Reduced Walker 256 carcinosarcoma growth in vasopressin-deficient Brattleboro rats.

The growth pattern of carcinosarcoma Walker 256 was studied in rats with different levels of vasopressin in the blood. The Brattleboro rats are unable to synthesize vasopressin in a consequence of deletion in the coding gene. Hybrids from crossbreeding of the mutant Brattleboro and normal WAG rats inherit the one intact vasopressin gene and hold nearly normal hormone level. It was found that non-strain-specific carcinosarcoma Walker 256 intensively grows in WAG rats and their offsprings from crossbreeding with Brattleboro rats, and tumor development is equally terminated in them by death. Carcinosarcoma grows less intensely in Brattleboro rats; the tumor nodes increased only within the first 2 weeks, after which, the tumor began to decrease and eventually disappeared. Infusion of exogenous vasopressin to Brattleboro rats intensifies a tumor growth in the first 2 weeks after the inoculation of Walker 256 cells; however, it does not prevent a following regression and resorption of tumors.