Kentsin

Kentsin, a contraceptive tetrapeptide, is originally extracted from hamster embryos. Kentsin prevents the maturation of Graafian follicles and consequently inhibits ovulation. Kentsin has opiate properties on gastrointestinal motility^[1][3][5]. In Vitro:Kentsin (100 μg/mL, 18 h) increases endogenous xenotropic virus expression in K-Balb 19a/h cells transformed with Kirsten sarcoma virus^[2].
Kentsin (30 μM) does not inhibit electrically stimulated contractions of the guinea pig ileum (GPI) or mouse vas deferens (MVD)^[1].
In Vivo:Kentsin (0-100 μg, i.c.v. or intrathecal administration) produces analgesia in both the hotplate and abdominal stretch tests^[1].
Kentsin (20 and 100 ng/kg, i.c.v.) inhibits the antral motility index and disrupts the jejunal migrating motor complex in fasted dogs^[3].
Kentsin (4.0 μg/kg, i.c.v. 2 hours after the beginning of a meal) restores the “fasted” (the migrating myoelectric complex of intestinal motility), and can be blocked by previous Naloxone (400 μg/kg, i.c.v.)^[4].