Habenular nuclei specifically bind synthetic arginine vasotocin

The antidiuretic activity of an arginine vasotocin (AVT) solution (10 microU/ml) was studied in comparison with an arginine vasopressin (AVP) solution (10 microU/ml) after their incubation for 1 h at 37 degrees C with the supernatants (S) or the pellets (P) of the habenular nuclei (HN) or frontal cortex (FC) fragments homogenized in saline solution, removed from adult or newborn rats. Both SHN and SFC from adults inactivated about 5 microU/ml AVT and 10 microU/ml AVP, PHN and not PFC inactivated only about 7 microU/ml. In newborns the phenomena were in the same direction, but the specific inactivation of AVT by the PHN was of about twice greater than in adults. The results are interpreted as suggesting that, in contrast to an unspecific inactivation from S, probably of an enzymatic nature, the PHN specifically bind AVT and that this activity is greater in newborn than in adult rats.