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

与去甲肾上腺素的浓度相比，人牙髓中的DOPA含量相对较高。用酪氨酸羟基酶、L芳香氨基酸脱羧酶、多巴胺-β-羟基酶、苯乙醇胺-N-甲基转移酶等催化多巴胺、多巴胺、去甲肾上腺素和肾上腺素的酶的免疫细胞化学方法，研究了人牙髓中儿茶酚胺的局部产生。小动脉周围可见丰富的TH和AADC免疫反应神经纤维。小动脉壁可见胸径细小的珠状免疫反应曲张。TH免疫反应阳性神经纤维也见于细胞富集区。未观察到特异性PNMT免疫反应。结果提示，人牙髓中的某些神经纤维可能合成儿茶酚胺生物合成的终产物去甲肾上腺素。AADC和COMT定位于人牙髓血管壁。这一定位提示COMT和AADC在DOPA代谢方面的功能关系。小动脉内皮细胞含有COMT。这一结果表明COMT对儿茶酚胺具有酶屏障作用，可能是血-牙髓屏障。血管壁内皮细胞的COMT活性通过提供儿茶酚失活的途径，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存在于小动脉的平滑肌细胞中。这些小动脉的平滑肌细胞可能起到类似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.