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This Article Full Text Full Text (PDF) All Versions of this Article: 286/6/H2133    most recent 00869.2003v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (6) Citing Articles via Google Scholar Google Scholar Articles by Costoli, T. Articles by Sgoifo, A. Search for Related Content PubMed PubMed Citation Articles by Costoli, T. Articles by Sgoifo, A.

Effects of chronic psychosocial stress on cardiac autonomic responsiveness and myocardial structure in mice

¹Dipartimento di Biologia Evolutiva e Funzionale, Università di Parma, 43100 Parma; ²Istituto di Psicologia, Università di Milano, 20134 Milan; ³Dipartimento di Patologia e Medicina di Laboratorio, Università di Parma, 43100 Parma; and ⁴Dipartimento di Biologia Cellulaire e Neuroscienze, Istituto Superiore di Sanità, 00161 Rome, Italy

Submitted 10 September 2003 ; accepted in final form 9 February 2004

Repeated single exposures to social stressors induce robust shifts of cardiac sympathovagal balance toward sympathetic dominance both during and after each agonistic interaction. However, little evidence is available regarding possible persistent pathophysiological changes due to chronic social challenge. In this study, male CD-1 mice (n = 14) were implanted with a radiotelemetry system for electrocardiographic recordings. We assessed the effects of chronic psychosocial stress (15-day sensory contact with a dominant animal and daily 5-min defeat episodes) on 1) sympathovagal responsiveness to each defeat episode, as measured via time-domain indexes of heart rate variability (R-R interval, standard deviation of R-R interval, and root mean square of successive R-R interval differences), 2) circadian rhythmicity of heart rate across the chronic challenge (night phase, day phase, and rhythm amplitude values), and 3) amount of myocardial structural damage (volume fraction, density, and extension of fibrosis). This study indicated that there was habituation of acute cardiac autonomic responsiveness, i.e., the shift of sympathovagal balance toward sympathetic dominance was significantly reduced across repeated defeat episodes. Moreover, animals exhibited significant changes in heart rate rhythmicity, i.e., increments in day and night values and reductions in the rhythm amplitude, but these were limited to the first 5 days of chronic psychosocial stress. The volume fraction of fibrosis was sixfold larger than in control animals, because of the appearance of many microscopic scarrings. In summary, although mice appeared to adapt to chronic psychosocial stress in terms of acute cardiovascular responsiveness and heart rate rhythmicity, structural alterations occurred at the myocardial level.

social stress; sympathovagal balance; heart rate variability; cardiac fibrosis; circadian rhythms

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