Immunohistochemical localization of adenosine A 1 receptors in human brain regions

Abstract

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 2a, A 2b and A 3). Here we report the development of anti-human adenosine A 1, receptor anti-peptide polyclonal antibodies and their use to define the distribution of A 1, receptors in human brain regions, spinal cord and trigeminal ganglia by an immunohistochemical approach. Although the distribution 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 immunohistochemical means. Our localization data broadly agree with immunohistochemical data published for the human brain obtained using other experimental approaches. Furthermore, we have demonstrated the novel finding that abundant expression of the adenosine A 1, receptor protein occurs in the trigeminal ganglia, which may be suggestive of a role of this receptor in analgesia.