| Sleep is an advanced function of brain. Enough sleep is the basis of the health. It can restore our body, integrate and consolidate the memory. It is also an essential part of our health.Sleep deprivation (SD) is an important experimental method to study sleep dysfunction, which means the subject is restricted to have less sleeping time than normal physiological needs. SD, as a strong stressor, may have multiple effects on human bodies. It may affect our study, memory, physiological change, bizarre behavior, neurotransmitters disturbance and hormone imbalance. SD may also affect functions of multiple systems. From the aspect of cardiovascular system, it can increase blood pressure, stimulate sympathetic nerves, disturb endocrine functions, and release some inflammatory factors. Sleep dysfunction can also increase the risk of cardiovascular diseases. In the epidemiologic surveys and case control studies, we found that the risk of cardiovascular diseases for patients complaining of decreased sleeping time and sleeping problems increased. And some sudden deaths cases caused by insufficient sleep or overwhelmed work were also reported. SD can be divided into total sleep deprivation (TSD), and partial sleep deprivation (PSD). PSD is defined as in the given time, missing of sleep or some sleeping phases specifically decreasing during sleeping, which decrease total sleep time. PSD has a very similar pattern with the common sleep dysfunction we encounter in our daily life, so it is more valuable to study.In this study, we established the PSD rat models, than we investigated the effects of PSD on body mass, cardioelectrical activity, inflammatory and biochemical parameters, function of vascular endothelium related parameters, and the microscopic structure of cardiac muscle in rats helping to provide more clues about occurrence and/or development of coronary heart disease.The project had two main parts:First:The establishment and evaluation of PSD rat models. According to some relevant research, there are several ways to establish PSD rat model. One of the method is that we put a subject rat into a box covered by nets preventing rat from escaping, in which, the water depth is about 1.5cm, to establish the PSD rat model, which is easy and accessible. And we used the exhaustive swimming time that rats were loaded with 5% percent weight of itself to evaluate PSD rat models.Second, after we established PSD models, we investigated the effects of PSD on body mass, cardioelectrical activity, inflammatory and biochemical parameters, function of vascular endothelium related parameters, and the microscopic structure of cardiac muscle in rats. To observe the change of body mass, cardioelectrical activity and through the serum test to evaluate if the PSD has short-term effects on inflammatory reaction, blood sugar and lipid metabolism, function of vascular endothelium, and the microscopic structure of cardiac tissues provided more evidence if PSD could cause cardioelectrical change and cardiac cells injury. ChapterⅠThe establishment and evaluation of PSD rat modelsObjective:to establish and evaluate PSD rat models.Method:18 6w male Sprague-Dawley rats. Adaptive feeding for 8w until body mass was between 380g-450g. We randomly divided rats into control group and experimental group, with 9 rats in each group. At 12AM everyday, we put rats separately into a box covered by nets preventing rat from escaping, in which, the water depth was about 1.5 cm and fresh water and food were provided, and took them out at 8 AM on the next morning and put them into dry cages to have a rest. We put them back into the previous boxes at 12AM. So the PSD is 20h per day for 10d. For control group, we didn’t have any interventions. At 8Am on the day before PSD, after PSD1d, PSD3d, PSD5d, PSD7d, PSD9d, we had the rats struggle to swim loaded with 5% percent weight of itself in a barrel, with water depth about 50cm, temperature around 24±2℃and record the time (starting from the rat contacted the water surface to rat’s nose tip was completely under water for 10s.)Results:As PSD prolonged, the time that experimental rats used to struggle to swim with weight decreased, but the control group had no change. Time of struggle swimming with weight of experimental group after PSD5d (P=0.013), PSD7d (P=0.001), PSD9d (P=0.001) had statistic difference with that before PSD. These two groups have statistic significance after PSD1d (t=-3.703, P=0.002), PSD3d (t=-5.124, P=0.000), PSD5d (t=-4.274, P=0.001), PSD7d (t=-6.192, P=0.000), PSD9d(t=-8.154,P=0.000).Conclusion:In the condition of room temperature 22～26℃, relative humidity 65%, and day to night alternation for 12h, having rat in a box covered by nets preventing rat from escaping, in which, the water depth is about 1.5 cm and fresh water and food were provided,20h for continuous 10d can establish a PSD rat model. Using the time of exhaustive swimming loaded with 5% percent weight of itself with water depth about 50cm, temperature around 24±2℃to evaluate the PSD rat model is workable.Chapter II Effects of PSD on body mass, cardioelectrical activity, inflammatory