Variation factors of paraoxonase in blood and in HDL lipoproteins in dairy cow

Paraoxonase-1 (PON) is an antioxidant enzyme synthesized by liver and mainly associated with high density lipoproteins (HDL). Aim of this study was to investigate the alterations of PON1 activity in plasma (pPON) or bound to HDL (HDL-PON) in relation to inflammatory conditions and physiological stages. Between -30 to +300 days from calving, 9 cows were monitored for metabolic and inflammatory profiles, milk yield, body condition score and feed intake. Cows were divided in 2 groups based on their response to postpartum inflammatory stimulus (high and low Liver Functionality Index: HI-LFI and LO-LFI). pPON decreased after calving (P<0.05) and was directly correlated with milk yield (r=0.48; P<0.01), albumins and other indirect indexes of negative acute phase proteins (-APP: cholesterol and retinol binding protein). On the contrary, pPON was inversely related with the +APP (haptoglobin, ceruloplasmin) and related indexes (bilirubin, ROM). The correlation between pPON and HDL-PON was low. After calving, the HI-LFI vs LO-LFI group had higher -APP and pPON levels, lower HDL-PON level and displayed better performances. Overall results demonstrated that pPON has a similar behavior in comparison to -APP, confirming previous data. The results suggested that pPON activity could represent an useful marker to assess the severity of postpartum inflammatory phenomena and their consequences.