title: Antagonism of ionotropic glutamate receptors attenuates chemical ischemia-induced injury in rat primary cultured myenteric ganglia.
abstract: Alterations of the enteric glutamatergic transmission may underlay changes in the function of myenteric neurons following intestinal ischemia and reperfusion (I/R) contributing to impairment of gastrointestinal motility occurring in these pathological conditions. The aim of the present study was to evaluate whether glutamate receptors of the NMDA and AMPA/kainate type are involved in myenteric neuron cell damage induced by I/R. Primary cultured rat myenteric ganglia were exposed to sodium azide and glucose deprivation (in vitro chemical ischemia). After 6 days of culture, immunoreactivity for NMDA, AMPA and kainate receptors subunits, GluN(1) and GluA(1-3), GluK(1-3) respectively, was found in myenteric neurons. In myenteric cultured ganglia, in normal metabolic conditions, -AP5, an NMDA antagonist, decreased myenteric neuron number and viability, determined by calcein AM/ethidium homodimer-1 assay, and increased reactive oxygen species (ROS) levels, measured with hydroxyphenyl fluorescein. CNQX, an AMPA/kainate antagonist exerted an opposite action on the same parameters. The total number and viability of myenteric neurons significantly decreased after I/R. In these conditions, the number of neurons staining for GluN1 and GluA(1-3) subunits remained unchanged, while, the number of GluK(1-3)-immunopositive neurons increased. After I/R, -AP5 and CNQX, concentration-dependently increased myenteric neuron number and significantly increased the number of living neurons. Both -AP5 and CNQX (100-500 µM) decreased I/R-induced increase of ROS levels in myenteric ganglia. On the whole, the present data provide evidence that, under normal metabolic conditions, the enteric glutamatergic system exerts a dualistic effect on cultured myenteric ganglia, either by improving or reducing neuron survival via NMDA or AMPA/kainate receptor activation, respectively. However, blockade of both receptor pathways may exert a protective role on myenteric neurons following and I/R damage. The neuroprotective effect may depend, at least in part, on the ability of both receptors to increase intraneuronal ROS production.
authors.affiliation: Department of Clinical and Experimental Medicine, University of Insubria, Varese, Italy.
authors.forename: Elisa
authors.initials: E
authors.lastname: Carpanese
authors.affiliation: Department of Surgical and Morphological Sciences, University of Insubria, Varese, Italy.
authors.forename: Paola
authors.initials: P
authors.lastname: Moretto
authors.affiliation: Department of Clinical and Experimental Medicine, University of Insubria, Varese, Italy.
authors.forename: Viviana
authors.initials: V
authors.lastname: Filpa
authors.affiliation: Department of Clinical and Experimental Medicine, University of Insubria, Varese, Italy.
authors.forename: Silvia
authors.initials: S
authors.lastname: Marchet
authors.affiliation: Department of Internal Medicine and Therapeutics, University of Pavia, Pavia, Italy.
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Moro
authors.affiliation: Department of Internal Medicine and Therapeutics, University of Pavia, Pavia, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Crema
authors.affiliation: Department of Internal Medicine and Therapeutics, University of Pavia, Pavia, Italy.
authors.forename: Gianmario
authors.initials: G
authors.lastname: Frigo
authors.affiliation: Department of Clinical and Experimental Medicine, University of Insubria, Varese, Italy.
authors.forename: Cristina
authors.initials: C
authors.lastname: Giaroni
mesh_terms: D015763:2-Amino-5-phosphonovalerate / Q000494:pharmacology; D018750:6-Cyano-7-nitroquinoxaline-2,3-dione / Q000494:pharmacology; D000818:Animals; D002452:Cell Count; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D005724:Ganglia / Q000098:blood supply / Q000166:cytology / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism; D007150:Immunohistochemistry; D007511:Ischemia / Q000139:chemically induced / Q000503:physiopathology; D008297:Male; D009197:Myenteric Plexus / Q000098:blood supply / Q000378:metabolism*; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism; D018091:Receptors, AMPA / Q000037:antagonists & inhibitors / Q000378:metabolism; D058468:Receptors, Ionotropic Glutamate / Q000037:antagonists & inhibitors / Q000378:metabolism*; D018092:Kainic Acid Receptors / Q000037:antagonists & inhibitors / Q000378:metabolism; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors / Q000378:metabolism; D015427:Reperfusion Injury / Q000503:physiopathology; D019810:Sodium Azide / Q000494:pharmacology
chemical_list: D015763:2-Amino-5-phosphonovalerate; D018750:6-Cyano-7-nitroquinoxaline-2,3-dione; D018691:Excitatory Amino Acid Antagonists; D005947:Glucose; D017382:Reactive Oxygen Species; D018091:Receptors, AMPA; D058468:Receptors, Ionotropic Glutamate; D018092:Kainic Acid Receptors; D016194:Receptors, N-Methyl-D-Aspartate; D019810:Sodium Azide