Homeostatic Scaling of Vesicular Glutamate and GABA Transporter Expression in Rat Neocortical Circuits

Homeostatic control of pyramidal neuron firing rate involves a functional balance of feedforward excitation and feedback inhibition in neocortical circuits. Here, we reveal a dynamic scaling in vesicular excitatory (vesicular glutamate transporters VGLUT1 and VGLUT2) and inhibitory (vesicular inhibitory amino acid transporter VIAAT) transporter mRNA and synaptic protein expression in rat neocortical neuronal cultures, using a well established in vitro protocol to induce homeostatic plasticity. During the second and third week of synaptic differentiation, the predominant vesicular transporters expressed in neocortical neurons, VGLUT1 and VIAAT, are both dramatically upregulated. In mature cultures, VGLUT1 and VIAAT exhibit bidirectional and opposite regulation by prolonged activity changes. Endogenous coregulation during development and homeostatic scaling of the expression of the transporters in functionally differentiated cultures may serve to control vesicular glutamate and GABA filling and adjust functional presynaptic excitatory/inhibitory balance. Unexpectedly, hyperexcitation in differentiated cultures triggers a striking increase in VGLUT2 mRNA and synaptic protein, whereas decreased excitation reduces levels. VGLUT2 mRNA and protein are expressed in subsets of VGLUT1-encoded neocortical neurons that we identify in primary cultures and in neocortex in situ and in vivo. After prolonged hyperexcitation, downregulation of VGLUT1/synaptophysin intensity ratios at most synapses is observed, whereas a subset of VGLUT1-containing boutons selectively increase the expression of VGLUT2. Bidirectional and opposite regulation of VGLUT1 and VGLUT2 by activity may serve as positive or negative feedback regulators for cortical synaptic transmission. Intracortical VGLUT1/VGLUT2 coexpressing neurons have the capacity to independently modulate the level of expression of either transporter at discrete synapses and therefore may serve as a plastic interface between subcortical thalamic input (VGLUT2) and cortical output (VGLUT1) neurons.

[1]  T. Ishikawa,et al.  Developmental Increase in Vesicular Glutamate Content Does Not Cause Saturation of AMPA Receptors at the Calyx of Held Synapse , 2003, The Journal of Neuroscience.

[2]  R. Edwards,et al.  Postnatal development of the glutamate vesicular transporter VGLUT1 in rat cerebral cortex. , 2003, Brain research. Developmental brain research.

[3]  C. Stevens,et al.  Heterogeneity of Release Probability, Facilitation, and Depletion at Central Synapses , 1997, Neuron.

[4]  T. Ishikawa,et al.  A Single Packet of Transmitter Does Not Saturate Postsynaptic Glutamate Receptors , 2002, Neuron.

[5]  H. Atwood,et al.  Quantal Size and Variation Determined by Vesicle Size in Normal and Mutant Drosophila Glutamatergic Synapses , 2002, The Journal of Neuroscience.

[6]  H. Markram,et al.  Organizing principles for a diversity of GABAergic interneurons and synapses in the neocortex. , 2000, Science.

[7]  M. Schäfer,et al.  Identification of the Differentiation-Associated Na+/PI Transporter as a Novel Vesicular Glutamate Transporter Expressed in a Distinct Set of Glutamatergic Synapses , 2002, The Journal of Neuroscience.

[8]  Guosong Liu,et al.  Local structural balance and functional interaction of excitatory and inhibitory synapses in hippocampal dendrites , 2004, Nature Neuroscience.

[9]  N. Axmacher,et al.  Transmitter metabolism as a mechanism of synaptic plasticity: a modeling study. , 2004, Journal of neurophysiology.

[10]  R. Fremeau,et al.  VGLUTs define subsets of excitatory neurons and suggest novel roles for glutamate , 2004, Trends in Neurosciences.

[11]  E. Jorgensen,et al.  Identification and characterization of the vesicular GABA transporter , 1997, Nature.

