Biological underpinnings of breastfeeding challenges: the role of genetics, diet, and environment on lactation physiology
Lactation is a dynamic process that has evolved to produce a complex biological fluid that provides nutritive and nonnutritive factors to the nursing offspring. It has long been assumed that once lactation is successfully initiated, the primary factor regulating milk production is infant demand. Thus, most interventions have focused on improving breastfeeding education and early lactation support. However, in addition to infant demand, increasing evidence from studies conducted in experimental animal models, production animals, and breastfeeding women suggests that a diverse array of maternal factors may also affect milk p...
Source: AJP: Endocrinology and Metabolism - August 7, 2016 Category: Endocrinology Authors: Lee, S., Kelleher, S. L. Tags: Reviews Source Type: research
Elevated expression of the Sertoli cell androgen receptor disrupts male fertility
Recently, we created a unique gain-of-function mouse model with Sertoli cell-specific transgenic androgen receptor expression (TgSCAR) showing that SCAR activity controls the synchronized postnatal development of somatic Sertoli and Leydig cells and meiotic-postmeiotic germ cells. Moderate TgSCAR (TgSCARm) expression reduced testis size but had no effect on male fertility. Here, we reveal that higher TgSCAR expression (TgSCARH) causes male infertility. Higher SCAR activity, shown by upregulated AR-dependent transcripts (Rhox5, Spinw1), resulted in smaller adult TgSCARH testes (50% of normal) despite normal or elevated circ...
Source: AJP: Endocrinology and Metabolism - July 20, 2016 Category: Endocrinology Authors: Hazra, R., Upton, D., Desai, R., Noori, O., Jimenez, M., Handelsman, D. J., Allan, C. M. Tags: Articles Source Type: research
Proposed mechanisms for oligonucleotide IMT504 induced diabetes reversion in a mouse model of immunodependent diabetes
Type 1 diabetes (T1D) originates from autoimmune β-cell destruction. IMT504 is an immunomodulatory oligonucleotide that increases mesenchymal stem cell cloning capacity and reverts toxic diabetes in rats. Here, we evaluated long-term (20 doses) and short-term (2–6 doses) effects of IMT504 (20 mg·kg–1·day–1 sc) in an immunodependent diabetes model: multiple low-dose streptozotocin-injected BALB/c mice (40 mg·kg–1·day–1 ip for 5 consecutive days). We determined blood glucose, glucose tolerance, serum insulin, islet morphology, islet infiltration, serum cytokines,...
Source: AJP: Endocrinology and Metabolism - July 20, 2016 Category: Endocrinology Authors: Bianchi, M. S., Bianchi, S., Hernado-Insua, A., Martinez, L. M., Lago, N., Libertun, C., Chasseing, N. A., Montaner, A. D., Lux-Lantos, V. A. Tags: Articles Source Type: research
The expansion of adult stem/progenitor cells and their marker expression fluctuations are linked with pituitary plastic adaptation during gestation and lactancy
Extensive evidence has revealed variations in the number of hormone-producing cells in the pituitary gland, which occur under physiological conditions such as gestation and lactancy. It has been proposed that new hormone-producing cells differentiate from stem cells. However, exactly how and when this takes place is not clear. In this work, we used immunoelectron microscopy to identify adult pituitary stem/progenitor cells (SC/P) localized in the marginal zone (MZ), and additionally, we detected GFRa2-, Sox2-, and Sox9-positive cells in the adenoparenchyma (AP) by fluorescence microscopy. Then, we evaluated fluctuations of...
Source: AJP: Endocrinology and Metabolism - July 20, 2016 Category: Endocrinology Authors: Vaca, A. M., Guido, C. B., Sosa, L. d. V., Nicola, J. P., Mukdsi, J., Petiti, J. P., Torres, A. I. Tags: Articles Source Type: research
Accuracy and precision of quantitative 31P-MRS measurements of human skeletal muscle mitochondrial function
Although theoretically sound, the accuracy and precision of 31P-magnetic resonance spectroscopy (31P-MRS) approaches to quantitatively estimate mitochondrial capacity are not well documented. Therefore, employing four differing models of respiratory control [linear, kinetic, and multipoint adenosine diphosphate (ADP) and phosphorylation potential], this study sought to determine the accuracy and precision of 31P-MRS assessments of peak mitochondrial adenosine-triphosphate (ATP) synthesis rate utilizing directly measured peak respiration (State 3) in permeabilized skeletal muscle fibers. In 23 subjects of different fitness ...
