在应激低反应期新生大鼠的海马和视交叉上核核受体-MR、GR表达的变化

EXPRESSION CHANGES OF MINERALOCORTICOID AND GLUCOCORTICOID RECEPTORS IN THE HIPPOCAMPUS AND THE SUPRACHIASMATIC NUCLEUS OF NEWBORN RATS DURING STRESS HYPORESPONSIVE PERIOD

目的搞清新生大鼠HPA轴改变在应激低反应时期(stress hyporesponsive period、SHRP))的核受体-MR(盐皮质激素受体)和GR(糖皮质激素受体)在海马和视交叉上核(SCN)的表达变化。从而进一步了解新生大鼠发育时间对MR和GR的影响。方法本研究应用免疫荧光技术研究了生后4d(PD4)和生后12d(PD12)的新生大鼠海马和SCN的MR、GR的表达。同时采用RIA方法测定了血清中皮质类固醇的浓度水平。结果RIA结果显示在应激低反应期给予刺激,血清皮质类固醇水平没有明显改变。在海马,PD12较PD4,MR-和GR-i mmunoreactivity在CA1区表达增强;在齿状回没有明显变化;在海马门(hilus)减弱。而在海马的CA3区和SCN中,PD4 GR-ir强烈表达,在PD12却下降。同时也发现在hilus细胞出现GR和nestin(巢蛋白)阳性表达的共存,但是却没有发现MR和nestin的共存。结论新生大鼠阶段,发育时间对MR和GR的影响因区域不同影响不同。GR和nestin(巢蛋白)的共存为探讨在新生大鼠阶段GR对神经干细胞的分化有否影响提供了实验资料。本研究也为进一步研究新生大鼠应激低反应状态下海马及SCN与低活性的HPA轴的关系提供了形态学依据。

Objective To study the distribution of nuclear receptors-mineralocorticoid receptor（MR） and glucocorticoid receptor（GR） in the hippocampus and the suprachiasmatic nucleus（SCN） during the stress hyporesponsive period（SHRP） of newborn rats,and to understand the effect of developmental time on MR and GR in newborn.MethodsWe investigated the expression of MR and GR in hippocampus and SCN at two SHRP timepoints（postnatal days 4 and 12 using immunofluorescence.ResultsDifferent expressions of MR and GR were found.On PD12,increased MR-/GR-immunoreactivity intensity in CA1,no change of MR-/GR-ir intensity the dentate gyrus and decreased MR/ GR-ir intensity in the hilus were observed as compared to those on PD4.In the hippocampal CA3 and the SCN,no GR-ir was observed on PD12.ConclusionThis result suggests that the effect of developmental time on the expressions of MR and GR differs among various regions in postnatal life.Meanwhile,we also observed co-expression of GR-ir and nestin-ir（neuronal stem cell marker） in the hilus,whereas no co-expression of MR-ir and nestin-ir was found.This observation suggests the effect of GR on proliferation,survival and differentiation of neuronal stem cells during the early postnatal period.