Imaki T, Nahan J L, Rivier C, Sawchenko P E, Vale W
Clayton Foundation Laboratories for Peptide Biology, Salk Institute, La Jolla, California 92037.
J Neurosci. 1991 Mar;11(3):585-99. doi: 10.1523/JNEUROSCI.11-03-00585.1991.
The regulation of corticotropin-releasing factor (CRF) mRNA expression in the rat brain by glucocorticoids and stress was examined by Northern blot analysis and in situ hybridization histochemistry. Rats either were exposed to a single electrical footshock session and killed 2, 4, 12, or 24 hr later (acute stress), or were subjected to the same regimen twice daily for 3 or 7 d and killed on the day following the last session (chronic stress). Rats placed in the experimental chamber but not administered shock comprised a "sham-handling" group. Chronic (7 d) intermittent footshock stress resulted in an 84 +/- 26% (P less than 0.05) increase in CRF mRNA levels in the whole hypothalamus as detected by Northern blot analysis and a 97 +/- 29% (P less than 0.05) increase in the paraventricular nucleus (PVN) as detected using in situ hybridization. No significant change in CRF mRNA levels was observed in the hypothalamus at any time up to 24 hr after a single exposure to footshock stress. A different pattern of results was obtained in other CRF-expressing cell groups. In Barrington's nucleus (a pontine micturition center), both acute and chronic stress produced significant increases in CRF mRNA, while in the olfactory bulb, both paradigms resulted in decreased levels. By Northern blot analysis, CRF mRNA in the olfactory bulb declined steadily, beginning at 4 hr after acute stress, and reached significance at 24 hr (69.2 +/- 1.9% of control, P less than 0.05). Levels from chronically (7 d) stressed animals declined to 54.1 +/- 5.1% of control value (P less than 0.05). Analysis of hybridization histochemical material revealed that both the number of positively hybridized cells and the number of silver grains per cell in the mitral and external plexiform layers of the bulb decreased following acute and chronic stress. However, CRF mRNA levels in the olfactory bulb were decreased to a comparable extent in the sham-handling group, suggesting that exposure to a novel environment can effect a decrease in CRF mRNA levels in the olfactory bulb. To provide comparisons with the effects of manipulation of glucocorticoid status, comparable analyses were carried out in separate groups of animals following adrenalectomy (ADX) with and without corticosteroid replacement. After ADX, CRF mRNA levels in the whole hypothalamus increased 60 +/- 5% (P less than 0.05) and were normalized following dexamethasone replacement. In contrast to the hypothalamus, no effects of steroid manipulation on CRF mRNA levels in the olfactory bulb, midbrain, cerebral cortex, or brain stem were detected.(ABSTRACT TRUNCATED AT 400 WORDS)
通过Northern印迹分析和原位杂交组织化学法，研究了糖皮质激素和应激对大鼠脑中促肾上腺皮质激素释放因子（CRF）mRNA表达的调节。将大鼠单次暴露于电休克足底刺激，分别在2、4、12或24小时后处死（急性应激），或者每天进行两次相同的刺激方案，持续3或7天，并在最后一次刺激后的第二天处死（慢性应激）。置于实验箱但未接受电击的大鼠组成“假处理”组。通过Northern印迹分析检测，慢性（7天）间歇性足底电击应激导致整个下丘脑CRF mRNA水平增加84±26%（P<0.05）；使用原位杂交检测，室旁核（PVN）中CRF mRNA水平增加97±29%（P<0.05）。单次暴露于足底电击应激后24小时内，下丘脑CRF mRNA水平在任何时间均未观察到显著变化。在其他表达CRF的细胞组中获得了不同的结果模式。在Barrington核（脑桥排尿中枢），急性和慢性应激均使CRF mRNA显著增加，而在嗅球，两种应激模式均导致CRF mRNA水平下降。通过Northern印迹分析，嗅球中的CRF mRNA从急性应激后4小时开始稳步下降，在24小时时达到显著水平（为对照的69.2±1.9%，P<0.05）。慢性（7天）应激动物的CRF mRNA水平降至对照值的54.1±5.1%（P<0.05）。对杂交组织化学材料的分析显示，急性和慢性应激后，嗅球的二尖瓣层和外丛状层中阳性杂交细胞的数量以及每个细胞的银粒数量均减少。然而，假处理组嗅球中的CRF mRNA水平也下降到了类似程度，这表明暴露于新环境可导致嗅球中CRF mRNA水平降低。为了与糖皮质激素状态改变的影响进行比较，在分别进行了肾上腺切除术（ADX）且有或没有皮质类固醇替代的动物组中进行了类似分析。ADX后，整个下丘脑的CRF mRNA水平增加了60±5%（P<0.05），地塞米松替代后恢复正常。与下丘脑相反，未检测到类固醇处理对嗅球、中脑、大脑皮层或脑干中CRF mRNA水平有影响。（摘要截短至400字）
