急性热应激与热惊厥幼龄大鼠脑内Fos的免疫反应性及ZnT3 mRNA原位杂交研究

Fos immunoreactivity and ZnT3 in situ hybridization studies in weanling rats following heat stress and febrile convulsions

目的探讨热应激（HS）和热性惊厥（FC）对脑内Fos免疫反应性和ZnT3 mRNA定位表达的影响，揭示FC发生的神经解剖学机制和对海马苔藓纤维发芽相关基因ZnT3表达的影响，为临床合理干预提供依据。方法采用热水浴诱导21日龄大鼠FC模型，应用免疫组织化学技术对HS和FC大鼠Fos免疫反应性在不同脑区的定位表达进行比较分析，采用原位杂交技术对海马ZnT3 mRNA表达进行检测。结果①Fos—IR阳性细胞的分布：正常对照组大鼠大脑皮层偶见零星淡染的圆形棕褐色细胞核，无定位分布特征；HS组Fos—IR阳性细胞分布具有明显群集分布特征，丘脑内呈典型核特异性分布，主要位于丘脑中线一带，即自侧脑室的背侧部沿中线延伸至第三脑室的背侧部，下丘脑室旁核（PVN）小细胞部明显表达，而下丘脑外侧区（LH）、下丘脑腹内侧核（VMH）、弓状核（Arc）和下丘脑视上核（SON）则无表达，大脑皮层见于杏仁周皮质（PIR）、内嗅皮质（Ent）、嗅周皮质（PRH）、顶皮质（PAR）、压部后皮质（RSG、RSA）、额皮质（Fr）等区域，PIR和Ent主要见于Ⅱ层。海马内偶见阳性细胞，杏仁核阴性。FC组海马明显表达，在丘脑和下丘脑则呈弥漫性分布，缺乏明显核团分布特征，PIR和Ent全层分布，Ⅱ、Ⅳ～Ⅵ层明显表达。②FC组海马区域可见明显ZnT3 mRNA表达，而HS组和对照组无明显表达。结论①Fos—IR阳性神经元图布（mapping）：HS组特征性分布于PVN小细胞部和丘脑中线一带核团，在大脑皮层以PIR和EntII层分布为主，海马表达极弱；FC组大鼠则以海马，杏仁核，大脑皮层Ⅱ、Ⅳ-Ⅵ层为主，丘脑和下丘脑呈均匀泛化分布，丘脑中线一带缺乏核团分布特征。这种神经解剖学的差异可能是造成HS和FC大鼠行为学迥异的基础。②FC组海马ZnT3 mRNA明显表达提示FC组海马区域存在异常增高的锌离子转运。

Objectives To analyze the expression of Fos immunoreactivity and ZnT3 mRNA in rat brain following heat stress and febrile convulsions, in order to find out the influence of FC on hippocampal mossy fiber - related gene ZnT3 expression and the underlying neuroanatomical mechanisms. Methods Warm water induced rat FC model was developed, immunohistochemistry and in situ hybridization methods were used in this study. Results ①The distribution of Fos - IR positive neurons ： very few or no Fos - IR neurons were seen in the control rat. In contrast, in HS group, subnucleus - specific Fos - IR positive neurons were found in the thalamic midline nucleus, paraventricular hypothalamic nucleus （ PVN ） , piriform cortex （ PIR ） , entorhinal cortex （ Ent, mainly in Ⅱ layer ） , Very few positive neurons were seen in hippocampus and negative in amygdala, In FC rats, however, abundant induction of Fos -IR was found in hippocampus, amygdala, and cerebral cortex （ mainly in Ⅱ , Ⅳ-Ⅵ layers of Ent ）. Fos - IR neurons were well - distributed in thalamus, without characteristic subnucleus - specific distribution. ②No ZnT3 mRNA positive cells were seen in HS and control group. In contrast, abundant induction of ZnT3 mRNA positive cells were seen in hippocampus of FC group. Conclusions ①The Mapping of Fos - IR positive neurons ： subnucteus - specific Fos - IR positive neurons were＇ found in the hypothalamic parvicel -lular paraventricular neurons and thalamic midline nucleus in HS group, In cerebral cortex, Fos -IR neurons were mainly distributed in piriform cortex and entorhinal cortex （ mainly in Ⅱ layer） , Very few posi- tive neurons were seen in hippocampus and negative in amygdala. In contrast to HS rats, abundant induction of Fos - IR was found in hippoeampus, amygdala, and cerebral cortex （ mainly in Ⅱ , Ⅳ - Ⅵ layers of Ent ） of FC rats, Fos - IR neurons were well - distributed in thalamus,without characteristic subnucleus - specific distribution. The results demonstrated that the above neuroanatomical difference may be the underlying mechanisms for different behavioral changes in HS and FC rats. ②There was elevated zinc metabolism in hippocampus of FC group.