Immunohistochemical localization of adenosine A(1) receptors in human brain regions

Adenosine exerts its physiological actions by binding to G-protein coupled receptors, four of which have been identified and cloned to date (A(1), A(2 a), A(2b) and A(3)). Here we report the development of anti-human adenosine A(1), receptor antipeptide polyclonal antibodies and their use to define t he distribution of A(1), receptors in human brain regions, spinal cord and trigeminal ganglia by an immunohistochemical approach. Although the distrib ution of adenosine A(1), receptor and its mRNA in the human brain has been investigated in the past by autoradiography and in situ hybridization, this is the first demonstration of localization of the A(1), receptors by immun ohistochemical means. Our localization data broadly agree with immunohistoc hemical data published for the human brain obtained using other experimenta l approaches. Furthermore, we have demonstrated the novel finding that abun dant expression of the adenosine A(1), receptor protein occurs in the trige minal ganglia, which may be suggestive of a role of this receptor in analge sia. (C) 2001 Elsevier Science ireland Ltd. All rights reserved.