Minireview: histamine receptors in brain.

The recent availability of selective pharmacological tools has allowed several classes of histamine receptors to be characterized in brain by assessment of biochemical, neurophysiological and behavioral responses as well as by radioligand binding studies. H₁-receptors might be coupled to translocation of calcium ions and H₂-receptors to an adenylate cyclase. Histamine receptors, distinct from the H₁- and H₂-receptors, might also be present as suggested by electrophysiological and binding studies. The possible involvement of cerebral histamine receptors in the sedative activity of H₁-antihistamines, in the hypotensive activity of clonidine and in the antidepressant activity of tricyclic compounds is discussed.