低氧性肺动脉高压大鼠肺内5-HT(下标 1B)受体的分布和表达变化
摘要
AIM: To investigate the changes of 5-hydroxytryptamine (5-HT) levels and to observe the expression and distribution of 5-HT(subscript 1B) receptors in the lung tissues of hypoxic pulmonary hypertension (HPH) rats for exploring the mechanisms of hypoxic pulmonary hypertension. METHODS: Forty male Sprague-Dawley rats were randomly divided into 4 groups: normoxia control (control group), 3 weeks hypoxia group, 4 weeks hypoxia group and 5 weeks hypoxia group. The rats in normoxia control group stayed in normal environment. The rats in 3 weeks hypoxia group, 4 weeks hypoxia group and 5 weeks hypoxia group were kept respectively in hypoxia chamber for 3 weeks, 4 weeks and 5 weeks respectively to establish the HPH animal model. After HPH was established, the mean pulmonary pressure (mPAP) and the right ventricular systolic pressure (RVSP) were recorded by a micro-catheter. RV/(LV + S) ratio was calculated to assess the right ventricular hypertrophy. 5-HT levels in plasma and lung tissues of HPH rats were measured by ELISA. The expression and distribution of 5-HT(subscript 1B) receptors in the lung tissues were measured by the methods of immunohistochemistry and Western blotting. RESULTS: Compared to the normoxia controls, mPAP, RVSP and RV/(LV + S)% in 3 weeks hypoxic rats increased significantly (P＜0.05), and continued to increase following prolonged hypoxia. The results of ELISA showed that 5-HT levels in plasma and lung tissues of HPH rats continued to increase following prolonged hypoxic exposure (P＜0.05). The 5-HT(subscript 1B) receptors were localized mainly in the intima of the pulmonary arteries in normal rats. Exposed to hypoxia, the immuno-reactivity for 5-HT(subscript 1B) receptors increased in the media of pulmonary arteries in 3 weeks hypoxic rats, particularly those bordering the adventitia. The increase in the expression of 5-HT(subscript 1B) receptor was observed following prolonged hypoxic exposure. The results of Western blotting showed the same changes o