Temporal dissociation of the feedback effects of dendritically co-released peptides on rhythmogenesis in vasopressin cells
Temporal dissociation of the feedback effects of dendritically co-released peptides on rhythmogenesis in vasopressin cells
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DOI：
10.1016/j.neuroscience.2003.11.038
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发表时间：
2004-01-01
期刊：
影响因子：
3.3
通讯作者：
Leng, G
中科院分区：
文献类型：
--
作者：
Brown, CH;Ludwig, M;Leng, G
加压素神经元以有节奏的“相”模式发射动作电位，其特征是活动和静默的交替周期。加压素和强啡肽共同包装在神经分泌囊泡中，这些囊泡从加压素细胞的树突和终末排出，两者都通过自身调节机制参与了时相活动模式的产生。本研究记录了乌拉坦麻醉大鼠视上核加压素细胞自发时相活动的记录，用V(1)加压素受体拮抗剂OPC 21268或K-阿片受体拮抗剂去甲肾上腺素。OPC 21268在每次放电过程中都会增加放电频率，而去甲肾上腺素兴奋在每次放电过程中都会出现，这表明在发作过程中kappa-阿片受体机制正在逐渐激活。为了确定棘波后兴奋性的变化是否可以解释这些影响，我们绘制了动作电位在前一个动作电位(危险函数)之后随时间放电的概率图，发现与放电频率类似，这一概率在每次放电过程中也被opc 21268升高，而去甲肾上腺素的兴奋效应在每次放电过程中逐渐增加。因此，这些共同释放的多肽的反馈效应的时间组织是不同的，加压素有效地导致整体兴奋性的立即下降，而强啡肽在每次爆发的过程中导致尖峰后兴奋性的进行性下降。(C)2004年IBRO。爱思唯尔有限公司出版。保留所有权利。
Vasopressin neurones fire action potentials in a rhythmic 'phasic' pattern, characterised by alternating periods of activity and silence. Vasopressin and dynorphin are co-packaged in neurosecretory vesicles that are exocytosed from vasopressin cell dendrites and terminals and both have been implicated in the generation of phasic activity patterning through autoregulatory mechanisms. Here, identified supraoptic nucleus vasopressin cells exhibiting spontaneous phasic activity were recorded from urethane-anaesthetised rats administered the V(1) vasopressin receptor antagonist, OPC 21268, or the K-opioid receptor antagonist, nor-binaltorphimine. OPC 21268 elevated firing rate throughout each burst whereas nor-binaltorphimine excitation emerged over the course of each burst, indicating a progressive activation of kappa-opioid receptor mechanisms during bursts. To determine whether changes in post-spike excitability could account for these effects, we plotted the probability of action potential firing with time after the preceding action potential (hazard function) and found that, similarly to firing rate, this too was elevated by OPC 21268 throughout each burst whilst the excitatory effects of nor-binaltorphimine progressively increased over the course of each burst. Thus, the temporal organisation of the feedback effects of these co-released peptides is different, with vasopressin effectively causing an immediate reduction in overall excitability whilst dynorphin causes a progressive decrease in post-spike excitability over the course of each burst. (C) 2004 IBRO. Published by Elsevier Ltd. All rights reserved.