RationaleHuman epidemiology and animal studies have convincingly shown the long-lasting impact of early life experiences on the development of individual differences in stress responsiveness in later life. The interplay between genes and environment underlies this phenomenon.ObjectivesWe provide an overview of studies investigating the impact of early life experiences on the development of individual differences in neuroendocrine stress responsiveness in adulthood and address (1) impact of environment on later stress phenotypes, (2) role of genetic factors in modulating the outcome of environment, and (3) role of nonshared environmental experience in the outcome of gene × environment interplays. We present original findings where we investigated the influence of nonshared experiences in terms of individual differences in maternal care received, on the development of stress phenotype in later life in rats.ResultsEnvironmental influences in early life exert powerful effects on later stress phenotypes, but they do not always lead to expression of diseases. Heterogeneity in response is explained by the role of particular genetic factors in modulating the influence of environment. Nonshared experiences are important in the outcome of gene × environment interplays in humans. We show that nonshared experiences acquired through within-litter variation in maternal care in rats predict the stress phenotype of the offspring.ConclusionThe outcome of early experience is not deterministic and depends on several environmental and genetic factors interacting in an intricate manner to support stress adaptation. The degree of “match” and “mismatch” between early and later life environments predicts resilience and vulnerability to stress-related diseases, respectively.Electronic supplementary materialThe online version of this article (doi:10.1007/s00213-010-2118-y) contains supplementary material, which is available to authorized users.

No abstract

No abstract

No abstract

Olfactory bulbectomy (OBX) in rats causes several behavioral and neurochemical CNS changes, reminiscent of symptoms of human depression. Such depression-like behavior after OBX can be reversed with antidepressants. Recently, a connection between the vasopressin 1b (V1b) receptor and the development of depression has been suggested; therefore, a vasopressin V1b receptor antagonist (SSR149415) was investigated in the OBX model. Male rats received olfactory bulbectomy or sham surgery. After recovery, animals received 14 consecutive daily doses of SSR149415 (10 or 30 mg/kg), imipramine (20 mg/kg), or vehicle (5% hydroxy-propyl methylcellulose). Animals were tested in an open field after acute treatment, on days 7 and 14 of treatment and 1 week after cessation of treatment. Similar to imipramine, repeated, but not acute, administration of SSR149415 completely reversed OBX-induced hyperactivity, leaving activity in shams unaffected. This reversal of OBX-induced hyperactivity in the SSR149415 treated rats was still present 7 days after cessation of treatment. Although the behavioral effects of treatment with SSR149415 were specific for the OBX animals, adrenal gland weights were reduced in both sham and OBX animals treated with 30 mg/kg SSR149415. Chronic but not acute administration of SSR149415 normalizes OBX-induced hyperactivity up to 1 week after cessation of treatment, suggesting that a V1b receptor antagonist may have long-lasting antidepressant activity.