Laflamme N, Barden N, Rivest S
Laboratory of Molecular Endocrinology, Laval University, Québec, Canada.
J Mol Neurosci. 1997 Jun;8(3):165-79. doi: 10.1007/BF02736831.
The purpose of this study was to investigate the effect of the immune activator lipopolysaccharide (LPS) on the expression of corticotropin-releasing factor (CRF) and glucocorticoid receptor (GR) mRNA in the paraventricular nucleus (PVN) of transgenic mice with impaired GR function caused by endogenous expression of GR antisense RNA. At 3 and 8 wk of age, control and transgenic mice were sacrificed 4.5 h after a single ip administration of LPS (100 micrograms/100 g of body wt) or vehicle. Frozen brains were mounted on a microtome and cut in 20-microns sections. mRNAs encoding CRF and GR were assayed by in situ hybridization histochemistry using 35S-labeled riboprobes, and localization of Fos-immunoreactive (Fos-ir) nuclei was determined by immunocytochemistry. Basal expression of CRF mRNA in the PVN, central nucleus of the amygdala (CeA), and geniculate complex (GN) was similar in the control and transgenic mice. LPS induced a comparable neuronal activation in the PVN of control and transgenic mice as revealed by the number of Fos-ir neurons. Moreover, the endotoxin caused a significant increase in the CRF mRNA levels within the PVN and CeA, an effect observed in both animal models. The endotoxin did not notably modulate CRF expression in other regions, such as GN. Although GR mRNA was expressed in the PVN of control mice under basal conditions, this transcript was not detected in this hypothalamic structure in LPS-treated and transgenic animals. This indicated that endogenous Type II GR mRNA is decreased in the PVN of mice expressing Type II GR antisense RNA and that gene is downregulated by LPS. Hybridization signal for CRF and GR transcripts was not notably altered by the age of mice. These results provide evidence that the basal expression of CRF and the increase of neuroendocrine CRF transcription in response to immunogenic challenges are not significantly affected by impairment of the Type II GR function.
本研究旨在探讨免疫激活剂脂多糖（LPS）对因内源性表达糖皮质激素受体（GR）反义RNA而导致GR功能受损的转基因小鼠室旁核（PVN）中促肾上腺皮质激素释放因子（CRF）和糖皮质激素受体（GR）mRNA表达的影响。在3周龄和8周龄时，对对照小鼠和转基因小鼠单次腹腔注射LPS（100微克/100克体重）或溶剂后4.5小时处死。将冷冻的脑标本固定在切片机上，切成20微米厚的切片。使用35S标记的核糖探针通过原位杂交组织化学法检测编码CRF和GR的mRNA，并通过免疫细胞化学法确定Fos免疫反应性（Fos-ir）细胞核的定位。对照小鼠和转基因小鼠PVN、杏仁核中央核（CeA）和膝状体复合体（GN）中CRF mRNA的基础表达相似。如Fos-ir神经元数量所示，LPS在对照小鼠和转基因小鼠的PVN中诱导了相当的神经元激活。此外，内毒素导致PVN和CeA内CRF mRNA水平显著升高，在两种动物模型中均观察到这种效应。内毒素并未显著调节其他区域（如GN）的CRF表达。虽然基础条件下对照小鼠的PVN中表达GR mRNA，但在LPS处理的和转基因动物的该下丘脑结构中未检测到该转录本。这表明表达II型GR反义RNA的小鼠PVN中内源性II型GR mRNA减少，且该基因被LPS下调。CRF和GR转录本的杂交信号未因小鼠年龄而显著改变。这些结果证明，II型GR功能受损对CRF的基础表达以及免疫原性刺激后神经内分泌CRF转录的增加没有显著影响。
