Fattori di variazione della paraoxonasi nel sangue nella bovina da latte

[Autom. eng. transl.] Paraoxonase (PON) is an antioxidant enzyme of liver synthesis mainly associated with HDL lipoproteins. It is known that PON is reduced during inflammatory states, but in dairy cattle the variation factors have been little investigated. In the present study we aimed to evaluate the effect of the physiological stage and of the inflammatory conditions in the peripartum on the PON content in plasma (PONp) and in HDL lipoproteins (PON-HDL), in 9 multi-polar Friesian cows. On the plasma taken at -30, 7, 30, 60, 90, 120, 180, 240, 300 days from delivery (DIM) a broad metabolic-inflammatory profile was determined, as well as the activity of PONp and PON , HDL. For each cow, milk production, fattening status, food intake and health status were also detected. To assess the negative consequences of the inflammatory state in the peripartum, the cows were divided into two groups (high = HI and low = LO) based on the Liver Functionality Index (LFI), which evaluates the variations of albumins, cholesterol and bilirubin in the first 30 DIM. The statistical analysis was performed with ANOVA for repeated observations, considering physiological and LFI phases as main factors, and calculating the simple correlation indices over the entire period, at -30 / + 90 and + 120 / + 300 DIM. PONp decreased after delivery (P <0.05), but progressively increased returning to the pre-delivery values from DIM 120. The PON-HDL level (expressed per mg of lipoprotein) showed a similar trend, but the dry values were the highest. The correlation between the two parameters, calculated over the entire period, was modest (r = 0.24; P <0.05), probably due to a different binding affinity of the enzyme with increasing lipoproteins in the blood. The main blood changes observed throughout the period concerned the energy balance indexes and those of the inflammatory state. Among the former, NEFA and β-hydroxy butyrate showed the peak at DIM 7 and from DIM 90 returned to pre-birth levels. Among the latter, the acute phase proteins showed the typical variations of the peripartum: peak positive (+ APP) at DIM 7 and then gradual decline (haptoglobin and ceruloplasmin), minimum of negative (-APP) to DIM 7 followed by a more or less rapid increase (albumins; cholesterol, as an index of lipoproteins; retinol, as an index of its carrier protein). Bilirubin and reactive oxygen metabolites (ROM) showed a similar trend to + APP. The most interesting correlations are those referred to the peripartite (from -30 to +90 DIM). PONp was positively correlated with –APP: cholesterol (r = 0.29; P <0.06), albumins (r = 0.49; P <0.001) and retinol (r = 0.37; P <0 , 05). Negative correlations have instead emerged between PONp and + APP: haptoglobin (r = -0.31; P <0.05), bilirubin (r = -0.42; P <0.01) and ROM (r = -0, 46; P <0.01). In advanced lactation, PONp presented correlations only with albumins (r = 0.60; P <0.001) and retinol (r = 0.42; P <0.05). Considering the PON-HDL the correlations with the + APP are confirmed, while with the –APP it remains only with the albumins. With reference to the severity of post-natal inflammatory phenomena, cows with the most severe consequences (LO), as attested by a slower recovery of the -APP, showed a slower postpartum increase in PONp (P <0.10 at DIM 30 vs HI); on the contrary, PON-HDL levels have always remained higher (ns). This increased concentration, despite the lower lipoprotein level (vs HI), suggests a modified functional PON ratio within HDL lipoproteins. These results confirm the relationship of PON with inflammatory processes, partly because it follows the reduction of HDL in peripart