THE existence of a CRF-dependent inhibition of GnRH transcription was investigated using a neuronal GnRH-expressing cell line (Gn11) stably transfected with mouse (−611 bp) or chicken (−3000 bp) GnRH promoter/luciferase reporter constructs. The presence of the CRF-R1 receptor was established using a specific CRFR1 antiserum. After 7 h of incubation, urotensin-I and sauvagine increased the mouse GnRH-reporter bioluminescence by 1.3- and 1.2-fold, respectively, compared with control cells. Subsequently, CRF, urotensin-I and sauvagine decreased luciferase reporter activity to about 60% of the control values after 14 h. Similar trends occurred with the chicken GnRH promoter with UI increasing reporter gene activity 2.4-fold over the controls after 14 h incubation. These data provide additional evidence for the direct regulation of GnRH transcription by CRF-like peptides.