Paraquat Exposure Up-regulates Cyclooxygenase-2 in the Lungs, Liver and Kidneys in Rats

Paraquat is a commonly used herbicide in many countries which can lead to systematic poisoning on exposure, In this study, paraquat (PQ)-induced changes in the expression of Cyclooxygenase-2 (COX-2) along with biochemical and histopathological changes in the lungs, liver and kidneys were studied. Twenty four male Wistar rats (180-200 g) were exposed either against saline as control group or various doses of PQ (3.5, 7 and 10 mg/kg, SC) as test groups for 7 consecutive days. The animals in test groups demonstrated a significant increase of malondialdehyde and NO contents, while a remarkable decrease of total thiol molecules was recorded. Histopathological studies revealed a severe alveolar edema and hemorrhages in the lungs, congestion and glycogen degeneration in the liver and multifocal interstitial nephritis along with proximal tubular degeneration in the kidneys. PQ up-regulated the COX-2 expression at mRNA level significantly in the examined organs. This data suggest that the PQ-induced oxidative disturbances and pathological damages can be attributed to the upregulation of COX-2 in examined organs.