地塞米松对卵蛋白所致哮喘大鼠下丘脑-垂体-肾上腺皮质轴及骨代谢的影响

目的：观察地塞米松对卵蛋白（Ovalbumin,OVA）所致哮喘大鼠的不同阶段（撤停前、撤停中、撤停后）下丘脑-垂体-肾上腺皮质轴（HPA轴）及骨代谢的影响。方法：90只大鼠随机分为正常对照组、哮喘模型组和地塞米松干预组,每组30只。每组根据处死时间的不同（实验第49、77、91天）随机各分为3个亚组,每组10只。以卵蛋白注射致敏结合卵蛋白雾化激发的方法建立大鼠哮喘模型。实验第35天开始,地塞米松干预组大鼠腹腔注射地塞米松0.5mg/kg,至实验第48天（撤停前阶段）;第49天开始按照每周0.1mg/kg的剂量递减地塞米松用量,至实验第76天（撤停中阶段）;第77天停用地塞米松,观察至实验第90天（撤停后阶段）。哮喘模型组及地塞米松干预组同时每周2次给予1%OVA生理盐水溶液雾化吸入。检测不同阶段各组大鼠脾脏及肾上腺指数、血清皮质酮（CORT）、血浆促肾上腺皮质激素（ACTH）、下丘脑促肾上腺皮质激素释放激素（CRH）及血浆骨钙素（BGP）含量。结果：（1）第49天,正常对照组、哮喘模型组、地塞米松干预组大鼠脾脏指数分别为1.504±0.213、1.548±0.208、1.254±0.239,肾上腺指数分别为0.132±0.039、0.108±0.027、0.065±0.017,CORT含量分别为（2301±628）、（1658±486）和（235±160）ng/L,ACTH含量分别为（62.7±17.4）、（32.7±17.2）和（19.7±8.8）ng/L,CRH含量分别为（5.77±2.01）、（4.20±1.87）和（3.40±1.28）ng/（mg.prot）,BGP含量分别为（5.22±2.14）、（3.64±1.40）和（0.65±0.62）μg/L。哮喘模型组ACTH及CRH含量均明显低于正常对照组（P（0.01,P（0.05）;地塞米松干预组CRH含量明显低于正常对照组,其他各项指标明显低于正常对照组和哮喘模型组（均P〈0.01）。（2）第77天,正常对照组、哮喘模型组、地塞米松干预组大鼠脾脏指数分别为1.515±0.169、1.567±0.180）、1.287±0.380,肾上腺指数分别为0.112±0.058、0.100±0.027、0.069±0.022,CORT含量分别为（2433±379）、（1905±410）和（355±239）ng/L,ACTH含量分别为（65.3±31.0）、（38.4±11.7）和（39.6±14.9）ng/L,CRH含量分别为（5.05±1.62）、（4.15±1.39）和（3.04±1.37）ng/（mg.prot）,BGP含量分别为（2.63±0.96）、（2.50±1.20）和（0.79±0.53）μg/L。哮喘模型组CORT含量明显低于正常对照组（P〈0.01）;地塞米松干预组除ACTH外其他各项指标均明显低于正常对照组和哮喘模型组（P〈0.05或0.01）。（3）第91天,正常对照组、哮喘模型组、地塞米松干预组大鼠脾脏指数分别为1.463±0.190、1.786±0.316、2.278±0.412,肾上腺指数分别为0.112±0.021、0.110±0.020、0.093±0.017,CORT含量分别为（2627±509）、（2318±364）和（2212±400）ng/L,ACTH含量分别为（63.0±33.5）、（48.8±19.9）和（30.7±19.1）ng/L,CRH含量分别为（5.39±1.40）、（3.80±0.94）和（3.67±1.09）ng/（mg.prot）,BGP含量分别为（4.58±2.19）、（3.21±1.34）和（1.93±0.91）μg/L。哮喘模型组脾脏指数明显高于正常对照组（P〈0.01）,CRH含量明显低于正常对照组（P〈0.01）;地塞米松干预组脾脏指数明显高于正常对照组和哮喘模型组（P〈0.01）,肾上腺指数、ACTH、BGP含量明显低于正常对照组和哮喘模型组（P〈0.05,P〈0.01）,CORT和CRH含量明显低于正常对照组（P〈0.05,P〈0.01）。结论：地塞米松干预对哮喘模型大鼠HPA轴具有很强的抑制作用,干预的不同阶段对HPA轴相关指标的抑制作用不同,并均抑制骨代谢。

Effects of dexamethasone on hypothalamic-pituitary-adrenocortical axis and bone metabolism in rats with ovalbumin-induced asthma

