Nociceptive and edematogenic responses elicited by a crude bristle extract of Lonomia obliqua caterpillars.
Lyophilized Lonomia obliqua crude bristle extract (LOCBE) diluted in physiological saline (15, 35 and 50 microg of protein/paw) was injected in the plantar surface of the hind paw of the rat, causing a nociceptive response which lasted from 30 to a maximum of 50 min, peaking in the first 5 min. The animals also presented hematuria and nasal bleeding. Nociception was inhibited by indomethacin pretreatment (2.5 mg/kg, i.p., 60 min before), but not by guanethidine (30 mg/kg/day, s.c., for 3 days) or loratadine (5 mg/kg, p.o., 60 min before). LOCBE injection also produced paw edema peaking 1 h after injection and lasting for 6 h. Loratadine pretreatment, but neither guanethidine nor indomethacin, reduced edema. After the period of overt nociception, a nociceptive aftersensation response could be evoked up to 6 h after by immersing the paw into cold water (15 degrees C) for 10 s. Capsaicin (1.6 microg), formalin (0.5%) or prostaglandin E(2) (500 ng) did not produce the same aftersensation phenomenon. These results suggest that LOCBE-induced nociception is largely facilitated by prostaglandin production, and edematogenic response seems to be facilitated by prostanoids and histamine. Finally, LOCBE induced a state of sensitization to cold, which seemed to be specific as it was not caused by other noxious chemicals.
de Castro Bastos
Lúcia
L
Department of Pharmacology, Federal University of Santa Catarina, P.O. Box 476, Florianópolis, SC 88040-900, Brazil.
Veiga
Ana Beatriz Gorini
AB
Guimarães
Jorge A
JA
Tonussi
Carlos Rogério
CR
D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal; D001180:Arthropod Venoms / Q000008:administration & dosage / Q000633:toxicity*; D004305:Dose-Response Relationship, Drug; D004487:Edema / Q000139:chemically induced*; D006145:Guanethidine; D007213:Indomethacin; D017336:Loratadine; D008297:Male; D010146:Pain / Q000139:chemically induced*; D051381:Rats; D017208:Rats, Wistar
D000894:Anti-Inflammatory Agents, Non-Steroidal; D001180:Arthropod Venoms; D017336:Loratadine; D007213:Indomethacin; D006145:Guanethidine