Ca2+ responses in enteric glia are mediated by connexin-43 hemichannels and modulate colonic transit in mice.
BACKGROUND & AIMS
In the enteric nervous system, neurotransmitters initiate changes in calcium (Ca(2+) responses) in glia, but it is not clear how this process affects intestinal function. We investigated whether Ca(2+)-mediated responses in enteric glia are required to maintain gastrointestinal function.


METHODS
We used in situ Ca(2+) imaging to monitor glial Ca(2+) responses, which were manipulated with pharmacologic agents or via glia-specific disruption of the gene encoding connexin-43 (Cx43) (hGFAP::CreER(T2+/-)/Cx43(f/f) mice). Gastrointestinal function was assessed based on pellet output, total gut transit, colonic bead expulsion, and muscle tension recordings. Proteins were localized and quantified by immunohistochemistry, immunoblot, and reverse transcription polymerase chain reaction analyses.


RESULTS
Ca(2+) responses in enteric glia of mice were mediated by Cx43 hemichannels. Cx43 immunoreactivity was confined to enteric glia within the myenteric plexus of the mouse colon; the Cx43 inhibitors carbenoxolone and 43Gap26 inhibited the ability of enteric glia to propagate Ca(2+) responses. In vivo attenuation of Ca(2+) responses in the enteric glial network slowed gut transit overall and delayed colonic transit--these changes are also observed during normal aging. Altered motility with increasing age was associated with reduced glial Ca(2+)-mediated responses and changes in glial expression of Cx43 messenger RNA and protein.


CONCLUSIONS
Ca(2+)-mediated responses in enteric glia regulate gastrointestinal function in mice. Altered intercellular signaling between enteric glia and neurons might contribute to motility disorders.
['McClain|Jonathon|J|', 'Grubišić|Vladimir|V|', 'Fried|David|D|', 'Gomez-Suarez|Roberto A|RA|', 'Leinninger|Gina M|GM|', 'Sévigny|Jean|J|', 'Parpura|Vladimir|V|', 'Gulbransen|Brian D|BD|']
D000818:Animals D015415:Biomarkers D015153:Blotting, Western D015220:Calcium Channels D020013:Calcium Signaling D003106:Colon D018031:Connexin 43 D017615:Enteric Nervous System D005260:Female D005772:Gastrointestinal Transit D007150:Immunohistochemistry D008297:Male D051379:Mice D008810:Mice, Inbred C57BL D018345:Mice, Knockout D009457:Neuroglia D060888:Real-Time Polymerase Chain Reaction D020133:Reverse Transcriptase Polymerase Chain Reaction
enteric glia connexin-43 enteric nervous system calcium Ca(2+) Cx43 carbenoxolone Aging messenger RNA ADP ATP CBX EG ENS ER(T2) GFAP Intestinal Nervous System Mouse Model Purines adenosine diphosphate adenosine triphosphate glial fibrillary acidic protein i-cKO inducible and conditional knockout mRNA moa months of age mutated estrogen receptor