Blatchford D, Holzbauer M
Br J Pharmacol. 1976 Jun;57(2):279-93. doi: 10.1111/j.1476-5381.1976.tb07478.x.
1 A detailed investigation into the postnatal development of the activity of the enzyme monoamine oxidase (MAO) in the rat and domestic pig was carried out. 2 MAO activity was measured in littermate male rats aged between 3 and 122 days belonging to six breeding colonies. The tissues studied were three brain regions in which monoamines may play a role in neuronal transmission (septum, hypothalamus, corpus striatum) and, for comparison, in the cerebellum. Liver, heart and adrenal glands were the peripheral organs studied. The following substrates were used to measure MAO activity in each tissue homogenate: kynuramine, tyramine, dopamine, tryptamine and 5-hydroxytryptamine (5-HT). 3 MAO activity towards kynuramine, tyramine and dopamine increased after birth in all brain regions and also in the liver, to reach maximal values between days 40 and 80. In the heart and the adrenal glands enzyme activity remained low up to 30-40 days and then increased steeply. This was the case in all litters examined. 4 All tissues deaminated more tyramine than dopamine. In the liver, the ratio of the quantities of tyramine deaminated/dopamine deaminated was approx. 2 at all ages. In the homogenates of whole brains (including or excluding the hypothalamus and striatum) this ratio was also 2 at all ages. In contrast in the isolated striatum and hypothalamus it was first much higher and reached a value of 2 only at an age of about 20 days. This may indicate an independent development of a dopamine and a tyramine deaminating enzyme system in discrete brain regions. It was suggested, that the low ability to deaminate dopamine in discrete brain regions may be due to the local presence of an enzyme inhibitor which becomes too diluted to be active in homogenates of whole brain. 5 Deamination of tryptamine in the striatum decreased between day 5 and 20 in 3 out of 4 colonies tested. There was a large fall in the deamination of 5-HT in all tissues of one group of rats, but in another 4 groups the tissues of the 5 day old rats deaminated smaller amounts of 5-HT than those of the older rats. 6 Purified hypothalamic mitochondria from 40 day old rats deaminated more tyramine and dopamine but not tryptamine per mg protein than those from 5 day old rats. 7 In the domestic pig there was a significant rise in the values in hippocampal MAO activity towards dopamine and tyramine from the foetus (55 day gestation) to the 1 week old piglet. A further steady rise up to week 6 was indicated, but this rise was not statistically significant. The difference between rat and pig probably reflected the much higher degree of maturity of the latter at birth. 8 In the hippocampus of the pig the ratio between the amount of tyramine deaminated/dopamine deaminated decreased from greater than 10 (foetus) to 4.8 in the 6 week old pig and 2 in the adult.
1 对大鼠和家猪体内单胺氧化酶（MAO）活性的产后发育进行了详细研究。2 在属于六个繁殖群体、年龄在3至122天之间的同窝雄性大鼠中测量了MAO活性。所研究的组织是单胺可能在神经元传递中起作用的三个脑区（隔区、下丘脑、纹状体），作为对照，还研究了小脑。肝脏、心脏和肾上腺是所研究的外周器官。在每个组织匀浆中使用以下底物来测量MAO活性：犬尿胺、酪胺、多巴胺、色胺和5-羟色胺（5-HT）。3 所有脑区以及肝脏中，MAO对犬尿胺、酪胺和多巴胺的活性在出生后增加，在第40至80天达到最大值。在心脏和肾上腺中，酶活性在30至40天之前一直较低，然后急剧增加。所有检查的窝仔都是这种情况。4 所有组织对酪胺的脱氨基作用比对多巴胺的脱氨基作用更强。在肝脏中，不同年龄酪胺脱氨基量与多巴胺脱氨基量之比约为2。在全脑匀浆（包括或不包括下丘脑和纹状体）中，该比例在所有年龄也为2。相比之下，在分离的纹状体和下丘脑中，该比例最初要高得多，仅在约20日龄时才达到2。这可能表明在离散的脑区中多巴胺和酪胺脱氨基酶系统的独立发育。有人提出，离散脑区中多巴胺脱氨基能力较低可能是由于局部存在一种酶抑制剂，在全脑匀浆中其被稀释得过于厉害而失去活性。5 在测试的4个群体中的3个群体中，纹状体中色胺的脱氨基作用在第5天至20天之间下降。一组大鼠的所有组织中5-HT的脱氨基作用大幅下降，但在另外4组中，5日龄大鼠组织中5-HT的脱氨基量比年龄较大的大鼠少。6 40日龄大鼠纯化的下丘脑线粒体每毫克蛋白质对酪胺和多巴胺的脱氨基作用比对5日龄大鼠的更强，但对色胺则不然。7 在家猪中，从胎儿（妊娠55天）到1周龄仔猪，海马中MAO对多巴胺和酪胺的活性值显著升高。表明直至第6周还有进一步的稳步上升，但这种上升在统计学上不显著。大鼠和猪之间的差异可能反映了后者出生时更高的成熟度。8 在猪的海马中，酪胺脱氨基量与多巴胺脱氨基量之比从大于10（胎儿）降至6周龄猪的4.8和成年猪的2。
