Protein deficiency and nutritional recovery modulate insulin secretion and the early steps of insulin action in rats

Maternal malnutrition was shown to affect early growth and leads to permanent alterations in insulin secretion and sensitivity of offspring. In addition, epidemiological studies showed an association between low birth weight and glucose intolerance in adult life. To understand these interactions better, we investigated the insulin secretion by isolated islets and the early events related to insulin action in the hind-limb muscle of adult rats fed a diet of 17% protein (control) or 6% protein [low (LP) protein] during fetal life, suckling and after weaning, and in rats receiving 6% protein during fetal life and suckling followed by a 17% protein diet after weaning (recovered). The basal and maximal insulin secretion by islets from rats fed LP diet and the basal release by islets from recovered rats were significantly lower than that of control rats. The dose-response curves to glucose of islets from LP and recovered groups were shifted to the right compared to control islets, with the half-maximal response (EC 50) occurring at 16.9 ± 1.3, 12.4 ± 0.5 and 8.4 ± 0.1 mmol/L, respectively. The levels of insulin receptor, as well as insulin receptor substrate-1 and phosphorylation and the association between insulin receptor substrate-1 and phosphatidylinositol 3-kinase were greater in rats fed a LP diet than in control rats. In recovered rats, these variables were not significantly different from those of the other two groups. These results suggest that glucose homeostasis is maintained in LP and recovered rats by an increased sensitivity to insulin as a result of alterations in the early steps of the insulin signal transduction pathway.

Glucose homeostasis in pregnant rats submitted to dietary protein restriction

In the present work, we examined the effects of feeding a low protein diet during pregnancy on glucose-induced insulin secretion and glucose homeostasis in rats. Young (60 days), pregnant (P) or non-pregnant (NP) rats were fed during pregnancy or for 21 days (the NP) a normal (17%) or a low (6%) protein diet. Serum glucose and insulin levels and pancreas insulin content in the fed state; total area under serum glucose curve (AG) after a glucose load and serum glucose disappearance rate (Kitt) after insulin administration; as well as 86Rb outflow, 45Ca uptake and insulin secretion by isolated pancreatic islets in response to glucose were evaluated. Serum glucose was lower in 17%-P (12%) and 6%-P (27%) than in corresponding NP-rats. Serum insulin was higher in 17%- P (153%) and 6%-P (77%) compared to the corresponding NP-rats. Pancreatic insulin was higher in 6%-rats (55%) than in 17%-rats. No differences were found in AG among the groups whereas Kitt was lower in 6%-NP and higher in 6%-P than in the equivalent 17% rats. Increasing glucose concentration from 2.8 to 16.7 mmol/l, reduced 86Rb outflow from isolated islets from all groups. Increasing glucose concentration from 2.8 to 16.7 mmol/l elevated 45Ca uptake by 17%-NP (47%), 17%-P (40%) and 6%-P (214%) islets but not by 6%-NP ones. The increase in 45Ca uptake was followed by an increase in insulin release by the 17%-NP (2767%), 17%-P (2850%) and 6%-P (1200%) islets. In conclusion, 6%-P rats show impaired glucose induced insulin secretion related to reduced calcium uptake by pancreatic islets. However, the poor insulin secretion did not fully compensate the high peripheral sensitivity to the hormone, resulting in hypoglycemia.

Kinetic study of the plastoquinone pool availability correlated with H2O2 release in seawater and antioxidant responses in the red alga Kappaphycus alvarezii exposed to single or combined high light, chilling and chemical stresses

