Effects of four dopamine agonists on l-tetrahydropalmatine-induced analgesia and electroacupuncture analgesia in rabbits.
The effects of icv 4 dopamine (DA) agonists on analgesia caused by iv l-tetrahydropalmatine (THP) 8 mg/kg or by electro-acupuncture (EA) were studied by using the potassium iontophoretic dolorimetry in rabbits. The results showed that both THP-induced analgesia and EA analgesia were markedly attenuated by icv of DA or apomorphine (Apo), 2 mixed D1/D2 agonists. Similar results were obtained when SKF-38393, a selective D1 agonist, was applied. On the contrary, quinpirole hydrochloride (Qui), a selective D2 agonist, was found to enhance the analgesic action of THP or EA. However, DA, Apo, SKF-38393 or Qui per se did not influence the baseline pain threshold. All these observations indicate that functional alterations in DA receptor activities may be involved in THP-induced analgesia and EA analgesia, in which D1 and D2 subtype receptors exert different roles.
Wu
G
G
Department of Neurobiology, Shanghai Medical University, China.
Jiang
J W
JW
Wu
G C
GC
Cao
X D
XD
D015647:2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine / Q000494:pharmacology; D015667:Acupuncture Analgesia; D000470:Alkaloids / Q000494:pharmacology*; D000818:Animals; D001058:Apomorphine / Q000494:pharmacology; D001600:Berberine Alkaloids / Q000494:pharmacology*; D004298:Dopamine / Q000494:pharmacology; D015259:Dopamine Agents / Q000494:pharmacology*; D015671:Electroacupuncture; D004873:Ergolines / Q000494:pharmacology; D005260:Female; D007276:Injections, Intraventricular; D008297:Male; D010146:Pain / Q000503:physiopathology*; D010147:Pain Measurement; D019257:Quinpirole; D011817:Rabbits; D011954:Receptors, Dopamine / Q000187:drug effects; D017447:Receptors, Dopamine D1; D017448:Receptors, Dopamine D2; D012684:Sensory Thresholds / Q000187:drug effects; D013237:Stereoisomerism
D000470:Alkaloids; D001600:Berberine Alkaloids; D015259:Dopamine Agents; D004873:Ergolines; D011954:Receptors, Dopamine; D017447:Receptors, Dopamine D1; D017448:Receptors, Dopamine D2; D019257:Quinpirole; C014215:tetrahydropalmatine; D015647:2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine; D001058:Apomorphine; D004298:Dopamine