulating body fat metabolism (Suo and Wang, 2015). Obesity can cause serious increase in vivo tumor necrosis factor α content in patients. Research at this stage considers that this phenomenon is mainly related to low-grade inflammation and natural immunity (Liu and Liu, 2012). The author conducted meticulous research on 120 male SD rats, and applied rat test results in human clinical therapy (Song et al., 2014). The structure chart of tumor necrosis factor α is shown in Fig. 1.
Figure 1.
Structure chart of tumor necrosis factor α.
2. Materials and methods
2.1. General information
The subjects selected in this study are SD rats born after three weeks, with delactation of 3 days, 120 healthy male rats. After three-day adaptive feeding of rats, the rats were randomized, namely high-fat group and control group, respectively 60. The rats received eating and drinking on their own, and were housed in separate ventilated cages. Each rat was recorded once a week (Jiang and Jiang, 2014). After raising a total of six months, rat weight is observed. Based on different weight of different rats, 60 high-fat fed rats are divided into obesity and obesity resistant groups (Hao et al., 2010).
2.2. Preparation of samples
High fat diet is used for a period of six months of feeding. After obese rat model is successfully established, let rats eat 12 h, anesthesia disposal of rats is applied with 2% intraperitoneal injection of pentobarbital, and femoral vein of rats is removed , venous blood serum is collected, to be stored at a temperature of minus 20°. Perirenal fat tissue, omental adipose tissue and tissue surrounding testis of rats are weighted. The total weight of rat fat is equal to the sum of the three (August et al., 2016, Wang et al., 2014). The fat tissue surrounding testis is shown in Fig. 2.
Figure 2.
Fat tissue surrounding testis.
2.3. Level determination
Tumor necrosis factor α, MDA and glutathione levels were measured and the method chosen is enzyme combined immunization method. Specific steps follow relevant operating instructions. The MDA formula is shown in Fig. 3.
Figure 3.
MDA formula.
2.4. Statistics
Relevant data obtained in this study were tested with package SPSS15.0. Measurement data obtained in the study are denoted by ( ± s) and tested with t test. Experimental data obtained by the two sets of statistics are P < 0.05, which indicates that effect after group therapy is with significant difference.
3. Results
3.1. Total weight of rats and fat
During the study, the total weight of overall fat of SD rats was observed. It can be found that, weight of obesity group rats is markedly increased compared to that of control group, and there was a significant increase in total weight of fat compared with control group, but without significant statistical difference. The Comparison of body weight of control group, obesity group and obesity resistant group rats is shown in Table 1.
Table 1.
Comparison of body weight of control group, obesity group and obesity resistant group rats ( ± s).
| Item | Control group | Obesity group | Obesity resistant group |
|---|---|---|---|
| Weight | 401.29 ± 116.87 | 665.21 ± 170.08 | 387.19 ± 51.39 |
| Fat weight | 19.99 ± 14.29 | 65.71 ± 28.69 | 31.98 ± 12.98 |
3.2. Comparison of content of serum tumor necrosis factor α, malondialdehyde and glutathione
Serum tumor necrosis factor-α levels of obesity and obesity resistant group rats are significantly increased compared to normal control group rats. There is no statistical difference between obesity and obesity resistant group (Xu et al., 2011, Aldea et al., 2016, Huang et al., 2012). There exists no statistical significance in content and level of malondialdehyde and glutathione in obesity and obesity resistant groups, but with difference from control group (shown in Table 2).
Table 2.
