Navarro X, Kennedy W R
Department of Neurology, University of Minnesota, Minneapolis.
Brain Res. 1988 Oct 25;463(1):174-81. doi: 10.1016/0006-8993(88)90543-4.
This study demonstrates that the number of sweat glands (SGs) innervated by individual peripheral nerves in the mouse hind paw decreases with aging but the ability for reinnervation by collateral sprouting is maintained throughout life. In one experiment, the saphenous, peroneal and tibial nerves were cut and tied, denervating all SGs of the hind paw except those receiving axons from the intact sural nerve. In another, the saphenous was the only nerve left intact. The initial number of SGs supplied only by the single intact nerve was significantly higher in young adult than older mice. The capacity of the sural and saphenous nerves to collaterally reinnervate the denervated SGs was followed by serial testing for the return of sensitivity to pilocarpine stimulation. Collaterally reinnervated SGs appeared during the second and third weeks postoperation adjacent to already active SGs, thereby increasing the total sweat area of the intact nerve, and its SG number about 3, 2 and 5 times for the sural, and 8, 2 and 2 times for saphenous nerve, in young, adult and old animals respectively. Reinnervation was slightly faster and the degree of extension greater in young than adult mice, and the degree of extension was decreased in older mice. These observations suggest that the number of sudomotor axons in the peripheral nerve, as well as their capacity for collateral reinnervation, is reduced with aging.
本研究表明，小鼠后爪中由单个外周神经支配的汗腺数量随衰老而减少，但通过侧支芽生进行再支配的能力在整个生命过程中得以维持。在一项实验中，切断并结扎隐神经、腓总神经和胫神经，使后爪除接受完整的腓肠神经轴突的汗腺外的所有汗腺失神经支配。在另一项实验中，仅保留隐神经完整。仅由单一完整神经供应的汗腺初始数量在年轻成年小鼠中显著高于老年小鼠。通过对毛果芸香碱刺激敏感性恢复的系列测试来跟踪腓肠神经和隐神经对失神经支配的汗腺进行侧支再支配的能力。在术后第二和第三周，在已活跃的汗腺附近出现侧支再支配的汗腺，从而增加了完整神经的总出汗面积，其汗腺数量在幼年、成年和老年动物中，腓肠神经分别增加约3倍、2倍和5倍，隐神经分别增加8倍、2倍和2倍。幼年小鼠的再支配速度略快于成年小鼠，延伸程度也更大，而老年小鼠的延伸程度降低。这些观察结果表明，外周神经中支配汗腺的轴突数量及其侧支再支配能力会随衰老而降低。
