Allodynia evoked by intrathecal administration of prostaglandin F2 alpha to conscious mice.
The intrathecal administration of prostaglandin F2 alpha to conscious mice resulted in spontaneous agitation and touch-evoked agitation (allodynia) in the animals. The maximum allodynia induced by prostaglandin F2 alpha was observed at 10-15 min after intrathecal injection, and the response did not disappear by 120 min. Prostaglandin F2 alpha produced allodynia over a wide range of dosage from 0.1 pg to 2.5 micrograms/mouse. Dose dependency of prostaglandin F2 alpha for allodynia showed a skewed bell-shaped pattern, and the maximal allodynic effect was observed at 1.0 microgram. This allodynia was dose-dependently relieved by alpha 1-adrenergic (methoxamine), alpha 2-adrenergic (clonidine), and A1-adenosine (RPIA) agonists. Clonidine was 1.5 orders of magnitude more potent than methoxamine in blocking prostaglandin F2 alpha-induced allodynia. The blockade by clonidine was dose-dependently reversed by the alpha 2-adrenergic antagonist yohimbine but not by the alpha 1-adrenergic antagonist prazosin. These results demonstrate that prostaglandin F2 alpha administered intrathecally induces allodynia in conscious mice and that the allodynia involves the alpha 2-adrenergic and A1-adenosine systems. Because this allodynia has a clear resemblance to the characteristics of chronic pain in patients with causalgia and reflex sympathetic dystrophy, prostaglandin F2 alpha may be involved in allodynia observed with these disorders.
Minami
Toshiaki
T
Department of Anesthesiology, Osaka Medical College, TakatsukiJapan Department of Cell Biology, Osaka Bioscience Institute, SuitaJapan.
Uda
Rumiko
R
Horiguchi
Shigeko
S
Ito
Seiji
S
Hyodo
Masayoshi
M
Hayaishi
Osamu
O
D000241:Adenosine / Q000494:pharmacology; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects; D015237:Dinoprost / Q000008:administration & dosage; D004305:Dose-Response Relationship, Drug; D007278:Injections, Spinal; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D010146:Pain / Q000139:chemically induced*; D011930:Reaction Time / Q000187:drug effects; D013566:Sympathomimetics / Q000494:pharmacology
D013566:Sympathomimetics; D015237:Dinoprost; D000241:Adenosine