1.7 expression in vasopressin- and oxytocin-producing magnocellular neurosecretory cells in supraoptic nucleus. Magnocellular neurosecretory neurons (MSN) of the supraoptic nucleus (SON) exhibit robust vasopressin and oxytocin immunolabeling (green). MSN of the SON display Nav1.7 immunoreactivity (red). Double-immunocytochemical studies with antibodies to vasopressin or oxytocin and Nav1.7 demonstrate that both peptide-producing cell-types exhibit co-localization (magenta) with Nav1.7. Merged image of vasopressin or oxytocin with Nav1.7 is presented as magenta to enhance visualization of co-localization.