br Author contributions br Acknowledgements We thank Dr Bob

Author contributions
Acknowledgements We thank Dr. Bob Hammer and the Transgenic Core Facility at UTSW for the generation of the transgenic lines, John Shelton and the Histology Core for assistance with histology and the UTSW Metabolic Core Unit for help in phenotyping. We acknowledge support from the National Institutes of Health (grants R01-DK55758, R01-DK99110 and P01-DK88761 to PES). WLH is supported by a R00-DK094973 and JDRF Award 5-CDA-2014-185-A-N. JYX is supported by a NIH fellowship F30-DK100095. JAJ is supported by NIH fellowship F30-DK108534. MJP is supported by a fellowship from the NW NARCH and NIHT32-GM008203.
Introduction Adiponectin, the most abundant secretory product of white adipose tissue, is a 30-kDa protein with structural features of the collagen superfamily [1]. Circulating adiponectin is composed of trimers (low molecular weight), combinations formed by a dimer of trimers (middle molecular weight), and complexes of six trimers (high molecular weight) [2]. Adiponectin also occurs in a smaller globular form, but plasma adiponectin is nearly always found in full-length form [3]. Adiponectin regulates energy homeostasis by fatty Letermovir oxidation, glucose uptake, and inhibition of gluconeogenesis. These lead to intensified thermogenesis and weight loss [4]. Adiponectin acts as an insulin-sensitizing agent by reducing hepatic glucose production and enhancing insulin action in the liver. Adiponectin levels are low in insulin-resistant subjects regardless of body weight, and they increase in insulin-sensitive states [5], [6]. In contrast to other adipokines, adiponectin levels are reduced in obesity. Circulating adiponectin concentrations in plasma range from 2 to 10 μg/mL and reveal a sexual dimorphism, with females having higher levels of adiponectin than males [7], [8]. The biological actions of adiponectin are mediated by 2 seven-transmembrane receptors, AdipoR1 and AdipoR2. AdipoR1 demonstrates higher affinity for adiponectin in the form of a trimer, and it is found in the highest concentrations in skeletal muscles, whereas AdipoR2, which is found mainly in the liver, shows greater affinity for middle molecular weight and high molecular weight forms [9]. AdipoR1 activates AMP kinase and mitogen-activated kinase pathways, whereas AdipoR2 acts mainly through the PPARα pathway [10]. Reproduction is dependent on energy availability. Adiponectin may serve as a signal-linking metabolic status with endocrine control of reproduction. It affects the reproductive system by exerting central effects on the hypothalamus and pituitary, peripheral effects on the ovaries and the uterus, and direct effects on the oocytes and embryos [11], [12]. The presence of the adiponectin system (adiponectin, AdipoR1, and AdipoR2) has been confirmed in human, rat, and porcine hypothalami [13], [14], pituitary glands [15], [16], and ovaries [17], [18], [19], [20] and in human, mouse, and porcine uteri [19], [21], [22], [23]. High circulating adiponectin levels appear to be associated with in vitro fertilization success [24], and serum adiponectin levels are reduced in women with endometriosis [25], polycystic ovarian syndrome [26], and endometrial cancer [27]. Changes in the expression of the adiponectin system in the porcine uterus and variations in plasma adiponectin levels in cyclic pigs further suggest that adiponectin expression and secretion are regulated by gonadal steroids or other hormones that control the estrous cycle [20], [23].
Materials and methods
Results
Discussion In the present study, the adiponectin system has been identified in the porcine endometrium (epithelial glandular cells, luminal epithelial cells, and stromal cells) and myometrium (longitudinal and circular muscle layers) on Days 10 to 11 of the estrous cycle and Days 10 to 11, 12 to 13, 15 to 16, 27 to 28, and 30 to 32 of gestation; in the conceptuses on Days 15 to 16, 27 to 28, and 30 to 32 of gestation; and in the trophoblasts on Days 27 to 28 and 30 to 32 of gestation. Our results demonstrate considerable variations in the expression of specific mRNAs and the corresponding proteins. The reason that no correlations or even opposite pattern of expression between protein concentrations and gene transcripts was found can probably be attributed to the transcriptional and post-transcriptional regulation (RNA processing and stability), differences in mRNA and protein stability, functioning feedbacks that suppress mRNA expression through high protein concentrations, and attenuation of post-transcriptional processes through high levels of gene expression [28]. Moreover, circulating adiponectin could also be accounting for the total adiponectin measured by Western blotting.