Classically, hypothalamic neuroendocrine cells that synthesise oxytocin and vasopressin were categorised in two major cell types: the magnocellular and parvocellular neurones. It was assumed that magnocellular neurones project exclusively to the pituitary gland where they release oxytocin and vasopressin into the systemic circulation. The parvocellular neurones, on the other hand, project within the brain to regulate discrete brain circuitries and behaviours. Within the last few years, it has become evident that the classical view of these projections is outdated. It is now clear that oxytocin and vasopressin in the brain are released extrasynaptically from dendrites and from varicosities in distant axons. The peptides act principally to modulate information transfer through conventional synapses (such as glutamate synapses) by actions at respective receptors that may be preferentially localised to synaptic regions (on either side of the synapse) to alter the ‘gain’ of conventional synapses.

中文翻译：

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大脑中催产素和加压素系统的多面性

经典地，合成催产素和加压素的下丘脑神经内分泌细胞分为两种主要细胞类型：大细胞神经元和小细胞神经元。据推测，大细胞神经元仅投射到垂体，在那里它们将催产素和加压素释放到体循环中。另一方面，细小细胞神经元在大脑内投射以调节离散的大脑回路和行为。在过去的几年里，很明显这些预测的经典观点已经过时了。现在很清楚，大脑中的催产素和加压素是从树突和远处轴突的静脉曲张中突触外释放的。