CORTICOTROPIN-RELEASING FACTOR RECEPTORS IN INFLAMED TISSUE - AUTORADIOGRAPHIC IDENTIFICATION

We have shown that injecting corticotropin releasing factor (CRF) into inflamed rat paws causes the local release of endogenous opioids to i nhibit pain. The purpose of the current study was to visualize CRF rec eptors by means of in vitro receptor autoradiography. We used I-125-CR F as a ligand on sections of popliteal lymph nodes, subcutaneous tissu e of hind paws and spleen of rats. The density of I-125-CRF labelled r eceptors was higher in inflamed lymph nodes than in noninflamed lymph nodes (P=0.0431, Wilcoxon test). Similarly, the density of CRF recepto rs was significantly higher in inflamed than in noninflamed paws (P=0. 0431, Wilcoxon test). This increase in CRF receptors indicates an upre gulation of CRF binding sites in inflamed tissue. These findings are c onsistent with our in vivo studies which have shown potent antinocecip tive effects of locally applied CRF in inflamed but not in noninflamed tissue.