Engelmann M, Ebner K, Landgraf R, Wotjak C T
Max Planck Institute of Psychiatry, Munich, Germany.
Brain Res. 1998 May 11;792(2):343-7. doi: 10.1016/s0006-8993(98)00243-1.
The hypothalamic suprachiasmatic nucleus (SCN) is the predominant pacemaker of the mammalian brain that generates and controls circadian rhythms of various endocrine and behavioral processes. Different lines of evidence suggest that stress interferes with the maintenance of such rhythms. As a first approach to investigate whether the neuropeptide arginine vasopressin (AVP), which shows circadian rhythms of synthesis and release within the SCN, might contribute to this stress-induced alterations in circadian rhythms, we monitored acute effects of swim stress on the intra-SCN release of AVP in male rats by means of the microdialysis technique. A 10-min forced swimming session triggered a marked but relatively short-lasting increase in the intranuclear release of AVP (to approx. 440%). This effect was restricted to the area containing predominantly somata and dendrites of vasopressinergic neurons, since no changes in AVP release could be measured in one of their major projection areas, the nucleus of the dorsomedial hypothalamus. Our data provide evidence that the amount of AVP released within the SCN can vary widely not only in accordance with AVP's intrinsically regulated circadian rhythm but also in response to a physiologically relevant stressor. In this way, the neuropeptide may contribute to the regulation of endocrine and behavioral rhythms particularly in challenging situations associated with resettings of the endogenous clock.
下丘脑视交叉上核（SCN）是哺乳动物大脑的主要起搏器，它产生并控制各种内分泌和行为过程的昼夜节律。不同的证据表明，压力会干扰这些节律的维持。作为研究神经肽精氨酸加压素（AVP）是否可能导致这种应激诱导的昼夜节律改变的第一步，AVP在SCN内的合成和释放呈现昼夜节律，我们通过微透析技术监测了游泳应激对雄性大鼠SCN内AVP释放的急性影响。10分钟的强迫游泳会引发AVP核内释放显著但相对短暂的增加（达到约440%）。这种效应仅限于主要包含加压素能神经元胞体和树突的区域，因为在其主要投射区域之一，即下丘脑背内侧核中，未检测到AVP释放的变化。我们的数据表明，SCN内释放的AVP量不仅会根据AVP内在调节的昼夜节律而大幅变化，还会对生理相关应激源作出反应。通过这种方式，该神经肽可能有助于调节内分泌和行为节律，特别是在与内源性生物钟重置相关的具有挑战性的情况下。
