Inorganic arsenic exposure affects pain behavior and inflammatory response in rat.
Inorganic arsenic (iAs) contamination of drinking water is a worldwide problem associated with an increased risk for the development of various types of cancer and noncancerous damage. In vitro studies have suggested that iAs can modulate the activity of macrophages producing an over-expression of cyclooxygenase-2 (COX-2) and resulting in an increase in prostaglandin E(2) (PGE(2)) concentrations in endothelial cells. These effects may lead to an in vivo enhancement of inflammatory and pain responses. Our aim was to determine the effect of a single dose of arsenic or subchronic exposure to arsenic on pain behavior and tissue inflammation in rats. Rats were given a single dose of sodium arsenite (0.1, 1 and 10 mg/kg i.p.) or submitted to subchronic exposure to arsenic added to the drinking water for 4 weeks (0.1, 1, 10 and 100 ppm). Inflammatory pain was assessed by using the formalin and tail-flick tests, while inflammation was evaluated with the carrageenan model. Arsenite did not induce pain or significant inflammation by itself. In contrast, arsenite in both single dose administration and subchronic exposure increased not only the inflammatory process and the underlying hyperalgesic pain, but also induced a decrease in the pain threshold. Alterations in pain processing were dependent on the arsenic dose and the length of exposure, and the underlying mechanism involved an increased release of local PGE(2). These results suggest that inorganic arsenic exposure enhances pain perception and exacerbates the pathological state of inflammatory diseases.
Aguirre-Bañuelos
Patricia
P
Facultad de Ciencias Químicas, Universidad Autónoma de San Luis Potosí, San Luis Potosí, 78200 México.
Escudero-Lourdes
Claudia
C
Sanchez-Peña
Luz Carmen
LC
Del Razo
Luz Maria
LM
Perez-Urizar
Jose
J
D000818:Animals; D018053:Arsenites / Q000008:administration & dosage / Q000633:toxicity*; D001522:Behavior, Animal / Q000187:drug effects*; D002351:Carrageenan; D015232:Dinoprostone / Q000378:metabolism; D004195:Disease Models, Animal; D004334:Drug Administration Schedule; D005260:Female; D005557:Formaldehyde; D007249:Inflammation / Q000139:chemically induced* / Q000503:physiopathology; D010146:Pain / Q000209:etiology / Q000503:physiopathology; D010147:Pain Measurement; D017288:Pain Threshold / Q000187:drug effects; D051381:Rats; D017208:Rats, Wistar; D017670:Sodium Compounds / Q000008:administration & dosage / Q000633:toxicity*; D013623:Tail; D014874:Water Pollutants, Chemical / Q000008:administration & dosage / Q000633:toxicity*; D014881:Water Supply
D018053:Arsenites; D017670:Sodium Compounds; D014874:Water Pollutants, Chemical; D005557:Formaldehyde; C017947:sodium arsenite; D002351:Carrageenan; D015232:Dinoprostone