Moderate differences in plasma leptin in mares have no effect on either the amino acid or the fatty acid composition of the uterine fluid

Female mammalian reproductive functions are closely linked to body condition and metabolic status. Energy homeostasis is regulated by endocrine hormones such as insulin, IGF-I, leptin and adiponectin via the hypothalamic-pituitary-adrenal axis. These metabolic hormones and their receptors are also expressed in reproductive tissues and the embryo. We investigated the relationship between circulating leptin and the fatty acid (FA) and amino acid (AA) composition of the equine uterine fluid (UF) and peripheral blood plasma (BP) by using a mass spectrometry-based approach. UF and BP were collected from ten broodmares on days 6 and 7 post ovulation, respectively. The mares were retrospectively assigned to two groups according to their BP leptin concentrations (high leptin (> 1.6 ng/ml) versus low leptin (<0.8 ng/ml)). Specific AA and FA compositions for BP and UF were found with different levels of respective metabolite abundances. The main FAs in BP were stearic, palmitic and linoleic acid. In UF, the three most abundant FAs were eicosapentaenoic, arachidonic and stearic acid. The AA profile of BP was dominated by glycine, glutamine, serine and alanine, which were likewise among the highly abundant AAs in UF. In UF, glutamic acid had by far the highest concentration. Therefore, BP leptin concentration within a physiological range do not seem to affect the specific FA nor the AA composition of the UF. The composition of the UF may therefore be mediated by local rather than by peripheral metabolic hormones.

Metabolic and satiating effects and consumer acceptance of a fibre-enriched Leberkas meal: a randomized cross-over trial

PURPOSE

The Western diet is poor in dietary fibre and previous efforts to increase fibre intake were not successful. The aim of this study was to develop sensorically appealing, fibre-enriched convenience foods. As a showcase, we prepared a fibre-enriched, fat-reduced Leberkas served in a roll and compared the reformulated product with the standard product.

METHODS

The design was a randomized, single-blinded cross-over study. A Leberkas meal enriched with 19.2 g of wheat fibre and resistant dextrin as well as fat- and energy-reduced (30% less calories) was served to 20 middle-aged healthy volunteers (10 male, 10 female) and compared to the standard product in a random order. Blood was repeatedly taken over a 4 h period to measure metabolic parameters as well as satiety hormones, such as glucagon-like-peptide 1, cholecystokinin, peptide YY. Satiety and consumer acceptance of the fibre-enriched meal were assessed by visual analogue scales and a questionnaire.

RESULTS

The fibre-enriched meal showed very small significant effects at only single time points in postprandial blood glucose (at 120 min, p = 0.050) and glucose_AUC fibre 22,079 ± 2819, standard 22,912 ± 3583 (p = 0.030). The profiles of satiety hormones were comparable between both meals. No differences in subjective satiation, taste and consumer acceptance were observed between the two products, despite a marked reduction in fat and energy content of the reformulated product.

CONCLUSION

It is possible to enrich a popular convenience product with dietary fibre and to markedly reduce energy content without loss of sensory qualities or satiety suggesting that development and promotion of healthier convenience foods may be a useful strategy to tackle obesity and other diet-related diseases.

6 Decelerating embryo development? Characterisation of the uterine environment in European roe deer (Capreolus capreolus) during diapause

The early developing embryo faces a continuously changing microenvironment to supports its growth. In the European roe deer, this environment accompanies embryonic diapause, a period of up to 4 months in which fertilization and subsequent implantation are decoupled. Diapause is characterised by a deceleration of embryonic growth. In most ruminants such as cattle and sheep, interferon tau (IFNt) plays a major role in maternal recognition of pregnancy. Uniquely to ruminants, the roe deer embryo does not secrete IFNt. The roe deer was used as a model species to gain insights into the changing uterine environment devoid of IFNt that supports prolonged decelerated embryo development, resumption of developmental velocity, and subsequent implantation. Uterine fluid samples from 188 female does were collected during regular huntings between September and January, and 4 developmental stages-blastocysts at early, mid, and late diapause and elongated embryos (16, 57, 97, and 18 does per developmental stage, respectively)-were defined. The developmental stages were assigned based on morphological characteristics of the embryo and the embryonic genomic DNA content. For the analysis of amino acids (AA), all 188 uterine fluid samples were subjected to targeted liquid chromatography-tandem mass spectrometry. Almost all AA increased over the course of embryo development. Although most AA showed developmental stage-specific concentration peaks, serine, glycine, alanine, glutamate, and glutamine were most abundantly present irrespective of the developmental progression. For the analysis of the protein abundances in the uterine fluid in a selected subset of samples (n=5 per developmental stage), holistic liquid chromatography-tandem mass spectrometry identified and quantified a total of 819 proteins with a false discovery rate of &lt;1%. Comparison between the developmental stages revealed 106 differentially abundant proteins. Most changes in protein abundance that occurred related to embryo elongation. Interestingly, 713 proteins remained stable during embryo development, indicating that these proteins may contribute to prolonged embryo survival during embryonic diapause. The differentially abundant proteins were clustered with DAVID Bioinformatics Resources 6.8 (https://david.ncifcrf.gov/). The most enriched clusters were cell-cell adhesion, biosynthesis of AA and carbon metabolism, microtubule, structural molecule activity, and chaperone binding. The ongoing detailed identification of stably abundant proteins will advance our basic understanding of the embryos’ needs for sustained survival during prolonged decelerated development. In addition, a comparison with the protein abundances around the time of maternal recognition of pregnancy in other species could advance our knowledge on conserved proteins that support embryo development and establishment of pregnancy in mammals. Our findings may contribute to defining optimal in vitro embryo culture conditions in a species-independent manner and potentially identify factors capable of halting embryo development.