al-Shamma H A, Arnold A P
Department of Physiological Science, University of California, Los Angeles 90095-1527, USA.
J Neurobiol. 1995 Nov;28(3):341-53. doi: 10.1002/neu.480280307.
In adult male rats, axotomy of the spinal nucleus of the bulbocavernosus (SNB) motoneurons transiently down-regulates androgen receptor (AR) immunoreactivity. The present study investigates the importance of target reinnervation in the recovery of AR expression in axotomized SNB motoneurons after short (up to 5 days) and long (1 to 6 weeks) periods of recovery. In the long-term recovery experiment, animals were divided into two groups. In one, the two stumps of the cut pudendal nerve, which carries the axons of the SNB motoneurons, were sutured together immediately after axotomy. In the second group, the proximal stump was ligated immediately after axotomy to prevent target reinnervation. Axotomy of the SNB motoneurons caused a significant down-regulation in AR immunoreactivity within 3 days. At 6 weeks, AR immunoreactivity was still depressed in ligated animals but had recovered to control levels in resutured animals. The recovery in the resutured group was coincident with the first signs of reinnervation of the target perineal muscles, although reinnervation seemed to lag behind AR immunoreactivity. SNB soma size was significantly reduced 2 weeks after axotomy and returned to control levels after 6 weeks of recovery only in the resutured animals. These findings suggest that the target perineal muscles play a role in the regulation of AR expression and androgen sensitivity in the SNB motoneurons, perhaps mediated by muscle-derived trophic factors.
在成年雄性大鼠中，球海绵体肌脊髓核（SNB）运动神经元的轴突切断会短暂下调雄激素受体（AR）的免疫反应性。本研究调查了在短期（长达5天）和长期（1至6周）恢复后，靶标重新支配在轴突切断的SNB运动神经元中AR表达恢复过程中的重要性。在长期恢复实验中，动物被分为两组。在一组中，携带SNB运动神经元轴突的切断的阴部神经的两个残端在轴突切断后立即缝合在一起。在第二组中，轴突切断后立即结扎近端残端以防止靶标重新支配。SNB运动神经元的轴突切断在3天内导致AR免疫反应性显著下调。在6周时，结扎动物的AR免疫反应性仍处于抑制状态，但在重新缝合的动物中已恢复到对照水平。重新缝合组的恢复与靶标会阴肌重新支配的最初迹象同时出现，尽管重新支配似乎落后于AR免疫反应性。轴突切断2周后，SNB胞体大小显著减小，仅在重新缝合的动物中，恢复6周后才恢复到对照水平。这些发现表明，靶标会阴肌在SNB运动神经元中AR表达和雄激素敏感性的调节中起作用，可能是由肌肉衍生的营养因子介导的。
