Antidiuretic Hormone Bio-assay in Rats with Hereditary Hypothalamic Diabetes Insipidus (Brattleboro Strain)

Rats homozygous for hereditary hypothalamic diabetes insipidus (DI) were used in a hydrated-rat bio-assay for antidiuretic hormone (ADH). DI rats were more sensitive than normal rats to the USP posterior pituitary reference standard by a factor of about 2. In the measurement of ADH activity in plasma samples from undisturbed rats, the use of DI rats as assay animals allowed detection of lower levels of circulating ADH activity than was possible using normal assay animals. Pretreatment of DI rats with subcutaneous vasopressin for a period of time necessary to obtain maximum urine concentration did not alter their sensitivity to intravenous injections of the reference standard. (Endocrinology 80: 211, 1967).