Jonathon McClain1, Vladimir Grubišić2, David Fried3, Roberto A Gomez-Suarez2,4, Gina M Leinninger1, Jean Sévigny5,6, Vladimir Parpura2,7, Brian D Gulbransen1. 1. Neuroscience Program and Department of Physiology, Michigan State University, 567 Wilson Road, East Lansing, MI, 48824 USA. 2. Department of Neurobiology, Center for Glial Biology in Medicine, Atomic Force Microscopy and Nanotechnology Laboratories, Civitan International Research Center, Evelyn F. McKnight Brain Institute, University of Alabama, Birmingham, AL 35294, USA. 3. Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI 48824. 4. Department of Pediatrics Division of Pediatric Gastroenterology Hepatology And Nutrition at Nemours Chlidren's Hospital. Orlando, FL 32827, USA. 5. Département de microbiologie-infectiologie et d'immunologie, Faculté de Médecine, Université Laval, Québec, QC, Canada. 6. Centre de recherche du CHU de Québec, Québec, QC, G1V 4G2 Canada. 7. Department of Biotechnology, University of Rijeka, 51000 Rijeka, Croatia.
Abstract
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.
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.
Authors: Radoslaw Dobrowolski; Philipp Sasse; Jan W Schrickel; Marcus Watkins; Jung-Sun Kim; Mindaugas Rackauskas; Clemens Troatz; Alexander Ghanem; Klaus Tiemann; Joachim Degen; Feliksas F Bukauskas; Roberto Civitelli; Thorsten Lewalter; Bernd K Fleischmann; Klaus Willecke Journal: Hum Mol Genet Date: 2007-11-13 Impact factor: 6.150
Authors: Todd A Fiacco; Cendra Agulhon; Sarah R Taves; Jeremy Petravicz; Kristen B Casper; Xinzhong Dong; Ju Chen; Ken D McCarthy Journal: Neuron Date: 2007-05-24 Impact factor: 17.173