Under biotic/abiotic stresses, the red alga Kappaphycus alvarezii reportedly releases massive amounts of H2O2 into the surrounding seawater. As an essential redox signal, the role of chloroplast-originated H2O2 in the orchestration of overall antioxidant responses in algal species has thus been questioned. This work purported to study the kinetic decay profiles of the redox-sensitive plastoquinone pool correlated to H2O2 release in seawater, parameters of oxidative lesions and antioxidant enzyme activities in the red alga Kappaphycus alvarezii under the single or combined effects of high light, low temperature, and sub-lethal doses of 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) and 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone (DBMIB), which are inhibitors of the thylakoid electron transport system. Within 24 h, high light and chilling stresses distinctly affected the availability of the PQ pool for photosynthesis, following Gaussian and exponential kinetic profiles, respectively, whereas combined stimuli were mostly reflected in exponential decays. No significant correlation was found in a comparison of the PQ pool levels after 24 h with either catalase (CAT) or ascorbate peroxidase (APX) activities, although the H2O2 concentration in seawater (R = 0.673), total superoxide dismutase activity (R = 0.689), and particularly indexes of protein (R = 0.869) and lipid oxidation (R = 0.864), were moderately correlated. These data suggest that the release of H2O2 from plastids into seawater possibly impaired efficient and immediate responses of pivotal H2O2-scavenging activities of CAT and APX in the red alga K. alvarezii, culminating in short-term exacerbated levels of protein and lipid oxidation. These facts provided a molecular basis for the recognized limited resistance of the red alga K. alvarezii under unfavorable conditions, especially under chilling stress. © 2006 Elsevier B.V. All rights reserved.

Modulation of insulin secretion by physical training during recovery from protein malnutrition in rats

Objective: The purpose of the present study was to examine insulin secretion in rats submitted to protein restriction and nutritional recovery associated or not to physical training. Methods: The experiment was designed in two sets of five weeks each. In the first set the rats were fed a nonnal-protein diet(17%-control group) or a low-protein diet (6%-malnourished group) for five weeks. After this, all animals were fed the 17% protein diet and separated into four groups: sedentary control(SC); trained eontrol(TC); sedentary recovered(SR) and trained recovered(TR). TC and TR rats performed swimming exercise. Results: The results indicated efficiency of the 6% protein diet in producing signs of malnutrition, as reduction in body weight gain and serum albumin levels, as well as liver fat. Serum insulin in the fed state and insulin secretion by isolated pancreatic islets in response to glucose were Keduced,but peripheral sensitivity to insulin was increased and glucose tolerance was not changed in the protein deficient rats, indicating adaptation to malnutrition. Diet protocol for nutritional recovery was efficient in repairing body weight gain, serum albumin and liver fat levels of the previously malnourished rats. Glucose induced insulin release by pancreatic islets remained low after nutritional recovery. Insulin secretion by the islets isolated from rats submitted to exercise training during nutritional recovery was improved when compared with the sedentary animals. Conclusion: This indicates that exercise training may be useful in the treatment of protein calorie malnutrition, concerning to glucose induced insulip secretion.

Female sex hormones mediate the allergic lung reaction by regulating the release of inflammatory mediators and the expression of lung E-selectin in rats

Background: Fluctuations of estradiol and progesterone levels caused by the menstrual cycle worsen asthma symptoms. Conflicting data are reported in literature regarding pro and anti-inflammatory properties of estradiol and progesterone.Methods: Female Wistar rats were ovalbumin (OVA) sensitized 1 day after resection of the ovaries (OVx). Control group consisted of sensitized-rats with intact ovaries (Sham-OVx). Allergic challenge was performed by aerosol (OVA 1%, 15 min) two weeks later. Twenty four hours after challenge, BAL, bone marrow and total blood cells were counted. Lung tissues were used as explants, for expontaneous cytokine secretion in vitro or for immunostaining of E-selectin.Results: We observed an exacerbated cell recruitment into the lungs of OVx rats, reduced blood leukocytes counting and increased the number of bone marrow cells. Estradiol-treated OVx allergic rats reduced, and those treated with progesterone increased, respectively, the number of cells in the BAL and bone marrow. Lungs of OVx allergic rats significantly increased the E-selectin expression, an effect prevented by estradiol but not by progesterone treatment. Systemically, estradiol treatment increased the number of peripheral blood leukocytes in OVx allergic rats when compared to non treated-OVx allergic rats. Cultured-BAL cells of OVx allergic rats released elevated amounts of LTB4 and nitrites while bone marrow cells increased the release of TNF-α and nitrites. Estradiol treatment of OVx allergic rats was associated with a decreased release of TNF-α, IL-10, LTB4 and nitrites by bone marrow cells incubates. In contrast, estradiol caused an increase in IL-10 and NO release by cultured-BAL cells. Progesterone significantly increased TNF- α by cultured BAL cells and bone marrow cells.Conclusions: Data presented here suggest that upon hormonal oscillations the immune sensitization might trigger an allergic lung inflammation whose phenotype is under control of estradiol. Our data could contribute to the understanding of the protective role of estradiol in some cases of asthma symptoms in fertile ans post-menopausal women clinically observed. © 2010 de Oliveira et al; licensee BioMed Central Ltd.

