Short-Term Treatment with Bisphenol-A Leads to Metabolic Abnormalities in Adult Male Mice

Bisphenol-A (BPA) is one of the most widespread endocrine disrupting chemicals (EDC) used as the base compound in the manufacture of polycarbonate plastics. Although evidence points to consider exposure to BPA as a risk factor for insulin resistance, its actions on whole body metabolism and on insulin-sensitive tissues are still unclear. The aim of the present work was to study the effects of low doses of BPA in insulin-sensitive peripheral tissues and whole body metabolism in adult mice. Adult mice were treated with subcutaneous injection of 100 µg/kg BPA or vehicle for 8 days. Whole body energy homeostasis was assessed with in vivo indirect calorimetry. Insulin signaling assays were conducted by western blot analysis. Mice treated with BPA were insulin resistant and had increased glucose-stimulated insulin release. BPA-treated mice had decreased food intake, lower body temperature and locomotor activity compared to control. In skeletal muscle, insulin-stimulated tyrosine phosphorylation of the insulin receptor β subunit was impaired in BPA-treated mice. This impairment was associated with a reduced insulin-stimulated Akt phosphorylation in the Thr308 residue. Both skeletal muscle and liver displayed an upregulation of IRS-1 protein by BPA. The mitogen-activated protein kinase (MAPK) signaling pathway was also impaired in the skeletal muscle from BPA-treated mice. In the liver, BPA effects were of lesser intensity with decreased insulin-stimulated tyrosine phosphorylation of the insulin receptor β subunit

BPA treatment leads to increased IRS-1 protein in basal conditions and alters insulin signaling in insulin stimulated conditions in the liver.

<p>(<b>A</b>) Total IRS-1 protein expression (n = 4). (<b>B</b>) Akt protein expression (n = 5). α-tubulin was used as an internal control. (<b>C</b>) IR tyrosine phosphorylation (n = 5–7), (<b>D</b>) Akt phosphorylation (Ser⁴⁷³) (n = 5–7), (<b>E</b>) Akt phosphorylation (Thr³⁰⁸) (n = 5–7), (<b>F</b>) ERK1/2 phosphorylation (n = 4–7). Statistical differences were determined by Student's t test *, p<0.05. Data are expressed as mean ±S.E.M.</p

In vivo parameters and glucose stimulated insulin secretion in vehicle and BPA-treated mice for 8 days.

<p>(<b>A</b>) Blood glucose levels in fasted and fed state (n = 7–9), (<b>B</b>) Plasma non-esterified fatty acids (NEFA) (n = 7–9). (<b>C</b>) Plasma insulin (n = 6–8). (<b>D</b>) Glucose-induced insulin secretion in isolated islets from vehicle and BPA treated mice. Isolated islets were incubated with 2.8 or 16.7 mM glucose for 1 hour (n = 12). Statistical differences were determined by Student's t test *, p<0.05. Data are expressed as mean ±S.E.M.</p

BPA treatment leads to increased IRS-1 protein in basal conditions and alters insulin signaling in insulin-stimulated conditions in skeletal muscle

<p>. (<b>A</b>) Total IRS-1 protein expression levels (n = 5). (<b>B</b>) Akt protein expression (n = 4). α-tubulin was used as an internal control. (<b>C</b>) IR tyrosine phosphorylation after insulin stimulation in vehicle and BPA treated animals (n = 5–7), (<b>D</b>) Akt phosphorylation (Ser⁴⁷³) (n = 5–7) and (<b>E</b>) Akt phosphorylation (Thr³⁰⁸) in the same conditions as panel C (n = 4–5) (<b>F</b>) ERK1/2 phosphorylation (n = 4–6). Statistical differences were determined by Student's t test *, p<0.05. Data are expressed as mean ±S.E.M.</p

BPA treatment leads to insulin resistance and impairments in whole-body energy homeostasis.

<p>(<b>A</b>) Intraperitoneal glucose tolerant test in mice treated with vehicle or BPA. Plasma glucose concentration during the ipGTT (n = 7–8). (<b>B</b>) Intraperitoneal insulin tolerant test. Plasma glucose concentration during the ipITT (n = 7–8). (<b>C</b>) Respiratory exchange ratio (RER) assed over 24 h (n = 6). (<b>D</b>) Food Intake assed over 24 h (n = 6) (<b>E</b>) Ambulatory Activity assed over 24 h (n = 6). (<b>F</b>) Body temperature assed over 24 h (n = 6). Statistical differences were determined by Student's t test *, p<0.05; **, p<0.01. Data are expressed as mean ±S.E.M.</p

Transected tendon treated with a new fibrin sealant alone or associated with adipose-derived stem cells

Tissue engineering and cell-based therapy combine techniques that create biocompatible materials for cell survival, which can improve tendon repair. This study seeks to use a new fibrin sealant (FS) derived from the venom of Crotalus durissus terrificus, a biodegradable three-dimensional scaffolding produced from animal components only, associated with adipose-derived stem cells (ASC) for application in tendons injuries, considered a common and serious orthopedic problem. Lewis rats had tendons distributed in five groups: normal (N), transected (T), transected and FS (FS) or ASC (ASC) or with FS and ASC (FS + ASC). The in vivo imaging showed higher quantification of transplanted PKH26-labeled ASC in tendons of FS + ASC compared to ASC on the 14th day after transection. A small number of Iba1 labeled macrophages carrying PKH26 signal, probably due to phagocytosis of dead ASC, were observed in tendons of transected groups. ASC up-regulated the Tenomodulin gene expression in the transection region when compared to N, T and FS groups and the expression of TIMP-2 and Scleraxis genes in relation to the N group. FS group presented a greater organization of collagen fibers, followed by FS + ASC and ASC in comparison to N. Tendons from ASC group presented higher hydroxyproline concentration in relation to N and the transected tendons of T, FS and FS + ASC had a higher amount of collagen I and tenomodulin in comparison to N group. Although no marked differences were observed in the other biomechanical parameters, T group had higher value of maximum load compared to the groups ASC and FS + ASC. In conclusion, the FS kept constant the number of transplanted ASC in the transected region until the 14th day after injury. Our data suggest this FS to be a good scaffold for treatment during tendon repair because it was the most effective one regarding tendon organization recovering, followed by the FS treatment associated with ASC and finally by the transplanted ASC on the 21st day. Further investigations in long-term time points of the tendon repair are needed to analyze if the higher tissue organization found with the FS scaffold will improve the biomechanics of the tendons81COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESPsem informação2012/14973-