Selective Brain Distribution and Distinctive Synaptic Architecture of Dual Glutamatergic-GABAergic Neurons

Cell Rep. 2018 Jun 19;23(12):3465-3479. doi: 10.1016/j.celrep.2018.05.063.


For decades, it has been thought that glutamate and GABA are released by distinct neurons. However, some mouse neurons innervating the lateral habenula (LHb) co-release glutamate and GABA. Here, we mapped the distribution of neurons throughout the rat brain that co-express vesicular transporters for the accumulation of glutamate (VGluT2) or GABA (VGaT) and for GABA synthesis (GAD). We found concentrated groups of neurons that co-express VGluT2, VGaT, and GAD mRNAs within subdivisions of the ventral tegmental area (VTA), entopeduncular (EPN), and supramammillary (SUM) nuclei. Single axon terminals established by VTA, EPN, or SUM neurons form a common synaptic architecture involving asymmetric (putative excitatory) and symmetric (putative inhibitory) synapses. Within the LHb, which receives co-transmitted glutamate and GABA from VTA and EPN, VGluT2 and VGaT are distributed on separate synaptic vesicles. We conclude that single axon terminals from VGluT2 and VGaT co-expressing neurons co-transmit glutamate and GABA from distinct synaptic vesicles at independent synapses.

Keywords: GABA; GABA-glutamate co-release; co-transmission; entopeduncular nucleus; glutamate; hippocampus; lateral habenula; supramammillary nucleus; ventral tegmental area.

Publication types

  • Research Support, N.I.H., Intramural

MeSH terms

  • Animals
  • Axons / metabolism
  • Axons / ultrastructure
  • Brain / metabolism*
  • Entopeduncular Nucleus / metabolism
  • GABAergic Neurons / metabolism*
  • Glutamate Decarboxylase / metabolism
  • Glutamates / metabolism*
  • Male
  • Models, Biological
  • Rats, Sprague-Dawley
  • Synapses / metabolism*
  • Synapses / ultrastructure
  • Synaptic Vesicles / metabolism
  • Synaptic Vesicles / ultrastructure
  • Tissue Distribution
  • Ventral Tegmental Area / metabolism
  • Vesicular Glutamate Transport Protein 2 / metabolism
  • Vesicular Inhibitory Amino Acid Transport Proteins / metabolism
  • gamma-Aminobutyric Acid / metabolism


  • Glutamates
  • Vesicular Glutamate Transport Protein 2
  • Vesicular Inhibitory Amino Acid Transport Proteins
  • gamma-Aminobutyric Acid
  • Glutamate Decarboxylase