Annexin-A1 peptide down-regulates the leukocyte recruitment and up-regulates interleukin-10 release into lung after intestinal ischemia-reperfusion in mice

Background: Intestinal ischemia/reperfusion (IR) injury is a serious and triggering event in the development of remote organ dysfunction, from which the lung is the main target. This condition is characterized by intense neutrophil recruitment, increased microvascular permeability. Intestinal IR is also responsible for induction of adult respiratory distress syndrome, the most serious and life-threatening form of acute lung injury. The purpose of this study was to investigate the effect of annexin-A1 protein as an endogenous regulator of the organ remote injury induced by intestinal ischemia/reperfusion. Male C57bl/6 mice were subjected to intestinal ischemia, induced by 45 min occlusion of the superior mesenteric artery, followed by reperfusion. Results: The intestinal ischemia/reperfusion evoked a high intensity lung inflammation as indicated by the number of neutrophils as compared to control group. Treatment with annexin-A1 peptidomimetic Ac2-26, reduced the number of neutrophils in the lung tissue and increased its number in the blood vessels, which suggests a regulatory effect of the peptide Ac2-26 in the neutrophil migration. Moreover, the peptide Ac2-26 treatment was associated with higher levels of plasma IL-10. Conclusion: Our data suggest that the annexin-A1 peptidomimetic Ac2-26 treatment has a regulatory and protective effect in the intestinal ischemia/reperfusion by attenuation of the leukocyte migration to the lung and induction of the anti-inflammatory cytokine IL-10 release into the plasma. The anti-inflammatory action of annexin-A1 and its peptidomimetic described here may serve as a basis for future therapeutic approach in mitigating inflammatory processes due to intestinal ischemia/reperfusion. © 2013 Guido et al.; licensee BioMed Central Ltd.

Anti-inflammatory mechanisms of the annexin A1 protein and its mimetic peptide Ac2-26 in models of ocular inflammation in vivo and in vitro

Annexin A1 (AnxA1) is a protein that displays potent anti-inflammatory properties, but its expression in eye tissue and its role in ocular inflammatory diseases have not been well studied. We investigated the mechanism of action and potential uses of AnxA1 and its mimetic peptide (Ac2-26) in the endotoxin-induced uveitis (EIU) rodent model and in human ARPE-19 cells activated by LPS. In rats, analysis of untreated EIU after 24 and 48 h or EIU treated with topical applications or with a single s.c. injection of Ac2-26 revealed the anti-inflammatory actions of Ac2-26 on leukocyte infiltration and on the release of inflammatory mediators; the systemic administration of Boc2, a formylated peptide receptor (fpr) antagonist, abrogated the peptide's protective effects. Moreover, AnxA1-/- mice exhibited exacerbated EIU compared with wild-type animals. Immunohistochemical studies of ocular tissue showed a specific AnxA1 posttranslational modification in EIU and indicated that the fpr2 receptor mediated the anti-inflammatory actions of AnxA1. In vitro studies confirmed the roles of AnxA1 and fpr2 and the protective effects of Ac2-26 on the release of chemical mediators in ARPE-19 cells. Molecular analysis of NF-κB translocation and IL-6, IL-8, and cyclooxygenase-2 gene expression indicated that the protective effects of AnxA1 occur independently of the NF-κB signaling pathway and possibly in a posttranscriptional manner. Together, our data highlight the role of AnxA1 in ocular inflammation, especially uveitis, and suggest the use of AnxA1 or its mimetic peptide Ac2-26 as a therapeutic approach. Copyright © 2013 by The American Association of Immunologists, Inc.

