Influence of cortical synaptic input on striatal neuronal dendritic arborization and sensitivity to excitotoxicity in corticostriatal coculture.
Corticostriatal cocultures are utilized to recapitulate the cortex-striatum connection in vitro as a convenient model to investigate the development, function, and regulation of synapses formed between cortical and striatal neurons. However, optimization of this dissociated neuronal system to more closely reproduce in vivo circuits has not yet been explored. We studied the effect of varying the plating ratio of cortical to striatal neurons on striatal spiny projection neuron (SPN) characteristics in primary neuronal cocultures. Despite the large difference in cortical-striatal neuron ratio (1:1 vs. 1:3) at day of plating, by 18 days in vitro the difference became modest (∼25% lower cortical-striatal neuron ratio in 1:3 cocultures) and the neuronal density was lower in the 1:3 cocultures, indicating enhanced loss of striatal SPNs. Comparing SPNs in cocultures plated at a 1:1 vs. 1:3 ratio, we found that resting membrane potential, input resistance, current injection-induced action potential firing rates, and input-output curves were similar in the two conditions. However, SPNs in the cocultures plated at the lower cortical ratio exhibited reduced membrane capacitance along with significantly shorter total dendritic length, decreased dendritic complexity, and fewer excitatory synapses, consistent with their trend toward reduced miniature excitatory postsynaptic current frequency. Strikingly, the proportion of NMDA receptors found extrasynaptically in recordings from SPNs was significantly higher in the less cortical coculture. Consistently, SPNs in cocultures with reduced cortical input showed decreased basal pro-survival signaling through cAMP response element binding protein and enhanced sensitivity to NMDA-induced apoptosis. Altogether, our study indicates that abundance of cortical input regulates SPN dendritic arborization and survival/death signaling.
Graduate Program in Neuroscience, University of British Columbia, Vancouver, Canada; Department of Psychiatry and Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, Canada; and.
Caodu
C
Buren
School of Medicine, Zhejiang University, Hangzhou, Zhejiang, China.
Gaqi
G
Tu
Department of Psychiatry and Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, Canada; and.
Matthew P
MP
Parsons
Department of Psychiatry and Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, Canada; and.
Marja D
MD
Sepers
Department of Psychiatry and Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, Canada; and lynn.raymond@ubc.ca.
Lynn A
LA
Raymond
D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D050882:CREB-Binding Protein / Q000378:metabolism; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology; D018920:Coculture Techniques; D003342:Corpus Striatum / Q000166:cytology; D003712:Dendrites / Q000187:drug effects* / Q000502:physiology*; D000076122:Disks Large Homolog 4 Protein; D051937:Dopamine and cAMP-Regulated Phosphoprotein 32 / Q000378:metabolism; D004622:Embryo, Mammalian; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology*; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects; D051528:Guanylate Kinases / Q000378:metabolism; D008564:Membrane Potentials / Q000187:drug effects; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D016202:N-Methylaspartate / Q000494:pharmacology*; D009474:Neurons / Q000166:cytology* / Q000187:drug effects; D016194:Receptors, N-Methyl-D-Aspartate / Q000378:metabolism; D013569:Synapses / Q000187:drug effects / Q000502:physiology*
D000076122:Disks Large Homolog 4 Protein; C501447:Dlg4 protein, mouse; D051937:Dopamine and cAMP-Regulated Phosphoprotein 32; D018690:Excitatory Amino Acid Agonists; D008565:Membrane Proteins; D008869:Microtubule-Associated Proteins; C079240:Mtap2 protein, mouse; D016194:Receptors, N-Methyl-D-Aspartate; D016202:N-Methylaspartate; D050882:CREB-Binding Protein; D051528:Guanylate Kinases
NMDA receptors; cell survival; dendritic arborization; excitatory synapse; primary neuronal coculture