ghrelin is a gut peptide composed of 28 amino acids mostly secreted in the gastric fundus mucosa. It was isolated and described in 1999 by Kojima et al. and only three years later its specific receptor, ghsR1a, was also identified. ghrelin, the endogenous ligand for the gh secretagogue receptor, is the only peripheral orexigenic hormone that activates the receptors to be found especially in the appetite center (hypothalamus and pituitary gland). ghrelin is present in human plasma in two forms: an inactive form known as deacylated ghrelin, and an active form called acylated ghrelin synthesized under the action of ghrelin O-acyltransferase enzyme (gOAT). The literature even mentions an extremely complex ghrelin/gOAT/ghsR system involved in the regulation of human energy, metabolism and adaptation of energy homeostasis to environmental changes. In humans, there is a preprandial rise and a postprandial fall in plasma ghrelin levels, which strongly suggest that the peptide plays a physiological role in meal initiation and may be employed in determining the amount and quality of ingested food. Besides the stimulation of food intake, ghrelin determines a decrease in energy expenditure and promotes the storage of fatty acids in adipocytes. Thus, in the human body ghrelin induces a positive energy balance, an increased adiposity gain, as well as an increase in caloric storage, seen as an adaptive mechanism to caloric restriction conditions. In the current world context, when we are witnessing an increasing availability of food and a reduction of energy expenditure to a minimum level, these mechanisms have become pathogenic. As a consequence, the hypothesis that ghrelin is involved in the current obesity epidemic has been embraced by many scholars and researchers
Clinical studies investigating the relationship between fibroblast growth factor 23 (FGF23) and bone mass are controversial, especially in the healthy renal population. Our study is one of the forefronts investigating the relationship between FGF23 and bone mass parameters in the general population, according to age, sex, menopausal, and nutritional status. Cross-sectional study enrolling 123 volunteers between 20–80 years of age without primary osteoporosis under treatment nor secondary osteoporosis, where bone mass (bone mineral density-BMD, bone mineral content-BMC; assessed by Dual X-Ray Absorptiometry-DXA), body composition (DXA evaluation), and also the serum levels of FGF23, parathormone (PTH), 25(OH)D, bone resorption marker C-terminal telopeptide of type I collagen (CTx) and leptin were determined. FGF23 was negatively and independently associated with BMD and/or BMC in all groups. FGF23 contributed to up to 10% (p <0.05) of femoral neck BMD variance in postmenopausal women, but was not an accurate discriminator of normal versus low bone mass (AUC=0.622±0.076). FGF23 did not correlate with 25(OH)D, CTx, body weight, body composition parameters or leptin. FGF23 was independently associated with PTH in premenopausal women and men only. FGF23 was negatively associated with bone mass parameters in both sexes, but was not a fine discriminator between normal bone mass and osteopenia/osteoporosis. The mechanism through which FGF23 acts upon the bone seems independent of the nutritional status, requiring further investigation.
The present study shows that LM and sex hormones-namely estradiol-are the main determinants of bone mass in young and middle-aged men. The effects of BMI upon BMD seem to be largely mediated by LM. Lifestyle interventions should focus on preserving LM in men for improved bone outcomes.
Background Despite the increased fracture risk, bone mineral density (BMD) is variable in type 1 (T1D) and type 2 (T2D) diabetes mellitus. We aimed at comparing independent BMD predictors in T1D, T2D and control subjects, respectively. Methods Cross-sectional case-control study enrolling 30 T1D, 39 T2D and 69 age, sex and body mass index (BMI) – matched controls that underwent clinical examination, dual-energy X-ray absorptiometry (BMD at the lumbar spine and femoral neck) and serum determination of HbA1c and parameters of calcium and phosphate metabolism. Results T2D patients had similar BMD compared to T1D individuals (after adjusting for age, BMI and disease duration) and to matched controls, respectively. In multiple regression analysis, diabetes duration – but not HbA1c- negatively predicted femoral neck BMD in T1D (β= -0.39, p = 0.014), while BMI was a positive predictor for lumbar spine (β = 0.46, p = 0.006) and femoral neck BMD (β = 0.44, p = 0.007) in T2D, besides gender influence. Age negatively predicted BMD in controls, but not in patients with diabetes. Conclusions Long-standing diabetes and female gender particularly increase the risk for low bone mass in T1D. An increased body weight partially hinders BMD loss in T2D. The impact of age appears to be surpassed by that of other bone regulating factors in both T1D and T2D patients.
International health organizations recognize the increasing importance of environmental exogenous agents in relation with endocrine system. The endocrine disruptors alter the proper functioning of the endocrine pathway with important consequences on human health. In recent years, more studies came to asses the exposure to multiple endocrine disrupting chemicals on animals and humans. This article summarizes data concerning the effects of different types of endocrine disruptors such as: phytoestrogens, bisphenol, diethylstilbestrol, phthalates, dioxin and pesticides on endocrine system and the sequelae on endocrine functions. Many endocrine disrupting compounds adversely impact the following functions: metabolic rate, sex development, insulin production and utilization, growth, stress response, gender behavior, reproduction. The action to disrupt the endocrine pathway is possible via nuclear receptors, through membrane receptors, neurotransmitter receptors, orphan receptors and enzymatic pathways involved in the hormonal synthesis. Elucidation of the role of endocrine disruptors in human health will provide insights into the assessment of environmental exposure and risk. Further epidemiological and toxicological studies are needed to evaluate the exposure to multiple endocrine disrupting compounds.
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