Increased vasopressin secretion and release in mice transgenic for the rat arginine vasopressin gene

The rat arginine vasopressin (AVP) genomic sequence has been utilized to develop a line of transgenic mice homozygous and heterozygous for the transgene. Expression of the rat AVP gene was demonstrated by Southern blotting and resulted in increased amounts of AVP in hypothalamus and frontotempo- ral brain cortex. Secretion of AVP from the neurohypophysial system results in an increased concentration of the hormone in the plasma and in an increased excretion in the urine in amounts three to five times those of normal mice. Extraneural ectopic hormone production was found only in the pancreas. Despite chronic hypersecretion of AVP, 24-hour urine volume and osmolality did not show evidence of increased antidiuretic hormone action on the kidney, so that, under basal conditions, the water balance in the animals is unaffected.