Inhibitory effect of processed Aconiti tuber on the development of antinociceptive tolerance to morphine: evaluation with a thermal assay.
In the previous studies, we demonstrated that an oriental herbal medicine processed Aconiti tuber (PAT) at subanalgesic doses could inhibit the development of mechanical antinociceptive tolerance to morphine using the tail pressure test. In the present study, we evaluated whether PAT could inhibit thermal antinociceptive tolerance to morphine using the high temperature (55 degrees C) hot plate test. Mice received subcutaneous morphine (10mg/kg), and oral PAT at doses that did not inhibit the hot plate response (0.3, 0.5, 1.0, and 2.0 g/kg), once daily for 14 days. The thermal nociceptive latency was measured at 30 min after daily morphine injections. Compared with placebo, oral PAT partially and dose-dependently inhibited the development of morphine tolerance in morphine-naïve mice, and reversed already-developed morphine tolerance in morphine-tolerant mice. These data suggested that PAT at subanalgesic doses could dose-dependently inhibit and reverse thermal antinociceptive tolerance to morphine.
Shu
Haihua
H
Department of Anesthesiology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan.
Hayashida
Masakazu
M
Chiba
Shunsuke
S
Sekiyama
Hiroshi
H
Kitamura
Takayuki
T
Yamada
Yoshitsugu
Y
Hanaoka
Kazuo
K
Arita
Hideko
H
D031841:Aconitum / Q000737:chemistry*; D000700:Analgesics / Q000627:therapeutic use*; D000818:Animals; D004361:Drug Tolerance; D006358:Hot Temperature; D008297:Male; D051379:Mice; D009020:Morphine / Q000627:therapeutic use*; D010146:Pain / Q000188:drug therapy*; D008517:Phytotherapy; D035281:Plant Tubers / Q000737:chemistry; D010946:Plants, Medicinal
D000700:Analgesics; D009020:Morphine