Carob fruit extract-enriched meat improves pancreatic beta-cell dysfunction, hepatic insulin signaling and lipogenesis in late-stage type 2 diabetes mellitus model.

The inclusion of functional bioactive compounds of dietary fiber in meat products has been demonstrated to exert a significant impact on human health. Carob fruit extract (CFE) is a dietary fiber rich in proanthocyanidins with known antioxidant, hypolipidemic and hypoglycemic effects. Consumption of CFE-enriched meat (CFE-RM) may provide interesting benefits in late-stage type 2 diabetes mellitus (T2DM). To explore the antidiabetic mechanisms of CFE-RM, we used a model of late-stage T2DM in Wistar rats fed a high-saturated-fat/high-cholesterol diet (Chol-diet) and injected streptozotocin plus nicotinamide (D group). The effects of CFE-RM were tested by incorporating it into the diet as preventive strategy (ED group) or curative treatment (DE group). CFE-RM had a positive effect on glycemia, enhancing hepatic insulin sensitivity and improving pancreatic ß-cell regeneration in both ED and DE groups. Western blotting and immunohistochemistry suggested that CFE-RM increased levels of insulin receptor ß and phosphatidylinositol-3-kinase, as well as the downstream target phospho-Akt (at Ser473). CFE-RM also up-regulated glucose transporter 2, which improves the insulin-mediated glucose uptake by the liver, and promoted phosphorylation of glycogen synthesis kinase-3ßprotein (at ser9), consequently increasing the hepatic glycogen content. In addition, CFE-RM decreased fatty liver by suppressing de novo lipogenesis activation due to down-regulation of liver X receptor-α/ß, sterol regulatory element binding protein-1c and carbohydrate-response element-binding protein transcription factors. Our findings suggest that the consumption of CFE-RM included in the diet as a functional food should be considered as a suitable nutritional strategy to prevent or manage late-stage T2DM.

Organic silicon protects human neuroblastoma SH-SY5Y cells against hydrogen peroxide effects.

BACKGROUND: Hydrogen peroxide (H2O2) is a toxic agent that induces oxidative stress and cell death. Silicon (Si) is a biological element involved in limiting aluminium (Al) absorption with possible preventive effects in Alzheimer's disease. However, Si has not yet been associated with other neuroprotective mechanisms. METHODS: The present experiments evaluated in the SH-SY5Y human neuroblastoma cell line the possible role of different Si G5 (50-1000 ng/mL) concentrations in preventing cellular death induced by H2O2 (400 µM, 24 hours). RESULTS: Our findings showed that H2O2 promoted cell death in the human SH-SY5Y cell cultures and this could be prevented by Si treatment. The loss in cell viability mediated by H2O2 was due to an apoptotic and necrotic process. Apoptotic death was incurred by regulating caspase-8 activity in the extrinsic pathway. The apoptotic and necrotic cell death induced by H2O2 was almost totally reversed by Si (50-500 ng/mL), indicating that it down-regulates both processes in H2O2 treated cells. CONCLUSIONS: According to our data, Si is able to increase SH-SY5Y cell survival throughout partially blocking cellular damage related to oxidative stress through a mechanism that would affect H2O2/ROS elimination.

Alteration in cell cycle-related proteins in lymphoblasts from carriers of the c.709-1G>A PGRN mutation associated with FTLD-TDP dementia.

Frontotemporal lobar degeneration with neuronal inclusions containing TAR DNA binding protein 43 (TDP-43) is associated in most cases with null-mutations in the progranulin gene (PGRN). While the mechanisms by which PGRN haploinsufficiency leads to neurodegeneration remained speculative, increasing evidence support the hypothesis that cell cycle reentry of postmitotic neurons precedes many instances of neuronal death. Based in the mitogenic and neurotrophic activities of PGRN, we hypothesized that PGRN deficit may induce cell cycle disturbances and alterations in neuronal vulnerability. Because cell cycle dysfunction is not restricted to neurons, we studied the influence of PGRN haploinsufficiency, on cell cycle control in peripheral cells from patients suffering from frontotemporal dementia, bearing the PGRN mutation c.709-1G>A. Here we show that progranulin deficit increased cell cycle activity in immortalized lymphocytes. This effect was associated with increased levels of cyclin-dependent kinase 6 (CDK6) and phosphorylation of retinoblastoma protein (pRb), resulting in a G(1)/S regulatory failure. A loss of function of TDP-43 repressing CDK6 expression may result from altered subcellular TDP-43 distribution. The distinct functional features of lymphoblastoid cells from c.709-1 G>A carriers offer an invaluable, noninvasive tool to investigate the etiopathogenesis of frontotemporal lobar degeneration.

