Coexistence of c-Fos and glucocorticoid receptor immunoreactivities in the CRF immunoreactive neurons of the paraventricular hypothalamic nucleus of the rat after acute immobilization stress

By means of triple immunofluorescence procedures the codistribution and coexistence of glucocorticoid receptor (GR), c-Fos and corticotropin-releasing factor (CRF) immunoreactive (IR) nerve cell profiles have been analyzed within the paraventricular hypothalamic nucleus at various rostrocaudal levels following acute immobilization stress (2 h) in the male rat. One population of CRF IR neurons is shown to contain both nuclear GR and c-Fos immunoreactivities following the stress, while another contains GR immunoreactivity alone. These results indicate heterogeneities among parvocellular CRF paraventricular hypothalamic nerve cell populations in the response to acute immobilization stress.