Characterization of adiponectin concentrations and molecular weight forms in serum, seminal plasma, and ovarian follicular fluid from cattle.

Adiponectin (AdipoQ), an adipocyte-derived hormone, is one of the most abundant adipokines in the blood circulation. Adiponectin has various metabolic functions, such as improving insulin sensitivity in humans and rodents. The role of AdipoQ in reproduction is not yet fully understood, but the expression of AdipoQ in reproductive tissues has been observed in various animals and humans, including chicken testis, bovine ovary, and human placenta. The objective of this study was to characterize AdipoQ in the bovine body fluids related to reproduction. Therefore, we evaluated the seminal plasma (SP) from breeding bulls (n = 29) and follicular fluid (FF) from heifers (n = 14), and we also collected blood samples from these animals. In addition, blood samples from other bulls (n = 30) and heifers (n = 14) were assayed for AdipoQ. The concentrations were assessed using a bovine-specific ELISA, and the molecular weight (MW) pattern of the AdipoQ protein was estimated by the Western blot analysis. The SP AdipoQ concentrations were approximately 180-fold lower compared with that in the serum concentrations. Furthermore, the AdipoQ concentrations in the serum and SP were positively correlated. The MW patterns of AdipoQ in the serum and SP were different such that the high MW form of AdipoQ was more abundant in the SP than serum. The AdipoQ concentrations in the serum and SP also increased with age: old bulls (>6 years) had higher AdipoQ concentrations in the serum and SP than bulls aged 24 months or lesser (P < 0.05). In the FF, the AdipoQ concentrations were 1.6-fold lower than those in the corresponding serum samples, and the concentrations in the serum and FF were not correlated (P > 0.1). In the FF, only the middle MW forms of AdipoQ were detectable by Western blotting. The MW pattern in the serum did not differ between the sexes. Our data provide both the AdipoQ concentration and the MW patterns for bovine body fluids related to reproduction.

Supplementation with conjugated linoleic acids extends the adiponectin deficit during early lactation in dairy cows.

Decreasing insulin sensitivity (IS) in peripheral tissues allows for partitioning nutrients towards the mammary gland. In dairy cows, extensive lipid mobilization and continued insulin resistance (IR) are typical for early lactation. Adiponectin, an adipokine, promotes IS. Supplementation with conjugated linoleic acids (CLA) in rodents and humans reduces fat mass whereby IR and hyperinsulinemia may occur. In dairy cows, CLA reduce milk fat, whereas body fat, serum free fatty acids and leptin are not affected. We aimed to investigate the effects of CLA supplementation on serum and adipose tissue (AT) adiponectin concentrations in dairy cows during the lactation driven and parity modulated changes of metabolism. High yielding cows (n=33) were allocated on day 1 post partum to either 100 g/day of a CLA mixture or a control fat supplement (CON) until day 182 post partum. Blood and subcutaneous (sc) AT (AT) biopsy samples were collected until day 252 post partum to measure adiponectin. Serum adiponectin decreased from day 21 pre partum reaching a nadir at calving and thereafter increased gradually. The distribution of adiponectin molecular weight forms was neither affected by time, parity nor treatment. Cows receiving CLA had decreased serum adiponectin concentrations whereby primiparous cows responded about 4 weeks earlier than multiparous cows. The time course of adiponectin concentrations in sc AT (corrected for residual blood) was similar to serum concentrations, without differences between CLA and CON. CLA supplementation attenuated the post partum increase of circulating adiponectin thus acting towards prolongation of peripartal IR and drain of nutrients towards the mammary gland.