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The interaction between prolactin (PRL) and ACTH in enhancing grooming behavior after intracerebroventricular (i.c.v.) administration was investigated in intact and endogenously hyperprolactinaemic rats. In intact rats, 4 h after the i.c.v. injection of rat PRL or ACTH, a subsequent administration of ACTH or rat PRL did induce similar excessive grooming as observed after the first injections. In hyperprolactinaemic rats, which displayed excessive grooming 12 days after homografting adenopituitaries under the kidney capsule, i.c.v. injection of rat PRL failed to enhance further the grooming activity while this behavior was substantially enhanced by i.c.v. injection of ACTH1-24. Twenty-six days after surgery, when the grooming activity of hyperprolactinaemic rats was at the same level as control animals, the i.c.v. injection of rat PRL was effective in inducing excessive grooming in control but not in hyperprolactinaemic animals. In contrast, at this time the i.c.v. injection of ACTH1-24 induced again excessive grooming in both hyperprolactinaemic and control rats. Accordingly, there was no cross-tolerance between PRL and ACTH in inducing excessive grooming, but hyperprolactinaemic rats became hyposensitive to exogenous PRL. It is suggested that although PRL and ACTH may affect common neurotransmitter systems in the brain, the two hormones probably act on independent neural mechanisms in inducing excessive grooming in the rat.

BOHUS, B., Tj. B. VAN WIMERSMA GREIDANUS AND D. DE WIED. Behavioral and endocrine responses of rats with hereditary hypothalamic diabetes insipidus (Brattleboro strain). PHYSIOL. BEHAV. 14(5) [609][610][611][612][613][614][615] 1975. -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 m acquiring and maintaining active and passive avoidance behavior. Behavioral deficits were most obwous in a step-through one-trial learning passive avoidance test and least in multiple trial one way active avoidance test. Plasma eortieosterone 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 cortieosterone 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 m open field behavior, in response threshold to electric footshock, and in a number of somatic endocrine parameters are reported and discussed. Hereditary hypothalamlc diabetes msipidusVasopressln Shuttle box avoidance Pole jumping avoidance Step-through passive avoidance Plasma corticosterone response Open field Footshock responsiveness Body growth Hypophysis Adrenal Testis VASOPRESSIN or antidiuretic hormone (ADH) of posterior pituitary origin plays an important role in the organization of adaptive behavior. Removal of the posterior lobe of the pituitary gland interferes with the maintenance of a shuttle box avoidance response in the rat which can be restored by treatment with pitressin or lysine-8-vasopressin (LVP) [21]. Impaired acquisition of a similar avoidance response which occurs after hypophysectomy is ameliorated by LVP [ 6]. In the intact rat the same preparations increase resistance to extinction of both a shuttle box and pole jumping avoidance response [23,24,29] and facilitate passive avoidance behavior [2,5]. These behavioral effects of vasopressin are of a long term nature and last much longer than can be accounted for by the actual presence of the peptide in the organism [6,23,24]. The effect of vasopressin on behavior is not due to its classical endocrine activities. Desglycinamide-8-1yslne vasopressin (DG-LVP), a peptide isolated from hog pituitary material which lacks almost all antidiuretic and pressor activities [26], also stimulates avoidance acquisition in hypophysectomized rats [8], increases resistance to extinction of a pole jumping avoidance response [26], and improves passive avoidance retention in the intact rat [15]. These 609 observations together with those showing similar behavioral effects of intracerebrally and peripherally administered LVP [29] led to the hypothesis th...