IZOTOTSIN (Isotocin, 4 serine, 8-isoleucine-oxytocin) — posterior pituitary hormone (neurohypophysis) of bony fishes. At mammals its analog is oxytocin (see), at birds, reptiles and amphibians — mezototsin, at cartilaginous fishes — glumitotsin. And. it was for the first time allocated in pure form and identified by R. Acher with sotr. in 1962. It concerns group of peptide hormones and is nonapeptide with the disulfide bridge
And. has same biol, activity, as well as oxytocin, but its action several times increases by a uterus in the presence of ions of magnesium. At fishes And., as well as other hormones of a neurohypophysis, the water salt metabolism regulates. Studying And. is of considerable interest to understanding of evolution of hormonal regulation of a water salt metabolism and disclosure of mechanisms biol, effects of posterior pituitary hormones.
Bibliography: Biochemistry of hormones and hormonal regulation, under the editorship of N. A. Yudayev, page 44, M., 1976; Yu. A. Struktur's Punks and property of hypophyseal hormones, Probl, endocrinins, and gormonoter., t. 20, No. 2, page 106. 1974, bibliogr.
Yu. A. Pankov.