The study for the mechanism of loss of hair after the transient ischemia

72 -kd热休克蛋白（HSP72）是细胞在缺血等应激情况下诱导的应激标志物之一。最近的研究表明，HSP72是一种保护细胞免受各种应激的“分子伴侣”，并且HSP72诱导的时间谱与缺血易感性有关。在本研究中，我们试图分析不同时期短暂缺血后皮瓣浅毛囊和深毛囊角质形成细胞HSP72诱导的时间谱，并探讨这两种细胞之间缺血耐受性差异的原因。采用Wister大鼠腹部皮瓣，将Wister大鼠分为3组：假对照组（n=27）、缺血2小时组（n=25）、缺血8小时组（n=25）。在再灌注后8、24、48、96小时和7天，我们检查它们的组织学变化，并进行HSP72和caspas3的免疫染色（每个时间点n=5）。此外，我们采用TUNEL染色检测细胞凋亡。结果，无论缺血应激如何，各组浅毛囊角质形成细胞在时间过程中均呈HSP72阳性，TUNEL染色不阳性。在深层毛囊中，假对照组细胞再灌注后无免疫反应性，TUNEL染色无阳性细胞。缺血2小时后，角质形成细胞对HSP72的反应性逐渐升高；因此在TUNEL染色中也没有阳性细胞。缺血8小时组，HSP72反应性在再灌注后8小时出现，在再灌注后24小时突然下降；结果TUNEL染色呈阳性。在再灌注8小时后，它们也表达了活性形式的caspase-3。我们认为这些HSP72的表达差异与深卵泡对缺血的易感性有关。8小时缺血仅引起深毛囊HSP72诱导功能紊乱，导致深毛囊角质形成细胞凋亡。这种凋亡伴随着caspase-3的激活。少

Seventy-two-kd heat-shock protein (HSP72) is one of the stress markers induced in cells under stress, such as in the case of ischemia. Recent studies have suggested that HSP72 is a "molecular chaperone" to protect cells from various kinds of stress, and that the temporal profile of HSP72 induction is related to ischemic vulnerability. In this study, we attempted to analyze the temporal profiles of HSP72 induction in keratinocytes in the shallow hair follicles and the deep hair follicles in skin flaps after various periods of transient ischemia, and we investigated the reason why there were differences in ischemic tolerance between these cells.We used the abdominal skin flap of Wister rats, which were divided into three groups: the sham control group (n=27), the 2-hour ischemia group (n=25), and the 8-hour ischemia group (n=25). At periods of 8, 24, 48, 96 hours, and 7 days after reperfusion, we examined them for any histological changes and performed immunostaining for HSP72 and caspas … More e-3 (n=5, each time point). In addition, we performed TUNEL stain for detecting apoptosis.As a result, the keratinocytes in the shallow hair follicles in all groups revealed positive for HSP72 through the time course, regardless of the ischemic stresses, and they were not positive for TUNEL stain. In the deep hair follicles, the cells in the sham control group revealed no immunoreactivity after the reperfusion, and they had no positive cell in TUNEL stain. In the 2-hour ischemia group, the keratinocytes gradually increased the reactivity for HSP72; consequently they also had no positive cell in TUNEL stain at all. In the 8-hour ischemia group, the reactivity for HSP72 was revealed at 8 hours after the reperfusion and suddenly decreased at 24 hour after the reperfusion; consequently they revealed positive for TUNEL stain. And they also expressed active form of caspase-3 at 8 hours after the reperfusion.We concluded that these differences of HSP72 expression were related to the deep follicle''s vulnerability to ischemia. The 8-hour ischemia induced the disturbance of HSP72 induction only in the deep hair follicles, consequently the keratinocytes in the deep hair follicles revealed apoptosis. And this apoptosis was accompanied with the activation of caspase-3. Less