Objective：To observe the effects of dexamethasone on hypothalamic-pituitary-adrenocortical（HPA） axis and bone metabolism in rats with ovalbumin-induced asthma at different stages of intervention（before withdrawal,during withdrawal,after withdrawal）.Methods：Ninety rats were randomly divided into three groups（30 rats in each group）：the normal control group,the asthmatic model group,the dexamethasone intervention group.The rats in each group were redivided respectively into 3 subgroups（10 rats in each subproup） according to the time to be sacrificed（on days 49,77,and 91）.The rat model of asthma was established by ovalbumin（OVA） injection sensitization followed by challenge with gaseous ovalbumin.Dexamethasone intervention group received intra-abdominal injection of dexamethasone 0.5 mg/kg from day 35 to day 48（at the stage before withdrawal）.The dose of dexamethasone was decreased by 0.1mg/kg every week from day 49 to day 76（at the stage during withdrawal）.Dexamethasone was stopped on day 77 and observations were carried on until day 90（at the stage after withdrawal）.Gaseous normal saline solution containing 0.1%OVA was inhaled twice a week in the asthmatic model and dexamethasone intervention groups.At all stages of the experiment,the indexes of spleen and adrenal,levels of serum CORT,plasma ACTH,hypothalamic CRH,and plasma BGP were measured.Results：（1） On day 49,in the normal control,asthmatic model,and dexamethasone intervention groups,the spleen indexes were 1.504±0.213,1.548±0.208,and 1.254±0.239,respectively;the adrenal indexes were 0.132±0.039,0.108±0.027,and 0.065±0.017,respectively;the levels of CORT were（2 301±628）ng/L,（1 658±486）ng/L,and（235±160）ng/L,respectively;the levels of ACTH were（62.7±17.4）ng/L,（32.7±17.2）ng/L,and（19.7±8.8）ng/L,respectively;the levels of CRH were（5.77±2.01）ng/mg·prot,（4.20±1.87）ng/mg·prot,and（3.40±1.28）ng/mg·prot,respectively;the levels of BGP were（5.22±2.14）μg/L,（3.64±1.40）μg/L,and（0.65±0.62）μg/L,respectively.The levels of ACTH and CRH in asthmatic model group were significantly lower than those in the normal control group（P0.01 and P0.05,respectively）.The level of CRH in dexamethasone intervention group was significantly lower than that in the normal control group.Other laboratory values in dexamethasone intervention group were significantly lower than those in the normal control and asthmatic model groups.（2） On day 77,in the normal control,asthmatic model,and dexamethasone intervention groups,the spleen indexes were 1.515±0.169,1.567±0.180,and 1.287±0.380,respectively;the adrenal indexes were 0.112±0.058,0.100±0.027,and 0.069±0.022,respectively;the levels of CORT were（2 433±379）ng/L,（1 905±410）ng/L,and（355±239）ng/L,respectively;the levels of ACTH were（65.3±31.0）ng/L,（38.4±11.7）ng/L,and（39.6±14.9）ng/L,respectively;the levels of CRH were（5.05±1.62）ng/mg·prot,（4.15±1.39）ng/mg·prot,and（3.04±1.37）ng/mg·prot,respectively;the levels of BGP were（2.63±0.96）μg/L,（2.50±1.20）μg/L,and（0.79±0.53）μg/L,respectively.The level of CORT in the asthmatic model group was significantly lower than that in the normal control group（P0.01）.The indexes of spleen and the adrenal,the levels of CORT,CRH,and BGP in the dexamethasone intervention group were significantly lower than those in the normal control and asthmatic model groups（P0.05 or P0.01）,except the level of ACTH.（3） On day 91,in the normal control,asthmatic model,and dexamethasone intervention groups,the spleen indexes were 1.463±0.190,1.786±0.316,and 2.278±0.412,respectively;the adrenal indexes were 0.112±0.021,0.110±0.020,and 0.093±0.017,respectively;the levels of CORT were（2 627±509）ng/L,（2 318±364）ng/L,and（2 212±400）ng/L,respectively;the levels of ACTH were（63.0±33.5）ng/L,（48.8±19.9）ng/L,and（30.7±19.1）ng/L,respectively;the levels of CRH were（5.39±1.40）ng/mg·prot,（3.80±0.94）ng/mg·prot,and（3.67±1.09）ng/mg·prot,respectively;the levels of BGP were（4.58±2.19）μg/L,（3.21±1.34）μg/L,and（1.93±0.91）μg/L,respectively.The spleen index in the asthmatic model group was significantly higher than that in the normal control group（P0.01）.The CRH level in the asthmatic model group was significantly lower than that in the normal control group（P0.01）.The spleen index in dexamethasone intervention group was significantly higher than that in the normal control and asthmatic model groups.The adrenal index,the levels of ACTH and BGP in dexamethasone intervention group were significantly lower than those in the normal control and asthmatic model groups（P0.05,P 0.01）.The levels of CORT and CRH in dexamethasone intervention group were significantly lower than those in the normal control group（P0.05,P0.01）.Conclusion：Dexamethasone has different inhibitory effect on HPA axis-related indexes at different stages in rats of asthmatic model.It also inhibit the bone metabolism at all stages.