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

与去甲肾上腺素的浓度相比，在人牙髓中发现了相对大量的多巴。通过酪氨酸羟化酶（TH）、L-芳香族氨基酸脱羧酶（AADC）、多巴胺-β-羟化酶（DBH）、苯乙醇胺-N-甲基转移酶（PNMT）的免疫细胞化学演示，研究了人牙髓中儿茶酚胺的局部产生，这些酶分别催化多巴、多巴胺、去甲肾上腺素和肾上腺素的形成。在小动脉周围观察到 TH 和 AADC 免疫反应性神经纤维的丰富神经支配。在小动脉壁上发现了 DBH 的细珠状免疫反应性静脉曲张。在细胞丰富区也观察到 TH 免疫反应性神经纤维。没有观察到特异性 PNMT 免疫反应性。结果表明，人牙髓中的一些诺夫纤维可能合成去甲肾上腺素，作为儿茶酚胺生物合成的最终产物。 AADC 和 COMT 位于人牙髓的血管壁中。这种定位表明 COMT 和 AADC 之间在多巴代谢方面存在功能关系。小动脉的内皮细胞含有 COMT。该结果表明对儿茶酚胺存在酶屏障；可能存在血牙髓屏障。血管壁内皮细胞中的 COMT 活性通过提供儿茶酚失活的手段，可能是正常条件下神经激素调节血流和血压的重要机制。 AADC 存在于小动脉的平滑肌细胞中。这些小动脉平滑肌细胞可能发挥类似APUD细胞的作用。

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.