Antinociceptive effects of the hydrophilic alpha 2-adrenoceptor agonist ST-91 in different test circumstances after intrathecal administration to Wistar rats.
The antinociceptive and motor effects of the hydrophilic alpha 2-adrenoceptor agonist ST-91 were studied after intrathecal administration to male Wistar rats in different heat-pain tests and different test settings. Intrathecal administration of ST-91 caused a dose-dependent increase in hind paw licking latency in the hot-plate test, while in contrast with morphine it had a much lower efficacy in the tail-flick test in freely moving conditions. Sprague-Dawley rats gave similar results to those for Wistar rats in this setting. However, when the tail-flick test was performed under chronic restraint conditions (after a 1-h restraining period), the compound caused a significant antinociception. No signs of motor impairment and no changes in electromyographic activity were detected after ST-91 administration. The results indicate a characteristic analgesic profile for ST-91. In the interpretation of ST-91 data, consideration should be paid both to test model differences and to test conditions.
Horváth
G
G
Department of Physiology, Albert Szent-Györgyi Medical University, Szeged, Hungary.
Dobos
I
I
Liszli
P
P
Klimscha
W
W
Szikszay
M
M
Benedek
G
G
D058647:Adrenergic alpha-2 Receptor Agonists; D000316:Adrenergic alpha-Agonists / Q000494:pharmacology*; D018712:Analgesics, Non-Narcotic / Q000494:pharmacology*; D000818:Animals; D003000:Clonidine / Q000031:analogs & derivatives* / Q000494:pharmacology; D007278:Injections, Spinal; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D017208:Rats, Wistar
D058647:Adrenergic alpha-2 Receptor Agonists; D000316:Adrenergic alpha-Agonists; D018712:Analgesics, Non-Narcotic; C011266:ST 91; D003000:Clonidine