Angiotensin II induces differential insulin action in rat skeletal muscle
Angiotensin II (ANGII) is reportedly involved in the development of skeletal muscle insulin resistance. The present investigation evaluated the effects of two ANGII doses on the phenotypic characteristics of insulin resistance syndrome and insulin action and signaling in rat skeletal muscle. Male Sprague–Dawley rats were infused with either saline (SHAM) or ANGII at a commonly used pressor dose (100 ng/kg/min; ANGII-100) or a higher pressor dose (500 ng/kg/min; ANGII-500) via osmotic minipumps for 14 days. We demonstrated that ANGII-100-infused rats exhibited the phenotypic features of non-obese insulin resistance sy...
Source: Journal of Endocrinology - February 9, 2017 Category: Endocrinology Authors: Surapongchai, J., Prasannarong, M., Bupha-Intr, T., Saengsirisuwan, V. Tags: Research Source Type: research
Sex differences in the development of prolactinoma in mice overexpressing hCG{beta}: role of TGF{beta}1
Female transgenic mice that overexpress the human chorionic gonadotrophin β subunit (hCGβ+) develop prolactinomas, whereas hCGβ+ males do not. The high levels of circulating hCG induce massive luteinization in the ovary of hCGβ+ females, and progesterone becomes the primary steroid hormone produced, but estradiol remains at physiological level. The involvement of high levels of progesterone in lactotroph proliferation is not clearly understood; hence, the pathogenesis of prolactinomas in hCGβ+ females remains unclear. TGFβ1 is an inhibitor of lactotroph function, and the reduced TGFβ1 act...
Source: Journal of Endocrinology - February 9, 2017 Category: Endocrinology Authors: Faraoni, E. Y., Camilletti, M. A., Abeledo-Machado, A., Ratner, L. D., De Fino, F., Huhtaniemi, I., Rulli, S. B., Diaz-Torga, G. Tags: Research Source Type: research
Regulation of aldosterone secretion by mineralocorticoid receptor-mediated signaling
We posit the existence of a paracrine/autocrine negative feedback loop, mediated by the mineralocorticoid receptor (MR), regulating aldosterone secretion. To assess this hypothesis, we asked whether altering MR activity in zona glomerulosa (ZG) cells affects aldosterone production. To this end, we studied ex vivo ZG cells isolated from male Wistar rats fed chow containing either high (1.6% Na+ (HS)) or low (0.03% Na+ (LS)) amount of sodium. Western blot analyses demonstrated that MR was present in both the ZG and zona fasciculata/zona reticularis (ZF/ZR/ZR). In ZG cells isolated from rats on LS chow, MR activation by fludr...
Source: Journal of Endocrinology - February 7, 2017 Category: Endocrinology Authors: Chong, C., Hamid, A., Yao, T., Garza, A. E., Pojoga, L. H., Adler, G. K., Romero, J. R., Williams, G. H. Tags: Research Source Type: research
Melanin-concentrating hormone in peripheral circulation in the human
Melanin-concentrating hormone (MCH) is a hypothalamic neuropeptide with a well-characterised role in energy homeostasis and emergent roles in diverse physiologic functions such as arousal, mood and reproduction. Work to date has predominantly focused on its hypothalamic functions using animal models; however, little attention has been paid to its role in circulation in humans. The aims of this study were to (a) develop a radioimmunoassay for the detection of MCH in human plasma; (b) establish reference ranges for circulating MCH and (c) characterise the pattern of expression of circulating MCH in humans. A sensitive and sp...
Source: Journal of Endocrinology - January 30, 2017 Category: Endocrinology Authors: Naufahu, J., Alzaid, F., Fiuza Brito, M., Doslikova, B., Valencia, T., Cunliffe, A., Murray, J. F. Tags: Research Source Type: research
Exogenous thyroxine improves glucose intolerance in insulin-resistant rats
Both hypothyroidism and hyperthyroidism are associated with glucose intolerance, calling into question the contribution of thyroid hormones (TH) on glucose regulation. TH analogues and derivatives may be effective treatment options for glucose intolerance and insulin resistance (IR), but their potential glucoregulatory effects during conditions of impaired metabolism are not well described. To assess the effects of thyroxine (T4) on glucose intolerance in a model of insulin resistance, an oral glucose tolerance test (oGTT) was performed on three groups of rats (n = 8): (1) lean, Long Evans Tokushima Otsuka (LETO), (2) obes...
