Changes on aortic diameter and number of Endothelin-B receptor in aortic endothelium of diabetes mellitus rat model after exercise

Background : Incidence and prevalence rate of diabetes mellitus (DM) were increased in recent years in various parts of the world. Diabetes mellitus had microvascular and macrovascular complications. Those complications of DM occurred due to vascular disorders. The complications include the decrease of endothelin B receptor (ETB) and reduce on blood vessels diameter. In vitro studies indicate shear stress can increase expression of ETB receptors on the endothelium. ETB receptors in endothelium have vasodilatation activity. Shear stress increases in physical exercise. Physical exercise known may improve ETB receptor number and also increase the diameter of blood vessels. Objective : This study aims to know the changes of aortic diameter and the number of ETB receptor expression in the aortic endothelium of DM rat model after exercise. Methods : This study is an experimental research design with a post-test only control group to measure the diameter of the aorta and ETB receptor expression in the aortic endothelium. Rat model of DM obtained by injecting streptozotocin 35mg/kgwb intra peritoneal Sprague Dawley male rats aged 11-12 weeks. Rats were divided into two groups, one group received regular physical exercise and other group without regular physical exercise. Physical exercise routine using a special treadmill for rat, low - moderate intensity, frequency 5x/week, for 9 weeks, with a week of adaptation using a speed of 5 m/min for 10 minutes, followed 8 weeks later using a gradual rise velocity of 5 m/min to 20 m/min for 60 minutes. Rat aortic diameter was measured by using a microscope optilab. Endothelin B receptor expression was calculated by the percentage of the ETB receptor in aortic endothelium which has been stained with immunohistochemical staining. Results : The mean results for the aortic lumen diameter in non-exercise group rat is 913.73 ± 62.08 ?m, and 1066.73 ± 28.58 ?m in exercise group (p value is 0.033). After immunohistochemistry staining for ETB, the results for non-exercise group is 49.37 ± 5.64 %, while for the exercise group the ETB receptors is 78.42 ± 5.84 % (p value is 0.006). Conclusion : There was an increasing of ETB receptor number and aortic diameter of DM rat model after regular physical exercise compared with the group of DM rat model without regular physical exercise. Bangladesh Journal of Medical Science Vol.15(3) 2016 p.381-384


Background:
Various epidemiological studies have shown a trend of increasing in the incidence and prevalence of diabetes mellitus (DM) in various parts of the world.World Health Organization (WHO) predicts an increase in the number of people with diabetes are quite large in the years to come.WHO predictions for Indonesia, the increase in the number of patients from 8.4 million in 2000 to around 21.3 million in 2030 1 .The amount of the estimated number of patients who suffer from diabetes is associated with reduced life expectancy ranges , increased micro-and macrovascular complications, and the decline in the quality of life 2 .Complications of diabetes include complications of acute and chronic complications.Acute complications such as iatrogenic hypoglycemia, diabetic ketoacidosis, hyperosmolar hyperglycemic non-ketotic coma, and lactic acidosis.Chronic complications including retinopathy, nephropathy, neuropathy, and diabetic coronary heart disease.The increase in diabetes complications result from blood vessel disorders, both macrovascular and microvaskular 3 .Vascular disorders preceded the increased viscosity of the blood flow, increasing the pressure received by the endothelium.Stresses imposed by the blood vessels which comes from the frictional forces due to blood flow (shear stress) 4 .Increased blood sugar levels will be followed by an increase in viscosity of the blood 5 proportional with shear stress 6 .Increased blood viscosity contributes to the increase in blood pressure with diabetes are thought to be contributing factors in the beginning of the failure of other organs in the DM complications 7 .Increase of blood pressure in diabetic patients is affected by an increase in blood viscosity, the formation of atherosclerosis in the blood vessels, reduced endothelin -B receptor continued to decline in the production of Nitric Oxide ( NO ) and prostacyclin, a decrease in insulin sensitivity, as well as an imbalance of vasoconstrictor and vasodilator 7 -11 .Number of endothelin -B receptors in the blood  Physical exercise routines that are used in this study is the use of physical exercise treadmill Gama special treat rat with low -moderate intensity, slope 0 0 , 5x/minggu frequency, the total time for 9 weeks, starting one week adaptation 5m/menit treadmill at a speed of over 10 minutes, followed by 8 weeks of the start -storey speed of 5 m / min to 20 m / min for 1 hour 15 .Rat aortic diameter is the diameter of the lumen of rat aortic preparations were stained with hematoxylin eosin staining which measured three times then taken using a microscope optilab.Expression of endothelin -B receptor is a percentage of the endothelin -B receptor in aortic endothelial which had been stained with immunohistochemicalstaining , which is calculated using formula 16 The number of positively stained endothelial cells x 100 % Total number of endothelial cells DM rat model is the male age of Sprague Dawley rats range 11-12 weeks induced with streptozotocin 35 mg / kg intraperitoneally a single dose, with a fasting blood glucose level > 140 mg / dl or blood sugar levels when > 200 mg / dl 17.18 .Ethical approval was taken Prior study.

Results and discussion:
This study using Sprague-Dawley male rats age range of 11-12 weeks, weighing between 250-300 g were divided into two groups.Rats divided into two groups.Exercise group and non-exercise group.Each group consisted of 8 rats.Rats were able to complete routine physical exercise protocol until the end of the study were 7 rats of exercise group, and 5 rats of non-exercise group.The results obtained during the study are as contained in Table 1.The mean results for the aortic lumen diameter DM group rat without regular physical exercise is 913.73 ± 62.08 µm and DM groups of rat with regular physical exercise 1066.73 ± 28.58 µm.Results of independent t-test trials for groups of diabetic rats with exercise and no exercise groups diabetic rats resulted in a p-value = 0.033, which means there is a significant difference between the two groups (p <0.05).

Parameter
Rats

Figure 1 .Figure 2 .
Figure 1.aortic lumen circumference measurement results using optilab a. DM group with exercise b.DM group without exercise

Table 1 .
Results of statistical analysis of the aortic lumen diameter, endothelin-B receptor, and the difference in blood pressure between groups After staining, the results obtained for the group of diabetic rats without regular physical exercise is the average percentage of 49.37 ± 5.64 % , while for the group of diabetic rats group with regular physical exercise mean obtained is 78.42 ± 5.84 %.Different test results using independent t -test showed no training for the DM group and DM group with the exercise value of p = 0.006 , this indicates a significant difference between the two groups.Pearson correlation test results between the variables showed that the diameter is not correlated with the percentage of endothelin -B receptor in aortic endothelial.Significance values obtained in the correlation test was p > 0.05.These results indicate that the correlation between the two variables was not statistically significant.R value for Pearson correlation test between the variable diameter and endothelin receptor number is 0,407, with a value of p = 0.189 which means there is no significance to the value of the correlation of two variables.