Vasotocin is a hormone found in various species of vertebrates. It is a nonapeptide, which means it is composed of nine amino acids. In different species, vasotocin has various synonyms that scientists use, including arginine vasotocin, lysine vasotocin, and isoaspartyl vasotocin. In birds and reptiles, it is called mesotocin, while in mammals, it is known as oxytocin. Vasotocin, or its synonyms, is involved in a wide range of physiological functions, including social behaviors, stress responses, water balance regulation, and reproductive activities. Understanding the different names for vasotocin is essential for any scientific research related to the hormone and its functions.