Inhibition of flank-marking behavior in golden hamsters by microinjection of a vasopressin antagonist into the hypothalamus.

Microinjection of arginine-vasopressin (AVP) into the medial preoptic area of the hypothalamus of the hamster stimulates flank marking, a complex stereotypic motor behavior involved in olfactory communication. Microinjection of an antagonist of AVP, [1-deaminopenicillamine-2-(O-methyl)-tyrosine]arginine-vasopressin, into the same site blocks both the effect of microinjected AVP as well as the natural flank-marking behavior normally elicited by placing a hamster into the recently vacated home cage of another hamster. This finding supports the notion that AVP is a transmitter in the expression of flank marking.