Resistin is produced principally by adipocytes in mice, whereas it is produced predominantly by peripheral blood mononuclear cells, macrophages and bone marrow cells in humans. The production of resistin in bovine adipose tissue has already been reported. We also demonstrated that plasma resistin concentration was significantly higher one week after calving than before calving or six weeks postpartum. Consistent with these results, we found that resistin mRNA and protein levels in subcutaneous adipose tissue were higher at 1 WPP than at 5 MG, suggesting that the high plasma concentrations of resistin at 1 WPP are generated by the adipose tissue. Lactation in dairy cows is known to be associated with many metabolic changes, including the loss of a large amount of adipose tissue. In our study, the animals lost more than 1 kg of body weight/day during early lactation. These results are consistent with those of Jarrige that indicates a mobilization of body fat from 15 to 60 kg after parturition. As expected,AS1517499 plasma NEFA concentration was also found to have increased considerably at 1 WPP, reflecting a high level of lipid mobilization. The plasma concentration profiles of NEFAs and resistin were similar during the peri-partum period. However, the nadir for plasma resistin was reached at 4 WPP while those for plasma NEFAs at 6 WPP. In vitro, in bovine adipose tissue explants from animals at about the same physiological status, we showed that recombinant bovine resistin at a concentration of 100 ng/ml increased the release of glycerol and the expression of the ATGL and HSL genes. This concentration is physiologically relevant because we measured a plasma resistin concentration of about 90 ng/ml at one week post-partum when plasma NEFAs were high. In adipose tissue of cows, hydrolysis of triacylglycerols is mediated by hormone-sensitive lipase under stimulation of catecholamines. Concomitantly with the decrease in HSL expression, plasma NEFA levels are high during the early postpartum period. Resistin induces lipolysis in human adipocytes. The secretion of GH is also high in early lactation. Growth hormone stimulates the mobilization of NEFAs from adipose tissue by inhibiting insulin-mediated lipogenesis and increasing the lipolytic response to beta adrenergic signals. However, the regulation of GH receptor expression in the adipose tissue of early lactation dairy cows is unclear. In rodents or human,Pancreatin GH increases resistin gene expression in white adipose tissue or serum resistin levels. Thus, we can hypothesis that resistin could participate to the in vivo GH effects on the adipose tissue of dairy cows. However, we observed that resistin induces in vitro mRNA expression of ATGL and HSL mRN on adipose tissue explants suggesting that resistin could also act independently of GH. We found that plasma insulin and glucose concentrations followed patterns typical of the peri-partum period, declining sharply at 1 WPP. By contrast, plasma resistin levels and the levels of resistin mRNA and protein in adipose tissue increased during this period. Komatsu et al. also reported higher levels of resistin production in adipose tissue and lower plasma insulin concentrations in dairy cows at peak lactation than in dry animals. Plasma concentrations of two other adipokines, leptin and adiponectin, have been analyzed in dairy cows.