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Impact of Mineralocorticoid, Glucocorticoid and Thyroid Hormones on Respiratory Control Development in Lithobates Catesbeianus
Author(s) -
Rousseau JeanPhilippe,
Dédé Djigo Aicha,
Kinkead Richard
Publication year - 2015
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.29.1_supplement.1033.3
Subject(s) - hormone , aldosterone , biology , medicine , endocrinology , corticosterone , respiratory system , brainstem , lithobates , mineralocorticoid , glucocorticoid , metamorphosis , anatomy , ecology , bullfrog , larva
The emergence of air breathing during Lithobates catesbeianus development requires significant changes to the brainstem circuits that generate and regulate breathing; however, the mechanisms responsible for this transformation remain largely unknown. Because this metamorphosis is regulated by hormones such as corticosterone, aldosterone, and thyroid hormone (T3), we tested the hypothesis that exposing the brainstem to these hormones augments the fictive air breathing frequency in Lithobates tadpoles. Brainstems were isolated from pre‐metamorphic tadpoles (TK V to X) and placed in a bottle containing artificial cerebrospinal fluid and one of the following hormones: aldosterone (100nM), corticosterone (100nM), T3 (100 nM) or a combination of two of the preceding components for 24 hours. The effect of hormone exposure on respiratory activity was quantified by extracellular recording of rhythmic motor output from cranial nerves V and X. By comparison with preparations subjected to sham treatment, hormone exposure generally increased fictive air breathing frequency; the highest lung burst frequency was observed in brainstems exposed to the aldosterone‐T3 combination. To assess the treatment effects on the overall system functionality, sham and hormone treated tadpoles were kept in a recording chamber for 24h after which we recorded their ventilator activity by measuring changes in buccal pressure. Interestingly, the results showed the same trend as the one observed with the brainstem preparation. We conclude that hormones play an important role in the maturation of the neural circuits that generate and regulate breathing in this species.