The vesicular glutamate transporter 1 ( xVGlut1) is expressed in discrete regions of the developing Xenopus laevis nervous system

As the major excitatory neurotransmitter in the vertebrate nervous system, glutamate not only plays an essential role in adult neural signaling, but has also been implicated as a trophic factor in neuronal cell maturation, differentiation, and survival. An essential component of the glutamatergic neurotransmission system is the family of glutamate transporters, a multigene family that codes for plasma membrane-bound as well as vesicle-bound proteins responsible for the removal of glutamate from the cleft and its re-uptake into the synaptic vesicle. Here we describe the spatial and temporal expression of the vesicular glutamate transporter ( xVGlut1) during the early developmental stages of the amphibian Xenopus laevis. RNAse protection analysis and in situ hybridization reveal that xVGlut1 is first expressed at late neurula stages in the developing spinal cord and trigeminal nerve. By tailbud stages xVGlut1 transcripts are detected in several of the cranial nerves, the pineal gland, and medial forebrain. By hatching stages xVGlut1 expression reappears in localized tracts within the spinal cord. Expression levels increase throughout development into adulthood.