Armstrong W E, Stern J E
Department of Anatomy and Neurobiology, University of Tennessee, Memphis College of Medicine 38163, USA.
Adv Exp Med Biol. 1998;449:67-77. doi: 10.1007/978-1-4615-4871-3_7.
Oxytocin and vasopressin neurons can be differentiated from one another, and from neurons in the immediately adjacent perinuclear zone, by their electrophysiological properties. In both sexes, oxytocin and vasopressin neurons are characterized by a prominent transient outward rectification which is conspicuously lacking in most perinuclear neurons. In addition, perinuclear neurons, some of which project to the supraoptic nucleus, exhibit a transient depolarization which underlies short bursts of spikes. Oxytocin neurons are characterized by: 1) the presence of a sustained outward rectifier above -50 mV, active below spike threshold; 2) a rebound depolarization following deactivation of the sustained rectification which can sustain short spike trains; and 3) a smaller transient outward rectification, probably associated with the potassium current, Ia. Vasopressin neurons show little of the sustained outward rectification and rebound depolarization, but have a stronger transient outward rectification. Although both cell types exhibit depolarizing afterpotentials, in vasopressin neurons these lead to plateau potentials underlying prolonged discharges. In oxytocin neurons, the depolarizing potential usually sustains a short spike discharge, but less often leads to prolonged bursts. These data suggest that the intrinsic properties of oxytocin and vasopressin neurons lead to quantitatively different forms of burst discharges, both of which may facilitate hormone release.
通过电生理特性，催产素神经元和加压素神经元能够彼此区分开来，也能与紧邻的核周区神经元区分开来。在两性中，催产素神经元和加压素神经元的特征是具有显著的瞬时外向整流，而大多数核周神经元明显缺乏这种特性。此外，一些投射到视上核的核周神经元表现出瞬时去极化，这是短串脉冲的基础。催产素神经元的特征如下：1）在高于 -50 mV 时存在持续外向整流，在动作电位阈值以下激活；2）持续整流失活后出现反极化，可维持短串动作电位；3）较小的瞬时外向整流，可能与钾电流 Ia 有关。加压素神经元几乎没有持续外向整流和反极化，但具有较强的瞬时外向整流。虽然两种细胞类型都表现出去极化后电位，但在加压素神经元中，这些后电位会导致延长放电的平台电位。在催产素神经元中，去极化电位通常维持短串动作电位放电，但较少导致延长的爆发式放电。这些数据表明，催产素神经元和加压素神经元的内在特性导致了数量上不同形式的爆发式放电，这两种放电形式都可能促进激素释放。
