Day R, Schafer M K, Collard M W, Watson S J, Akil H
University of Michigan, Mental Health Research Institute, Ann Arbor 48109.
Proc Natl Acad Sci U S A. 1991 Feb 15;88(4):1320-4. doi: 10.1073/pnas.88.4.1320.
Prodynorphin (proDyn) gene expression was examined in the rat adrenal gland. In situ hybridization revealed a heterogenous proDyn mRNA distribution limited almost exclusively to the adrenal cortex; the inner cortical layers contained the highest amounts. In the adrenal medulla, only scattered single cells were seen. By Northern (RNA) blot analysis, adrenocortical proDyn mRNA levels were highly abundant but of smaller size than proDyn transcripts found in the brain. Low levels of the brain-size proDyn mRNA transcript were detected but restricted to the medulla. A discrepancy was suggested when comparing the high abundance of proDyn mRNA levels with the low levels of proDyn-derived peptide in the adrenal. A hypothesis of nontranslation of the shorter proDyn mRNA by adrenocortical cells was rejected because polysomal loading analysis suggests that the mRNA is translated. We propose that adrenocortical proDyn-derived peptides are not targeted for storage but are released shortly after synthesis, thus accounting for low peptide levels. We also measured proDyn mRNA levels in response to stimuli known to affect adrenocortical cells and their most important function--steroidogenesis. Adrenals from hypophysectomized rats had less proDyn mRNA by a factor of 5 than adrenals from normal sham-operated rats. Normal levels were restored by adrenocorticotrophic hormone administration, indicating a potential importance of adrenal proDyn in the hypothalamic-adrenal-pituitary axis.
对大鼠肾上腺中的前强啡肽（proDyn）基因表达进行了检测。原位杂交显示，proDyn mRNA分布不均一，几乎仅局限于肾上腺皮质；皮质内层含量最高。在肾上腺髓质中，仅可见散在的单个细胞。通过Northern（RNA）印迹分析，肾上腺皮质proDyn mRNA水平非常丰富，但比在脑中发现的proDyn转录本尺寸小。检测到低水平的脑尺寸proDyn mRNA转录本，但仅限于髓质。比较肾上腺中proDyn mRNA水平的高丰度与proDyn衍生肽的低水平时，提示存在差异。肾上腺皮质细胞不翻译较短的proDyn mRNA这一假说被否定，因为多核糖体负载分析表明该mRNA被翻译。我们提出，肾上腺皮质proDyn衍生肽并非用于储存，而是在合成后不久即被释放，因此导致肽水平较低。我们还检测了已知影响肾上腺皮质细胞及其最重要功能——类固醇生成的刺激下的proDyn mRNA水平。与正常假手术大鼠的肾上腺相比，垂体切除大鼠的肾上腺proDyn mRNA减少了5倍。通过给予促肾上腺皮质激素可恢复正常水平，表明肾上腺proDyn在下丘脑-肾上腺-垂体轴中具有潜在重要性。
