Navarro X, Kamei H, Kennedy W R
Department of Neurology, University of Minnesota, Minneapolis 55455.
Brain Res. 1988 Apr 26;447(1):133-40. doi: 10.1016/0006-8993(88)90973-0.
This study demonstrates that regeneration of unmyelinated sudomotor axons in mice becomes progressively slower during aging. Identical lesions were made in mice aged 0, 2, 4, 6, 7, 24 and 60 weeks. The peroneal, sural and saphenous nerves were cut and tied to prevent regeneration. The sciatic nerve was then frozen at the thigh, leaving the hind paw completely denervated. By 7 days, sweat glands (SGs) of the paw had ceased sweating after pilocarpine injection. Subsequent regeneration of sudomotor axons was judged by the rate of return of pilocarpine sensitivity. SGs in the hind paws of normal newborn mice did not sweat at birth. Cholinergic stimulation first activated sweating at 13 days of life. The number of responsive SGs increased progressively to reach the adult level by 30 days. In one-week-old mice, whose sciatic nerve had been sectioned, the SG response to cholinergic stimulation was very delayed in time and reduced in number. Sweat glands of young mice, between 2 and 4 weeks of age, regained cholinergic sensitivity at a faster rate than mature animals and attained normal SG counts. Throughout a broad intermediate range of age in adulthood (7-24 weeks), the rate of sudomotor nerve regeneration was the same, but in older mice (60 weeks) it was slower and less complete.
本研究表明，在小鼠衰老过程中，无髓鞘的汗腺运动轴突的再生逐渐变慢。对0周龄、2周龄、4周龄、6周龄、7周龄、24周龄和60周龄的小鼠制造相同的损伤。切断并结扎腓总神经、腓肠神经和隐神经以阻止再生。然后将坐骨神经在大腿处冷冻，使后爪完全去神经支配。到第7天时，注射毛果芸香碱后爪部的汗腺停止出汗。随后通过毛果芸香碱敏感性恢复的速率来判断汗腺运动轴突的再生情况。正常新生小鼠后爪的汗腺在出生时不出汗。胆碱能刺激在出生后第13天首次激活出汗。有反应的汗腺数量逐渐增加，到30天时达到成年水平。在坐骨神经已被切断的1周龄小鼠中，汗腺对胆碱能刺激的反应在时间上非常延迟，且数量减少。2至4周龄幼鼠的汗腺比成年动物更快地恢复胆碱能敏感性，并达到正常的汗腺数量。在成年期的广泛中间年龄范围内（7至24周），汗腺运动神经再生的速率相同，但在老年小鼠（60周龄）中再生较慢且不完全。
