CRF(2-ALPHA) AND CRF(2-BETA) RECEPTOR MESSENGER-RNAS ARE DIFFERENTIALLY DISTRIBUTED BETWEEN THE RAT CENTRAL-NERVOUS-SYSTEM AND PERIPHERAL-TISSUES

We have recently described the cloning and characterization of a novel corticotropin-releasing factor receptor subtype (CRF(2)) from rat brain that exists in two alternatively spliced forms, CRF(2 alpha) and CRF(2 beta). These forms differ in their N-terminal coding sequence which results in the production of two distinct receptors of 411 and 431 amino acids, respectively. To assess whether these two forms might represent distinct targets for CRF action, RNase protection and in situ hybridization studies were performed using specific N-terminal cRNA probes. The results showed a differential distribution of the mRNAs for these two receptor forms in the rat. The mRNA for CRF(2 alpha) is found almost exclusively in the brain, particularly in the hypothalamus, lateral septum, and olfactory bulb, whereas the mRNA for CRF(2 beta) appears to be both in the brain and in the periphery, with the greatest abundance in the heart and skeletal muscle. Thus, the data suggest that these alternatively spliced forms of the CRF(2) receptor may represent functionally distinct CRF receptors. In addition, it highlights the importance of probe specificity for in situ hybridization studies.