Antinociceptive mechanism of L-DOPA.
The mechanism of L-DOPA for antinociception was investigated. Nociceptive behaviors in mice after an intrathecal (i.t.) administration of substance P were evaluated. L-DOPA (i.t.) dose-dependently attenuated the substance P-induced nociceptive behaviors. Co-administration of benserazide (i.t.), a DOPA decarboxylase inhibitor, abolished the antinociceptive effect of L-DOPA. The L-DOPA-induced antinociception was antagonized by sulpiride, a D2 blocker, but not by SCH 23390, a D1 blocker. These results suggest that L-DOPA relieves pain after conversion to dopamine, with the dopamine sedating pain transmission by way of the dopamine D2 receptor.
Department of Pharmacology, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima 890-8544, Japan.
Takao
T
Shimizu
Shin-ichi
S
Iwata
Hirofumi
H
Morioka
Takasi
T
Masuyama
Takeo
T
Fukuda
Masahiro
M
Nomoto
D000818:Animals; D001522:Behavior, Animal; D001545:Benserazide / Q000494:pharmacology; D001552:Benzazepines / Q000494:pharmacology; D004298:Dopamine / Q000008:administration & dosage; D015259:Dopamine Agents / Q000008:administration & dosage / Q000627:therapeutic use*; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D004791:Enzyme Inhibitors / Q000494:pharmacology; D007278:Injections, Spinal / Q000379:methods; D007980:Levodopa / Q000008:administration & dosage / Q000627:therapeutic use*; D008297:Male; D051379:Mice; D010146:Pain / Q000139:chemically induced / Q000188:drug therapy*; D010147:Pain Measurement / Q000379:methods; D013116:Spinal Cord / Q000187:drug effects / Q000382:microbiology; D013373:Substance P; D013997:Time Factors
D001552:Benzazepines; D015259:Dopamine Agents; D004791:Enzyme Inhibitors; D013373:Substance P; D007980:Levodopa; D001545:Benserazide; D004298:Dopamine