Theodosis Dionysia T, Koksma Jan-Jurjen, Trailin Andrei, Langle Sarah L, Piet Richard, Lodder Johannes C, Timmerman Jaap, Mansvelder Huibert, Poulain Dominique A, Oliet Stéphane H R, Brussaard Arjen B
Inserm, U 378, Bordeaux F33077 France; University Victor Segalen, Bordeaux F33077, France.
Mol Cell Neurosci. 2006 Apr;31(4):785-94. doi: 10.1016/j.mcn.2006.01.006. Epub 2006 Feb 20.
We here investigated inhibitory synapse turnover in the adult brain using the hypothalamic supraoptic nucleus where new synapses form during different physiological conditions, in particular on oxytocin neurons largely controlled by GABAergic inputs and locally released oxytocin. Patch clamp recordings and ultrastructural analysis of the nucleus in acute slices from late gestating rats showed that oxytocin and estrogen promoted rapid formation of inhibitory synapses. Thus, after 2-h exposure to a combination of oxytocin and 17-beta estradiol, the frequency of miniature inhibitory postsynaptic currents was significantly enhanced. Since their amplitude and presynaptic GABA release probability were unmodified, this indicated an increased number of synapses. Electron microscopy confirmed increased densities of symmetric, putative GABAergic synapses within 2-h exposure to the peptide or steroid, effects which were reversible and oxytocin receptor mediated. Our observations thus offer direct evidence that hypothalamic GABAergic microcircuitries can undergo rapid and functional remodeling under changing neuroendocrine conditions.
我们在此利用下丘脑视上核研究了成年大脑中抑制性突触的更新情况，在该区域，新突触会在不同生理条件下形成，尤其是在主要受γ-氨基丁酸（GABA）能输入和局部释放的催产素控制的催产素神经元上。对妊娠晚期大鼠急性脑片视上核进行的膜片钳记录和超微结构分析表明，催产素和雌激素促进了抑制性突触的快速形成。因此，在暴露于催产素和17-β雌二醇的组合2小时后，微小抑制性突触后电流的频率显著增加。由于其幅度和突触前GABA释放概率未发生改变，这表明突触数量增加。电子显微镜证实，在暴露于该肽或类固醇2小时内，对称的、假定的GABA能突触密度增加，这些效应是可逆的且由催产素受体介导。因此，我们的观察结果提供了直接证据，表明下丘脑GABA能微回路在不断变化的神经内分泌条件下可经历快速且功能性的重塑。
