Inorganic arsenic exposure affects pain behavior and inflammatory response in rat

• Published in: Toxicology and applied pharmacology 2008-06, Vol.229 (3), p.374-385
• Main Authors: Aguirre-Bañuelos, Patricia, Escudero-Lourdes, Claudia, Sanchez-Peña, Luz Carmen, Del Razo, Luz Maria, Perez-Urizar, Jose
• Format: Article
• Language: English
• Subjects: 60 APPLIED LIFE SCIENCES; Animals; ARSENIC; Arsenic in muscle; Arsenites - administration & dosage; Arsenites - toxicity; Behavior, Animal - drug effects; Biological and medical sciences; Carcinogenesis, carcinogens and anticarcinogens; Carrageenan; Chemical agents; Chemical and industrial products toxicology. Toxic occupational diseases; CONTAMINATION; Dinoprostone - metabolism; Disease Models, Animal; DOSES; DRINKING WATER; Drug Administration Schedule; Experimental pain; Female; FORMALDEHYDE; IN VITRO; IN VIVO; INFLAMMATION; Inflammation - chemically induced; Inflammation - physiopathology; Inflammatory pain; MACROPHAGES; Medical sciences; Metals and various inorganic compounds; NEOPLASMS; PAIN; Pain - etiology; Pain - physiopathology; Pain Measurement; Pain Threshold - drug effects; PROSTAGLANDINS; RATS; Rats, Wistar; SODIUM; Sodium Compounds - administration & dosage; Sodium Compounds - toxicity; Tail; Tissue inflammation; Toxicology; Tumors; Water Pollutants, Chemical - administration & dosage; Water Pollutants, Chemical - toxicity; Water Supply
• ISSN: 0041-008X; 1096-0333
• DOI: 10.1016/j.taap.2008.01.029

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.