Wierenga J M, Hollingworth R M
Department of Entomology, Purdue University, West Lafayette, Indiana.
J Neurochem. 1990 Feb;54(2):479-89. doi: 10.1111/j.1471-4159.1990.tb01897.x.
Several insect tissues were examined for their ability to take up octopamine in the presence and absence of sodium ions. The cockroach Malpighian tubules, ovary, and ventral nerve cord showed the highest level of sodium-dependent uptake. The adult firefly lantern exhibited substantial sodium-independent uptake. Some of these tissues were also examined for their ability to metabolize octopamine by N-acetylation. Measurable N-acetyltransferase activity was present in the cockroach ventral nerve cord, tobacco hornworm CNS, and firefly light organ. N-Acetylation is proposed to be the major metabolic pathway for octopamine in the cockroach (Periplaneta americana) nervous system. Several classes of compounds, including octopamine receptor agonists, tricyclic antidepressants, amphetamines, chloroethylbenzylamines, and some experimental insecticides, were tested for their ability to inhibit octopamine uptake and metabolism. The sodium-insensitive component of uptake was not inhibited by most compounds tested, but the sodium-sensitive component was strongly inhibited by xylamine, N-ethyl-N-chloroethyl-o-bromobenzylamine, and their aziridinium ions (60-100%). These compounds also effectively inhibited N-acetyl-transferase (IC50 values at or below 1 microM). Other good inhibitors of N-acetyltransferase included desipramine, synephrine, and an experimental insecticide, CGA 132427. Formamidine pesticides had limited effect on both processes, and neither action seems likely to be involved in their octopaminergic actions in vivo. Cocaine was unique in stimulating N-acetyltransferase activity. When inhibition of sodium-sensitive uptake is compared with inhibition of N-acetyltransferase in the cockroach ventral nerve cord, two groups of inhibitors are discernible. Type 1 compounds inhibit uptake without an effect on N-acetyltransferase, whereas type 2 compounds inhibit both processes. These results suggest a functional linkage between the uptake and acetylation of octopamine.
研究了几种昆虫组织在存在和不存在钠离子的情况下摄取章鱼胺的能力。蟑螂的马氏管、卵巢和腹神经索表现出最高水平的钠离子依赖性摄取。成年萤火虫发光器表现出大量的非钠离子依赖性摄取。还检测了其中一些组织通过N-乙酰化代谢章鱼胺的能力。在蟑螂腹神经索、烟草天蛾中枢神经系统和萤火虫发光器官中存在可测量的N-乙酰转移酶活性。有人提出N-乙酰化是蟑螂（美洲大蠊）神经系统中章鱼胺的主要代谢途径。测试了几类化合物，包括章鱼胺受体激动剂、三环抗抑郁药、苯丙胺、氯乙基苄胺和一些实验性杀虫剂，以检测它们抑制章鱼胺摄取和代谢的能力。大多数测试化合物对摄取的非钠离子敏感成分没有抑制作用，但对钠离子敏感成分有强烈抑制作用的是二甲胺、N-乙基-N-氯乙基-邻溴苄胺及其氮丙啶离子（60-100%）。这些化合物也有效抑制N-乙酰转移酶（IC50值在1 microM或以下）。其他N-乙酰转移酶的良好抑制剂包括地昔帕明、辛弗林和一种实验性杀虫剂CGA 132427。甲脒类杀虫剂对这两个过程影响有限，而且这两种作用似乎都不太可能参与它们在体内的章鱼胺能作用。可卡因在刺激N-乙酰转移酶活性方面是独特的。当比较蟑螂腹神经索中对钠离子敏感摄取的抑制与N-乙酰转移酶的抑制时，可以区分出两组抑制剂。第1类化合物抑制摄取而不影响N-乙酰转移酶，而第2类化合物抑制这两个过程。这些结果表明章鱼胺的摄取和乙酰化之间存在功能联系。
