Alterations in hypoglossal motor neurons due to GAD67 and VGAT deficiency in mice

Exp Neurol. 2017 Mar;289:117-127. doi: 10.1016/j.expneurol.2016.12.004. Epub 2016 Dec 10.


There is an emerging body of evidence that glycinergic and GABAergic synaptic inputs onto motor neurons (MNs) help regulate the final number of MNs and axonal muscle innervation patterns. Using mutant glutamate decarboxylase 67 (GAD67) and vesicular inhibitory amino acid transporter (VGAT) deficient mice, we describe the effect that deficiencies of presynaptic GABAergic and/or glycinergic release have on the post-synaptic somato-dendritic structure of motor neurons, and the development of excitatory and inhibitory synaptic inputs to MNs. We use whole-cell patch clamp recording of synaptic currents in E18.5 hypoglossal MNs from brainstem slices, combined with dye-filling of these recorded cells with Neurobiotin™, high-resolution confocal imaging and 3-dimensional reconstructions. Hypoglossal MNs from GAD67- and VGAT-deficient mice display decreased inhibitory neurotransmission and increased excitatory synaptic inputs. These changes are associated with increased dendritic arbor length, increased complexity of dendritic branching, and increased density of spiny processes. Our results show that presynaptic release of inhibitory amino acid neurotransmitters are potent regulators of hypoglossal MN morphology and key regulators of synaptic inputs during this critical developmental time point.

Keywords: Brainstem; Dendrites; Motor neuron; Spines; Synaptic currents.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Animals, Newborn
  • Biotin / analogs & derivatives
  • Biotin / pharmacokinetics
  • Brain Stem / cytology*
  • Dendritic Spines / genetics
  • Electric Stimulation
  • Electroporation
  • Embryo, Mammalian
  • Female
  • Glutamate Decarboxylase / deficiency*
  • Glutamate Decarboxylase / genetics
  • In Vitro Techniques
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Motor Neurons / physiology*
  • Neuronal Plasticity / genetics
  • Patch-Clamp Techniques
  • Pregnancy
  • Synaptic Potentials / genetics
  • Vesicular Inhibitory Amino Acid Transport Proteins / deficiency*
  • Vesicular Inhibitory Amino Acid Transport Proteins / genetics
  • gamma-Aminobutyric Acid / pharmacology


  • Vesicular Inhibitory Amino Acid Transport Proteins
  • Viaat protein, mouse
  • neurobiotin
  • gamma-Aminobutyric Acid
  • Biotin
  • Glutamate Decarboxylase
  • glutamate decarboxylase 1