[12]  C. Wermuth,et al.  Biochemical characterization of the interaction of three pyridazinyl-GABA derivatives with the GABAA receptor site , 1986, Brain Research.

[13]  J. Storm-Mathisen,et al.  The Expression of Vesicular Glutamate Transporters Defines Two Classes of Excitatory Synapse , 2001, Neuron.

[14]  W. Kloot,et al.  Vesicle size and transmitter release at the frog neuromuscular junction when quantal acetylcholine content is increased or decreased , 2002, The Journal of physiology.

[15]  Christian Stricker,et al.  Functional connectivity in layer IV local excitatory circuits of rat somatosensory cortex. , 2004, Journal of neurophysiology.

[16]  F. Fujiyama,et al.  Immunocytochemical localization of candidates for vesicular glutamate transporters in the rat cerebral cortex , 2001, The Journal of comparative neurology.

[17]  J. McLaurin,et al.  Interaction of human and mouse Aβ peptides , 2004 .

[18]  A. Ewing,et al.  VMAT-Mediated Changes in Quantal Size and Vesicular Volume , 2000, The Journal of Neuroscience.

[19]  Nathan R. Wilson,et al.  Presynaptic Regulation of Quantal Size by the Vesicular Glutamate Transporter VGLUT1 , 2005, The Journal of Neuroscience.

[20]  B. Giros,et al.  Cloning of a functional vesicular GABA and glycine transporter by screening of genome databases , 1997, FEBS letters.

[21]  J. Storm-Mathisen,et al.  Expression of the vesicular glutamate transporters during development indicates the widespread corelease of multiple neurotransmitters , 2004, The Journal of comparative neurology.

[22]  R. Fremeau,et al.  Uptake of glutamate into synaptic vesicles by an inorganic phosphate transporter. , 2000, Science.

[23]  C F Stevens,et al.  Nonsaturation of AMPA and NMDA receptors at hippocampal synapses. , 2000, Proceedings of the National Academy of Sciences of the United States of America.

[24]  M. Lindau,et al.  Secretory Vesicles Membrane Area Is Regulated in Tandem with Quantal Size in Chromaffin Cells , 2003, The Journal of Neuroscience.

[25]  S. Nelson,et al.  Selective reconfiguration of layer 4 visual cortical circuitry by visual deprivation , 2004, Nature Neuroscience.

[26]  Xin Wu,et al.  Regional expression and cellular localization of the Na(+)-dependent inorganic phosphate cotransporter of rat brain , 1995, The Journal of neuroscience : the official journal of the Society for Neuroscience.

[27]  D. Bruns,et al.  Quantal Release of Serotonin , 2000, Neuron.

[28]  Aaron DiAntonio,et al.  Increased Expression of the Drosophila Vesicular Glutamate Transporter Leads to Excess Glutamate Release and a Compensatory Decrease in Quantal Content , 2004, The Journal of Neuroscience.

[29]  David A Lewis,et al.  Pyramidal neuron local axon terminals in monkey prefrontal cortex: differential targeting of subclasses of GABA neurons. , 2003, Cerebral cortex.

[30]  Michael D. Ehlers,et al.  Homeostatic plasticity and NMDA receptor trafficking , 2005, Trends in Neurosciences.

[31]  H. Cline,et al.  Synaptogenesis: A Balancing Act between Excitation and Inhibition , 2005, Current Biology.

[32]  H. Atwood,et al.  Diversification of synaptic strength: presynaptic elements , 2002, Nature Reviews Neuroscience.

[33]  B. Sakmann,et al.  ‐Dynamic representation of whisker deflection by synaptic potentials in spiny stellate and pyramidal cells in the barrels and septa of layer 4 rat somatosensory cortex , 2002, The Journal of physiology.

[34]  J. Haycock,et al.  Synaptic Vesicle Transporter Expression Regulates Vesicle Phenotype and Quantal Size , 2000, The Journal of Neuroscience.

[35]  Christian Rosenmund,et al.  Identification of Differentiation-Associated Brain-Specific Phosphate Transporter as a Second Vesicular Glutamate Transporter (VGLUT2) , 2001, The Journal of Neuroscience.

