Rush R A, Abrahamson I K, Murdoch S Y, Renton F J, Wilson P A
Centre for Neuroscience, Flinders University of South Australia, Bedford Park.
Int J Dev Neurosci. 1986;4(5):483-92. doi: 10.1016/0736-5748(86)90030-4.
The expansor secundariorum is a unique smooth muscle of the avian wing that receives a dense sympathetic innervation and contains high concentrations of survival factors for sympathetic neurons. In the present study it has been possible to simultaneously examine the appearance of the neuronotrophic activity and the arrival of nerve fibres during the period of innervation. The results show that catecholamine containing nerve fibres can first be detected within the muscle on the fourteenth day of incubation (stage 40) followed by a rapid increase in the density of fibres during the next few days until the adult pattern is reached shortly before hatch. Biochemical estimation of the innervation process by measurement of dopamine beta-hydroxylase activity was supported by the histochemical findings. Estimation of neuronotrophic activity revealed that muscle from stage 40 embryos contains only low levels of activity which increases rapidly as innervation proceeds and further, that this increase in neuronotrophic activity was directly correlated with the dopamine beta-hydroxylase activities. Possible mechanisms regulating this dramatic increase in the specific activity of trophic factors are discussed.
次级扩张肌是鸟类翅膀中一种独特的平滑肌，它接受密集的交感神经支配，并且含有高浓度的交感神经元存活因子。在本研究中，能够在神经支配期间同时检查神经营养活性的出现和神经纤维的到达情况。结果表明，在孵化的第14天（第40阶段），肌肉内首先可以检测到含儿茶酚胺的神经纤维，随后在接下来的几天内纤维密度迅速增加，直到孵化前不久达到成年模式。通过测量多巴胺β-羟化酶活性对神经支配过程进行的生化评估得到了组织化学结果的支持。神经营养活性的评估显示，第40阶段胚胎的肌肉仅含有低水平的活性，随着神经支配的进行，活性迅速增加，而且，这种神经营养活性的增加与多巴胺β-羟化酶活性直接相关。讨论了调节营养因子比活性这种显著增加的可能机制。