Source: AJP: Endocrinology and Metabolism - July 20, 2016 Category: Endocrinology Authors: Layec, G., Gifford, J. R., Trinity, J. D., Hart, C. R., Garten, R. S., Park, S. Y., Le Fur, Y., Jeong, E.-K., Richardson, R. S. Tags: Articles Source Type: research
Glucose uptake saturation explains glucose kinetics profiles measured by different tests
In conclusion, glucose clearance in euglycemic and hyperglycemic clamps and oral tests can be described with a unifying model, consistent with the notions of glucose transport and able to reproduce the suppression of glucose clearance due to hyperglycemia observed in previous studies. The model may be important for the design of reliable glucose homeostasis simulators. (Source: AJP: Endocrinology and Metabolism)
Source: AJP: Endocrinology and Metabolism - July 20, 2016 Category: Endocrinology Authors: Bizzotto, R., Natali, A., Gastaldelli, A., Muscelli, E., Krssak, M., Brehm, A., Roden, M., Ferrannini, E., Mari, A. Tags: Articles Source Type: research
Insulin decreases atherosclerotic plaque burden and increases plaque stability via nitric oxide synthase in apolipoprotein E-null mice
In conclusion, we demonstrate that insulin treatment decreases atherosclerotic plaque burden and increases plaque stability through NOS-dependent mechanisms. (Source: AJP: Endocrinology and Metabolism)
Source: AJP: Endocrinology and Metabolism - July 20, 2016 Category: Endocrinology Authors: Mori, Y., Chiang, S., Bendeck, M. P., Giacca, A. Tags: Articles Source Type: research
Sodium nitrate co-ingestion with protein does not augment postprandial muscle protein synthesis rates in older, type 2 diabetes patients
The age-related anabolic resistance to protein ingestion is suggested to be associated with impairments in insulin-mediated capillary recruitment and postprandial muscle tissue perfusion. The present study investigated whether dietary nitrate co-ingestion with protein improves muscle protein synthesis in older, type 2 diabetes patients. Twenty-four men with type 2 diabetes (72 ± 1 yr, 26.7 ± 1.4 m/kg2 body mass index, 7.3 ± 0.4% HbA1C) received a primed continuous infusion of l-[ring-2H5]phenylalanine and l-[1-13C]leucine and ingested 20 g of intrinsically l-[1-13C]phenylalanine- and l-[1-13C]leucine-l...
Source: AJP: Endocrinology and Metabolism - July 20, 2016 Category: Endocrinology Authors: Kouw, I. W. K., Cermak, N. M., Burd, N. A., Churchward-Venne, T. A., Senden, J. M., Gijsen, A. P., van Loon, L. J. C. Tags: Articles Source Type: research
Mathematical modeling of the circadian dynamics of the neuroendocrine-immune network in experimentally induced arthritis
We present a mathematical model that describes the circadian interactions between mediators of the hypothalamic-pituitary-adrenal (HPA) axis and the proinflammatory cytokines. Model predictions demonstrate that chronically elevated cytokine expression results in the development of adrenal insufficiency and circadian variability in paw edema. Notably, our model also predicts that an increase in mean secretion of corticosterone (CST) after the induction of the disease is accompanied by a decrease in the amplitude of the CST oscillation. Furthermore, alterations in the phase of circadian oscillation of both cytokines and HPA ...
Source: AJP: Endocrinology and Metabolism - July 20, 2016 Category: Endocrinology Authors: Rao, R., DuBois, D., Almon, R., Jusko, W. J., Androulakis, I. P. Tags: Articles Source Type: research
Dynamics of glucagon secretion in mice and rats revealed using a validated sandwich ELISA for small sample volumes
In conclusion, dynamic analysis of glucagon secretion in rats and mice with the novel accurate sandwich enzyme-linked immunosorbent assay revealed extremely rapid and short-lived responses to arginine and rapid and profound suppression by glucose. (Source: AJP: Endocrinology and Metabolism)
Source: AJP: Endocrinology and Metabolism - July 20, 2016 Category: Endocrinology Authors: Wewer Albrechtsen, N. J., Kuhre, R. E., Windelov, J. A., Orgaard, A., Deacon, C. F., Kissow, H., Hartmann, B., Holst, J. J. Tags: Innovative Methodology Source Type: research
Targeted overexpression of mitochondrial catalase protects against cancer chemotherapy-induced skeletal muscle dysfunction
The loss of strength in combination with constant fatigue is a burden on cancer patients undergoing chemotherapy. Doxorubicin, a standard chemotherapy drug used in the clinic, causes skeletal muscle dysfunction and increases mitochondrial H2O2. We hypothesized that the combined effect of cancer and chemotherapy in an immunocompetent breast cancer mouse model (E0771) would compromise skeletal muscle mitochondrial respiratory function, leading to an increase in H2O2-emitting potential and impaired muscle function. Here, we demonstrate that cancer chemotherapy decreases mitochondrial respiratory capacity supported with comple...
