Katz D M, Adler J E, Black I B
Fed Proc. 1987 Jan;46(1):24-9.
Contrary to traditional teaching, mammalian primary sensory neurons may express catecholaminergic (CA) neurotransmitter characteristics in vivo. Sensory neurons in the nodose, petrosal, and dorsal root ganglia of rats express tyrosine hydroxylase, the rate-limiting enzyme in CA biosynthesis, and formaldehyde-induced CA fluorescence, in addition to other CA traits. These findings suggest that catecholamines may function as sensory as well as autonomic motor (e.g., sympathetic) neurotransmitters. Most CA cells in the petrosal ganglion project peripherally to the carotid body, which indicates a striking correlation between CA expression in sensory neurons and the pattern of sensory innervation. Inasmuch as petrosal ganglion afferents make synaptic contact with chemoreceptive glomus cells in the carotid body, it is likely that CA sensory neurons in the ganglion transmit chemoreceptor information to the brain stem. Comparison with sympathetic neurons indicates that some mechanisms of CA regulation, such as altered activity of tyrosine hydroxylase in response to depolarizing stimuli, are shared among sensory and traditional CA populations. Other mechanisms, including trophic regulation, appear to be distinct. Therefore, despite expression of common phenotypic traits, CA expression in diverse populations of peripheral neurons is not necessarily associated with a common repertoire of regulatory mechanisms.
与传统教学观点相反，哺乳动物的初级感觉神经元在体内可能表达儿茶酚胺能（CA）神经递质特征。大鼠的结状神经节、岩神经节和背根神经节中的感觉神经元除了表达其他CA特征外，还表达酪氨酸羟化酶（CA生物合成中的限速酶）以及甲醛诱导的CA荧光。这些发现表明，儿茶酚胺可能既作为感觉神经递质又作为自主运动（如交感神经）神经递质发挥作用。岩神经节中的大多数CA细胞向周围投射至颈动脉体，这表明感觉神经元中的CA表达与感觉神经支配模式之间存在显著相关性。由于岩神经节传入神经与颈动脉体中的化学感受性球细胞形成突触联系，神经节中的CA感觉神经元很可能将化学感受器信息传递至脑干。与交感神经元的比较表明，CA调节的一些机制，如酪氨酸羟化酶活性在去极化刺激下的改变，在感觉神经元和传统CA神经元群体中是共有的。其他机制，包括营养调节，似乎是不同的。因此，尽管表达了共同的表型特征，但外周神经元不同群体中的CA表达不一定与共同的调节机制相关。
