Histamine mediates the pro-inflammatory effect of latex of Calotropis procera in rats.
BACKGROUND
Calotropis procera is known to produce contact dermatitis and the latex of this plant produces intense inflammation when injected locally. However, the precise mode of its pro-inflammatory effect is not known. In present study we have pharmacologically characterized the inflammation induced by latex of C. procera in a rat paw edema model and determined the role of histamine in latex-induced inflammation.


METHODS
Inflammation was induced in the hind paw of rats by injecting different doses of dried latex (DL) of C. procera. The inhibitory effect of phenylbutazone, dexamethasone, celecoxib, cyproheptadine, chlorpheniramine and compound 48/80 on edema volume was evaluated and compared with that against carrageenan. The histamine content of DL was measured fluorometrically.


RESULTS
DL produced dose-dependent inflammation of the rat paw. Cyproheptadine and chlorpheniramine effectively inhibited DL-induced inflammation (90%; p < 0.01), while anti-inflammatory drugs phenylbutazone, dexamethasone and celecoxib were more effective against carrageenan-induced inflammation. Depletion of mast cell histamine by compound 48/80 produced a significant decrease in DL-induced inflammation as compared with carrageenan (500% versus 25%). DL was also found to contain about 6 microg/g of histamine.


CONCLUSIONS
Thus, our study shows that the biogenic amines play a significant role in C. procera latex-induced inflammation and antihistaminic drugs could be effectively used to inhibit inflammatory response elicited by exposure to latex.
Shivkar
Yatin M
YM
Department of Pharmacology, All India Institute of Medical Sciences, Ansari Nagar, New Delhi 110 029, India.
Kumar
Vijay L
VL
D000818:Animals; D031107:Calotropis / Q000009:adverse effects*; D002351:Carrageenan / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004487:Edema / Q000139:chemically induced; D006632:Histamine / Q000378:metabolism*; D007840:Latex / Q000494:pharmacology*; D020315:Latex Hypersensitivity / Q000276:immunology* / Q000378:metabolism; D008297:Male; D028321:Plant Preparations / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D003189:p-Methoxy-N-methylphenethylamine / Q000494:pharmacology
D007840:Latex; D028321:Plant Preparations; D003189:p-Methoxy-N-methylphenethylamine; D006632:Histamine; D002351:Carrageenan