Effect of chronic stimulation on streptozotocin-induced diabetic rats
〔Abstract〕 Objective To observe the effect of chronic stimulation (CMS) on the pathogenesis and progression of diabetes mellitus (DM) in rats and its role in the occurrence and development of DM. Methods The effects of CMS on biochemical parameters and behavior of rats were observed by using streptozotocin (STZ) plus high-fat and high-glucose diet to induce DM rats. Results Compared with the normal group, the blood glucose and serum insulin levels in the DM group and the DM+ CMS group increased (P<0.05), and there was significant insulin resistance. Compared with the normal group, the CMS group, In the DM group and the DM+ CMS group, the upper sputum time was shortened and the immobility time was prolonged (P<0.05). The number of times the DM+CMS group entered the open arm and the residence time were also significantly shortened (P<0.05). Compared with the normal group, serum cortisol levels were significantly increased in the experimental groups (P < 0.05). Conclusion Chronic stimulation itself can not directly induce DM, but its presence can aggravate insulin resistance in rats and promote the occurrence and development of DM.
[Key words] chronic stimulation; diabetes; forced swimming experiment; elevated cross maze
A large amount of data shows that chronic stimulation (CMS) has a very important impact on human health, especially for patients with diabetes (DM), but it is not clear what results CMS will have on the occurrence and development of DM. This experiment increased the factors of CMS based on the induction of DM by streptozotocin (STZ), and observed the effects of CMS factors on blood glucose, depression and anxiety behavior, serum cortisol and insulin levels in rats, thus determining the CMS pair. The influence of the occurrence and development of DM in rats.
1 Materials and methods
1. 1 Animal grouping and model preparation 48 clean Wistar male rats were randomly divided into four groups, the normal group: 12, no treatment; DM model group (DM group): 12, intraperitoneal injection of STZ (25 mg / kg dissolved in 0.1 mol / L citrate buffer, pH = 4. 45), while giving a high-fat and high-sugar diet, fasting blood glucose higher than 13. 6 mmol / L for DM modeling success; CMS Group: 12, given electric shock for 30 min, 45 °C thermal stimulation for 5 min, black and white inverted for 24 h, fasting for 40 h, forbidden water for 24 h, 4 °C ice water for 5 min, clip tail for 1 min, no stimulation 24 h, 28 d was 1 cycle, one stimulus was taken every day, and the same kind of stimulation was discontinuous; DM+ CMS group: 12, the CMS factor was increased based on the intraperitoneal injection of STZ+ high-fat and high-sugar diet. There were 4 deaths in the DM group and 2 deaths in the DM+ CMS group.
1. 2 specimen collection and indicator detection
1. 2. 1 Forced swimming (provided by Shanghai Xinsoft Information Technology Co., Ltd.) Behavioral determination of behavioral despair in rats before and after CMS, recording the upper and inactive time of rats within 5 min, before and after observation of CMS in rats Behavioral changes that produce depression, and experimental methods are detailed in the references.
1. 2. 2 Overhead Maze (provided by Shanghai Xinsoft Information Technology Co., Ltd.) Behavioral measurement record Behavioral indicators of rat cross maze before and after CMS within 5 min: 1 Entering open arm times (OE): Entering any open The number of arms is determined by the fact that all four paws of the rat enter the arm. One of the paws is completely withdrawn from the arm in the middle to complete the activity; 2 enters the open arm time (OT); 3 enters the closed arm number ( CE): The number of times to enter any closed arm, which is based on the fact that all 4 paws of the rat enter the arm. OE% = OE / (OE + CE) × 100%; OT% = OT / 300 s × 100%.
1. 2. 3 Blood glucose measurement After the experiment, the rats were fasted for 12 h, and the blood was taken from the internal iliac vein after ether anesthesia.
1. 2. 4 Determination of serum insulin and cortisol levels After the end of the experiment, fasting for 12 h, blood was taken from the internal iliac vein after ether anesthesia, serum was separated, and serum insulin and cortisol levels were determined by radioimmunoassay. Insulin resistance index (HOMA) = fasting insulin × fasting blood glucose / 22. 5.
1. 3 drugs and reagents STZ: American Sigma company. Insulin kit: Beijing North Institute of Biotechnology. Cortisol kit: Beijing North Institute of Biotechnology.
1. 4 Statistical analysis One-way ANOVA, LSD test and t test were performed using SPSS21. 0 software.
3 Discussion
Through long-term and irregular stimulation of animals, CMS causes changes in animal mental state, sensitivity to external stimuli, decreased self-regulation, neuro-endocrine system dysfunction, and emotional and behavioral disorders, which can lead to depression. And so on. As a chronic disease, DM has shown an increasing incidence in recent years, and it has become a major factor threatening people's health in today's society. With the accelerated pace of people's lives, various CMS factors have gradually increased in daily life.
The results of this experiment indicate that the psychological changes of MCS to animals are not enough to induce the occurrence of DM, but when CMS and other factors are combined to the body, it will greatly promote the occurrence and development of DM. This may be due to the psychological disorder and behavioral changes caused by the CMS itself, resulting in dysfunctional secretions in the body and changes in hormone levels. These changes further aggravate the occurrence of glucose metabolism disorders, thereby accelerating the occurrence and development of DM. . This result is consistent with the findings of foreign laboratories.
Forced swimming is a well-recognized indicator for evaluating depression in rats. We found that DM rats also showed different degrees of depression without CMS, and CMS aggravated this depression. Although CMS and DM itself can cause mild anxiety in rats, there is no significant difference before and after the experiment, and CMS combined with DM can cause obvious anxiety behavior in rats. This result further proves that CMS can aggravate the development of DM. CMS acts on DM rats in a form of psychological stress, which causes disorder of glucose metabolism, impaired glucose tolerance, and increased insulin levels in rats, resulting in a significant increase in insulin resistance, which leads to an increase in blood glucose and aggravation of DM progression. Hippocampus is a sensitive area of ​​stress damage and a high-level regulation center of HPA axis stress response. As a stressor, CMS can cause negative psychological and behavioral changes in the body, resulting in hippocampal structural and functional damage. The damage of hippocampus further increases the sensitivity of HPA axis to various stressors, which ultimately leads to an increase in the secretion of cortisol, which in turn promotes gluconeogenesis, increases insulin resistance, and promotes the development and progression of DM. . The results of this study show that both DM and CMS can cause an increase in cortisol, which may be a major factor in the development and progression of DM accelerated by CMS.
In summary, CMS itself is not the cause of DM, but CMS can accelerate and aggravate the occurrence and development of DM. This provides a reliable theoretical basis for the care of clinical DM patients, and should minimize the psychological and environmental stimuli of DM patients, which will help reduce the control of complications and conditions.
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