[36]  M. Poo,et al.  Expression of a Putative Vesicular Acetylcholine Transporter Facilitates Quantal Transmitter Packaging , 1997, Neuron.

[37]  I. Módy,et al.  Cell type‐ and synapse‐specific variability in synaptic GABAA receptor occupancy , 2000, The European journal of neuroscience.

[38]  M. C. Angulo,et al.  Molecular and Physiological Diversity of Cortical Nonpyramidal Cells , 1997, The Journal of Neuroscience.

[39]  J. Lübke,et al.  Reliable synaptic connections between pairs of excitatory layer 4 neurones within a single ‘barrel’ of developing rat somatosensory cortex , 1999, The Journal of physiology.

[40]  Niraj S. Desai,et al.  Activity-dependent scaling of quantal amplitude in neocortical neurons , 1998, Nature.

[41]  V. Murthy,et al.  Multiple forms of synaptic plasticity triggered by selective suppression of activity in individual neurons , 2002, Nature.

[42]  Grégory Dal Bo,et al.  Dopamine neurons in culture express VGLUT2 explaining their capacity to release glutamate at synapses in addition to dopamine , 2004, Journal of neurochemistry.

[43]  H. Nogami,et al.  Regional expression of a gene encoding a neuron-specific Na(+)-dependent inorganic phosphate cotransporter (DNPI) in the rat forebrain. , 2000, Brain research. Molecular brain research.

[44]  Sacha B. Nelson,et al.  Postsynaptic Depolarization Scales Quantal Amplitude in Cortical Pyramidal Neurons , 2001, The Journal of Neuroscience.

[45]  Masahiko Watanabe,et al.  Subtype switching of vesicular glutamate transporters at parallel fibre–Purkinje cell synapses in developing mouse cerebellum , 2003, The European journal of neuroscience.

[46]  S. Paul,et al.  Cloning and expression of a cDNA encoding a brain-specific Na(+)-dependent inorganic phosphate cotransporter. , 1994, Proceedings of the National Academy of Sciences of the United States of America.

[47]  C. Legay,et al.  Expression of vesicular glutamate transporters, VGLUT1 and VGLUT2, in cholinergic spinal motoneurons , 2004, The European journal of neuroscience.

[48]  G. Davis,et al.  Maintaining the stability of neural function: a homeostatic hypothesis. , 2001, Annual review of physiology.

[49]  A. Draguhn,et al.  Plasticity of rat central inhibitory synapses through GABA metabolism , 2001, The Journal of physiology.

[50]  J. Lübke,et al.  Columnar Organization of Dendrites and Axons of Single and Synaptically Coupled Excitatory Spiny Neurons in Layer 4 of the Rat Barrel Cortex , 2000, The Journal of Neuroscience.

[51]  Martin Wilson,et al.  Variation in GABA mini amplitude is the consequence of variation in transmitter concentration , 1995, Neuron.

[52]  M. Poo,et al.  Synaptic reliability correlates with reduced susceptibility to synaptic potentiation by brain-derived neurotrophic factor. , 1999, Learning & memory.

[53]  J DeFelipe,et al.  Postnatal development of the vesicular gaba transporter in rat cerebral cortex , 2003, Neuroscience.

[54]  J. Williams,et al.  How Does a Vesicle Know It Is Full? , 1997, Neuron.

[55]  Christian Rosenmund,et al.  An essential role for vesicular glutamate transporter 1 (VGLUT1) in postnatal development and control of quantal size. , 2004, Proceedings of the National Academy of Sciences of the United States of America.

[56]  D. Copenhagen,et al.  Vesicular Glutamate Transporters 1 and 2 Target to Functionally Distinct Synaptic Release Sites , 2004, Science.

[57]  H. Markram,et al.  Interneurons of the neocortical inhibitory system , 2004, Nature Reviews Neuroscience.

[58]  Guosong Liu.  Presynaptic control of quantal size: kinetic mechanisms and implications for synaptic transmission and plasticity , 2003, Current Opinion in Neurobiology.

