Cholinergic link in the histamine-mediated increase in homovanillic acid in the rat striatum.

Administration of 500 microng of histamine into the lateral brain ventricle of the rat produced a 50% increase in striatal HVA. The DA level remained unchanged. The histamine-mediated elevation of HVA was abolished by pre-treatment with the antihistaminic drug - mepyramine. Moreover atropine significantly reduced the histamine-induced increase of HVA. It is concluded that histamine primarily activates cholinergic neurons and that the changes in DA metabolism are a consequence of an increased cholinergic activity.