Source: Journal of Endocrinology - January 29, 2017 Category: Endocrinology Authors: Vazquez-Anaya, G., Martinez, B., Sonanez-Organis, J. G., Nakano, D., Nishiyama, A., Ortiz, R. M. Tags: Research Source Type: research
A causal role for hyperinsulinemia in obesity
Insulin modulates the biochemical pathways controlling lipid uptake, lipolysis and lipogenesis at multiple levels. Elevated insulin levels are associated with obesity, and conversely, dietary and pharmacological manipulations that reduce insulin have occasionally been reported to cause weight loss. However, the causal role of insulin hypersecretion in the development of mammalian obesity remained controversial in the absence of direct loss-of-function experiments. Here, we discuss theoretical considerations around the causal role of excess insulin for obesity, as well as recent studies employing mice that are genetically i...
Source: Journal of Endocrinology - January 29, 2017 Category: Endocrinology Authors: Templeman, N. M., Skovso, S., Page, M. M., Lim, G. E., Johnson, J. D. Tags: Review Source Type: research
Cancer cachexia differentially regulates visceral adipose tissue turnover
Cancer cachexia (CC) is a progressive metabolic syndrome that is marked by severe body weight loss. Metabolic disarrangement of fat tissues is a very early event in CC, followed by adipose tissue (AT) atrophy and remodelling. However, there is little information regarding the possible involvement of cellular turnover in this process. Thus, in this study, we evaluated the effect of CC on AT turnover and fibrosis of mesenteric (MEAT) and retroperitoneal (RPAT) adipose tissue depots as possible factors that contribute to AT atrophy. CC was induced by a subcutaneous injection of Walker tumour cells (2 x 107) in Wistar rats, an...
Source: Journal of Endocrinology - January 24, 2017 Category: Endocrinology Authors: Franco, F. d. O., Lopes, M. A., Henriques, F. d. S., Neves, R. X. d., Bianchi Filho, C., Batista, M. L. Tags: Research Source Type: research
Myoblast replication is reduced in the IUGR fetus despite maintained proliferative capacity in vitro
Adults who were affected by intrauterine growth restriction (IUGR) suffer from reductions in muscle mass and insulin resistance, suggesting muscle growth may be restricted by molecular events that occur during fetal development. To explore the basis of restricted fetal muscle growth, we used a sheep model of progressive placental insufficiency-induced IUGR to assess myoblast proliferation within intact skeletal muscle in vivo and isolated myoblasts stimulated with insulin in vitro. Gastrocnemius and soleus muscle weights were reduced by 25% in IUGR fetuses compared to those in controls (CON). The ratio of PAX7+ nuclei (a m...
Source: Journal of Endocrinology - January 24, 2017 Category: Endocrinology Authors: Soto, S. M., Blake, A. C., Wesolowski, S. R., Rozance, P. J., Barthels, K. B., Gao, B., Hetrick, B., McCurdy, C. E., Garza, N. G., Hay, W. W., Leinwand, L. A., Friedman, J. E., Brown, L. D. Tags: Research Source Type: research
Leptin stimulates bone formation in ob/ob mice at doses having minimal impact on energy metabolism
Leptin, the protein product of the ob gene, is essential for normal bone growth, maturation and turnover. Peripheral actions of leptin occur at lower serum levels of the hormone than central actions because entry of leptin into the central nervous system (CNS) is limited due to its saturable transport across the blood–brain barrier (BBB). We performed a study in mice to model the impact of leptin production associated with different levels of adiposity on bone formation and compared the response with well-established centrally mediated actions of the hormone on energy metabolism. Leptin was infused (0, 4, 12, 40, 140...
Source: Journal of Endocrinology - January 23, 2017 Category: Endocrinology Authors: Philbrick, K. A., Wong, C. P., Branscum, A. J., Turner, R. T., Iwaniec, U. T. Tags: Research Source Type: research
Molecular diversity of corticotropin-releasing hormone mRNA-containing neurons in the hypothalamus
Hormonal responses to acute stress rely on the rapid induction of corticotropin-releasing hormone (CRH) production in the mammalian hypothalamus, with subsequent instructive steps culminating in corticosterone release at the periphery. Hypothalamic CRH neurons in the paraventricular nucleus of the hypothalamus are therefore considered as ‘stress neurons’. However, significant morphological and functional diversity among neurons that can transiently produce CRH in other hypothalamic nuclei has been proposed, particularly as histochemical and molecular biology evidence associates CRH to both GABA and glutamate ne...
