Neurohypophysial Principles in Rats Homozygous and Heterozygous for Hypothalamic Diabetes Insipidus (Brattleboro Strain)

Abstract

Extracts of pituitary glands and hypothalami from rats with hereditary hypothalamic diabetes insipidus (DI), from rats heterozygous for the DI trait, and from normal rats have been assayed for neurohypophysial principles. Eleven of 12 rats with DI appeared to have no vasopressin in their pituitaries and little or none in their hypothalami. Their pituitary content of oxytocin was about 1/3 of normal. In heterozygotes, vasopressin content was reduced: to about 2/3 of normal in pituitaries and to 1/7 of normal in hypothalami. Pituitary content of oxytocin was normal in heterozygotes. The data strongly suggest that DI rats have an absolute, and heterozygotes a partial, genetic defect for synthesizing vasopressin. Oxytocin synthesis appears to be unimpaired in both DI and heterozygous rats.