title: The acute inhibition of enteric glial metabolism with fluoroacetate alters calcium signaling, hemichannel function, and the expression of key proteins.
abstract: Glia play key roles in the regulation of neurotransmission in the nervous system. Fluoroacetate (FA) is a metabolic poison widely used to study glial functions by disrupting the tricarboxylic acid cycle enzyme aconitase. Despite the widespread use of FA, the effects of FA on essential glial functions such as calcium (Ca2+) signaling and hemichannel function remain unknown. Therefore, our goal was to assess specifically the impact of FA on essential glial cell functions that are involved with neurotransmission in the enteric nervous system. To this end, we generated a new optogenetic mouse model to study specifically the effects of FA on enteric glial Ca2+signaling by crossing PC::G5-tdTomato mice with Sox10::creERT2mice. FA did not change the peak glial Ca2+response when averaged across all glia within a ganglion. However, FA decreased the percent of responding glia by 30% (P < 0.05) and increased the peak Ca2+response of the glial cells that still exhibited a response by 26% (P < 0.01). Disruption of Ca2+signaling with FA impaired the activity-dependent uptake of ethidium bromide through connexin-43 (Cx43) hemichannels (P < 0.05) but did not affect baseline Cx43-dependent dye uptake. FA did not cause overt glial or neurodegeneration, but glial cells significantly increased glial fibrillary acid protein by 56% (P < 0.05) following treatment with FA. Together, these data show that the acute impairment of glial metabolism with FA causes key changes in glial functions associated with their roles in neurotransmission and phenotypic changes indicative of reactive gliosis.
  
  
  
  Our study shows that the acute impairment of enteric glial metabolism with fluoroacetate (FA) alters specific glial functions that are associated with the modification of neurotransmission in the gut. These include subtle changes to glial agonist-evoked calcium signaling, the subsequent disruption of connexin-43 hemichannels, and changes in protein expression that are consistent with a transition to reactive glia. These changes in glial function offer a mechanistic explanation for the effects of FA on peripheral neuronal networks.
authors: Department of Physiology, Michigan State University, East Lansing, Michigan; and.
authors: Jonathon L
authors: JL
authors: McClain
authors: Department of Physiology, Michigan State University, East Lansing, Michigan; and gulbrans@msu.edu.|Neuroscience Program, Michigan State University, East Lansing, Michigan.
authors: Brian D
authors: 0000-0003-1145-3227
authors: BD
authors: Gulbransen
mesh_terms: D000244:Adenosine Diphosphate / Q000494:pharmacology; D000814:Aniline Compounds / Q000494:pharmacology; D000818:Animals; D020013:Calcium Signaling / Q000187:drug effects*; D002452:Cell Count; D018031:Connexin 43 / Q000378:metabolism*; D000067778:ELAV-Like Protein 3 / Q000378:metabolism; D000067779:ELAV-Like Protein 4 / Q000378:metabolism; D005260:Female; D005463:Fluoroacetates / Q000494:pharmacology*; D005786:Gene Expression Regulation / Q000187:drug effects* / Q000235:genetics; D005904:Glial Fibrillary Acidic Protein / Q000235:genetics / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D009197:Myenteric Plexus / Q000166:cytology*; D009457:Neuroglia / Q000187:drug effects*; D064568:S100 Calcium Binding Protein beta Subunit / Q000378:metabolism; D055757:SOXE Transcription Factors / Q000235:genetics / Q000378:metabolism; D014966:Xanthenes / Q000494:pharmacology
chemical_list: D000814:Aniline Compounds; D018031:Connexin 43; D000067778:ELAV-Like Protein 3; D000067779:ELAV-Like Protein 4; C490263:Elavl3 protein, mouse; C409648:Fluo 4; D005463:Fluoroacetates; D005904:Glial Fibrillary Acidic Protein; D064568:S100 Calcium Binding Protein beta Subunit; D055757:SOXE Transcription Factors; C527924:Sox10 protein, mouse; D014966:Xanthenes; D000244:Adenosine Diphosphate
keywords: autonomic nervous system; enteric glial cells; enteric nervous system; glia; intestine