Immunolocalization of biosynthetic and metablic enzymes of catecholamine in human dental pulp.

与去甲肾上腺素的浓度相比，人牙髓中多巴的含量相对较高。采用免疫细胞化学方法研究了酪氨酸羟化酶（TH）、l -芳香氨基酸脱羧酶（AADC）、多巴胺- β -羟化酶（DBH）、苯乙醇胺- n -甲基转移酶（PNMT）、多巴胺、多巴胺、去甲肾上腺素和肾上腺素形成酶在人牙髓中的局部生成。小动脉周围可见丰富的TH-和aadc免疫反应神经纤维。在小动脉壁上可见细小的珠状免疫反应性胸径静脉曲张。富细胞区也可见th免疫反应神经纤维。未观察到特异性PNMT免疫反应性。结果表明，人牙髓中的一些神经纤维可能作为儿茶酚胺生物合成的最终产物合成去甲肾上腺素。AADC和COMT定位于人牙髓血管壁。这种定位表明COMT和AADC在多巴代谢方面存在功能关系。小动脉内皮细胞含有COMT。这一结果表明对儿茶酚胺存在酶屏障；可能的血-牙髓屏障。血管壁内皮细胞中的COMT活性为儿茶酚的失活提供了一种手段，可能是正常情况下神经激素调节血流和血压的重要机制。AADC存在于小动脉平滑肌细胞中。这些小动脉的平滑肌细胞可能像APUD细胞一样起作用。

The relatively large amounts of DOPA as compared with the concentration of norepinephrine are found in human dental pulp. Local production of catecholamines in the human dental pulp was studied by immunocytochemical demonstration of tyrosine hydroxylase (TH), L-aromatic amino acid decarboxylase (AADC), dopamine-beta-hydroxylase (DBH) phenylethanolamine-N-methyltransferase (PNMT), the enzymes catalyzing the formation of DOPA,dopamine, norepinephrine and epinephrine, respectively. A rich innervation of TH- and AADC-immunoreactive nerve fibers was seen around the arterioles. The fine beaded immunoreactive varicosities of the DBH were found on the wall of arterioles. TH-immunoreactive nerve fibers were also observed in the cell rich zone. No specific PNMT immunoreactivity was observed. The results suggest that some norve fibers in the human dental pulp may synthesize norepinephrine as an end-product of catecholamine biosynthesis. AADC and COMT are localized in blood vessel walls of human dental pulp. This localization suggests a functional relationship between COMT and AADC with regard to the metabolism of DOPA.The endothelial cells of the arteriole contained COMT.This results suggest an enzymatic barrier to catecholamines ; a possible blood-dental pulp barrier. COMT activity in endothelial cells of vascular wall, by providing a means for the inactivation of catechols, may be an important mechanism for neurohormonal regulation of the blood flow and blood pressure under normal conditions. AADC was present in the smooth muscle cells of the arteriole. These smooth muscle cells of the arteriole may play a role like APUD cells.