title: Investigation of modulation of the alpha-2 receptor in tetrahydropalmatine (THP) analgesia in male Sprague-Dawley rats.
abstract: The increased use of nutraceuticals over the past 20 years makes it essential to know the effects these may have with anesthetics and analgesics (Kaye et al., 2000). Tetrahydropalmatine (THP), a derivative of the herb corydalis, may have analgesic properties (Hu & Jin, 2000a; Wei, Zou, Young, Dubner, & Ren, 1999); however, the mechanism of action is unclear. We proposed that THP may modulate alpha-2 receptors and interact with dexmedetomidine, a known alpha-2-receptor agonist, used for sedation. Fifty-five male Sprague-Dawley rats, divided into five groups, were administered the following by intraperitoneal injection: (1) vehicle, (2) dexmedetomidine, (3) THP, (4) THP and yohimbine, and (5) THP and dexmedetomidine. A baseline measurement of hot-plate latency was recorded, followed by an injection of appropriate compound(s). Testing occurred at 5, 10, 30, and 60 min after injections. Repeated measures ANOVA suggested a significant difference among groups (f = 8.09; p = 0.00). Post hoc Bonferroni suggested that THP significantly prolonged reaction time on the hot plate compared to vehicle (p =. 037). Rats injected with THP and yohimbine did not have significantly shorter latency times compared to those injected with THP alone suggesting that THP does not modulate alpha-2 receptors. Finally, rats injected with THP and dexmedetomidine did not demonstrate a significantly increased latency time compared to THP alone, suggesting no additive effect of THP.
authors.affiliation: US Army Graduate Program in Anesthesia Nursing, Fort Leonard Wood, MO 65473, USA. winston.bruce@us.army.mil
authors.forename: Winston
authors.initials: W
authors.lastname: Bruce
authors.forename: Heather
authors.initials: H
authors.lastname: Fonder
authors.forename: Joshua
authors.initials: J
authors.lastname: Compton
authors.forename: Normalynn
authors.initials: N
authors.lastname: Garrett
mesh_terms: D058647:Adrenergic alpha-2 Receptor Agonists / Q000494:pharmacology / Q000627:therapeutic use; D000698:Analgesia; D000700:Analgesics / Q000494:pharmacology* / Q000627:therapeutic use; D000704:Analysis of Variance; D000818:Animals; D001600:Berberine Alkaloids / Q000494:pharmacology* / Q000627:therapeutic use; D031311:Corydalis / Q000737:chemistry*; D020927:Dexmedetomidine / Q000494:pharmacology*; D041743:Herb-Drug Interactions; D006358:Hot Temperature; D006993:Hypnotics and Sedatives / Q000494:pharmacology; D008297:Male; D010146:Pain / Q000188:drug therapy; D017288:Pain Threshold / Q000187:drug effects; D008517:Phytotherapy; D010936:Plant Extracts / Q000494:pharmacology / Q000627:therapeutic use; D051381:Rats; D017207:Rats, Sprague-Dawley; D018341:Receptors, Adrenergic, alpha-2 / Q000378:metabolism*; D015016:Yohimbine / Q000494:pharmacology
chemical_list: D058647:Adrenergic alpha-2 Receptor Agonists; D000700:Analgesics; D001600:Berberine Alkaloids; D006993:Hypnotics and Sedatives; D010936:Plant Extracts; D018341:Receptors, Adrenergic, alpha-2; D015016:Yohimbine; C014215:tetrahydropalmatine; D020927:Dexmedetomidine