Influence of housing variables on the development of stress-sensitive behaviors in the rat

Abstract

• Laboratory bedding material inuences developmental programming of rats.• Bedding material during early life can alter stress sensitive measures in adulthood.• Corncob bedding during sensitive periods decreases adult measures of anxiety.• Bedding material during adulthood does not affect adult anxiety-like behavior. Diverse environments early in mammalian life can have profound inuences on the physiology and behavior of developing offspring. Environmental factors can inuence offspring development directly or through perturbations in parental care. In the current study, we wished to determine if the inuence of a single environmental variable, type of bedding material used in laboratory cages, is capable of altering physiological and behavioral outcomes in offspring. Female rats were housed in cages containing wood pulp or corncob bedding and allowed to mature. These rats, while housed on assigned bedding material, were bred and allowed to give birth. At weaning, male offspring were housed on one of the two bedding conditions and tested later in adulthood on stress-sensitive behavioral measures. Postmortem analysis of glucocorticoid receptor expression and CRH mRNA levels were also measured. Maternal care directed at the pups reared in the two different bedding conditions was also recorded. Rats reared from birth on corncob bedding exhibited decreased anxiety-like behavior, as adults, in both open eld and light-dark box tasks compared to wood pulp reared animals. Animals that received similar overall levels of maternal care, regardless of bedding condition, also differed in anxiety-like behaviors as adults, indicating that the bedding condition is capable of altering phenotype independent of maternal care. Despite observed behavioral differences in adult offspring reared in different bedding conditions, no changes in glucocorticoid receptor expression at the level of the hippocampus, frontal cortex, or corticotrophin releasing hormone (CRH) mRNA expression in the hypothalamus were observed between groups. These results highlight the importance of early life housing variables in programming stress-sensitive behaviors in adult offspring. a b s t r a c t a r t i c l e i n f oPublished by Elsevier Inc.

Subtle alterations in memory systems and normal visual attention in the GAERS model of absence epilepsy

“…In the present and previous study(Marques-Carneiro et al, 2014) most parameters measured inWistars sometimes differed from NECs and sometimes from GAERS, while the consequences of early life environment should be rather consistent, and thus concordant(Weaver et al, 2006;Masís-Calvo et al, 2013;Sakhai et al, 2013). This indicates that early life environment cannot be the only cause of the differences recorded in this study.…”

“…GAERS and NECs were born and raised under the exact same environmental conditions while Wistars were provided by a commercial breeder. Therefore, despite a general respect of strict national and international guidelines, which contributes to level rearing conditions, it cannot be excluded that gestation and early postnatal environmental conditions may have differed between Wistars and the two genetic groups in a way that could partly impact on the herein reported differences (Weaver et al, 2006;Masís-Calvo et al, 2013;Sakhai et al, 2013 …”

Rapid effects of estrogens on behavior: Environmental modulation and molecular mechanisms

“…More recent observations have demonstrated that the effects of corncob use extend beyond sexual and aggressive behavior. Male rats housed on corncob bedding have reduced anxiety-like behavior and decreased slow-wave sleep compared to rats raised on wood pulp based bedding [104, 105]. In addition, corncob bedding also reduced sex differences in social withdrawal behavior following social defeat stress [106].…”

Ethological concepts enhance the translational value of animal models

“…The impact of housing in an enriched environment versus a barren cage on normal neural development is widely known (e.g. Rosenzweig and Bennett, 1996;Sakhai et al, 2013). Another clear example is the reversal of memory deficits in mice with a depletion of the n-methyl-d-aspartate receptor in the CA1 region of the hippocampus observed when these mice were housed under enriched circumstances (Rampon et al, 2000).…”