Lack of anti-inflammatory effect of botulinum toxin type A in experimental models of inflammation.
Botulinum toxin type A (BTX-A) has a long-lasting antinociceptive activity and less clear effect on inflammation. It was proposed that these two effects share the same mechanism--the inhibition of neurotransmitter exocytosis from peripheral nerve endings. However, till now possible anti-inflammatory action of BTX-A did not evoke much attention. In the present paper, we investigate possible anti-inflammatory action of the toxin in carrageenan and capsaicin models of inflammation in rats. BTX-A (5 and 10 U/kg) was injected into the plantar surface of the rat right hind-paw pad 5 days before the injection of the carrageenan (1%) or capsaicin (0.1%) at the same site. Carrageenan-induced paw oedema and capsaicin-induced protein extravasation were measured. Control, inflamed and BTX-A pretreated inflamed paws were photographed and histopathological analysis (haematoxylin & eosin) was performed. Pretreatment with BTX-A had no effect on the size of carrageenan-induced paw oedema, measured as paw volume and weight or capsaicin-induced plasma extravasations, measured by Evans blue as a marker of protein leakage. Neither macroscopic nor microscopic analysis showed a significant difference between BTX-A pretreated and control inflamed tissue. Results show dissociation between the effect of BTX-A on pain and inflammation thus questioning the validity of the suggested assumption about the common peripheral mechanism of action.
Bach-Rojecky
Lidija
L
Department of Pharmacology, School of Pharmacy and Biochemistry, University of Zagreb, Zagreb, Croatia.
Dominis
Mara
M
Lacković
Zdravko
Z
D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000008:administration & dosage* / Q000627:therapeutic use; D019274:Botulinum Toxins, Type A / Q000008:administration & dosage* / Q000627:therapeutic use; D002211:Capsaicin / Q000633:toxicity; D002351:Carrageenan / Q000633:toxicity; D004195:Disease Models, Animal; D004487:Edema / Q000139:chemically induced / Q000188:drug therapy / Q000473:pathology*; D018836:Inflammation Mediators / Q000008:administration & dosage* / Q000627:therapeutic use; D008297:Male; D051381:Rats; D017208:Rats, Wistar
D000894:Anti-Inflammatory Agents, Non-Steroidal; D018836:Inflammation Mediators; D002351:Carrageenan; D019274:Botulinum Toxins, Type A; D002211:Capsaicin