and biochemical parameters, function of vascular endothelium, and the microscopic structure of cardiac muscle in rats.Experiment One:The effect of PSD on body weight in rats.Purpose:To observe the dynamic change of PSD on body weight in rats.Methods:18 6w male Sprague-Dawley rats, adaptive feeding for 8w until body mass were between 380g-450g. We randomly divided rats into control group and experimental group, with 9 rats in each group. At 12AM everyday, we put rats separately into a box covered by nets preventing rat from escaping, in which, the water depth was about 1.5cm and fresh water and food were provided, and took them out at 8AM on the next morning and put them into dry cages to have rest. We put them back into the previous boxes at 12AM. So the PSD was 20h per day for 10d. For control group, we didn’t have any intervention. At 8AM on the day before PSD, after PSD1d, PSD4d, PSD7d and PSDIOd we measured the rats’ body weight.Results:Experimental group:compared with that before PSD, the body weight after PSD1d (P=0.043), PSD4d (P=0.000), PSD7d (P=0.000), PSD10d (P=0.000) decreased gradually, and had statistic significance. Control Group:compared with that before PSD, the body weight after PSD1d (P=0.003), PSD4d (P=0.001), PSD7d (P=0.000), PSD10d (P=0.000) increased gradually, and had statistic significance. After PSD4d (t=-4.347, P=0.000), PSD7d (t=-4.765, P=0.000), PSD10d (t=-5.336, P=0.000), two groups had statistic significance.Conclusions:PSD can cause decrease of body weight in rats.Experiment Two:Effects of PSD on cardioelectrical activity in rats.Purpose:To observe the effects of PSD on surface electrocardiogram (S-ECG).Method:Established PSD models as "Experiment one". Had rats S-ECG tested at 8 AM on the day before PSD, after PSD Id, PSD4d, PSD7d and PSD10d. Before the test, we used 3% amobarbitol introperitoneal injection to anesthetize rats. Fixed the rats on supine position, inserted the electrodes subcutaneously, into left lower limb, right upper limb, and right lower limb respectively, digitized standard limb lead II and analyzed them. We used professional software to record and analyze. The analytic parameters were RR interval, heart rate (HR), P wave duration, P wave amplitude, PR interval, QRS interval, T wave amplitude, height of ST segment, QT interval, corrected QT interval (QTc interval), QT dispersion (QTd), corrected QT dispersion (QTcd).Results:Data on S-ECG had significant change. In experimental group, compared with that before PSD, QRS interval became wider (P=0.012), QT interval (P=0.000), QTc interval (P=0.001), QTd (P=0.020) and QTcd (P=0.030) increased. P wave amplitude (P=0.021) increased, ST segment (P=0.003) suppressed. Moreover, after PSD 10d, experimental rats had premature ventricular contractions.Conclusions:PSD has significant effects on cardioelectrical activity and tended to make it less stable and even ventricular arrhythmia.Experiment Three:Effects of PSD on inflammatory and biochemical parameters.Purpose:To observe the effects of PSD on blood sugar, total cholesterol (TC), triglyceride (TG), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), creatin kinase (CK), creatin kinase-MB (CK-MB), high-sensitivity C-reactive protein (Hs-CRP), and to find out the effects on blood sugar, lipid metabolism and inflammatory parameters in rats.Method:Established PSD models as "Experiment one". After PSD 10d, had two groups rats starve for 24 hours. Drew blood from abdominal aortic after anesthetizing by 3% amobarbitol introperitoneal injection. Took the supraserum after centrifuge and used AEROSET C8000 to test blood sugar, TC, TG, HDL-C, LDL-C, CK, CK-MB, and used Simens BN prospec to detect Hs-CRP.Results:Compared with control group, blood sugar in experimental group decreased (t=-2.974, P=0.009), TG decreased (t=-2.934, P=0.01). Change of TC, LDL-C, CK and CK-MB had no statistic significance. Hs-CRP level had no change.Conclusion:Short-term of PSD will not cause inflammatory reaction, but may increase metabolism to increased glucose, protein and lipid breakdown.Experiment Four:Effects of PSD on function of vascular endothelium, and the microscopic structure of cardiac muscle.Purpose:To observe the effects on function of vascular endothelium related parameters, and the microscopic structure of cardiac muscle.Method:Used the method in "experiment three" to take supraserum and used ELISA to test the concentration of vWf, ET-1, E-selectin, and tested NO by colorimetric determination. After drawing blood, opened the thoracic cavity immediately, exposed and isolated the heart. After cutting off small pieces of heart tissue, quickly fixation, dehydration, enmeshment, slicing, and staining, observed them under electromicroscope and took pictures.Results:There were no concentration changes of vWf, ET-1, E-selectin, NO in both groups. But under electromicroscope, we found that PSD caused cardiac tissue injury.Conclusions:PSD may cause cardiac tissue injury, but there is little evidence that PSD has effect on function of vascular endothelium in healthy rats. |
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