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Assessing the Chemosensitivity of a Potential Bullfrog Homologue to the Mammalian Retrotrapezoid Nucleus
Author(s) -
Reed Mitchell,
Iceman Kimberly,
Harris Michael,
Taylor Barbara
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.860.9
Subject(s) - locus coeruleus , biology , brainstem , neuroscience , bicuculline , microbiology and biotechnology , nucleus , genetics , receptor , gabaa receptor
Vertebrate breathing is controlled by a highly conserved brainstem neural network, with breathing driven by elevated CO 2 in body tissues/fluids. Many brainstem sites, such as the raphe', locus coeruleus, and the retrotrapezoid nucleus (RTN) contribute to this process, and their relative contributions vary according to CO 2 /pH level, arousal state, and development. The RTN is crucial for chemosensitivity in developing mammals. We used immunohistochemical markers identifying the mammalian RTN (presence of Phox2b transcription factor and vesicular glutamate transporter 2 (VGlut2), and absence of tyrosine hydroxylase (TH)) to demonstrate a homologous site present in larval bullfrogs. We tested the hypothesis that this region is chemosensitive by exposing brainstems from tadpoles of different developmental stages to normal and elevated CO 2 levels (1.5% and 5% CO 2 , normocapnia and hypercapnia respectively) both with and without fast synaptic blockade (CNQX, CPP, Strychnine, and Bicuculline). We then stained tissues for cFos, an indicator of neural activity, and markers identifying the mammalian RTN (Phox2b, VGlut2, and TH). Results suggest this region is sensitive to changes in CO 2 and potentially homologous to the mammalian RTN. These findings may provide insight into the evolution of chemosensory development and function.