Exposure to an antisense oligonucleotide decreases corticotropin-releasing factor receptor binding in rat pituitary cultures

Corticotropin-releasing factor (CRF) appears to integrate the endocrine, autonomic, immunologic, and behavioral responses of mammals to stress. To investigate further the role of CRF in the CNS, we have begun investigating the usefulness of «antisense knockdown» strategies directed against the CRF receptor using rat anterior pituitary gland primary cell cultures. The 15-mer antisense (5' CTG-CGG-GCG-CCG-TCC 3') and «scrambled» control (5' CGT-CCG-CGC-GCT-GCG 3') oligonucleotides were synthesized based on the rat CRF receptor sequence just downstream of the initiation codon. In each of four separate experiments, exposure to 10 μmol/L of antisense oligonucleotide for 40-67 h resulted in significant (17-36%) decreases in 125I-ovine CRF binding to pituitary cells as compared with either control (no oligonucleotide) or 10 μmol/L of «scrambled» oligonucleotide. Moreover, compared with scrambled oligonucleotide, exposure to 10 μmol/L of antisense oligonucleotide, which produced a 22% decrease in CRF receptor binding, also resulted in a significant attenuation of the adrenocorticotrophic hormone response following a 30-min challenge with 100 pmol/L of CRF. Thus, CRF receptor antisense oligonucleotides apparently reduce functional expression of CRF receptors. This technique may be useful in studying the kinetics of CRF receptor production and the physiological functions of CRF receptors within the CNS.