LOCALIZATION OF ALPHA(2A)-ADRENERGIC AND ALPHA(2B)-ADRENERGIC RECEPTOR SUBTYPES IN BRAIN

Recent studies have shown that all three subtypes of alpha(2)-adrenerg ic receptor (alpha(2)-AR) are found in brain. The purpose of this stud y 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-medull a, 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 s itu hybridization. Then we used the alpha(2A)- and alpha(2B)-AR probes for in situ hybrid ization on sagittal and coronal sections of rat br ain. Both alpha(2A) and alpha(2B) mRNA were detected throughout the br ain. Overall, there appears to be a greater expression of message for alpha(2A)- than alpha(2B)-AR in most brain areas, with the exception o f the thalamus. Developing these probes for in situ hybridization is a n important step for further studies on the exact role of the alpha(2) -AR subtypes in neurons that modulate cardiovascular function.