Abstract
Direct intraspinal injection of the catecholamines epinephrine and norepinephrine, and the α-adrenergic agents dexmedetomidine and clonidine, produced a dose-dependent elevation of pain thresholds in the Northern grass frog, Rana pipiens. Significant analgesic effects were noted for at least 4 h. The analgesic effect of intraspinal dexmedetomidine or epinephrine was blocked by systemic pretreatment with the α2-adrenoceptor antagonists, yohimbine and atipamezole, but not with the α1-adrenoceptor antagonist, prazosin. Dose-response analyses showed that dexmedetomidine, epinephrine, norepinephrine had similar analgesic potencies, but clonidine was significantly less potent. Analgesia was observed without accompanying motor or sedative effects. These results suggest that α2-adrenoceptor mechanisms which mediate analgesia may have evolved early in vertebrate evolution and that descending epinephrine-containing fibers in the amphibian nervous system may be the source of endogenous catecholamines regulating nociceptive sensitivity in the amphibian spinal cord.
| Original language | English |
|---|---|
| Pages (from-to) | 205-210 |
| Number of pages | 6 |
| Journal | European Journal of Pharmacology |
| Volume | 316 |
| Issue number | 2-3 |
| DOIs | |
| State | Published - 5 Dec 1996 |
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Keywords
- -Adrenoceptor
- Amphibian
- Analgesia
- Pain
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Spinal administration of adrenergic agents produces analgesia in amphibians. / Stevens, Craig; Brenner, George M.
In: European Journal of Pharmacology, Vol. 316, No. 2-3, 05.12.1996, p. 205-210.Research output: Contribution to journal › Article
TY - JOUR
T1 - Spinal administration of adrenergic agents produces analgesia in amphibians
AU - Stevens, Craig
AU - Brenner, George M.
PY - 1996/12/5
Y1 - 1996/12/5
N2 - Direct intraspinal injection of the catecholamines epinephrine and norepinephrine, and the α-adrenergic agents dexmedetomidine and clonidine, produced a dose-dependent elevation of pain thresholds in the Northern grass frog, Rana pipiens. Significant analgesic effects were noted for at least 4 h. The analgesic effect of intraspinal dexmedetomidine or epinephrine was blocked by systemic pretreatment with the α2-adrenoceptor antagonists, yohimbine and atipamezole, but not with the α1-adrenoceptor antagonist, prazosin. Dose-response analyses showed that dexmedetomidine, epinephrine, norepinephrine had similar analgesic potencies, but clonidine was significantly less potent. Analgesia was observed without accompanying motor or sedative effects. These results suggest that α2-adrenoceptor mechanisms which mediate analgesia may have evolved early in vertebrate evolution and that descending epinephrine-containing fibers in the amphibian nervous system may be the source of endogenous catecholamines regulating nociceptive sensitivity in the amphibian spinal cord.
AB - Direct intraspinal injection of the catecholamines epinephrine and norepinephrine, and the α-adrenergic agents dexmedetomidine and clonidine, produced a dose-dependent elevation of pain thresholds in the Northern grass frog, Rana pipiens. Significant analgesic effects were noted for at least 4 h. The analgesic effect of intraspinal dexmedetomidine or epinephrine was blocked by systemic pretreatment with the α2-adrenoceptor antagonists, yohimbine and atipamezole, but not with the α1-adrenoceptor antagonist, prazosin. Dose-response analyses showed that dexmedetomidine, epinephrine, norepinephrine had similar analgesic potencies, but clonidine was significantly less potent. Analgesia was observed without accompanying motor or sedative effects. These results suggest that α2-adrenoceptor mechanisms which mediate analgesia may have evolved early in vertebrate evolution and that descending epinephrine-containing fibers in the amphibian nervous system may be the source of endogenous catecholamines regulating nociceptive sensitivity in the amphibian spinal cord.
KW - -Adrenoceptor
KW - Amphibian
KW - Analgesia
KW - Pain
UR - http://www.scopus.com/inward/record.url?scp=0030571494&partnerID=8YFLogxK
U2 - 10.1016/S0014-2999(96)00681-4
DO - 10.1016/S0014-2999(96)00681-4
M3 - Article
C2 - 8982687
AN - SCOPUS:0030571494
VL - 316
SP - 205
EP - 210
JO - European Journal of Pharmacology
JF - European Journal of Pharmacology
SN - 0014-2999
IS - 2-3
ER -