Aszterbaum M, Feingold K R, Menon G K, Williams M L
Department of Dermatology, University of California, San Francisco 94143.
J Clin Invest. 1993 Jun;91(6):2703-8. doi: 10.1172/JCI116509.
The cutaneous permeability barrier to systemic water loss is mediated by hydrophobic lipids forming membrane bilayers within the intercellular domains of the stratum corneum (SC). The barrier emerges during day 20 of gestation in the fetal rat and is correlated with increasing SC thickness and increasing SC lipid content, the appearance of well-formed lamellar bodies in the epidermis, and the presence of lamellar unit structures throughout the SC. Because glucocorticoids accelerate lung lamellar body and surfactant maturation in man and experimental animals, these studies were undertaken to determine whether maternal glucocorticoid treatment accelerates maturation of the epidermal lamellar body secretory system. Maternal rats were injected with betamethasone or saline (control) on days 16-18, and pups were delivered prematurely on day 19. Whereas control pups exhibited immature barriers to transepidermal water loss (8.16 +/- 0.52 mg/cm2 per h), glucocorticoid-treated pups exhibited competent barriers (0.74 +/- 0.14 mg/cm2 per h; P < 0.001). Glucocorticoid treatment also: (a) accelerated maturation of lamellar body and SC membrane ultrastructure; (b) increased SC total lipid content twofold; and (c) increased cholesterol and polar ceramide content three- to sixfold. Thus, glucocorticoids accelerate the functional, morphological, and lipid biochemical maturation of the permeability barrier in the fetal rat.
皮肤对全身性水分流失的渗透屏障是由角质层（SC）细胞间区域内形成膜双层的疏水脂质介导的。该屏障在胎鼠妊娠第20天出现，与SC厚度增加、SC脂质含量增加、表皮中结构良好的板层小体的出现以及整个SC中板层单位结构的存在相关。由于糖皮质激素可加速人和实验动物肺板层小体和表面活性剂的成熟，因此进行了这些研究以确定母体糖皮质激素治疗是否会加速表皮板层小体分泌系统的成熟。在第16 - 18天给母鼠注射倍他米松或生理盐水（对照），并在第19天提前分娩幼崽。对照幼崽表现出对经表皮水分流失的不成熟屏障（每小时8.16±0.52 mg/cm²），而糖皮质激素处理的幼崽表现出有效的屏障（每小时0.74±0.14 mg/cm²；P < 0.001）。糖皮质激素治疗还：（a）加速了板层小体和SC膜超微结构的成熟；（b）使SC总脂质含量增加了两倍；（c）使胆固醇和极性神经酰胺含量增加了三到六倍。因此，糖皮质激素加速了胎鼠渗透屏障的功能、形态和脂质生化成熟。
