Magnocellular dendrites: prototypic receiver/transmitters

The hypothalamic magnocellular neurones of the supraoptic and paraventricular nuclei of mammals are among the best understood of all peptidergic neurones, and therefore serve as a model for understanding the functions of other peptidergic neurones. The release of vasopressin- and oxytocin-containing neurosecretory vesicles from their dendrites was first established 15 years ago. This local release is now known to have many functions, including controlling the interactions between oxytocin neurones and their surrounding glia, and facilitating and inhibiting the electrical activation of the neurones. Technical advances now permit dynamic analysis of dendritic release. Here, we review recent studies that focus on the conditional priming of dendritic peptide release by peptide-induced liberation of intracellular calcium, and the role of dendritic protein synthesis in the dendritic peptide release and the control of receptive properties of the neurones.