Serum tumor necrosis factor α, malondialdehyde and glutathione levels ( ± s) of control group, obesity group and obesity resistant group.
| Item | Control group | Obesity group | Obesity resistant group |
|---|---|---|---|
| Tumor necrosis factor | 10.58 ± 1.19 | 12.92 ± 0.63 | 12.19 ± 1.48 |
| Glutathione | 34.06 ± 6.39 | 18.81 ± 6.39 | 28.11 ± 2.28 |
| Malondialdehyde | 1.51 ± 0.33 | 1.99 ± 0.59 | 1.89 ± 0.27 |
3.3. Application of diet-induced model
In the current medical research on obesity, diet-induced animal obesity model has been very extensive. Some animals have obesity, referred to as obesity type, and some animals will not have obesity, referred to as obesity resistant type. Under the same high-fat diet, weight of obese rats will be significantly higher than that of obesity-resistant rats, which is mainly because catabolism of obesity resistant rats is relatively strong, without too much fat deposition.
Tumor necrosis factor-α is a multifunctional cytokine that can play different roles in different systems in the body. Tumor necrosis factor α with strong immune activity can have certain inflammatory reaction. With the increase in rat adipocytes, expression of tumor necrosis also will be significantly increased. Obesity, a result of combined action of genetic factors and environmental factors, is mainly related to high-energy and high-fat diet of human. Fat diet feeding method has now become a common conventional method of establishing obese animal models. Related studies show that after rats are fed with high-fat diet, physique of a part of rats is significantly increased, which shows that high-fat diet-induced obesity is with certain heterogeneity. Meanwhile, serum TG level of obese rats is significantly elevated, which will be affected by diet. The high-fat diet is shown in Fig. 4. Addition of some protein powder and lard in high fat diet will make intake of saturated fatty acids in rats increase significantly, thus effectively increasing synthetic amount of liver TG. Short-term high-fat diet has relatively great influence on cholesterol metabolism of rats. Adipose tissue is the most important endocrine trachea of human and animal body, which can secrete a variety of cytokines, such as adiponectin, leptin and tumor necrosis factor and can participate in regulation of the body’s energy and metabolism. Serum levels omentin-1 in high fat diet-induced insulin resistant rats are also significantly reduced. Targeting at different susceptibility principles of diet-induced obesity, this study used adult male SD rats for study. In this study, to achieve a better effect of obesity of rats, sometimes a long time is needed. Filtered samples in the study can provide comprehensive reflection of features of rats. In the process of measurement of obesity index, it can be found that, in the case that rat weight is consistent with wet weight of each part of fat, indicators are measured such as blood glucose, glycerol and fat content of rats, the indicators are compared with those of normal rats, and there exists statistically significant difference. The phenomenon of obesity susceptibility differences is common in humans and animals. Human obesity research can be done through animal experiments. The author analyzed obese body indicators through homemade fat diet. In the process, there was no impact on obesity modeling time, some rats showed significant obesity, while the other part of rats showed obesity resistance. Resistin is a protein specially secreted by fat cells that exist in obese rats, which can provide more effective mechanism for treatment of obesity and obesity resistance diseases. High fat diet will make rats have some oxidative stress reaction, thereby causing rat obesity, improving oxidative stress phenomena of rats, causing lipid in vivo or oxidation damage and leading to more fat deposits. During the study of application of rat test to obese patients, dietary situation of obese patients can be studied, and blood glucose, blood lipids and blood pressure and other indicators of obese patients can be effectively controlled, so that serious diabetes and chronic complications can be avoided for obese patients, harm of disease can be minimized and illness condition of obese patients can be effectively controlled.
Figure 4.
High-fat diet.
4. Discussion and conclusion
Obesity has become a serious disease, which can cause a number of serious diseases such as diabetes and high blood pressure. Thus, obese patients should reduce fat intake and make dietary reasonable control. Also, dietary fat intake of obese patients should be lowered, cholesterol intake should be reduced and obese patients’ blood glucose should be reasonably controlled. In the course of dietary management, nutrition treatment effect of obese patients should be effectively controlled, so that significant therapeutic effect can be received, which will provide some guidance and reference for clinical treatment work.
Acknowledgments
The research was supported by Shenzhen city science and technology research and development projects. Topic: Research on the relationship between diet induced obesity rat bile acids and intestinal microflora. Number: JCYJ20130402112843373.
Footnotes
Peer review under responsibility of King Saud University.
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