低压低氧对大鼠下丘脑Orexin A表达及舌下神经放电的影响

Orexin A and hypoglossal discharge in a rat model of chronic intermittent hypobaric hypoxia

目的:观察慢性间歇性低压低氧(chronic intermittent hypobaric hypoxia,CIHH)模型大鼠下丘脑OrexinA表达及舌下神经放电活动,探讨CIHH对呼吸活动调节的机制。方法:对正常成年雄性SD大鼠进行每天6 h的低压低氧处理,28 d后进行血气分析,采用免疫组织化学染色方法观察大鼠下丘脑Orexin A的表达,记录舌下神经放电作为观察呼吸活动的指标。结果:血气分析显示模型组大鼠的PO2下降,PCO2明显升高(P<0.05,n=6);模型组大鼠下丘脑Orexin A免疫阳性神经元的相对光密度值显著升高(P<0.01,n=5);舌下神经放电幅度积分面积减小(P<0.01,n=6),呼吸频率降低(P<0.05,n=6)。结论:CIHH使大鼠动脉血PO2下降、PCO2明显升高,舌下神经放电活动减弱。下丘脑Orexin A神经元表达的增加提示Orexin的确参与了对呼吸活动的调节,尤其在CIHH时发挥了重要作用。

Objective： To observe the expression of Orexin A in the hypothalamus and hypoglossal nerve discharge in a rat model of chronic intermittent hypobaric hypoxia（CIHH） and to investigate the mechanism of respiratory regulation in CIHH.Methods： Sprague-Dawley adult rats were exposed to hypobaric hypoxia 6 hours daily.At the end of 28 days,the rats were measured of blood gas.Expression of Orexin A in the hypothalamus was observed by immunohistochemistry.Hypoglossal nerve discharge was recorded.Results： Blood gas analysis showed that PO2 decreased,PCO2 increased（P0.05,n=6） in the model compared with control.The relative optical density of Orexin A positive cells in the hypothalamus was greater（P0.01,n=5） in the model compared with control.The integral area of hypoglossal nerve discharge decreased significantly（P0.01,n=6）,the respiratory frequency decreased（P0.05,n=6） in the model compared with control.Conclusion： There were arterial PO2 decreased and PCO2 increased,hypoglossal nerve discharge decreased in CIHH rats.Increased expression of Orexin A neurons in the hypothalamus suggest that Orexin is involved in the regulation of breathing,as well as an important role for Orexin in the CIHH.