Sodium Salicylate Decreases Glucose Turnover Rate in Periparturient Dairy Cows, Likely Through Enhanced Liver Insulin Sensitivity
Low-grade inflammation has been implicated as a contributor to metabolic disease during the transition to lactation. However, in previous work, administration of sodium salicylate (SS) for 7 d led to hypoglycemia in mature dairy cows in early lactation. The purpose of this study was to identify the mode of action underlying this response to SS. Twenty mature (3+ parity) cows were assigned alternately at time of calving to either control (CON) or SS treatments. CON treatment received a molasses carrier in drinking water while the SS received 2.5 g/L SS with the molasses carrier in drinking water for 7 d after parturition. Blood samples were collected daily. A glucose turnover assay was performed on day 7, followed by liver, muscle, and adipose tissue biopsies. Results were analyzed in the MIXED procedure of SAS with significance declared at P < 0.05. There were no treatment effects on DMI (P = 0.98) or water intake (P = 0.61). Tumor necrosis factor alpha (TNFa) mRNA expression was decreased by SS in adipose tissue (P = 0.09), but not in muscle (P = 0.97) or liver (P = 0.52), and plasma haptoglobin was not altered by treatment (P = 0.34). Though treatment did not alter plasma glucose or insulin concentrations, RQUICKI, a measure of insulin sensitivity, and plasma glucagon tended to be increased by SS (P = 0.08 for both). The insulin:glucagon ratio was increased by SS (P = 0.01). Cows on SS had a 25% decrease in glucose turnover rate (P = 0.05). There were no differences in mRNA expression of gluconeogenic genes in liver or of GLUT4 transporters in any of the tissues. These results indicate that SS may increase insulin sensitivity in mature fresh cows. This increase in sensitivity of insulin could explain the lower glucose turnover rate because of increased post-transcriptional inhibition of gluconeogenesis by insulin during SS treatment.
Keywords: NSAID, transition cow, insulin resistance