[Effect of anticonvulsant gabapentin on visceral nociception and its relationship with amino acid neurotransmitters released from spinal cord].
OBJECTIVE
To test whether gabapentin, an anticonvulsant, is able to inhibit responses to peritoneal irritation-induced visceral pain and to examine the effect of gabapentin on spinal cord amino acid release.


METHODS
Forty-eight SD rats randomly received intraperitoneal (i.p.) injection of saline or gabapentin (50, 100, or 200 mg.kg-1), and 40 minutes later, 0.6% acetic acid (4 ml.kg-1) was administrated intraperitoneally. The acetic acid-induced writhing assay was used to determine the degree of nociception. The beam balance task was employed to test a possible inhibitory or sedative effect of the central nervous system. Cerebrospinal fluid dialysate was collected by microdialysis from the spinal subarachnoid space in anesthetized rats. Concentrations of amino acids in the dialysate, including glutamate, aspartate, serine, glutamine and glycine, following i.p. injection of acetic acid were evaluated. The effects of pretreatment with saline or gabapentin (100 mg.kg-1 i.p.) on amino acid release were compared.


RESULTS
Gabapentin reduced writhing responses in a dose-related fashion. Beam-balance time was significantly shortened after pretreatment with 200 mg.kg-1 of gabapentin. Dialysate concentrations of glutamate, aspartate and serine increased significantly-following i.p. injection of acetic acid, while glutamine and glycine concentrations were not. When compared to saline-treated rats, animals pre-treated with 100 mg.kg-1 of gabapentin showed suppression of the acetic acid-induced increases in glutamate, aspartate and serine concentrations.


CONCLUSIONS
These data demonstrate that gabapentin effectively inhibited acetic acid-induced nociception, and the antinociceptive effect of gabapentin might correlate with the suppression of noxious-evoked release of excitatory amino acids in the spinal cord.
Feng
Yi
Y
Department of Anesthesiology, Peking University People's Hospital, Beijing 100044, China. yifeng65@263.net
Cui
Minglei
M
Willis
William D
WD
D000085:Acetates / Q000494:pharmacology*; D000588:Amines; D000818:Animals; D000927:Anticonvulsants / Q000494:pharmacology*; D003509:Cyclohexanecarboxylic Acids; D004305:Dose-Response Relationship, Drug; D000077206:Gabapentin; D008297:Male; D018377:Neurotransmitter Agents / Q000378:metabolism*; D010146:Pain / Q000188:drug therapy*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013116:Spinal Cord / Q000187:drug effects* / Q000378:metabolism; D014781:Viscera; D005680:gamma-Aminobutyric Acid
D000085:Acetates; D000588:Amines; D000927:Anticonvulsants; D003509:Cyclohexanecarboxylic Acids; D018377:Neurotransmitter Agents; D005680:gamma-Aminobutyric Acid; D000077206:Gabapentin