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Chronic elevation of corticosterone increases the ventilatory response to hypoxia in adult rats
Author(s) -
Fournier Sébastien,
Allard Mathieu,
Gulemetova Roumiana,
Kinkead Richard
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.4.a374-b
Subject(s) - corticosterone , medicine , endocrinology , hypoxia (environmental) , glucocorticoid , hypoxic ventilatory response , respiratory system , hormone , chemistry , oxygen , organic chemistry
Early life exposure to a stressor such as neonatal maternal separation (NMS) disrupts the normal functioning of the hypothalamo‐pituitary‐adrenal axis and results in chronic elevation of plasma corticosterone level in the adult rat. NMS alone has several functional outcomes including an increase in the hypoxic chemoreflex through mechanisms that remain unknown (Genest et al., 2004). In the present study, we hypothesized that chronic increase of plasma corticosterone alone can amplify the ventilatory response to hypoxia in adult rats. To test this, three groups of Sprague Dawley® male rats were used (i.e. control, sham, corticosterone implants). Rats subjected to chronic plasma corticosterone elevation received subcutaneously 300 mg of corticosterone implant 14 days prior to ventilatory measurements, whereas sham‐operated rats received placebo implants instead. Blood samples taken shortly after the experiments confirmed the efficiency of our protocol. Each group underwent a single session of plethysmographic measurement of respiratory activity under normoxic followed by hypoxic conditions (12%O 2 , 20 min). Rats implanted with corticosterone showed a ventilatory response to hypoxia significantly higher than sham and control rats. These data show that a chronic elevation of corticosterone increases the ventilatory response to hypoxia and suggest that chronic corticosterone elevation alone can contribute to the respiratory phenotype observed in NMS rats. Supported by the Canadian Institutes of Health Research.