Nichols N R, Finch C E
Andrus Gerontology Center, University of Southern California, Los Angeles 90089-0191.
Ann N Y Acad Sci. 1994 Nov 30;746:145-54; discussion 154-6. doi: 10.1111/j.1749-6632.1994.tb39225.x.
We used two methods to examine altered patterns of gene expression in rat hippocampus in response to administered glucocorticoids: analysis of RNA in vitro translation products on 2-d gels and cloning of cDNAs from a rat hippocampal library by differential hybridization (+/- CORT). We determined that two of the CORT-responsive cDNA clones encoded the 35- and 50-kd RNA translation products and identified them as GPDH and GFAP, respectively, by sequence analysis. Cloned mRNAs that increased and decreased in response to CORT were determined to be under positive and negative regulation by glucocorticoids in intact rats. Despite their similarities in glucocorticoid response characteristics, we found three subsets of hippocampal mRNA responses to CORT and shaking stress which differ in temporal and level-dependent aspects of CORT regulation. In addition, GPDH gene expression represents a glucocorticoid-dependent stress response which is rapidly increased in a dose- and stressor-dependent manner. It is a candidate for a sensitive indicator of stress responsiveness in the brain as a function of neuroendocrine activity. Mechanisms of adaptation to stress in the brain are likely to involve responses that are both mediated by glucocorticoids and opposed by them. GFAP and TGF-beta 1 mRNA responses may be examples of the latter, since they are decreased in response to glucocorticoids, are under negative regulation by glucocorticoids in intact rats, and are increased in response to brain injury and disease and during aging. If these astrocytic and microglial responses are involved in cellular defense mechanisms in the brain, then their regulation by glucocorticoids would be important in maintaining and restoring cellular homeostasis in physiological and pathophysiological states. Future studies using these sensitive probes for glucocorticoid-regulated gene expression may identify new mechanisms by which the brain coordinates acute and chronic responses to stress and disease.
一是在二维凝胶上分析RNA体外翻译产物，二是通过差异杂交（±皮质酮）从大鼠海马体文库中克隆cDNA。我们确定，两个对皮质酮有反应的cDNA克隆分别编码35-kd和50-kd的RNA翻译产物，并通过序列分析分别将它们鉴定为甘油磷酸脱氢酶（GPDH）和胶质纤维酸性蛋白（GFAP）。在完整大鼠中，确定对皮质酮反应性增加和减少的克隆mRNA分别受糖皮质激素的正调控和负调控。尽管它们在糖皮质激素反应特征上有相似之处，但我们发现海马体mRNA对皮质酮和摇晃应激的反应存在三个亚组，在皮质酮调节的时间和水平依赖性方面有所不同。此外，GPDH基因表达代表一种糖皮质激素依赖性应激反应，它以剂量和应激源依赖性方式迅速增加。作为神经内分泌活动的函数，它是大脑应激反应敏感性指标的候选者。大脑中应激适应机制可能涉及既由糖皮质激素介导又与之相反的反应。GFAP和转化生长因子-β1（TGF-β1）mRNA反应可能是后者的例子，因为它们对糖皮质激素反应而减少，在完整大鼠中受糖皮质激素负调控，并且在脑损伤、疾病和衰老过程中增加。如果这些星形胶质细胞和小胶质细胞反应参与大脑中的细胞防御机制，那么它们受糖皮质激素的调节对于在生理和病理生理状态下维持和恢复细胞内稳态将很重要。未来使用这些糖皮质激素调节基因表达的敏感探针进行的研究可能会发现大脑协调对压力和疾病的急性和慢性反应的新机制。
