模拟失重大鼠后肢动脉血管肾上腺素能神经支配的变化

目的以尾部悬吊４周大鼠模型模拟失重的影响，探讨模拟失重是否可引起动脉血管神经支配发生可塑性变化。方法用免疫组织化学（ＡＢＣ）方法，观察了对照（ＣＯＮ）、尾部悬吊４周（ＳＵＳ－４）和恢复１周（ＲＥＣ－１）大鼠后肢动脉血管周围肾上腺素能神经的变化。结果胫前动脉：ＳＵＳ－４组的肾上腺素能神经的密度较ＣＯＮ组显著降低（Ｐ＜０．０１）；在ＲＥＣ－１组则提高（Ｐ＜０．０５）。股四头肌内小动脉：肾上腺素能神经的密度无明显改变（Ｐ＞０．０５），但纤维变得更纤细，染色更浅淡；在ＲＥＣ－１组，神经纤维的密度较ＣＯＮ组升高１倍（Ｐ＜０．０１），且纤维粗，染色深，膨体更清晰。结论模拟失重４周可引起大鼠后肢动脉血管肾上腺素能神经支配处于低下状态，恢复１周后则处于增强状态。以上表明血管肾上腺素能神经支配对模拟失重下局部血液动力学改变颇为敏感，并能很快发生可塑性变化。

Changes in density of perivascular adrenergic nerve fibers to arterial vasculature of hindlimb muscles of tail suspended/recovered rats.

Objective To explore the effects of simulated microgravity on the perivascular innervation. Methods The distribution of adrenergic nerve fibers of the arteries/arterioles supplying the hindlimb muscles in control (CON),4 wk suspended (SUS 4),and 1 wk recovered (REC 1) rats were examined by the free floating ABC GDN immunostaining technique in whole mount preparations. Results The results revealed that there was hypoinnervation for adrenergic fibers around arteries/arterioles during the suspension period followed by hyperinnervation during recovery,for example, the densities of adrenergic fibers around anterior tibial arteries were significantly lower ( P <0.01) in SUS 4,and significantly higher ( P <0.01) in REC 1 as compared with that of the CON rats. Though the densities of adrenergic nerve fibers around arterioles within the vastus medialis did not undergo significant change ( P >0.05) in SUS 4 rats, the fibers were thinner and pale in staining However, in REC 1, the densities of adrenergic fibers around arterioles within the vastus intermedius were greater than that of the CON rats by a factor of at least 2. Moreover, the adrenergic fibers around these arterioles were thick and dark with their varicose swellings clearly discernible in REC 1 rats. Conclusions These data have provided the first evidence that the perivascular adrenergic innervation is quite sensitive to local hemodynamic changes induced by simulated microgravity and the adaptive change can occur rapidly.