Induction of the 72 kDa heat shock protein by glucose ingestion in black pregnant women

Obese Black women are at increased risk for development of gestational diabetes mellitus and have worse perinatal outcomes than do obese women of other ethnicities. Since hsp72 has been associated with the regulation of obesity-induced insulin resistance, we evaluated associations between glucose ingestion, hsp72 release and insulin production in Black pregnant women. Specifically, the effect of a 50-g glucose challenge test (GCT) on heat shock protein and insulin levels in the circulation 1 h later was evaluated. Hsp27 and hsp60 levels remained unchanged. In contrast, serum levels of hsp72 markedly increased after glucose ingestion (p = 0.0054). Further analysis revealed that this increase was limited to women who were not obese (body mass index <30). Insulin levels pre-GCT were positively correlated with body mass index (p = 0.0189). Median insulin concentrations also increased post GCT in non-obese women but remained almost unchanged in obese women. Post-GCT serum hsp72 concentrations were inversely correlated with post GCT insulin concentrations (p = 0.0111). These observations suggest that glucose intake during gestation in Black women rapidly leads to an elevation in circulating hsp72 only in non-obese Black women. The release of hsp72 may regulate the extent of insulin production in response to a glucose challenge and, thereby, protect the mother and/or fetus from development of hyperglycemia, hyperinsulinemia, and/or immune system alterations. © 2013 Cell Stress Society International.

Increased osseointegration effect of bone morphogenetic protein 2 on dental implants: An in vivo study

Application of recombinant human bone morphogenetic protein 2 (rhBMP-2) to implant surfaces has been of great interest due to its osteoinductive potential. However, the optimal coating methodology has not been clarified. The objective of the study was to determine whether the application of rhBMP-2 onto plasma-sprayed hydroxyapatite implant surfaces by immersion in protein solution before implant installation would result in significantly improved bone apposition. Using a sheep iliac model, titanium (Ti) and plasma-sprayed calcium-phosphate (PSCaP)-coated implants uncoated and coated with rhBMP-2 were assessed for their osteogenic effects in the peri-implant area over time in terms of osseointegration and de novo bone formation. After 3 and 6 weeks postoperatively, the samples were retrieved and were subjected to bone-to-implant contact (BIC) and bone area fraction occupancy (BAFO) evaluation. When rhBMP-2 was applied to the PSCaP surface, significant increases in BIC and BAFO were observed at 3 weeks in vivo, whereas when adsorbed directly onto the titanium implant surface, rhBMP-2 did not as effectively improve the bone response (although significantly higher than control Ti). The outcomes of the present study suggested that the combination of plasma-sprayed calcium-phosphate surface and rhBMP-2 coating significantly enhanced osseointegration, which validated the postulated hypothesis. © 2013 Wiley Periodicals, Inc.

Hypusine Modification of the Ribosome-binding Protein eIF5A, a Target for New Anti-Inflammatory Drugs: Understanding the Action of the Inhibitor GC7 on a Murine Macrophage Cell Line

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Evaluation of stryphnodendron sp. release using natural rubber latex membrane as carrier

