[Effects of N-methyl-D-aspartate receptor in visceral, hypersensitivity in rats with colonic inflammation].
OBJECTIVE
To investigate the effects of N-methyl-D-aspartate receptor (NMDAR) in the spinal dorsal horn in visceral hypersensitivity in rats with colonic inflammation.


METHODS
Seventy adult male Sprague-Dawley (SD) rats were randomly divided into the experimental group and the control group. Colonic inflammation was induced in the experimental rats by intraluminal administration of trinitrobenzenesulfonic acid (TNBS). Saline was administered intraluminally in the control rats. After 3, 7, 14, and 28 days of administration, abdominal contractions induced by inflation of a balloon colonically inserted were recorded in rats by implanting electrodes in the abdominal striated muscles. Immunohistochemistry method was used to study the expression of NMDAR1 and NMDAR2A/B in lumbarsacral spinal cord after inflammation.


RESULTS
Colonic distension evoked a significant increase of abdominal contractions after 3, 7 and 14 days of TNBS administration. After 28 days of TNBS administration, abdominal contractions were still significantly increased in 2 TNBS-treated rats compared with the control rats. After 7 and 14 days of TNBS administration, NMDAR1 and NMDAR2A/B-immunoreactive cells were significantly increased compared with the control group (P <0.05). Twenty-eight days after TNBS administration, the number of NMDAR1-IR and NMDAR2A/B-IR neurons was still significantly increased in 4 TNBS-treated rats compared with the saline-treated rats (P < 0.05).


CONCLUSIONS
NMDAR was involved in the transmission of visceral nociceptive stimuli. After the remission of colonic inflammation, increased expression of NMDAR1 and NMDAR2A/B in the spinal dorsal horn may induce persistent neuronal hyperactivity, which results in visceral hypersensitivity.
Sun
Yi-ning
YN
Faculty of Life Sciences, Northwestern Polytechnical University, Xi'an, China. LJY18272@163.com
Luo
Jin-yan
JY
Shang
Peng
P
Lan
Li
L
Rao
Zhi-ren
ZR
D000818:Animals; D003092:Colitis / Q000139:chemically induced / Q000378:metabolism*; D008297:Male; D020671:Posterior Horn Cells / Q000378:metabolism*; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D016194:Receptors, N-Methyl-D-Aspartate / Q000096:biosynthesis* / Q000235:genetics; D014302:Trinitrobenzenesulfonic Acid
D016194:Receptors, N-Methyl-D-Aspartate; D014302:Trinitrobenzenesulfonic Acid; C121001:NR2B NMDA receptor