Growth hormone upregulates intestinal trefoil factor expression in the ileum of rats after γ-radiation.

Growth hormone (GH) and intestinal trefoil factor (ITF) have been involved in intestinal protection and repair. This study investigates the effects of GH administration on ITF expression and histological changes associated with tissue injury in an intestinal rat model of radiation. Adult male rats were divided into four groups: control, GH, radiation and radiation + GH (GHyRAD). Ileum samples were obtained at 2 or 72 h after radiation and processed to determine ITF levels (mRNA and protein) by quantitative polymerase chain reaction, Western blot and immunohistochemistry. In addition, goblet ITF-positive cells were identified by immunohistochemistry at 72 h. Our results showed an upregulation of mRNA and protein production of ITF in ileum samples after GH and radiation + GH compared with control and irradiated samples. Irradiation alone affected ITF protein expression. However, irradiation after GH pretreatment produced the highest ITF mRNA and protein levels at both the tested time points. ITF-producing goblet cells were identified in intestinal villi (apical location). GH treatment increased the number of ITF-producing goblet cells, and radiation after GH treatment displayed further increase in the number of ITF-positive goblet cells. GH upregulates ITF in normal intestinal tissue. This upregulation is higher when radiation is given after GH treatment. Nevertheless, the mechanism by which GH regulates ITF expression remains unclear and is still under investigation. These results could open up new avenues in the therapeutic reparative and protective effects of GH during radiotherapy and chemotherapy.

Neurobiological and endocrine correlates of individual differences in spatial learning ability.

The polysialylated neural cell adhesion molecule (PSA-NCAM) has been implicated in activity-dependent synaptic remodeling and memory formation. Here, we questioned whether training-induced modulation of PSA-NCAM expression might be related to individual differences in spatial learning abilities. At 12 h posttraining, immunohistochemical analyses revealed a learning-induced up-regulation of PSA-NCAM in the hippocampal dentate gyrus that was related to the spatial learning abilities displayed by rats during training. Specifically, a positive correlation was found between latency to find the platform and subsequent activated PSA levels, indicating that greater induction of polysialylation was observed in rats with the slower acquisition curve. At posttraining times when no learning-associated activation of PSA was observed, no such correlation was found. Further experiments revealed that performance in the massed water maze training is related to a pattern of spatial learning and memory abilities, and to learning-related glucocorticoid responsiveness. Taken together, our findings suggest that the learning-related neural circuits of fast learners are better suited to solving the water maze task than those of slow learners, the latter relying more on structural reorganization to form memory, rather than the relatively economic mechanism of altering synaptic efficacy that is likely used by the former.

Modulation of hippocampal NCAM polysialylation and spatial memory consolidation by fear conditioning.

BACKGROUND: Cell adhesion molecule function is involved in hippocampal synaptic plasticity and associated with memory consolidation. At the infragranular zone of the dentate gyrus, neurons expressing the polysialylated form of the neural cell adhesion molecule (NCAM PSA) transiently increase their frequency 12 hours after training in different tasks. METHODS: Using immunohistochemical procedures, we investigated NCAM polysialylation following training in a contextual fear conditioning paradigm that employed increasing shock intensities to separately model stressful and traumatic experiences in adult male Wistar rats. RESULTS: Fear conditioning with a stressful.4-mA stimulus resulted in an increased frequency of dentate polysialylated neurons, the magnitude of which was indistinguishable from that observed following water maze training. By contrast, training with a traumatic 1-mA stimulus resulted in a significant decrease in the frequency of polysialylated neurons at the 12 hours posttraining time. Whereas sequential training in the water maze paradigm followed by fear conditioning resulted in potentiated consolidation of spatial information when conditioning involved a.4-mA stimulus, amnesia for spatial learning occurred when conditioning was performed with a 1-mA stimulus. CONCLUSIONS: These results suggest traumatic fear conditioning suppresses NCAM-PSA-mediated plasticity and the concomitant inability to store the trace of recently acquired information.