Racké K, Muscholl E
J Neurochem. 1986 Mar;46(3):745-52. doi: 10.1111/j.1471-4159.1986.tb13035.x.
Isolated rat neurointermediate lobes were incubated in vitro. The release of 3,4-dihydroxyphenylethylamine (dopamine, DA), dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA), and methoxyphenylethanol (MOPET) was determined by HPLC with electrochemical detection. Under resting conditions, the outflow of metabolites was 35-50 times that of DA. HVA accounted for 50%, DOPAC for 45%, and MOPET for 5% of the metabolites. Although an equivalent of 40-50% of the tissue DA content was released per hour as metabolites, the tissue DA content was not reduced after 110 min of incubation. The spontaneous outflow of DA and its metabolites was not affected by the DA uptake inhibitor GBR 12921 (100 nM). Pargyline (10 microM) caused a time-dependent decrease of all metabolites (up to 90%). In the presence of GBR 12921 and pargyline, the spontaneous outflow of DA increased sevenfold. Removal of the intermediate lobe caused a 78% reduction in tissue DA content and a corresponding reduction of the outflow of metabolites. Electrical stimulation of the pituitary stalk (0.2 ms, 10 V, 15 Hz, three times for 1 min at intervals of 1 min) induced an increase in outflow of DA and all metabolites. DA accounted for 15%, HVA for 41%, DOPAC for 32%, and MOPET for 12% of the evoked release. The electrically evoked release of DA increased fourfold in the presence of GBR 12921 or pargyline and the effects of both drugs were additive. The evoked release of metabolites was not significantly affected by GBR 12921 but completely abolished by pargyline. In conclusion, oxidative deamination and O-methylation are important pathways for the catabolism of DA in the neurointermediate lobe.(ABSTRACT TRUNCATED AT 250 WORDS)
将离体大鼠神经中间叶进行体外培养。采用高效液相色谱电化学检测法测定3,4-二羟基苯乙胺（多巴胺，DA）、二羟基苯乙酸（DOPAC）、高香草酸（HVA）和甲氧基苯乙醇（MOPET）的释放量。在静息条件下，代谢产物的流出量是DA的35 - 50倍。HVA占代谢产物的50%，DOPAC占45%，MOPET占5%。尽管每小时有相当于组织DA含量40 - 50%的量作为代谢产物释放，但孵育110分钟后组织DA含量并未降低。DA及其代谢产物的自发流出不受DA摄取抑制剂GBR 12921（100 nM）的影响。帕吉林（10 μM）导致所有代谢产物随时间减少（高达90%）。在GBR 12921和帕吉林存在的情况下，DA的自发流出增加了7倍。切除中间叶导致组织DA含量降低78%，代谢产物流出相应减少。垂体柄电刺激（0.2毫秒，10伏，15赫兹，间隔1分钟，每次1分钟，共3次）诱导DA和所有代谢产物流出增加。DA占诱发释放量的15%，HVA占41%，DOPAC占32%，MOPET占12%。在GBR 12921或帕吉林存在的情况下，电诱发的DA释放增加了4倍，两种药物的作用是相加的。代谢产物的诱发释放不受GBR 12921的显著影响，但被帕吉林完全消除。总之，氧化脱氨和O-甲基化是神经中间叶中DA分解代谢的重要途径。（摘要截短至250字）
