Sex-specific response of the vasopressin-reacting neurons of the paraventricular nucleus of the rat hypothalamus following chronic administration of met-enkephalin

Abstract

Using the peroxidase-antiperoxidase immunocytochernical technique, a morphometric study of the magnocellular neurons of the Paraventricular nucleus of the rat hypothalamus, reactive to specific anti-vasopressin rabbit serum, was made. Following systemic and chronic administration of met-enkephalin the number of immunoreactive neurons was higher, especially in females. Additionally, in the females, it was possible to observe an increase in the immunoreactivity and the presence of well-stained fibres. These findings suggest, especially in females, a blockage in the release of vasopressin, facilitating its immunocytochemical visualization.