Fig. 3

Glutamate released upon depolarization is reduced in Gpt2-null synaptosomes. A Schematic of the synaptosomes and evoking glutamate release from synaptic vesicles with 50 mM KCl. A representative trace of relative fluorescence intensity across time is shown (collected at excitation and emission wavelengths of 340 and 460 nm, respectively). Viability of synaptosomes was confirmed by adding 50 mM KCl to synaptosomes and comparing baseline (black) and evoked (red) glutamate levels in wild-type synaptosomes obtained at postnatal day 18 (P18). B Overall glutamate levels in the cytosolic fraction are reduced in Gpt2-null mice. Cytosol fraction of the forebrain was obtained by separating the supernatant from the crude synaptosomal pellet. Glutamate was detected by enzymatic method and expressed as µmol per mg of protein. Each dot represents a different synaptosome sample obtained from wild-type (black) or Gpt2-null (red) mice at P18. *P = 0.02. C Overall glutamate levels are reduced in Gpt2-null synaptosomes. Each dot represents a different synaptosome sample obtained from wild-type (black) or Gpt2-null (red) mice at P18. *P = 0.037. D Glutamate levels released upon depolarization are reduced in Gpt2-null synaptosomes. Each dot represents a different synaptosome sample obtained from wild-type (black) or Gpt2-null (red) mice at P18. *P = 0.01. E Released GABA levels were unchanged in Gpt2-null synaptosomes. Each dot represents a different synaptosome sample obtained from wild-type (black) or Gpt2-null (red) mice at P18. P = 0.44