Does the rat with hereditary hypothalamic diabetes insipidus have impaired avoidance learning and/or performance?

Avoidance learning and extinction of rats with hereditary hypothalamic diabetes insipidus (Brattleboro strain) were studied in 2 experiments that differed only in shock intensity. In both experiments rats homozygous for diabetes insipidus were more deficient in both escape and avoidance responding than were their heterozygous or normal controls. Although the hterozygous animals showed improved escape performance at the higher shock intensity, their avoidance behavior was not improved. The superiority of normal and heterozygous animals in extinction performance, relative to the homozygous animals, was eliminated or reversed when the differences in terminal acquisition performance were taken into account by analyses of covariance. Deficiency of ADH, therefore, may not result in faster extinction of avoidance behavior.