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.
Shimizu
Takao
T
Department of Pharmacology, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima 890-8544, Japan.
Iwata
Shin-ichi
S
Morioka
Hirofumi
H
Masuyama
Takasi
T
Fukuda
Takeo
T
Nomoto
Masahiro
M
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