Tuttle J B, Vaca K, Pilar G
Dev Biol. 1983 Jun;97(2):255-63. doi: 10.1016/0012-1606(83)90084-2.
The developmental influence of neuron-target interaction upon transmitter synthesis from labeled precursor and the capacity to release labeled transmitter were examined in dispersed cell cultures of embryonic ciliary ganglion neurons by comparing cultures of neurons plated alone and neurons plated upon pectoral myotubes. Of the total ACh synthesized from radiolabeled choline by neurons plated alone, more than half is via a Na+-dependent path, but a larger fraction of the synthesis is Na+ insensitive in culture than in mature neurons in vivo. In addition, at 1 week in culture the neurons lacking target failed to significantly increase ACh synthesis from the labeled choline in response to a previous high [K+]0 depolarization. Synthetic responsiveness to depolarization is a characteristic of mature nerve terminals in this preparation. One week after plating neurons onto myotube cultures, synthesis of ACh from the exogenous precursor is double that of sibling cultures lacking muscle, and prior depolarization with [K+]0 results in an increase in labeled product. Release from the labeled transmitter pool by the neurons with myotubes was also enhanced. [3H]ACh release elicited by depolarization via a Ca2+-dependent mechanism was more than fivefold higher in the cocultures. The influence of coculture with myotubes upon neuronal development is not duplicated by the neurons themselves despite formation of apparent interneuronal synapses (G. Crean, G. Pilar, J. Tuttle, and K. Vaca, 1982, J. Physiol. (London). 331, 87-104), by "fibroblasts" or medium conditioned over myotube cultures. Neurons under these conditions neither increase synthesis of [3H]ACh in response to a prior depolarization nor demonstrate enhanced basal [3H]ACh synthesis and release. Thus, coculture of embryonic ciliary ganglion neurons with a striated muscle target has a somewhat specific inductive effect, enhancing the capacity for neuronal [3H]ACh synthesis and release toward mature levels. This influence of a readily accessible target upon ciliary neuron cholinergic development in vitro may reflect a normal neuromuscular interaction occurring during embryogenesis.
通过比较单独接种的神经元培养物和接种在胸肌肌管上的神经元培养物，在胚胎睫状神经节神经元的分散细胞培养物中研究了神经元 - 靶标相互作用对来自标记前体的递质合成以及释放标记递质能力的发育影响。单独接种的神经元从放射性标记胆碱合成的总乙酰胆碱（ACh）中，超过一半是通过钠依赖性途径，但与体内成熟神经元相比，培养物中合成的较大部分对钠不敏感。此外，在培养1周时，缺乏靶标的神经元在先前的高[K⁺]₀去极化后，未能显著增加从标记胆碱合成的ACh。对去极化的合成反应性是该制剂中成熟神经末梢的一个特征。将神经元接种到肌管培养物1周后，来自外源性前体的ACh合成是缺乏肌肉的同窝培养物的两倍，并且先前用[K⁺]₀去极化导致标记产物增加。有肌管的神经元从标记递质池中释放的递质也增强。在共培养物中，通过钙依赖性机制去极化引起的[³H]ACh释放高出五倍多。尽管形成了明显的神经元间突触（G. Crean、G. Pilar、J. Tuttle和K. Vaca，1982年，《生理学杂志》（伦敦）。331, 87 - 104），但与肌管共培养对神经元发育的影响不会被神经元自身、“成纤维细胞”或肌管培养物条件培养基所复制。在这些条件下的神经元既不会响应先前的去极化而增加[³H]ACh的合成，也不会表现出增强的基础[³H]ACh合成和释放。因此，胚胎睫状神经节神经元与横纹肌靶标的共培养具有某种特定的诱导作用，将神经元[³H]ACh合成和释放能力提高到成熟水平。体外这种易于接近的靶标对睫状神经元胆碱能发育的影响可能反映了胚胎发生过程中正常的神经肌肉相互作用。
