Vasotocin

Vasotocin is an oligopeptide hybrid of oxytocin and vasopressin found in all non-mammalian vertebrates including birds, fish, amphibians and in fetal mammals. In mammals it appears to have similar biological properties to both oxytocin (stimulating reproductive tract contraction as in egg laying or birth) and vasopressin (diuretic and antidiuretic effects). It has been found to have effects on the regulation of REM sleep. It's functions in non-mammals are unknown.