Randle J C, Day T A, Jhamandas J H, Bourque C W, Renaud L P
Fed Proc. 1986 Aug;45(9):2312-7.
The neurosecretory neurons in the mammalian hypothalamic supraoptic nucleus receive prominent GABAergic and noradrenergic projections arising from local interneurons and the A1 cells in the ventrolateral medulla, respectively. Intracellular recordings in in vitro perfused hypothalamic explants reveal an abundance of spontaneous inhibitory postsynaptic potentials (IPSPs) and a compound IPSP after electrical stimulation in the diagonal band of Broca area. The sensitivity of both spontaneous and evoked IPSPs to intracellular chloride injection, bicuculline, and pentobarbital is consistent with a GABA-activated, chloride-mediated inhibitory synaptic input. Parallel changes in membrane voltage and conductance are present during applications of GABA and muscimol, with similar sensitivity to ionic manipulation, bicuculline, and pentobarbital. These observations contrast with the consistently excitatory effects that follow either the stimulation of A1 cells or the application of norepinephrine and alpha 1-adrenergic agonists. Norepinephrine induces membrane depolarizations and bursting activity patterns that are blocked by the selective alpha 1 antagonist prazosin. Membrane response to norepinephrine is voltage dependent and is associated with little change in conductance. GABA and norepinephrine are proposed as transmitters in the final central pathways that mediate information to supraoptic vasopressinergic neurons from peripheral baroreceptors and chemoreceptors, respectively.
哺乳动物下丘脑视上核中的神经分泌神经元分别接受来自局部中间神经元和延髓腹外侧A1细胞的显著GABA能和去甲肾上腺素能投射。在体外灌注的下丘脑外植体上进行的细胞内记录显示，在布罗卡区斜带进行电刺激后，出现大量自发抑制性突触后电位（IPSPs）和复合IPSP。自发和诱发的IPSPs对细胞内注射氯化物、荷包牡丹碱和戊巴比妥的敏感性与GABA激活、氯离子介导的抑制性突触输入一致。在应用GABA和蝇蕈醇期间，膜电压和电导存在平行变化，对离子操作、荷包牡丹碱和戊巴比妥具有相似的敏感性。这些观察结果与刺激A1细胞或应用去甲肾上腺素和α1肾上腺素能激动剂后始终产生的兴奋作用形成对比。去甲肾上腺素诱导膜去极化和爆发活动模式，这些被选择性α1拮抗剂哌唑嗪阻断。膜对去甲肾上腺素的反应是电压依赖性的，并且与电导的变化很小有关。GABA和去甲肾上腺素分别被认为是在最终中枢途径中传递信息的递质，这些途径分别将外周压力感受器和化学感受器的信息传递给视上核血管加压素能神经元。
