Schmidt K L, Henagan J M, Smith G S, Miller T A
J Surg Res. 1987 Sep;43(3):253-63. doi: 10.1016/0022-4804(87)90079-5.
The effect of 16,16 dimethyl prostaglandin E2 (PG) upon tight junctions (TJs) of adjacent surface mucous cells (SMCs) as a possible mechanism by which PGs mediate their protective effects was studied using transmission electron microscopy (TEM) and freeze fracture (FF) techniques. Fasted rats were subcutaneously injected with 10 micrograms/kg of PG or an equal volume of saline, followed 30 min later by 1 ml of oral 100% ethanol or saline. Ten or sixty minutes later, animals were sacrificed and stomach blocks were prepared for TEM or FF using standard techniques. Electron micrographs (X60,000) were obtained and the distance between SMC inner membrane leaflets was measured with a micrometer and expressed as TJ width. Stomach blocks for FF were stored at 4 degrees C, cryoprotected, freeze fractured, and photographed by TEM (X30,000). At 0.5-micron intervals, measurements of TJ strand number and depth were made. No statistical differences were found in TJ width or strand number of SMCs among the various experimental groups when compared with controls at each sacrifice time. At the 60 but not 10 min sacrifice time, TJ depth was greatly increased in cells treated with 10 micrograms/kg PG prior to ethanol exposure (P less than 0.025) in contrast to control mucosae. We conclude that 16,16-dimethyl PGE2 induces no changes in the structural composition of TJs as a possible explanation for its protective properties. The increase in TJ depth observed in ethanol exposed mucosa following PG pretreatment at the 60 min sacrifice time is most likely related to the architectural restructuring that occurs during reconstitution of damaged surface epithelium.
采用透射电子显微镜（TEM）和冷冻断裂（FF）技术，研究了16,16 - 二甲基前列腺素E2（PG）对相邻表面黏液细胞（SMC）紧密连接（TJ）的影响，这可能是PG介导其保护作用的一种机制。空腹大鼠皮下注射10微克/千克的PG或等体积的生理盐水，30分钟后口服1毫升100%乙醇或生理盐水。10或60分钟后，处死动物，采用标准技术制备用于TEM或FF的胃组织块。获取电子显微照片（放大60,000倍），用测微计测量SMC内膜小叶之间的距离，并表示为TJ宽度。用于FF的胃组织块保存在4℃，进行冷冻保护、冷冻断裂，并用TEM拍照（放大30,000倍）。每隔0.5微米测量TJ链的数量和深度。与各处死时间的对照组相比，各实验组SMC的TJ宽度或链数量均未发现统计学差异。与对照黏膜相比，在乙醇暴露前用10微克/千克PG处理的细胞中，在60分钟处死时TJ深度显著增加（P<0.025），但在10分钟处死时未增加。我们得出结论，16,16 - 二甲基PGE2不会诱导TJ结构组成的变化，这可能是其具有保护特性的一种解释。在60分钟处死时，PG预处理后乙醇暴露的黏膜中观察到的TJ深度增加很可能与受损表面上皮重建过程中发生的结构重组有关。
