Levodopa analgesia in experimental neuropathic pain.
Levodopa has been shown to produce analgesia in various clinical and experimental settings, but its use for chronic pain treatment has not been established. We have undertaken a study of the antiallodynic actions of levodopa in a rat model of painful mononeuropathy. When administered systemically, levodopa produced a decrease in tactile and cold allodynia lasting at least 3h. Direct intrathecal (i.t.) levodopa injection at lumbar levels produced a similar, though shorter, antiallodynic effect. This effect was blocked by the D2-type receptor antagonist sulpiride, which supports the involvement of the spinal dopaminergic system in the analgesic action of levodopa on neuropathic pain. These results provide experimental support on the antiallodynic effect of levodopa in neuropathic pain and suggest that at least part of the analgesic action takes place in the spinal cord and involves dopaminergic D2-type receptors.
Cobacho
Nuria
N
Servicio de Neurobiología-Investigación, Hospital Ramón y Cajal, Carretera de Colmenar km 9, 28034 Madrid, Spain.
De la Calle
José L
JL
González-Escalada
José R
JR
Paíno
Carlos L
CL
D000700:Analgesics / Q000627:therapeutic use*; D000818:Animals; D004195:Disease Models, Animal; D018492:Dopamine Antagonists / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D007839:Functional Laterality; D006930:Hyperalgesia / Q000188:drug therapy*; D007980:Levodopa / Q000627:therapeutic use*; D008297:Male; D009043:Motor Activity / Q000187:drug effects; D009437:Neuralgia / Q000188:drug therapy*; D010147:Pain Measurement; D017288:Pain Threshold / Q000187:drug effects; D011597:Psychomotor Performance / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D045442:Rotarod Performance Test / Q000379:methods; D013469:Sulpiride / Q000494:pharmacology; D013997:Time Factors
D000700:Analgesics; D018492:Dopamine Antagonists; D007980:Levodopa; D013469:Sulpiride