慢性肾衰大鼠下丘脑组织食欲素A、食欲素1型受体和瘦素受体表达的变化

Expression of Orexin A,Orexin Receptor -1,and Ob -R of Hypothalamus in Rats with Chronic Renal Failure

目的探讨大鼠慢性肾衰（CRF）动物模型下丘脑组织食欲素A及其前体mRNA（Prepro-OXmRNA）、食欲素１型受体（OX１R）及其mRNA和瘦素受体（ob-R）表达的变化。方法随机将６２只２００～２５０g雄性Wister大鼠分为：正常组（n＝５），假手术组（n＝２５），CRF组（n＝３２）。采用放射免疫法测定下丘脑组织食欲素A；逆转录-聚合酶链反应方法分析下丘脑组织Prepro-OXmRNA和OX１RmRNA的表达；免疫组化方法分析下丘脑组织食欲素A、OX１R和ob-R的表达；酶联免疫吸附法测定血清瘦素水平；生化自动分析仪测定血清肌酐。结果与假手术组大鼠相比，CRF大鼠下丘脑组织食欲素A水平明显下降并与血清瘦素水平呈显著负相关（r＝－０．６３，P＜０．００１）；CRF大鼠术后１２周的下丘脑组织Prepro-OXmRNA表达水平明显低于假手术组（P＜０．０１），并分别与血清瘦素水平和血清肌酐水平呈显著负相关（r＝－０．８１，P＜０．００１；r＝－０．６８，P＜０．０５）。CRF大鼠术后１２周下丘脑OX１RmRNA水平低于假手术组，但无显著差异（P＞０．０５）。CRF大鼠术后８周食欲素A阳性信号位于下丘脑组织神经元细胞的核周质，OX１R沿神经纤维走行分布，ob-R阳性信号位于下丘脑组织神经元细胞的胞膜，CRF组和假手术组大鼠相比。

Objective To examine the changes of expressions of orexin A,orexin receptor-1(OX 1 R),prepro-orexin(Prepro-OX)mRNA,OX 1 R mRNA and ob-R of hypothalamus in rats with chronic renal failure(CRF).Methods Sixty-two male Wister rats weighing200～250g were divided into three groups,including group1(normal,n=5),group2(sham-operated,n=25)and group3(CRF,n=32).Hypothalamus orexin A was assayed by radioimmunoassay.Serum leptin was assayed by enzyme linked immunosorbent assay.The expression of Prepro-OX mRNA and OX 1 R mRNA of hypothalamus were measured by reverse transcription polymerase chain reaction,and expression of orexin A,OX 1 R and ob-R by immunohistochemistry.Automatic biochemical analyzer was used to measure the serum creatinine.Results Hypothalamus orexin A levels were negatively correlated(r=-0.63,P<0.001)with serum leptin levels in the rats.The expression of hypothalamus Prepro-OX mRNA in CRF rats was significantly lower than that of sham-operation at week12(P<0.01).Hypothalamus Prepro-OX mRNA levels were negatively correlated(r=-0.81,P<0.001)with the levels of serum leptin and serum creatinine(r=-0.68,P<0.05)in the rats at week12.The expression of hypothalamus OX 1 R mRNA in CRF rats was lower than that of sham-operation at week12(P>0.05).Specific immunoreactivity for orexin A was present in perikeryon of the hypothalamus neuron.Specific OX 1 R-like immunoreactivity was observed in some nerve fibres.Specific immunoreactivity for ob-R was present in membranes of the hypothalamus neuron.Hypothalamus neurons of orexin A-like specific immunoreactivity in CRF rats were significantly fewer than those in sham operated rats at week8.Hypothalamus neurons of OX 1 R-like specific immunoreactivity in CRF rats were similar to those in sham-operated rat at week8.Hypothalamus neurons of ob-R-like specific immunoreactivity in CRF rats were significantly more than those in sham-operated rats at week8.Conclusions The lower hypothalamus orexin A levels may be induced by high serum leptin level in CRF rats.The lower expression of hypothalamus Prepro-OX mRNA in CRF rats may be one of the main causes inducing lower hypothalamus orexin A.The expression of OX 1 R in hypothalamus neurons is somewhat reduced and the expression of ob-R in hypothalamus neurons is somewhat raised in CRF rats.These remain to be studied further.