Israel Jean-Marc, Oliet Stéphane H, Ciofi Philippe
U1215, Neurocentre Magendie, Institut National de la Santé et de la Recherche MédicaleBordeaux, France; Université de BordeauxBordeaux, France.
Front Neurosci. 2016 Mar 31;10:109. doi: 10.3389/fnins.2016.00109. eCollection 2016.
Hypothalamic neurohormones are released in a pulsatile manner. The mechanisms of this pulsatility remain poorly understood and several hypotheses are available, depending upon the neuroendocrine system considered. Among these systems, hypothalamo-neurohypophyseal magnocellular neurons have been early-considered models, as they typically display an electrical activity consisting of bursts of action potentials that is optimal for the release of boluses of the neurohormones oxytocin and vasopressin. The cellular mechanisms underlying this bursting behavior have been studied in vitro, using either acute slices of the adult hypothalamus, or organotypic cultures of neonatal hypothalamic tissue. We have recently proposed, from experiments in organotypic cultures, that specific central pattern generator networks, upstream of magnocellular neurons, determine their bursting activity. Here, we have tested whether a similar hypothesis can be derived from in vitro experiments in acute slices of the adult hypothalamus. To this aim we have screened our electrophysiological recordings of the magnocellular neurons, previously obtained from acute slices, with an analysis of autocorrelation of action potentials to detect a rhythmic drive as we recently did for organotypic cultures. This confirmed that the bursting behavior of magnocellular neurons is governed by central pattern generator networks whose rhythmic drive, and thus probably integrity, is however less satisfactorily preserved in the acute slices from adult brains.
下丘脑神经激素以脉冲方式释放。这种脉冲性的机制仍知之甚少，根据所考虑的神经内分泌系统有几种假说。在这些系统中，下丘脑 - 神经垂体大细胞神经元很早就被视为模型，因为它们通常表现出由动作电位爆发组成的电活动，这种电活动最适合释放神经激素催产素和血管加压素的大剂量脉冲。这种爆发行为背后的细胞机制已在体外进行研究，使用的是成年下丘脑的急性切片或新生下丘脑组织的器官型培养物。我们最近从器官型培养实验中提出，在大细胞神经元上游的特定中枢模式发生器网络决定了它们的爆发活动。在此，我们测试了是否能从成年下丘脑急性切片的体外实验中得出类似的假说。为此，我们对之前从急性切片获得的大细胞神经元的电生理记录进行了筛选，通过分析动作电位的自相关来检测节律驱动，就像我们最近对器官型培养物所做的那样。这证实了大细胞神经元的爆发行为受中枢模式发生器网络控制，然而其节律驱动以及可能的完整性在成年大脑的急性切片中保存得不太理想。
