Immunohistochemical evidence against the coexistence of a corticotropin-releasing factor and oxytocin or vasopressin in the rat paraventricular nucleus.

A corticotropin-releasing factor (CRF), oxytocin and arginine-vasopressin were localized immunohistochemically in the paraventricular nucleus of colchicine-treated male rats. Small CRF-containing neurons were distributed in the parvocellular region. Some magnocellular neurons were also immuno-stained with anti-CRF serum, but after preabsorption of the antiserum with pure synthetic CRF, the staining of these magnocellular neurons was unaffected, which suggests that this CRF-positive reaction was non-specific. By comparing the distribution of CRF and oxytocin or vasopressin on serial 5 micron cryostat sections, it was revealed that CRF and oxytocin or CRF and vasopressin do not coexist in the same neuron.