Expression of functional tyrosine kinase B receptors by rhythmically active respiratory neurons in the pre-Botzinger complex of neonatal mice.

Muriel Thoby-Brisson (1, 2) , Bruno Cauli (3) , Jean Champagnat (1, 2) , Gilles Fortin (1, 2) , David M. Katz (4)

1 NGI - Neurobiologie génétique et intégrative
2 INAF - Institut de Neurobiologie Alfred Fessard
3 NDC - Neurobiologie et diversité cellulaire
4 Case Western Reserve, Department of Neurosciences

Genetic loss of brain-derived neurotrophic factor (BDNF) severely disrupts brainstem control of respiratory rhythmogenesis in newborn mice; however, the sites at which BDNF acts to regulate respiratory rhythmogenesis are unknown. Using immunochemical and multiplex RT-PCR analysis in mouse brainstem slices, we report that the BDNF receptor, Tyrosine kinase B (TrkB), is strongly expressed in the pre-Botzinger complex (PBC), the presumed site for rhythm generation, and colocalizes with neurokinin 1 (NK1), a marker of neurons critical for breathing. The period of the respiratory rhythm generated by PBC neurons in vitro was increased by 30% after BDNF treatment (100 ng/ml) and not by nerve growth factor (100 ng/ml) or BDNF (100 ng/ml) in the presence of the tyrosine kinase inhibitor K252a (200 nm). Both synaptic and voltage-dependent properties of PBC neurons were modified by BDNF. Synaptic currents underlying spontaneous rhythmic bursts and glutamate-evoked currents were enhanced by 66 and 33%, respectively. BDNF reduced the Ih current amplitude in rhythmic neurons by 46% and shifted its activation curve by -17 mV. All neurons expressing TrkB mRNA (n = 8) also expressed mRNAs for the Ih current [hyperpolarization-activated cyclic nucleotide-sensitive cation nonselective channel (HCN1)], and three of four NK1-positive neurons coexpressed TrkB and HCN mRNA. Six of 16 PBC neurons expressed BDNF mRNA, supporting the possibility of autocrine and paracrine actions of BDNF within the respiratory pattern generator. Our data demonstrate that BDNF can modulate respiratory network activity through TrkB signaling in rhythmic PBC neurons.

Mots clés: Animals Newborn; Brain-Derived Neurotrophic Factor; genetics metabolism; Cells Cultured; Electric Conductivity; Excitatory Postsynaptic Potentials; Immunohistochemistry; Medulla Oblongata; anatomy & histology physiology; Mice; Neurons drug effects; Patch-Clamp Techniques; Periodicity; RNA Messenger biosynthesis; Receptor trkB analysis; Respiratory Center; Transcription Genetic; Respiration; Rhythmic neurons; BDNF; Pre-Bötzinger complex; RT-PCR

Domaines: Neurosciences [q-bio.NC]

Muriel Thoby-Brisson, Bruno Cauli, Jean Champagnat, Gilles Fortin, David M. Katz. Expression of functional tyrosine kinase B receptors by rhythmically active respiratory neurons in the pre-Botzinger complex of neonatal mice.. Journal of Neuroscience, 2003, 23 (20), pp.7685-7689. ⟨hal-00083958⟩