HRH3 and Hypertension: Notably, the histamine‐induced decrease in MAP has been observed to be reversed by intracerebroventricular injection of thioperamide,[12] which was reported first to be a selective antagonist for H3R and identified later as an antihistamine at H3R and H4R with similar potential.[29] We thus propose a possible role of central H4R in blood pressure control, which may provide a highly specialized central target for hypertension.