| Objective The spontaneously hypertensive rats were used as a model in this experiment, in order to observe the effect of hot and humid environment(heat stress) on the injury of thoracic aorta, and study its possible mechanism. The heart blood and vessel function were comprehensively analyzed, in order to provide scientific theory for the prevention of cardiovascular diseases.Methods According to the different time in the thermal environment, Wistar-Kyoto rats(WKY) were randomly divided into 3 groups(n=8 each group): control group(WKY-CN), heat exposure 8 hours group(WKY-8), heat exposure 24 hours group(WKY-24). CN group exposed to a room temperature(24 ?); WKY-8 and WKY-24 group exposed to heat temperature(32?), relative humidity was 65%. Accordingly, Spontaneously Hypertensive rats(SHR) were randomly divided into 3 groups(n=8 each group):SHR-CN, SHR-8, SHR-24. After 7 days heat exposure, the weight, food consumption and blood pressure of rats were measured; the noradrenaline(NA)-induced contraction on aorta rings was measured by organ bath systems. Vascular morphology was observed. We determinated the IL-2, IL-12, e NOS levels by enzyme-linked immunoassay, tested the thermal exposure effect on lymphocyte proliferation by CCK-8. The expression of apoptotic genes and proteins in the thoracic aorta were measured.Results1. After the experiment, the weight of each group was rising(P<0.01), but SHR-24. Weight of SHR-24 is abnormally reduced. The weight of growth in SHR rats is slower(P<0.05).2. After heat exposure, systolic and diastolic blood pressure are obviously increased in WKY-24, SHR-8, SHR-24(P<0.05).3. The vasoreactivities in WKY-8 and WKY-24 were increased obviously than that of WKY-CN(P<0.05). The vasoreactivities in SHR were all increased obviously than that of WKY(P<0.05).Compared with SHR-CN group, the vasoreactivities in SHR-8 and SHR-24 group was increased obviously(P<0.01).4. In WKY-24 group, endometrial cells connected loosely, and endodermis was partly missing, but better than WKY-8 group. Most of the endothelial cells were lost, vascular intima was incomplete, some elastic fiber and collagen fiber is thicker, cell distribution was disorderly in the SHR-8 group, SHR-24 and SHR-8 group were similar, but SHR-24 group is better.5. Compared with WKY-CN, the content of e NOS in WKY-24 was lower(P<0.05). Compared with SHR-CN, the content of e NOS in SHR-24 was lower the weight of growth in SHR rats is slower(P<0.05). Compared with WKY-24, the content of e NOS in SHR-24 was lower(P<0.01).6. The content of IL-12 in WKY-8 and SHR-8 were increased obviously than that of CN(P<0.05). Compared with WKY, the IL-2 and IL-12 were lower obviously(P<0.01). The hot and humid environment enhance the ability of lymphocyte proliferation(P<0.05).7. In the high temperature and high humidity environment, the expression of Caspase-3 was increased obviously(P<0.05), the expressions of Bcl-2 in rats were all decreased obviously(P<0.05) than that of room temperature. The expressions of Caspase-3 in SHR were all increased obviously(P<0.05) than that of WKY. Compared with WKY-CN, the apoptosis gene of Bax was up-regulation in WKY-8(P<0.05). Compared with SHR-CN group, the expression of Bax in SHR-8 and SHR-24 group was increased significantly(P<0.01). In the high temperature and high humidity environment, the expressions of Bax in SHR were all increased significantly than that of WKY(P<0.01).8. In the high temperature and high humidity environment, western blotting indicated that the protein expression of Bax was increased(P<0.01), accompanied by the reduced in Bcl-2(P<0.01).Conclusion As a result, thoracic aortic structure and function of rats in the hot and humid environment were injured,related to cell apoptosis, more seriously in SHR. The cell apoptosis in discontinuous thermal environment was more serious. |
PDF Full Text Request