Corticotropin-releasing factor receptors in the rabbit brain visualized by in vitro autoradiography

Corticotropin-releasing factor (CRF) binding sites were visualized in the rabbit brain by in vitro autoradiography using the radioligand 125I-[Tyr0]ovine CRF. The radioligand binding to sections of rabbit cingulate cortex were competed for by ovine and rat CRF with inhibitory constants (Ki) of 26 and 37 nM, respectively, whereas sauvagine and alpha-helical CRF9-41 were approximately 10-fold less potent. In the rabbit brain, the highest densities of binding sites for CRF are found in the pineal gland and the choroid plexus. The cerebral cortex is labelled throughout, with the highest concentration of binding sites in the piriform and primary olfactory divisions. In the cerebellar cortex, the granular layer is more intensely labelled than the molecular layer. The distribution of CRF binding sites in the hippocampus follows a laminar pattern; the molecular layer of the dentate gyrus is intensely labelled, the oriens, radiatum and lacunosum moleculare layers of Ammon's horn contain moderate densities of binding and no binding is observed in the granular layer of the dentate gyrus and the pyramidal cell layer. The ventral subnucleus of the lateral septum, the zonal and superficial layers of the superior colliculus contain high densities of receptors. A moderate concentration of binding sites is observed in the caudate nucleus, putamen, bed nucleus of the stria terminalis, paraventricular, anterodorsal and anteroventral thalamic nuclei and the medial nucleus of the mammillary body.(ABSTRACT TRUNCATED AT 250 WORDS)