Components of the neuronal exocytotic machinery in the anterior pituitary of the ovariectomised ewe and the effects of oestrogen in gonadotropes as studied with confocal microscopy

Abstract

We have investigated exocytotic proteins in ovine pituitary cells and sought to identify changes in expression of these proteins related to the effects of estrogen on luteinising hormone (LH) secretion in the ovariectomised ewe. Sheep were treated with either oestradiol benzoate, or oil (i.m.) and blood samples collected for LH assay. Pituitaries were perfusion-fixed and dual-label immunohistochemistry was performed to identify hormone-secreting cells, and colocalise synaptic proteins within different cell types. Synaptophysin, SNAP-25, VAMP-2, rab3A, Munc-18-1, alpha/beta-SNAP, csp, and secretogranin II were detected in gonadotropes and somatotropes. Lactotropes were positive for SNAP-25 an..