Human hypothalamus and intestine contain a hydra-neuropeptide

From human hypothalamus and intestine a substance was isolated which has the same physico-chemical and biological properties as the head activator from hydra. The hypothalamus of an adult man contained activity corresponding to at least 10(8) hydra. An intestine of a 3-month-old human embryo contained approx. 10(5) hydra equivalents and that of a 6-month-old embryo 10(6). A gradual increase in content of head activator during development was also found in rat intestine.