Topographical and Physiological Characterization of Interneurons That Express Engrailed-1 in the Embryonic Chick Spinal Cord

• DOI: 10.1152/jn.2000.84.5.2651
• Publication Date: 2017-12-21T13:51:23Z
• Authors: Peter Wenner; Michael J. O'Donovan; Michael P. Matise
• Keywords: Interneuron; engrailed; Ganglionic eminence

A number of homeodomain transcription factors have been implicated in controlling the differentiation various types neurons including spinal motoneurons. Some these proteins are also expressed interneurons, but their function is unknown. Progress understanding role interneuronal development has slow because synaptic connections which part define identity, difficult to establish. Using whole cell recording isolated cord chick embryos, we assessed lumbosacral interneurons expressing Engrailed-1 (En1) factor. Specifically established whether En1-expressing made direct with motoneurons and they constitute a single interneuron class. Cells were labeled biocytin subsequently processed for En1 immunoreactivity. Our findings indicate that cells sensory afferents diverse, suggesting population was heterogeneous. In addition, tested similar protein many did not. The majority sampled did, however, exhibit connection likely be GABAergic. Because our physiological methods underestimate motoneurons, it possible great majority, perhaps all, make results raise possibility could involved interneuron-motoneuron connectivity its expression not restricted distinct functional subclass ventral interneuron. These constrain hypotheses about En-1 function.