The present invention provides transgenic mice deficient in urocortin. Urocortin null mutant mice are hypersensitive to stress and display heightened anxiety-like behaviors in the elevated plus maze and open field tests. These mice also demonstrate physiological alterations in auditory thresholds and distortion product otoacoustic emissions. These results indicate that urocortin plays a modulatory role in anxiety-related behaviors and in contributing to the establishment of auditory thresholds. Such urocortin deficient mutant mice can provide useful models in the study of anxiety pathology and hearing physiology at the biochemical and molecular levels.