Source: Journal of Endocrinology - January 23, 2017 Category: Endocrinology Authors: Romanov, R. A., Alpar, A., Hokfelt, T., Harkany, T. Tags: Review Source Type: research
Jab1 is a T2-dependent coactivator or a T3-dependent corepressor of TRB1-mediated gene regulation
Thyroid hormones (THs) induce pleiotropic effects in vertebrates, mainly through the activation or repression of gene expression. These mechanisms involve thyroid hormone binding to thyroid hormone receptors, an event that is followed by the sequential recruitment of coactivator or corepressor proteins, which in turn modify the rate of transcription. In the present study, we looked for specific coregulators recruited by the long isoform of the teleostean thyroid hormone receptor beta 1 (L-Trb1) when bound to the bioactive TH, 3,5-T2 (T2). We found that jun activation domain-binding protein1 (Jab1) interacts with L-Trb1 + T...
Source: Journal of Endocrinology - January 22, 2017 Category: Endocrinology Authors: Hernandez-Puga, G., Mendoza, A., Leon-del-Rio, A., Orozco, A. Tags: Research Source Type: research
Glucocorticoid receptor alters isovolumetric contraction and restrains cardiac fibrosis
Corticosteroids directly affect the heart and vasculature and are implicated in the pathogenesis of heart failure. Attention is focussed upon the role of the mineralocorticoid receptor (MR) in mediating pro-fibrotic and other adverse effects of corticosteroids upon the heart. In contrast, the role of the glucocorticoid receptor (GR) in the heart and vasculature is less well understood. We addressed this in mice with cardiomyocyte and vascular smooth muscle deletion of GR (SMGRKO mice). Survival of SMGRKO mice to weaning was reduced compared with that of littermate controls. Doppler measurements of blood flow across the mit...
Source: Journal of Endocrinology - January 22, 2017 Category: Endocrinology Authors: Richardson, R. V., Batchen, E. J., Thomson, A. J. W., Darroch, R., Pan, X., Rog-Zielinska, E. A., Wyrzykowska, W., Scullion, K., Al-Dujaili, E. A. S., Diaz, M. E., Moran, C. M., Kenyon, C. J., Gray, G. A., Chapman, K. E. Tags: Research Source Type: research
Esculentin-2CHa(1-30) and its analogues: stability and mechanisms of insulinotropic action
The insulin-releasing effects, cellular mechanisms of action and anti-hyperglycaemic activity of 10 analogues of esculentin-2CHa lacking the cyclic C-terminal domain (CKISKQC) were evaluated. Analogues of the truncated peptide, esculentin-2CHa(1–30), were designed for plasma enzyme resistance and increased biological activity. Effects of those analogues on insulin release, cell membrane integrity, membrane potential, intracellular Ca2+ and cAMP levels were determined using clonal BRIN-BD11 cells. Their acute effects on glucose tolerance were investigated using NIH Swiss mice. d-Amino acid substitutions at positions 7...
Source: Journal of Endocrinology - January 22, 2017 Category: Endocrinology Authors: Vasu, S., McGahon, M. K., Moffett, R. C., Curtis, T. M., Conlon, J. M., Abdel-Wahab, Y. H. A., Flatt, P. R. Tags: Research Source Type: research
Interplay between the endocrine and circadian systems in fishes
The circadian system is responsible for the temporal organisation of physiological functions which, in part, involves daily cycles of hormonal activity. In this review, we analyse the interplay between the circadian and endocrine systems in fishes. We first describe the current model of fish circadian system organisation and the basis of the molecular clockwork that enables different tissues to act as internal pacemakers. This system consists of a net of central and peripherally located oscillators and can be synchronised by the light–darkness and feeding–fasting cycles. We then focus on two central neuroendocr...
Source: Journal of Endocrinology - January 18, 2017 Category: Endocrinology Authors: Isorna, E., de Pedro, N., Valenciano, A. I., Alonso-Gomez, A. L., Delgado, M. J. Tags: Review Source Type: research
Acute effect of exercise intensity and duration on acylated ghrelin and hunger in men
In conclusion, exercise intensity, and to a lesser extent duration, are determinants of the acylated ghrelin response to acute exercise. (Source: Journal of Endocrinology)
Source: Journal of Endocrinology - January 16, 2017 Category: Endocrinology Authors: Broom, D. R., Miyashita, M., Wasse, L. K., Pulsford, R., King, J. A., Thackray, A. E., Stensel, D. J. Tags: Research Source Type: research
