Pre- and post-hatching developmental changes in beta-adrenoceptor subtypesin chick brain

This study used [H-3]CGP 12177 as a radioligand to determine the beta 1 and beta 2-adrenoceptor changes from the pre-hatching E17 stage, where the bet a 2 subtype is first detected, to the post-hatching P30 stage. While beta 1 -adrenoceptors were found to be present from E18 and were limited to cerebe llum and hyperstriatum in all stages studied, beta 2-adrenoceptors showed a wider distribution throughout the brain. In most of the structures analyse d both beta 1- and beta 2-adrenoceptor binding values reached a maximum in the P2 stage, followed by a decrease over the following days. A second incr ease in both subtypes was detected again in the P15 and P30 stages. These r esults support the notion of a specific role for beta-adrenoceptors in neur al plasticity in the first week after hatching and suggest that the P2 subt ype is the main adrenoceptor in chick brain throughout its development. (C) 1998 Elsevier Science B.V. All rights reserved.