Franklin S O, Yoburn B C, Zhu Y S, Branch A D, Robertson H D, Inturrisi C E
Department of Pharmacology, Cornell University Medical College, New York, NY 10021.
Brain Res Mol Brain Res. 1991 Jun;10(3):241-50. doi: 10.1016/0169-328x(91)90067-8.
The distribution and characteristics of preproenkephalin (PPenk) mRNA and enkephalin-containing (EC) peptides are compared in CNS and adrenal tissues from Syrian hamsters and Sprague-Dawley rats. Total cellular RNA extracts from both rat and hamster tissues produce a single hybridization band of PPenk mRNA of approximately 1500 bases when analyzed by Northern blot hybridization. Quantitation by solution hybridization reveals that in the hamster the highest levels of PPenk mRNA are found in adrenal (16.3 +/- 1.4 pg equivalents/micrograms RNA (mean +/- S.E.M.)) and striatum (13.3 +/- 0.7), followed by hypothalamus (0.8 +/- 0.2), and hippocampus (0.4 +/- 0.2). In the rat the highest levels of PPenk mRNA are in the striatum (35 +/- 2 pg/micrograms RNA) followed by the hypothalamus (3.0 +/- 0.5), hippocampus (0.3 +/- 0.1) and adrenal (0.18 +/- 0.04). Thus, the rank order of abundance of PPenk mRNA is similar in these CNS tissues for rat and hamster. The hamster adrenal levels are more than 90-fold greater than those of the rat. The abundance of EC peptides in both hamster and rat tissues mirror the rank order found with PPenk mRNA. Hamster adrenal contains the highest level of EC peptides (441 +/- 37 pmol/mg protein (mean +/- S.E.M.)) which is more than 400-fold greater than that of the rat adrenal and 8- to 12-fold greater than that found in rat and hamster striatum or hypothalamus. Both size exclusion chromatography and Western blot analysis indicate that EC peptides in hamster adrenal are predominantly large proenkephalin-like peptides with approximately 6 copies of Met- and 1 copy of Leu-enkephalin and that included in their number is a prominent EC peptide with a molecular weight of 34 kDa. Unilateral denervation of the hamster adrenal results in a time-dependent ipsilateral decrease in EC peptide and PPenk mRNA levels. Thus, by day 8 postsurgery, PPenk mRNA levels have declined by an average of 80% while EC peptides are reduced by 68% when compared to the innervated contralateral adrenal. These results demonstrate the great abundance of PPenk mRNA and EC peptides in the hamster adrenal. They also demonstrate the apparent need for transsynaptic impulse activity to maintain the high steady-state levels of PPenk and EC peptides. These characteristics of the hamster adrenal system provide opportunities for physiological and pharmacological investigations of the regulation of proenkephalin gene expression.
比较叙利亚仓鼠和斯普拉格 - 道利大鼠中枢神经系统（CNS）及肾上腺组织中前脑啡肽原（PPenk）mRNA和含脑啡肽（EC）肽的分布与特征。用Northern印迹杂交分析大鼠和仓鼠组织的总细胞RNA提取物时，均产生一条约1500个碱基的PPenk mRNA杂交带。溶液杂交定量分析显示，仓鼠中PPenk mRNA水平最高的是肾上腺（16.3±1.4 pg当量/μg RNA（平均值±标准误））和纹状体（13.3±0.7），其次是下丘脑（0.8±0.2）和海马体（0.4±0.2）。大鼠中PPenk mRNA水平最高的是纹状体（35±2 pg/μg RNA），其次是下丘脑（3.0±0.5）、海马体（0.3±0.1）和肾上腺（0.18±0.04）。因此，大鼠和仓鼠这些中枢神经系统组织中PPenk mRNA丰度的排序相似。仓鼠肾上腺中的水平比大鼠高出90多倍。仓鼠和大鼠组织中EC肽的丰度与PPenk mRNA的排序一致。仓鼠肾上腺中EC肽水平最高（441±37 pmol/mg蛋白质（平均值±标准误）），比大鼠肾上腺高出400多倍，比大鼠和仓鼠的纹状体或下丘脑高出8至12倍。尺寸排阻色谱和蛋白质印迹分析均表明，仓鼠肾上腺中的EC肽主要是类似前脑啡肽原的大肽，含有约6个甲硫氨酸脑啡肽拷贝和1个亮氨酸脑啡肽拷贝，其中包括一种分子量为34 kDa的突出EC肽。仓鼠肾上腺单侧去神经支配导致EC肽和PPenk mRNA水平随时间同侧下降。因此，术后第8天，与有神经支配的对侧肾上腺相比，PPenk mRNA水平平均下降80%，而EC肽减少68%。这些结果表明仓鼠肾上腺中PPenk mRNA和EC肽含量丰富。它们还表明明显需要经突触冲动活动来维持PPenk和EC肽的高稳态水平。仓鼠肾上腺系统的这些特征为前脑啡肽原基因表达调控的生理学和药理学研究提供了机会。
