Astrocyte secreted proteins selectively increase hippocampal GABAergic axon length, branching, and synaptogenesis.
Astrocytes modulate the formation and function of glutamatergic synapses in the CNS, but whether astrocytes modulate GABAergic synaptogenesis is unknown. We demonstrate that media conditioned by astrocytes, but not other cells, enhanced GABAergic but not glutamatergic axon length and branching, and increased the number and density of presynaptically active GABAergic synapses in dissociated hippocampal cultures. Candidate mechanisms and factors, such as activity, neurotrophins, and cholesterol were excluded as mediating these effects. While thrombospondins secreted by astrocytes are necessary and sufficient to increase hippocampal glutamatergic synaptogenesis, they do not mediate astrocyte effects on GABAergic synaptogenesis. We show that the factors in astrocyte conditioned media that selectively affect GABAergic neurons are proteins. Taken together, our results show that astrocytes increase glutamatergic and GABAergic synaptogenesis via different mechanisms and release one or more proteins with the novel functions of increasing GABAergic axon length, branching and synaptogenesis.
Department of Neuroscience, University of Pennsylvania School of Medicine, 215 Stemmler Hall, Philadelphia, PA 19104-6074, USA.
Ethan G
EG
Hughes
Sarina B
SB
Elmariah
Rita J
RJ
Balice-Gordon
D000818:Animals; D001253:Astrocytes / Q000166:cytology / Q000378:metabolism*; D001369:Axons / Q000378:metabolism / Q000648:ultrastructure*; D015415:Biomarkers / Q000378:metabolism; D002352:Carrier Proteins / Q000378:metabolism; D002478:Cells, Cultured; D018920:Coculture Techniques; D017077:Culture Media, Conditioned / Q000737:chemistry / Q000378:metabolism*; D018698:Glutamic Acid / Q000378:metabolism; D006624:Hippocampus / Q000166:cytology* / Q000196:embryology; D008565:Membrane Proteins / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000378:metabolism; D009474:Neurons / Q000166:cytology / Q000378:metabolism; D051381:Rats; D013569:Synapses / Q000502:physiology* / Q000648:ultrastructure; D019699:Thrombospondins / Q000378:metabolism; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
D015415:Biomarkers; D002352:Carrier Proteins; D017077:Culture Media, Conditioned; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D019699:Thrombospondins; C073441:gephyrin; D018698:Glutamic Acid; D005680:gamma-Aminobutyric Acid