Abstract BACKGROUND: Inflammation and oxidative stress are associated with cardiovascular diseases and underlying atherosclerosis. The high density lipoprotein (HDL)-associated paraoxonase-1 (PON1) enzyme is known to be involved in the protection of serum lipids from such oxidation. Nonetheless, the disturbances of lipid profile during nematode-infected model have not yet been studied. Therefore, we aimed to explore the effects of Nippostrongylus brasiliensis infection in male Wistar rats, a model of human gastrointestinal nematode infections, on hepatic PON1 synthesis and the levels of lipid parameters. MATERIALS AND METHODS: Nippostrongylus brasiliensis-infected rats fed standard and high-fat diets. Serum paraoxonase and arylesterase activities were measured on day 0, 2, 4, 7, and 14 post-infection (PI). Hepatic PONs and pro-inflammatory cytokines mRNA expression levels were evaluated in a standard diet-fed groups, and the disturbances in lipid profile as well as the levels of thiobarbituric acid reactive species (TBARS) and oxidized-LDL (Ox-LDL) were measured in high-fat diet-fed groups. RESULTS: We found that N. brasiliensis-infected rats fed the standard diet show a significant reduction in serum PON1 activity and down-regulation of hepatic PON1 mRNA expression as well as up-regulation of hepatic IL-1β, IL-β receptor (R), TNF-α, and TNFR1 mRNA expressions in association with hepatic recruitments of Kupffer cells and neutrohils. In the presence of the high-fat diet, N. brasiliensis infection increases serum triglycerides, total cholesterol, LDL/VLDL, TBARS and Ox-LDL as well as decreases serum HDL coinciding with a maximum serum PON1 reduction. CONCLUSIONS: Nippostrongylus brasiliensis infection can induce atherogenic lipid profile and reduce serum PON1 activity.