The effects of CRF and urocortins on the preference for social novelty of mice

Abstract

The aim of the present study was to determine the role of corticotropin-releasing factor (CRF), the urocortins (UCN 1, UCN 2 and UCN 3) and their receptors (CRF₁ and CRF₂) in the preference for social novelty of mice. Male CFLP mice were administered intracerebroventricularly (ICV) with CRF, UCN 1, UCN 2 or UCN 3 and/or antalarmin or astressin 2B, selective antagonists of CRF₁ receptor and CRF₂ receptor, respectively. The mice were investigated in a Crawley social interaction test arena consisting of three chambers: an unknown female was set in the first chamber and a known female, with which the male was familiarized previously for 24h, was set in the third chamber. First the tested male was habituated with the middle chamber for 5min and then allowed to explore the remaining chambers for 5min, during which the number of entries and the time of interaction were measured. CRF decreased significantly the number of entries and the time of interaction with the unknown female, but not the known female. UCN 1 decreased significantly the number of entries into the chamber of the unknown female, but not the known female, without changing the time of interaction. All decreasing effects were reversed by antalarmin, but not astressin 2B. UCN 2 and UCN 3 didn't influence significantly any of the parameters. The present study suggests that CRF and UCN 1 decrease the preference for social novelty by activating CRF₁ receptor, while UCN 2 and UCN 3, activating selectively CRF₂ receptor, do not participate to male-female interaction.

Keywords: CRF; Mice; Social novelty; Urocortins.