Lack of peripheral analgesia mediated by intraplantar administration of neostigmine in carrageenan-injected rats.
OBJECTIVE
The aim of the study was to test the peripheral analgesic action of neostigmine. Intraplantar administration of neostigmine was studied in carrageenan-injected rats.


METHODS
After assessing baseline values (T0) for paw circumference and the paw withdrawal threshold on both hind paws, the right hind paw was injected with 0.2 mL of 1% carrageenan and the left hind paw with 0.2 mL of saline (0.9% NaCl). Two hours later (T1), both hindpaws were tested for inflammation (paw circumference) and for hyperalgesia (paw withdrawal threshold) and subsequently 20 microg of neostigmine was injected in the right hind paw. The paw withdrawal threshold was tested again 10 (T2), 20 (T3) and 60 min (T4) and paw circumference 60 min (T4) after neostigmine injection.


RESULTS
Carrageenan injection in the right hindpaw was associated with a decrease in the paw withdrawal threshold reflecting mechanical hyperalgesia (P < 0.001) and an increase in paw circumference reflecting oedema (P < 0.001) in the right hind paw when compared with the left side from T1 to T4. Neostigmine had no effect on paw circumference and the paw withdrawal threshold at measuring points T2, T3 and T4 when compared with T1 in the right hindpaw.


CONCLUSIONS
Our results support the lack of peripheral analgesic effect of neostigmine.
Bouaziz
H
H
Laboratoire d'Anesthésie Réanimation Chirurgicale, Université Paris Sud, Département d'Anesthésie Réanimation Chirurgicale, Hôpital Bicêtre, Bicêtre, France.
Gentili
M E
ME
Girard
F
F
Mazoit
J X
JX
Benhamou
D
D
Laxenaire
M C
MC
Fletcher
D
D
D000700:Analgesics / Q000494:pharmacology*; D000818:Animals; D002351:Carrageenan; D002800:Cholinesterase Inhibitors / Q000008:administration & dosage / Q000494:pharmacology*; D005528:Foot; D006930:Hyperalgesia / Q000139:chemically induced / Q000517:prevention & control; D007249:Inflammation / Q000139:chemically induced / Q000523:psychology*; D007267:Injections; D008297:Male; D009388:Neostigmine / Q000008:administration & dosage / Q000494:pharmacology*; D010147:Pain Measurement / Q000187:drug effects; D017288:Pain Threshold / Q000187:drug effects; D017933:Peripheral Nervous System / Q000187:drug effects*; D051381:Rats; D017208:Rats, Wistar
D000700:Analgesics; D002800:Cholinesterase Inhibitors; D009388:Neostigmine; D002351:Carrageenan