Source: AJP: Endocrinology and Metabolism - July 20, 2016 Category: Endocrinology Authors: Gilliam, L. A. A., Lark, D. S., Reese, L. R., Torres, M. J., Ryan, T. E., Lin, C.-T., Cathey, B. L., Neufer, P. D. Tags: Call for Papers Source Type: research
A high-fat diet impairs cooling-evoked brown adipose tissue activation via a vagal afferent mechanism
In dramatic contrast to rats on a control diet, rats maintained on a high-fat diet (HFD) failed to activate brown adipose tissue (BAT) during cooling despite robust increases in their BAT activity following direct activation of their BAT sympathetic premotor neurons in the raphe pallidus. Cervical vagotomy or blockade of glutamate receptors in the nucleus of the tractus solitarii (NTS) reversed the HFD-induced inhibition of cold-evoked BAT activity. Thus, a HFD does not prevent rats from mounting a robust, centrally driven BAT thermogenesis; however, a HFD does alter a vagal afferent input to NTS neurons, thereby preventin...
Source: AJP: Endocrinology and Metabolism - July 20, 2016 Category: Endocrinology Authors: Madden, C. J., Morrison, S. F. Tags: Call for Papers Source Type: research
A single session of neuromuscular electrical stimulation does not augment postprandial muscle protein accretion
The loss of muscle mass and strength that occurs with aging, termed sarcopenia, has been (at least partly) attributed to an impaired muscle protein synthetic response to food intake. Previously, we showed that neuromuscular electrical stimulation (NMES) can stimulate fasting muscle protein synthesis rates and prevent muscle atrophy during disuse. We hypothesized that NMES prior to protein ingestion would increase postprandial muscle protein accretion. Eighteen healthy elderly (69 ± 1 yr) males participated in this study. After a 70-min unilateral NMES protocol was performed, subjects ingested 20 g of intrinsically l...
Source: AJP: Endocrinology and Metabolism - July 4, 2016 Category: Endocrinology Authors: Dirks, M. L., Wall, B. T., Kramer, I. F., Zorenc, A. H., Goessens, J. P. B., Gijsen, A. P., van Loon, L. J. C. Tags: Articles Source Type: research
Maternal obesity is associated with ovarian inflammation and upregulation of early growth response factor 1
Obesity impairs reproductive functions through multiple mechanisms, possibly through disruption of ovarian function. We hypothesized that increased adiposity will lead to a proinflammatory gene signature and upregulation of Egr-1 protein in ovaries from obese (OB; n = 7) compared with lean (LN; n = 10) female Sprague-Dawley rats during the peri-implantation period at 4.5 days postcoitus (dpc). Obesity was induced by overfeeding (40% excess calories for 28 days) via total enteral nutrition prior to mating. OB dams had higher body weight (P < 0.001), greater fat mass (P < 0.001), and reduced lean mass (P < 0.05) and...
Source: AJP: Endocrinology and Metabolism - July 4, 2016 Category: Endocrinology Authors: Ruebel, M., Shankar, K., Gaddy, D., Lindsey, F., Badger, T., Andres, A. Tags: Articles Source Type: research
Metabolic activity of brown, "beige," and white adipose tissues in response to chronic adrenergic stimulation in male mice
Classical brown adipocytes such as those found in interscapular brown adipose tissue (iBAT) represent energy-burning cells, which have been postulated to play a pivotal role in energy metabolism. Brown adipocytes can also be found in white adipose tissue (WAT) depots [e.g., inguinal WAT (iWAT)] following adrenergic stimulation, and they have been referred to as "beige" adipocytes. Whether the presence of these adipocytes, which gives iWAT a beige appearance, can confer a white depot with some thermogenic activity remains to be seen. In consequence, we designed the present study to investigate the metabolic activity of iBAT...
Source: AJP: Endocrinology and Metabolism - July 4, 2016 Category: Endocrinology Authors: Labbe, S. M., Caron, A., Chechi, K., Laplante, M., Lecomte, R., Richard, D. Tags: Call for Papers - Novel Aspects of Adipocyte Biology Source Type: research
