Isolation and properties of sheep neurohypophysial nerve terminals

Nerve terminals were isolated from sheep posterior pituitary lobes using a collagenase digestion technique. Freshly dispersed terminals, and terminals cultured for up to 3 days were examined by immunofluorescence microscopy. Immunohistochemical results suggested the presence of immunoreactive-neurophysin, -oxytocin and -vasopressin in membrane-bound structures. Membrane depolarization induced by high concentrations of potassium ions stimulated oxytocin release. This release was attenuated in the absence of calcium ions. The calcium ionophore, A23187, was also an effective stimulator of oxytocin secretion. These data suggest that neurohypophysial nerve terminals prepared by a collagenase dispersion procedure may be suitable for the investigation of posterior pituitary secretion mechanisms.