Department of Oral and Maxillofacial Surgery, Hannover Medical School, Hannover, Germany.
Head Face Med. 2011 Nov 18;7:22. doi: 10.1186/1746-160X-7-22.
It is widely known that stress conditioning can protect microcirculation and induce the release of vasoactive factors for a period of several hours. Little, however, is known about the long-term effects of stress conditioning on microcirculation, especially on the microcirculation of the periosteum of the calvaria. For this reason, we used intravital fluorescence microscopy to investigate the effects of heat shock priming on the microcirculation of the periosteum over a period of several days.
Fifty-two Lewis rats were randomized into eight groups. Six groups underwent heat shock priming of the periosteum of the calvaria at 42.5°C, two of them (n = 8) for 15 minutes, two (n = 8) for 25 minutes and two (n = 8) for 35 minutes. After 24 hours, a periosteal chamber was implanted into the heads of the animals of one of each of the two groups mentioned above. Microcirculation and inflammatory responses were studied repeatedly over a period of 14 days using intravital fluorescence microscopy. The expression of heat shock protein (HSP) 70 was examined by immunohistochemistry in three further groups 24 hours after a 15-minute (n = 5), a 25-minute (n = 5) or a 35-minute (n = 5) heat shock treatment. Two groups that did not undergo priming were used as controls. One control group (n = 8) was investigated by intravital microscopy and the other (n = 5) by immunohistochemistry.
During the entire observation period of 14 days, the periosteal chambers revealed physiological microcirculation of the periosteum of the calvaria without perfusion failures. A significant (p < 0.05) and continuous increase in functional capillary density was noted from day 5 to day 14 after 25-minute heat shock priming. Whereas a 15-minute exposure did not lead to an increase in functional capillary density, 35-minute priming caused a significant but reversible perfusion failure in capillaries. Non-perfused capillaries in the 35-minute treatment group were reperfused by day 10. Immunohistochemistry demonstrated an increase in cytoprotective HSP70 expression in the periosteum after a 15-minute and a 35-minute heat shock pretreatment when compared with the control group. The level of HSP70 expression that was measured in the periosteum after 25 minutes of treatment was significantly higher than the levels observed after 15 or 35 minutes of heat shock exposure.
A few days after heat shock priming over an appropriate period of time, a continuous increase in functional capillary density is seen in the periosteum of the calvaria. This increase in perfusion appears to be the result of the induction of angiogenesis.
众所周知，应激预处理可保护微血管并诱导血管活性因子释放数小时。然而，人们对应激预处理对微血管的长期影响知之甚少，特别是对颅骨骨膜的微血管影响。为此，我们使用活体荧光显微镜研究了热休克预处理对骨膜微血管的影响，时间跨度为数天。
52 只 Lewis 大鼠随机分为 8 组。6 组大鼠颅骨骨膜行 42.5°C 的热休克预处理，其中 2 组（n=8）预处理 15 分钟，2 组（n=8）预处理 25 分钟，2 组（n=8）预处理 35 分钟。在上述每组中的 2 个组的 24 小时后，将一个骨膜室植入动物头部。使用活体荧光显微镜重复研究了 14 天内的微循环和炎症反应。另外 3 组大鼠在 15 分钟（n=5）、25 分钟（n=5）或 35 分钟（n=5）热休克处理后 24 小时通过免疫组织化学检查热休克蛋白（HSP）70 的表达。另外 2 组未进行预处理作为对照组。一组对照组（n=8）通过活体显微镜检查，另一组（n=5）通过免疫组织化学检查。
在整个 14 天的观察期间，骨膜室显示出颅骨骨膜的生理性微血管循环，没有灌注失败。25 分钟热休克预处理后，从第 5 天到第 14 天，功能性毛细血管密度显著（p<0.05）且持续增加。而 15 分钟的暴露并没有导致功能性毛细血管密度增加，35 分钟的预处理导致毛细血管出现显著但可恢复的灌注失败。在 35 分钟治疗组中，无灌注的毛细血管在第 10 天重新灌注。免疫组织化学显示，与对照组相比，15 分钟和 35 分钟热休克预处理后，骨膜中细胞保护性 HSP70 表达增加。25 分钟治疗后骨膜中 HSP70 表达水平明显高于 15 分钟或 35 分钟热休克暴露后的水平。
在适当的时间进行热休克预处理几天后，颅骨骨膜的功能性毛细血管密度持续增加。这种灌注增加似乎是血管生成的结果。
