Katz D M, Adler J E, Black I B
Brain Res. 1986 Oct 15;385(1):68-73. doi: 10.1016/0006-8993(86)91548-9.
To determine whether similar molecular mechanisms regulate the same proteins in diverse neuronal populations, the present study compared regulation of tyrosine hydroxylase (TOH) in placodal sensory and neural crest-derived sympathetic neurons in tissue culture. Long-term explant cultures of adult nodose and petrosal sensory ganglia (NPG) contained abundant TOH-immunoreactive neurons and exhibited TOH catalytic activity, as in vivo. After an initial decline during the first week of culture, enzyme activity was maintained at a stable plateau of 60% of zero time values for at least 3 weeks. However, exposure of 2-week-old cultures to depolarizing concentrations of potassium (K+; 40 mM) increased TOH activity approximately two-fold; total protein was unchanged, suggesting that the rise was due to increased TOH specific activity. Therefore, membrane depolarization in vitro appears to regulate this specific catecholaminergic (CA) trait in sensory, as in sympathetic CA cells. In sympathetic neurons, NGF regulates TOH activity throughout life. In marked contrast, TOH activity in adult NPG cultures was unchanged in the presence of 0, 10 or 100 units NGF/ml or in the presence of high concentrations of antiserum against the beta-subunit of NGF. Adult sympathetic neurons, however, grown under identical conditions, exhibited a 5- to 10-fold rise in TOH activity in the presence of NGF. Thus, unlike sympathetics, CA metabolism in adult NPG neurons is not regulated by NGF in vitro; NGF is therefore unlikely to mediate target effects on CA metabolism in placodal sensory neurons in vivo. Our findings indicate that certain mechanisms of CA regulation are shared by placodal sensory and neural crest-derived sympathetic neurons, whereas others are not.(ABSTRACT TRUNCATED AT 250 WORDS)
为了确定相似的分子机制是否在不同的神经元群体中调控相同的蛋白质，本研究比较了组织培养中，基板感觉神经元和神经嵴衍生的交感神经元中酪氨酸羟化酶（TOH）的调控情况。成年结状和岩神经节（NPG）的长期外植体培养物中含有丰富的TOH免疫反应性神经元，并表现出TOH催化活性，如同在体内一样。在培养的第一周出现初始下降后，酶活性在至少3周的时间内维持在零时间值的60%这一稳定水平。然而，将2周龄的培养物暴露于去极化浓度的钾（K+；40 mM）中，TOH活性增加了约两倍；总蛋白不变，这表明活性增加是由于TOH比活性增加所致。因此，体外膜去极化似乎在感觉神经元中，如同在交感CA细胞中一样，调控这种特定的儿茶酚胺能（CA）特性。在交感神经元中，NGF终生调控TOH活性。与之形成鲜明对比的是，在成年NPG培养物中，无论存在0、10或100单位/毫升的NGF，还是存在高浓度的抗NGFβ亚基抗血清，TOH活性均无变化。然而，在相同条件下培养的成年交感神经元，在存在NGF时，TOH活性升高了5至10倍。因此，与交感神经元不同，成年NPG神经元中的CA代谢在体外不受NGF调控；因此，NGF不太可能介导体内对基板感觉神经元CA代谢的靶效应。我们的研究结果表明，基板感觉神经元和神经嵴衍生的交感神经元共享某些CA调控机制，而其他机制则不然。（摘要截短至250字）
