Mitani F, Ogishima T, Miyamoto H, Ishimura Y
Department of Biochemistry, School of Medicine, Keio University, Tokyo, Japan.
Endocr Res. 1995 Feb-May;21(1-2):413-23. doi: 10.3109/07435809509030457.
A novel layer of cells that do not contain both P450aldo and P45011 beta has been discovered between the zonae glomerulosa and fasciculata of the rat adrenal cortex. Since P450aldo and P45011 beta are the enzymes responsible for the formation of aldosterone and corticosterone, respectively, the cells in that zone are presumably inert in synthesizing both aldosterone and corticosterone, in other words, the layer is composed of cells that have no zone-specific endocrine function as an adrenocortical component. Cytologically, the layer consists of tightly packed cells, which contain a lesser amount of lipid droplet than the cells in the other zones, and appears as a white ring or a white zone in the double immunostaining with anti P450aldo and anti P45011 beta. Upon angiotensin II-stimulation evoked by Na-deficiency, the number of the zona glomerulosa cells expressing P450aldo increases for the initial 2 or 3 days and then the P450aldo-containing zona glomerulosa cells begin to proliferate. Thus angiotensin II serves as a proliferator of the zona glomerulosa cells of the rat adrenal cortex. During the period, the thickness of the white zone decreases for initial 3 days and becomes constant after 5 or 6 days, being about 5% of the total cell number of the adrenal cortex. When localization of replicating cells was examined in the adrenal cortex, they were found to be concentrated in and around the white zone. Then the pulse-chase experiments with BrdU showed that the labeled cells migrated out of the white zone and into the zonae fasciculata and reticularis. The localization of the replicating cells in the regenerating adrenal cortex was also around the region between the zonae glomerulosa and fasciculata. On the basis of these findings, we suggest that the newly discovered cell layer (the white zone) is the stem cell zone of the rat adrenal cortex.
在大鼠肾上腺皮质的球状带和束状带之间发现了一层新的细胞，这些细胞不同时含有11β-羟化酶（P45011β）和醛固酮合成酶（P450aldo）。由于P450aldo和P45011β分别是负责醛固酮和皮质酮形成的酶，因此该区域的细胞可能在合成醛固酮和皮质酮方面均无活性，换句话说，该层由作为肾上腺皮质成分不具有区域特异性内分泌功能的细胞组成。从细胞学角度来看，该层由紧密排列的细胞组成，其含有的脂滴数量比其他区域的细胞少，并且在用抗P450aldo和抗P45011β进行双重免疫染色时呈现为白色环或白色带。在缺钠引起的血管紧张素II刺激下，表达P450aldo的球状带细胞数量在最初2或3天增加，然后含P450aldo的球状带细胞开始增殖。因此，血管紧张素II是大鼠肾上腺皮质球状带细胞的增殖剂。在此期间，白色带的厚度在最初3天减小，在5或6天后变得恒定，约占肾上腺皮质细胞总数的5%。当在肾上腺皮质中检查复制细胞的定位时，发现它们集中在白色带及其周围。然后用5-溴脱氧尿嘧啶核苷（BrdU）进行脉冲追踪实验表明，标记细胞从白色带迁移到束状带和网状带。再生肾上腺皮质中复制细胞的定位也在球状带和束状带之间的区域周围。基于这些发现，我们认为新发现的细胞层（白色带）是大鼠肾上腺皮质的干细胞区。