[59]  S. Nelson,et al.  BDNF Has Opposite Effects on the Quantal Amplitude of Pyramidal Neuron and Interneuron Excitatory Synapses , 1998, Neuron.

[60]  W. Wadman,et al.  Homeostatic scaling of neuronal excitability by synaptic modulation of somatic hyperpolarization-activated Ih channels. , 2004, Proceedings of the National Academy of Sciences of the United States of America.

[61]  M. Schäfer,et al.  Molecular Cloning and Functional Identification of Mouse Vesicular Glutamate Transporter 3 and Its Expression in Subsets of Novel Excitatory Neurons* , 2002, The Journal of Biological Chemistry.

[62]  B. Giros,et al.  The Existence of a Second Vesicular Glutamate Transporter Specifies Subpopulations of Glutamatergic Neurons , 2001, The Journal of Neuroscience.

[63]  T. Schikorski,et al.  Inactivity Produces Increases in Neurotransmitter Release and Synapse Size , 2001, Neuron.

[64]  E. Pothos,et al.  Vesicular Transport Regulates Monoamine Storage and Release but Is Not Essential for Amphetamine Action , 1997, Neuron.

[65]  G. Brewer,et al.  Optimized survival of hippocampal neurons in B27‐supplemented neurobasal™, a new serum‐free medium combination , 1993, Journal of neuroscience research.

[66]  J. Erickson,et al.  Vesicular neurotransmitter transporters , 1997, Molecular Neurobiology.

[67]  V. Pickel,et al.  The Localization of the Brain-Specific Inorganic Phosphate Transporter Suggests a Specific Presynaptic Role in Glutamatergic Transmission , 1998, The Journal of Neuroscience.

[68]  Javier DeFelipe,et al.  Cortical interneurons: from Cajal to 2001. , 2002, Progress in brain research.

[69]  R. Tsien,et al.  Activity-dependent regulation of dendritic synthesis and trafficking of AMPA receptors , 2004, Nature Neuroscience.

[70]  G G Turrigiano,et al.  Brain-Derived Neurotrophic Factor Mediates the Activity-Dependent Regulation of Inhibition in Neocortical Cultures , 1997, The Journal of Neuroscience.

[71]  G. Turrigiano,et al.  Postsynaptic Expression of Homeostatic Plasticity at Neocortical Synapses , 2005, The Journal of Neuroscience.

[72]  E. Pothos,et al.  Regulation of Quantal Size by Presynaptic Mechanisms , 2000, Reviews in the neurosciences.

[73]  R. Tsien,et al.  Variability of Neurotransmitter Concentration and Nonsaturation of Postsynaptic AMPA Receptors at Synapses in Hippocampal Cultures and Slices , 1999, Neuron.

[74]  P. Somogyi,et al.  Target-cell-specific facilitation and depression in neocortical circuits , 1998, Nature Neuroscience.

[75]  J. Erickson,et al.  Active Transport of Acetylcholine by the Human Vesicular Acetylcholine Transporter* , 1996, The Journal of Biological Chemistry.

[76]  Mark C. W. van Rossum,et al.  Activity Deprivation Reduces Miniature IPSC Amplitude by Decreasing the Number of Postsynaptic GABAA Receptors Clustered at Neocortical Synapses , 2002, The Journal of Neuroscience.

[77]  Chris J. McBain,et al.  Interneurons unbound , 2001, Nature Reviews Neuroscience.

[78]  N. Bazan,et al.  Cyclooxygenase-2 regulates prostaglandin E2 signaling in hippocampal long-term synaptic plasticity. , 2002, Journal of neurophysiology.

[79]  Karl Zilles,et al.  Functional diversity of layer IV spiny neurons in rat somatosensory cortex: quantitative morphology of electrophysiologically characterized and biocytin labeled cells. , 2004, Cerebral cortex.

[80]  S. Nelson,et al.  Homeostatic plasticity in the developing nervous system , 2004, Nature Reviews Neuroscience.