Adiponectin in the mandibular glands of cows fed a diet supplemented with essential fatty acids

The adipokine adiponectin is mainly expressed in adipose tissue but also found in human and mice salivary glands. Recent studies have shown that there is a relationship between the expression of adipokines and the characteristics of the diet. In particular, the n-3 fatty acids status is positively linked with plasma adiponectin concentrations. In this study, the presence and distribution of adiponectin in the bovine mandibular gland (MG) were investigated to test possible effects from different compositions of dietary fatty acids. Rumen fistulated Holstein cows (n=38, 11.000 kg milk in 2nd lactation) were fitted with abomasal infusion tubes and fed a corn silage based total mixed ration. Cows were infused twice daily with either coconut oil delivering medium-chain fatty acids (CTRL: 76 g/d), linseed-safflower oil mix, delivering mainly n-3 fatty acids (EFA: 78 + 4 g/d, respectively), LUTALIN (content ofc9,tll and tl0,cl2 conjugated linoleic acids (CLA) in equal amounts; 10 g/d), or EFA + CLA from 9 wk antepartum to 9 wk postpartum. MG were quickly removed after slaughter and processed for routinely tissue preparation. The immunohistochemical reaction was visualised using a polyclonal anti-adiponectin antibody and DAB as chromogen. The software ImageJ, IHC Profiler plugin, was used for the analysis of the immunoreaction. The immunohistochemical study showed a positive reaction for adiponectin in the cytoplasm of ductal epithelial cells and in the serous acinar cells in the CTRL animals. Cows supplemented with EFA or CLA or both showed a positive signal for adiponectin only in the serous cells . These results showed that adiponectin is present in the CTRL bovine MG with a distribution that reflects what has been already described in humans and mice. The differences are linked with the supplements and may suggest a negative effect of fatty acids on local adiponectin production.