Receptor for arginine vasopressin. The activity of this receptor is mediated by G proteins which activate a phosphatidyl-inositol-calcium second messenger system. Has been involved in social behaviors, including affiliation and attachment. Differences in regional receptor expression in the brain as well as differences in social behavior may result from a highly variable repetitive sequence in the 5' flanking region of AVPR1A. One such allelic variant has been linked to autism. Belongs to the G-protein coupled receptor 1 family. Vasopressin/oxytocin receptor subfamily.