Study on endothelial function of cerebral vessels in aged rats with chronic intermittent hypoxia / 中华老年医学杂志

ABSTRACT

Objective To investigate the expression of endothelin-1 (ET-1 ), nitrogen monoxidium (NO), vascular endothelial growth factor (VEGF) and brain tissue VEGF induced by chronic intermittent hypoxia (CIH) in aged rats. Methods The CIH model of aged rat was established by using intermittent hypoxia. The levels of ET-1, NO and VEGF in the plasma were detected at 3, 6 and 9 weeks after experiment in each group. The expression of VEGF in brain tissues and the pathological changes of the vessels of the cerebra and the ratio between the thickness of vessel wall and external diameter (WT%) were observed. Results In CIH group, the ET-1 and VEGF levels increased, however NO level decreased. The levels of ET-1 and VEGF were higher at 3 weeks in CIH group than in UC group (t=2.47 and 2.38, both P<0.05), however NO level was lower in CIH group than in UC group (t=2.39, P<0.05). VEGF levels increased significantly at 9 weeks in CIH as compared with UC group [(171.1±13.5) pg/ml vs. (109.8±8.6) pg/ml, t = 3.46, P< 0.01]. The levels of VEGF in CIH group increased remarkably at 9 weeks as compared with 3 weeks [(129.3±12.3) pg/ml, t=2.38, P<0.053. VEGF levels in CIH group showed positive correlation with the time of intermittent hypoxia. The changes of cerebral vessels in UC group were not found, while the aged rats in CIH group showed cerebral neuron cells swelling and blood vessel hyperplasia. The WT% of cerebral small artery was more apparent in CIH group than in UC group at 3 weeks (t=2.34,P<0.05). The expression of VEGF in cerebra was higher in CIH group than in UC group in the three stages (r=2.37, P<0.05). There was an aggravated tendency in the change of the expression of brain tissue VEGF and WT% over time. The change was more apparent at 9 weeks than at 3 weeks (t=2.32 and 2.35, both P<0.05). Conclusions CIH can induce an increase in the expression of ET-1 and VEGF, a decrease in the expression of NO in aged rats. The over expression of VEGF and the disbalance of ET-1 and NO levels can cause brain cellular swelling, arteriola vessel wall thickening,lumens stenosis.