The effects of preweaning handling and postweaning housing on behavior and resistance to deprivation induced stress in the rat

Abstract

Two experimental variables were combined in a factorial design to study their effects on measures of emotionality and stress. These were infantile handling versus no handling of rats, and rearing of the animals in either a standard laboratory cage or a small mouse cage between weaning and 53 days of age ( N = 12 Holtzman rats per group, with equal numbers of males and females). On Days 42-45, the animals were given daily tests in the open field. On Days 45-53, they were put on a 47 hr food and water deprivation schedule. All animals were sacrificed on Day 53 and autopsied for ulceration. Analysis of the dependent measures revealed that rats handled prior to weaning were more active than nonhandled controls in the open field apparatus; animals housed in standard laboratory cages after weaning were more active than rats housed in small cages; and females were more active than males. Weight retention data indicated that the preweaning experience, postweaning housing condition, and sex of the animal influenced the pattern of weight loss over 8 days of deprivation. The ulceration analysis revealed that preweaning handling alone was effective in reducing starvation induced ulcerogenesis.Rats handled prior to weaning can be differentiated in adulthood on various behavioral and physiological indices (Bovard, 1958, Denenberg, 1964. The effect of this experimental manipulation is to produce organisms which are less reactive in

Preweaning enrichment has no lasting effects on adult hippocampal neurogenesis in four‐month‐old mice

“…1966; Denenberg et al . 1967; Schapiro & Vukovich 1970; Schaefer & Darbes 1972; Labarba et al . 1974; Fernandez‐Teruel et al .…”

“…The major issue here is the question of the nature and dosage of this interference. Accordingly, experimental paradigms, results and conclusions differ considerably in the literature (Denenberg et al 1966;Denenberg et al 1967;Schapiro & Vukovich 1970;Schaefer & Darbes 1972;Labarba et al 1974;Fernandez-Teruel et al 1997). Nevertheless, some general statements can be made.…”

“…To test for functional effects of the enrichment paradigm in our study, we examined locomotor activity and exploratory behavior in an automated open field assay (Schaefer & Darbes 1972). Adult hippocampal neurogenesis was examined by labeling proliferating neural progenitor cells in the subgranular zone of the hippocampal dentate gyrus with the proliferation marker bromodeoxyuridine (BrdU), as well as subsequent immunohistochemical detection of BrdU together with markers for neuronal and glial phenotypes.…”