Conditional rhythmicity of ventral spinal interneurons defined by expression of the Hb9 homeodomain protein.
The properties of mammalian spinal interneurons that underlie rhythmic locomotor networks remain poorly described. Using postnatal transgenic mice in which expression of green fluorescent protein is driven by the promoter for the homeodomain transcription factor Hb9, as well as Hb9-lacZ knock-in mice, we describe a novel population of glutamatergic interneurons located adjacent to the ventral commissure from cervical to midlumbar spinal cord levels. Hb9+ interneurons exhibit strong postinhibitory rebound and demonstrate pronounced membrane potential oscillations in response to chemical stimuli that induce locomotor activity. These data provide a molecular and physiological delineation of a small population of ventral spinal interneurons that exhibit homogeneous electrophysiological features, the properties of which suggest that they are candidate locomotor rhythm-generating interneurons.
Wilson
Jennifer M
JM
Department of Anatomy and Neurobiology, Dalhousie University, Halifax, Nova Scotia, B3H 1X5, Canada.
Hartley
Robert
R
Maxwell
David J
DJ
Todd
Andrew J
AJ
Lieberam
Ivo
I
Kaltschmidt
Julia A
JA
Yoshida
Yutaka
Y
Jessell
Thomas M
TM
Brownstone
Robert M
RM
D000818:Animals; D002417:Cattle; D004594:Electrophysiology; D005786:Gene Expression Regulation; D049452:Green Fluorescent Proteins / Q000235:genetics; D013006:Growth Hormone / Q000235:genetics; D018398:Homeodomain Proteins / Q000235:genetics*; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D007395:Interneurons / Q000502:physiology*; D051379:Mice; D008822:Mice, Transgenic; D011401:Promoter Regions, Genetic; D012326:RNA Splicing; D011995:Recombination, Genetic; D013116:Spinal Cord / Q000502:physiology*; D014157:Transcription Factors / Q000235:genetics*; D001616:beta-Galactosidase / Q000235:genetics
D018398:Homeodomain Proteins; D014157:Transcription Factors; C084059:Hb9 protein, mouse; D049452:Green Fluorescent Proteins; D013006:Growth Hormone; D001616:beta-Galactosidase