| Objective: Diabetic cystopathy (DCP) is one of common complication of diabetes mellitus. Impacting human'health status and life quality, this disease is thought more and more highly. The pathogenesy of DCP is not overall clear in recent time. But whichever factor wants to affect the urocystic functions or shaps, it would be finished with the detrusor of bladder. So it has become a hot spot to study muscle's factors. On one hand, people had found that the relaxation function of detrusor of bladder was injured in the earlier period of diabetes mellitus by the way of animal experiments. On the other hand,β3-adrenergic receptor(β3-AR)is the most important factor to accommodate the relaxation of musculus detrusor vesicae of human and rats. on these grounds, in this study, we observed the expression ofβ3-adrenergic receptor in the bladder of rats with diabetes and determined the relationship between diabetic cystopathy (DCP) andβ3-adrenergic receptor in the bladder detrusor smooth muscle by using diabetic model. Furthermore, the role ofβ3-adrenergic receptor in the development of DCP was explored in this study, which might provide experimental basis for us to cure DCP by using highly selectiveβ3-adrene- rgic receptor agonist. Methods: Eighty female Wistar rats (weight 180–200g) were randomly divided into the diabetic model group (n=40)and the normal control group(n=40). the diabetic model rats were randomly divided into 5 groups and the experiments were car- ried out after 2 weeks, 4 weeks, 6 weeks, 8 weeks and 10 weeks in order. The normal control group was set up at every experi- ment time . That is 2-week-diabetic model group and the normal control group, the 4-week-diabetic model group and the normal control group, the 6-week-diabetic model group and the normal control group, the 8-week-diabetic model group and the normal control group, the 10-week-diabetic model group and the normal control group (n=8). The type 1 diabetes mellitus rats were induced by peritoneal injection of the streptozotocin (STZ), 60mg/kg. The normal control group was producted by peritoneal injection of Citric Acid buffer with the equal volum. Diabetes was confirmed in STZ-injected rats by measurement of plasma glucose concentration in blood samples from the tail vein. The blood glucose (BG) of tail vein were measured after 72 hours of injection of STZ, when BG>16.7mmo1/L and extended in one week. All rats were feed for common forage and were taken food and water freely. The experiments were carried out at corresponding time after the model was successfully set up, and the blood glucose of tail vein were measured again in order to eliminate those rats (BG≤16.7 mmol/L). The bladders were completely cut down and the bladder wet weight was measured. After Haematoxylin-Iraq red (HE) staining, the changes of the shapes about detrusor of bladder of diabetic rats were observed under the light microscope. The amounts ofβ3-adrenergic receptor protein in the cell of detrusor of bladder were measured by the method of Western blotting. The datas were analyzed by t and t' test with SPSS 13.0 system software and the result was mean±standard deviation (Mean±Std.).Result:1. The common behavior of rats:After the model being successfully set up, we observed the rats with naked eye: The rats in diabetic model was observed in whole body, which were shown that their skin and capill lost gloss and they drank more water and ate more food and urinated more urine and excreted more thin excrement. The blood glucose in the diabetic model group'rats was obviously higher than that in the normal control group'rats[2w:(34.4±0.4mmol/L)vs(4.4±0.4mmol/L),4w: (32.6±3.7mmol/L)vs(5.2±0.5mmol/L),6w:(35.1±3.7mmol/L)vs(5.5±0.2mmol/L),8w:(30.9±3.3mmol/L)vs(4.8±0.3mmol/L),10w:(34.2±2.9mmol/L)vs(4.5±0.6mmol/L)(P<0.05)] The body weight of the diabetic model group'rats grew slower than that of the normal control group'rats [2w:(188.05±10.03g) vs(212.80±10.26g),4w:(190.22±8.31g)vs(258.22±10.31g),6w:(188.06±13.52g)vs(311.80±8.92g),8w:(174.83±12.18g)vs(342.80±16.91g),10w:(175.23±11.23g)vs(345.16±15.22g)(P<0.05)].The bladder wet weight of the diabetic model group'rats was obviously heavier than that of the normal control group'rats [2w:(183.99±14.89 mg)vs(150.34±5.30mg),4w:(200.17±14.40mg)vs(150.48±9.86 mg),6w:(207.27±17.92mg)vs(152.90±9.83mg),8w:(210.58±20.95mg)vs(148.04±9.72mg),10w:(223.94±20.45mg)vs(145.28±11. 60mg)(P<0.05)]. The blood glucose and the body weight and the bladder wet weight of every diabetic model group'rats had no significant deviation.2. Routine pathologic examinations of the bladder detrusor smooth muscle: Under the light microscope, detrusor structure of every group of rats was observed. Normal control group: Transitional epithelium cell arrangement was neat, membrana propria was integrity. The size and shape of detrusor cell was homogeneous and muscle fiber was arranged in order. Structure of muscle bundles was close and the gap was filled by phoroplast tissue. Diabetic model group: Transitional epithelium cell arrangement was not neat. Membrana propria was hype- remia and dropsy and size of decompensated detrusor muscle cell was large and the degeneration appeared, the shape was diverse and interstitial collagen component increased. After that, Muscle fiber was arranged disorder and out of order, cross of muscle fiber was full and space between the muscle fiber was enlarged obviously. The collagen and fiber structure was obvio- usly proliferated and a lot of collagen could be seen. Finally detrusor cell atrophied, reduced or even disappeared, and only a lot of collagen and elastic fiber components could be seen.3. The chang inβ3-AR protein of the bladder detrusor smo- oth muscle: The result of western blotting demonstrated that the amount ofβ3-AR protein in diabetic rat bladder was increased than control bladder [2w:(0.73±0.09)vs(0.35±0.04), 4w:(0.81±0.13)vs(0.32±0.06),6w:(0.72±0.05)vs(0.33±0.04),8w:(0.55±0.07)vs(0.33±0.06),10w:(0.52±0.07)vs(0.33±0.05)(P<0.05)], what's more important, the amount ofβ3-AR protein in 2-week-diabet- ic model group, 4-week-diabetic model group and 6-wee- k-diabetic model group increased more obvious.Conclusion: The bladder detrusor smooth muscle of every diabetic model rats group was injured. The expressed levels ofβ3-adrenergic receptor were increased in the bladder detrusor smooth muscle of every diabetic model rats group with STZ injection. The expressed change ofβ3-adrenergic receptor pla- yed an important role in the development of DCP. |
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