Intrathecal adenosine A1 receptor agonist attenuates hyperalgesia without inhibiting spinal glutamate release in the rat.
The analgesia effects of intrathecal adenosine A1 receptor agonist, R-PIA, on the hyperalgesia and CSF-glutamate release after formalin injection into the rat paw were evaluated. R-PIA significantly and dose-dependently attenuated increases in flinching behavior, and this attenuating effect was reversed by the adenosine A1 receptor antagonist, aminophylline. Morphine blocked flinchs, however MK-801 partially abolished. The increase in CSF-glutamate release evoked by formalin stimulation was inhibited by morphine but not by either R-PIA or MK-801. These findings suggest that the intrathecal adenosine A1 receptor agonist provokes analgesic effect via the postsynaptic action independent of an effect upon spinal glutamate release.
Department of Laboratory Sciences, Yamaguchi University School of Medicine, Ube, Yamaguchi, Japan.
Syuichiro
S
Yamamoto
Osamu
O
Nakanishi
Tomohiro
T
Matsui
Noriyuki
N
Shinohara
Hiroyuki
H
Kinoshita
Clinton
C
Lambert
Toshizo
T
Ishikawa
D000241:Adenosine / Q000008:administration & dosage* / Q000031:analogs & derivatives*; D058907:Adenosine A1 Receptor Agonists; D000818:Animals; D018698:Glutamic Acid / Q000378:metabolism*; D006930:Hyperalgesia / Q000188:drug therapy*; D007278:Injections, Spinal; D008297:Male; D010147:Pain Measurement / Q000187:drug effects / Q000379:methods; D051381:Rats; D017207:Rats, Sprague-Dawley; D043682:Receptor, Adenosine A1 / Q000502:physiology; D013116:Spinal Cord / Q000187:drug effects* / Q000378:metabolism
D058907:Adenosine A1 Receptor Agonists; D043682:Receptor, Adenosine A1; C047235:N-(1-methyl-2-phenylethyl)adenosine; D018698:Glutamic Acid; D000241:Adenosine