Stojilkovic Stanko S
Section on Cellular Signaling, Endocrinology and Reproduction Research Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892-4510, USA.
Biol Res. 2006;39(3):403-23. doi: 10.4067/s0716-97602006000300004. Epub 2006 Nov 7.
All secretory anterior pituitary cells exhibit spontaneous and extracellular calcium-dependent electrical activity, but differ with respect to the patterns of firing and associated calcium signaling and hormone secretion. Thus, somatotrophs and lactotrophs fire plateau-bursting action potentials spontaneously and without coupling to calcium release from intracellular stores, which generate calcium signals of sufficient amplitude to keep steady hormone release. In these cells, both spontaneous electrical activity and basal hormone secretion can be further amplified by activation of Gq/11 and Gs-coupled receptors and inhibited by Gi/o/z-coupled receptors. In contrast, gonadotrophs fire single, high-amplitude spikes with limited ability to promote calcium influx and exocytosis, whereas activated Gq/11-coupled receptors in these cells transform single-action potential spiking into the plateau-bursting type of electrical activity and trigger periodic high-amplitude calcium signals and exocytosis of prestored secretory vesicles. Here, we review biochemical and biophysical aspects of spontaneous and receptor-controlled electrical activity, calcium signaling, and hormone secretion in pituitary cells.
所有垂体前叶分泌细胞均表现出自发性和细胞外钙依赖性电活动，但在放电模式、相关钙信号传导及激素分泌方面存在差异。因此，生长激素细胞和催乳激素细胞自发产生平台爆发式动作电位，且不与细胞内钙库的钙释放偶联，由此产生的钙信号幅度足以维持激素的稳定释放。在这些细胞中，自发电活动和基础激素分泌均可通过激活Gq/11和Gs偶联受体进一步增强，并被Gi/o/z偶联受体抑制。相比之下，促性腺激素细胞产生单个高幅度尖峰，促进钙内流和胞吐作用的能力有限，而这些细胞中激活的Gq/11偶联受体可将单动作电位尖峰转变为平台爆发式电活动类型，并触发周期性高幅度钙信号以及预存分泌囊泡的胞吐作用。在此，我们综述垂体细胞中自发性和受体控制的电活动、钙信号传导及激素分泌的生化和生物物理方面。
