To determinewhether in Apoe−/− mice increased signaling of thesereceptors contributed to the increased measures of anxiety,3–5-month-old wild-type and Apoe−/− mice wereassessed in the elevated plus maze 1 hour afterintraperitoneal administration of the H1 antagonistmepyramine (5.6 mg/kg), the H2 antagonist zolantidine(10 mg/kg), or saline. This evidence concerns the gene APOE and Anxiety.