抄録
The serotonergic Innervation of neurons containing vasopressin (VP) was examined by electron microscopy using a method of pre-embedding peroxidase-antiperoxidase (PAP) to show serotonin with post-embedding immunocolloidal gold staining (IGS) to show VP in the same tissue sections. Serotonin-like immunoreactive (serotonin-LI) terminals were found to make direct contact with VP-like immunoreactive (VP-LI) neurons at the light microscopic level. Ultrastructural observation revealed that serotonin-LI axon terminals, containing immunoreactive granular vesicles (70-80 nm in diameter), formed synapses with magnocellular neurosecretory neurons in the supraoptic nucleus (SON) and the paraventricular nucleus (PVN) . In the combined PAG-IGS preparations, PAP-labeled serotonergic axon terminals appeared at times making synaptic contacts with IGS-labeled VP-LI cell bodies and dendritic processes. These findings provide morphological evidence of direct synaptic influence of serotonergic elements on the secretory activity of VP-containing neurons in the rat hypothalamic SON and PVN.
