Localization of alpha(2A)- and alpha(2B)-adrenergic receptor subtypes in brain

Recent studies have shown that all three subtypes of alpha(2)-adrenergic receptor (alpha(2)-AR) are found in brain. The purpose of this study was to map the subtype localization of the alpha(2A)- and alpha(2B)-ARS in brain structures. RNase protection shows that both the alpha(2A)- and alpha(2B)-ARs are detectable in cortex, cerebellum, pons-medulla, and hypothalamus. We tested probes derived from the alpha(2A)- and alpha(2B)-AR cDNAs on cell lines that express each of the alpha(2)-AR subtypes to establish the subtype specificity of these probes for in situ hybridization. Then we used the alpha(2A)- and alpha(2B)-AR probes for in situ hybrid ization on sagittal and coronal sections of rat brain. Both alpha(2A) and alpha(2B) mRNA were detected throughout the brain. Overall, there appears to be a greater expression of message for alpha(2A)- than alpha(2B)-AR in most brain areas, with the exception of the thalamus. Developing these probes for in situ hybridization is an important step for further studies on the exact role of the alpha(2)-AR subtypes in neurons that modulate cardiovascular function.