Neuroscientists have discovered a population of cells in the smell-perception area of the rat brain that express the hormone vasopressin. Blocking vasopressin in this region, called the olfactory bulb, impairs the animals' ability to recognize other rats by smell, the study found.Vasopressin plays vital roles in many body tissues, such as regulating water absorption in the kidneys and salt content in the blood.But in the past few years, the hormone has attracted attention for its role in complex social behaviors. For instance, some studies have found that individuals with autism, who have impaired personal relationships, have increased levels of vasopressin in blood plasma compared with healthy controls.The new rat work, published 18 March in Nature, adds to several rodent studies showing that vasopressin and its sister brain chemical, oxytocin, control a range of social and reproductive behaviors, from wooing a mate to caring for pups. After years of striking discoveries in animals, geneticists and neuroscientists are beginning to take a closer look at how the hormones affect human social behavior, according to a review published 25 March in Neuron.Read more at...SFARI, May 2010.