Natural rubber latex from Hevea brasiliensis has interesting characteristics related to this work such as: it is easy to manipulate, low cost, can stimulate the natural angiogenesis, is a biocompatible material and presents high mechanical resistance. The aim of this study was to develop a novel sustained delivery system for Stryphnodendron sp. based on Natural Rubber Latex (NRL) membranes and to study the Stryphnodendron sp. delivery system behavior. Stryphnodendron sp., commonly known as barbatimao is extensively used in folk medicine for the treatment of diarrhoea, gynaecological problems and for healing wounds. The stem bark of this species is mentioned in the Brazilian Pharmacopeia with a content of at least 20% of tannins. Previous studies showed significant cicatrizant properties, anti-inflammatory activity and gastric anti-ulcerogenic effects for the stem bark crude extract. One possible way to accelerate the tissue repair process, it was incorporated the Stryphnodendron sp. extract in NRL membranes. Stryphnodendron sp extract was incorporated into the NRL, by mixing it in solution for in vitro protein delivery experiments. Results show that the NRL membrane can release Stryphnodendron sp. for up to 49.89% of its Stryphnodendron sp. content for up 400 h. The kinetics of the extract release could be fitted with double exponential function, with two characteristic times of 0.78 and 133.22 h. In this study, we demonstrated that the induced angiogenesis provided by NRL membranes combined with a controlled release of extract is relevant for biomedical applications.

Effects of protein supplementation frequency on physiological responses associated with reproduction in beef cows

The objective of this experiment was to determine if frequency of protein supplementation impacts physiological responses associated with reproduction in beef cows. Fourteen nonpregnant, nonlactating beef cows were ranked by age and BW and allocated to 3 groups. Groups were assigned to a 3 x 3 Latin square design, containing 3 periods of 21 d and the following treatments: 1) soybean meal supplementation daily (D), 2) soybean meal supplementation 3 times/week (3WK), and 3) soybean meal supplementation once/week (1WK). Within each period, cows were assigned to an estrus synchronization protocol: 100 mu g of GnRH + controlled internal drug release device (CIDR) containing 1.38 g of progesterone (P-4) on d 1, 25 mg of PGF(2 alpha) on d 8, and CIDR removal + 100 mu g of GnRH on d 11. Grass-seed straw was offered for ad libitum consumption. Soybean meal was individually supplemented at a daily rate of 1 kg/cow (as-fed basis). Moreover, 3WK was supplemented on d 0, 2, 4, 7, 9, 11, 14, 16, and 18 whereas 1WK was supplemented on d 4, 11, and 18. Blood samples were collected from 0 (before) to 72 h after supplementation on d 11 and 18 and analyzed for plasma urea-N (PUN). Samples collected from 0 to 12 h were also analyzed for plasma glucose, insulin, and P-4 (d 18 only). Uterine flushing fluid was collected concurrently with blood sampling at 28 h for pH evaluation. Liver biopsies were performed concurrently with blood sampling at 0, 4, and 28 h and analyzed for mRNA expression of carbamoyl phosphate synthetase I (CPS-I; h 28) and CYP2C19 and CYP3A4 (h 0 and 4 on d 18). Plasma urea-N concentrations were greater (P < 0.01) for 1WK vs. 3WK from 20 to 72 h and greater (P < 0.01) for 1WK vs. D from 16 to 48 h and at 72 h after supplementation (treatment x hour interaction, P < 0.01). Moreover, PUN concentrations peaked at 28 h after supplementation for 3WK and 1WK (P < 0.01) and were greater (P < 0.01) at this time for 1WK vs. 3WK and D and for 3WK vs. D. Expression of CPS-I was greater (P < 0.01) for 1WK vs. D and 3WK. Uterine flushing pH tended (P <= 0.10) to be greater for 1WK vs. 3WK and D. No treatment effects were detected (P >= 0.15) on expression of CYP2C19 and CYP3A4, plasma glucose, and P-4 concentrations, whereas plasma insulin concentrations were greater (P <= 0.03) in D and 3WK vs. 1WK. Hence, decreasing frequency of protein supplementation did not reduce uterine flushing pH or plasma P-4 concentrations, which are known to impact reproduction in beef cows.

Protective effects of the galectin-1 protein on in vivo and in vitro models of ocular inflammation

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)