N-Methyl-D-aspartate receptor antagonism decreases motility and inflammatory activation in the early phase of acute experimental colitis in the rat.
BACKGROUND
Inflammatory bowel diseases are accompanied by severe motility disorders. The aim of our study was to investigate whether the blockade of peripheral N-methyl-D-aspartate (NMDA)-sensitive glutamate receptors (NMDA-Rs) alters motility changes in chemically induced acute colitis and how this modulation is accomplished.


METHODS
The inflammatory and motility changes in 2,4,6-trinitrobenzenesulfonic acid (TNBS)-induced colitis were studied in anaesthetized Wistar rats following treatment with the natural NMDA-R antagonist kynurenic acid (KynA) or SZR-72, a blood-brain barrier-permeable synthetic KynA analogue. The macrohaemodynamics, serosal microcirculation (visualized by intravital videomicroscopy), plasma levels of tumour necrosis factor alpha (TNF-alpha), inflammatory enzyme activities (xanthine oxidoreductase (XOR), myeloperoxidase (MPO) and nitric oxide synthase (NOS)), and colonic motility (with a strain-gauge technique) were evaluated 17 h after colitis induction and compared with the control conditions.


RESULTS
The TNBS enema induced a systemic hyperdynamic circulatory reaction, increased the serosal capillary blood flow, significantly elevated the mucosal XOR, MPO and NOS activities and augmented the colonic motility relative to the controls. The NMDA-R antagonist treatment with KynA or SZR-72 significantly reduced the XOR, NOS and MPO activities, decreased the motility and increased the tone of the colon.


CONCLUSIONS
These data demonstrate a potential modulatory mechanism of NMDA-R in altered colonic motility in TNBS colitis. Inhibition of the enteric NMDA-Rs may provide a therapeutic option via which to influence intestinal hypermotility, microcirculatory changes and inflammatory activation simultaneously.
Varga
G
G
Institute of Surgical Research, Szent-Györgyi Albert Medical and Pharmaceutical Centre, University of Szeged, Szeged, Hungary.
Erces
D
D
Fazekas
B
B
Fülöp
M
M
Kovács
T
T
Kaszaki
J
J
Fülöp
F
F
Vécsei
L
L
Boros
M
M
D000704:Analysis of Variance; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D003092:Colitis / Q000139:chemically induced / Q000378:metabolism / Q000503:physiopathology*; D003106:Colon / Q000187:drug effects / Q000378:metabolism / Q000503:physiopathology*; D004195:Disease Models, Animal; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D005769:Gastrointestinal Motility / Q000187:drug effects* / Q000502:physiology; D007249:Inflammation / Q000378:metabolism* / Q000503:physiopathology; D007736:Kynurenic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D008297:Male; D019001:Nitric Oxide Synthase / Q000378:metabolism; D009195:Peroxidase / Q000378:metabolism; D011897:Random Allocation; D051381:Rats; D017208:Rats, Wistar; D016194:Receptors, N-Methyl-D-Aspartate / Q000378:metabolism*; D013997:Time Factors; D014302:Trinitrobenzenesulfonic Acid / Q000633:toxicity; D014409:Tumor Necrosis Factor-alpha / Q000097:blood; D014969:Xanthine Oxidase / Q000378:metabolism
D018691:Excitatory Amino Acid Antagonists; D016194:Receptors, N-Methyl-D-Aspartate; C533052:SZR 72; D014409:Tumor Necrosis Factor-alpha; D014302:Trinitrobenzenesulfonic Acid; D009195:Peroxidase; D019001:Nitric Oxide Synthase; D014969:Xanthine Oxidase; D007736:Kynurenic Acid