Behavioral and endocrine responses of rats with hereditary hypothalamic diabetes insipidus (Brattleboro strain)

Abstract

Behavioral and endocrine profiles were established of homozygous (HO-DI) and heterozygous (HE-DI) rats with hereditary hypothalamic diabetes insipidus in comparison to Wistar strain rats. HO-DI rats were inferior in acquiring and maintaining active and passive avoidance behavior. Behavioral deficits were most obvious in a step-through one-trial learning passive avoidance test and least in multiple trial one way active avoidance test. Plasma corticosterone levels determined after the retention test appeared to be closely related to the passive avoidance behavior of the HO-DI rats. Passive avoidance immediately after the single learning trial was associated with elevated plasma corticosterone level; absence of avoidance and absence in plasma corticosterone elevation was observed 24 hr after learning. These observations are compatible with the hypothesis that vasopressin is involved in the consolidation and/or retrieval of learned responses. Differences between HO-DI and Wistar rats in open field behavior, in response threshold to electric footshock, and in a number of somatic endocrine parameters are reported and discussed.