Crisp K M, Mesce K A
Graduate Program in Neuroscience and Department of Entomology, University of Minnesota, 1980 Folwell Ave., St. Paul, MN 55108, USA.
J Comp Physiol A Neuroethol Sens Neural Behav Physiol. 2003 Jun;189(6):461-70. doi: 10.1007/s00359-003-0424-0. Epub 2003 May 21.
Focally treating the head brain of the medicinal leech Hirudo medicinalis with various biogenic amines affected the initiation, termination and maintenance of fictive swimming (i.e., the neural correlate of swimming). Application of serotonin to saline surrounding only the head brain inhibited fictive swimming, whereas removing serotonin induced swimming. This contrasts sharply with previous observations that serotonin applied to the nerve cord induces swimming. Although application of octopamine to the brain activated swimming, a mixture of octopamine and serotonin inhibited swimming. Subsequent removal of this mixture from the brain activated robust swimming and was more potent for activating swimming than either the removal of serotonin or the application of octopamine. Swim episodes induced by brain-specific manipulations of octopamine had more swim bursts per episode than those induced by serotonin. These brain-specific effects of the amines on fictive swimming are probably due to the modulation of higher-order circuits that control locomotion in the leech. We observed that serotonin or a mixture of serotonin and octopamine hyperpolarized an identified descending brain interneuron known as Tr2. Removal of the mixture caused Tr2 to exhibit membrane potential depolarizations that correlated in time with the expression of swim episodes.
用各种生物胺对局灶性处理药用水蛭医蛭的头部脑区，会影响虚构游泳（即游泳的神经关联）的起始、终止和维持。仅将血清素应用于包围头部脑区的盐溶液中会抑制虚构游泳，而去除血清素则会诱发游泳。这与之前将血清素应用于神经索会诱发游泳的观察结果形成鲜明对比。尽管将章鱼胺应用于脑部会激活游泳，但章鱼胺和血清素的混合物会抑制游泳。随后从脑部去除这种混合物会激活强烈的游泳，并且比单独去除血清素或应用章鱼胺更有效地激活游泳。由脑部特异性操作章鱼胺诱发的游泳发作每发作的游泳爆发次数比由血清素诱发的更多。这些胺类对虚构游泳的脑部特异性作用可能是由于对控制水蛭运动的高阶回路的调节。我们观察到血清素或血清素与章鱼胺的混合物会使一种被鉴定为Tr2的下行脑中间神经元超极化。去除该混合物会导致Tr2表现出膜电位去极化，其时间与游泳发作的表现相关。
