Corticotropin-releasing hormone receptor (type I) antisense targeting reduces anxiety

Two brain-derived corticotropin-releasing hormone receptors have been cloned, termed corticotropin-releasing hormone receptors type I and type 2. Antisense oligodeoxynucleotides targeted to the cloned rat and mouse corticotropin-releasing hormone receptors type I messenger RNA reduced the binding of the natural ligand of the corticotropin-releasing hormone receptors type I and also the release of adenocorticotrophic hormone in primary rat anterior pituitary cells and in clonal mouse pituitary cells (AtT-20) by up to 60% in an application time-dependent manner. Studies on intracellular uptake of fluorescence-labelled oligodeoxynucleotides indicated a cytoplasmic accumulation starting within two to four hours after application of oligodeoxynucleotides in vitro. In vivo, antisense oligodeoxynucleotides infused intra-cerebroventricularly reduced binding of radiolabelled corticotropin-releasing hormone receptors in central sites of the rat brain. Anxiety induced by i.c.v. administration of corticotropin-releasing hormone was attenuated by corticotropin-releasing hormone receptors type I antisense treatment as determined in the elevated plus maze and in the novel open field test. The corticotropin-releasing hormone-induced behavioural changes were absent in corticotropin-releasing hormone receptors type I antisense-pretreated animals. These results show that the selected antisense probes used were able to suppress corticotropin-releasing hormone receptors type I function in vitro as well as in vivo and suggest that the development of drugs blocking this specific receptor might lead to a novel class of anxiolytics.