Social defeat (SD) has been implicated in different modulatory effects of physiology and behaviour including learning and memory. We designed an experiment to test the functional role of monoamine oxidase (MAO) in regulation of synaptic transmission, synaptic plasticity and memory in goldfish Carassius auratus. To test this, individuals were divided into three groups: (i) control; (ii) social defeat (SD) group (individuals were subjected to social defeat for 10 min by Pseudotropheus demasoni) and (iii) SD + MAO inhibitor pre-treated group. All experimental groups were subjected to spatial learning and then memory. Our results suggest that SD affects a spatial learning and memory, whereas SD exerts no influence on MAOI pre-treated group. In addition, we noted that the expression of monoamine oxidase-A (MAO-A) was up-regulated and level of serotonin (5-hydroxytryptamine; 5-HT), expression of serotonin transporter (SERT), synaptophysin (SYP), synaptotagmin −1 (SYT-1), N-methyl-D-asparate (NMDA) receptors subunits (NR2A and NR2B), postsynaptic density-95 (PSD-95) and brain-derived neurotrophic factor (BDNF) were reduced by SD, while MAOIs pretreatment protects the effect of SD. Taken together, our results suggest that MAO is an essential component in the serotonergic system that finely tunes the level of 5-HT, which further regulates the molecules involving in synaptic transmission, synaptic plasticity and memory.

社会失败（SD）与生理和行为的不同调节作用有关，包括学习和记忆。我们设计了一个实验来测试单胺氧化酶（MAO）在调节金鱼Car鱼突触传递，突触可塑性和记忆中的功能作用。为了检验这一点，将个人分为三组：（i）对照；（ii）社交挫败（SD）小组（个人因假性伪劣demasoni遭受社交挫败10分钟）和（iii）SD + MAO抑制剂预处理组。对所有实验组进行空间学习，然后进行记忆。我们的结果表明，SD影响空间学习和记忆，而SD对MAOI预处理组没有影响。此外，我们注意到单胺氧化酶-A（MAO-A）的表达被上调，血清素（5-羟色胺; 5-HT）的水平，血清素转运蛋白（SERT），突触素（SYP），突触标记素的表达-1（SYT-1），N-甲基-D降低SD中的天冬氨酸（NMDA）受体亚基（NR2A和NR2B），突触后密度95（PSD-95）和脑源性神经营养因子（BDNF），而MAOIs预处理可保护SD的作用。两者合计，我们的结果表明，MAO是血清素能系统中的重要组成部分，可微调5-HT的水平，该水平进一步调节了涉及突触传递，突触可塑性和记忆的分子。