4.ストレスと学習: 母体ストレスの仔に対する可塑的変化

概要

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To more precisely understand the predisposition factors for depressive illness and post-traumatic stress disorder, it is necessary to make an animal model revealing the dysregulation of Hypothalamo-Pituitary-Adrenal (HPA) axis, which is frequently seen in depressive illness and stress-related disorder. In the present study, we have investigated the effects of prenatal stress on the adrenocortical response and behavioral alterations to stressful stimuli in adult offspring, since the decreased or the enhanced suppression of HPA response are frequently observed in depressive illness and post-traumatic stress disorder, respectively. Our results are summarized as follows :<BR>1. Prenatal saline injection stress produced the disinhibition of HPA response to conditioned fear stress in adult male offspring. In addition, the prolonged immobility duration in the forced swimming stress was observed in the prenatally stressed groups compared with controls. Taken together, the prenatal saline injection stress model may have a face validity as an animal model of depression.<BR>2. In contrast, prenatal saline injection stress produced the enhanced suppression of HPA response to conditioned fear stress in adult female offspring, suggesting that the prenatal saline injection stress model modified by some sex steroids may provide a good tool to investigate the pathophysiology of post-traumatic stress disorder.