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A low-protein diet during pregnancy prevents modifications in intercellular communication proteins in rat islets.

Marçal-Pessoa AF, Bassi-Branco CL, Salvatierra Cdos S, Stoppiglia LF, Ignacio-Souza LM, de Lima Reis SR, Veloso RV, de Barros Reis MA, Carneiro EM, Boschero AC, Arantes VC, Latorraca MQ - Biol. Res. (2015)

Bottom Line: The low-protein diet reduced the levels of connexin 36 and β-catenin protein in pancreatic islets.The low-protein diet during pregnancy did not alter these mRNA and protein levels, but avoided the increase of levels of phospho-[Ser(279/282)]-connexin 43 in islets.Short-term protein restriction during pregnancy prevented the Cx43 phosphorylation, but this event did not interfer in the insulin secretion.

View Article: PubMed Central - PubMed

Affiliation: Mestrado em Ciências da Saúde, Faculdade de Ciências Médicas, Universidade Federal de Mato Grosso, Cuiabá, Mato Grosso, Brazil. anabiorq@usp.br.

ABSTRACT

Background: Gap junctions between β-cells participate in the precise regulation of insulin secretion. Adherens junctions and their associated proteins are required for the formation, function and structural maintenance of gap junctions. Increases in the number of the gap junctions between β-cells and enhanced glucose-stimulated insulin secretion are observed during pregnancy. In contrast, protein restriction produces structural and functional alterations that result in poor insulin secretion in response to glucose. We investigated whether protein restriction during pregnancy affects the expression of mRNA and proteins involved in gap and adherens junctions in pancreatic islets. An isoenergetic low-protein diet (6% protein) was fed to non-pregnant or pregnant rats from day 1-15 of pregnancy, and rats fed an isocaloric normal-protein diet (17% protein) were used as controls.

Results: The low-protein diet reduced the levels of connexin 36 and β-catenin protein in pancreatic islets. In rats fed the control diet, pregnancy increased the levels of phospho-[Ser(279/282)]-connexin 43, and it decreased the levels of connexin 36, β-catenin and beta-actin mRNA as well as the levels of connexin 36 and β-catenin protein in islets. The low-protein diet during pregnancy did not alter these mRNA and protein levels, but avoided the increase of levels of phospho-[Ser(279/282)]-connexin 43 in islets. Insulin secretion in response to 8.3 mmol/L glucose was higher in pregnant rats than in non-pregnant rats, independently of the nutritional status.

Conclusion: Short-term protein restriction during pregnancy prevented the Cx43 phosphorylation, but this event did not interfer in the insulin secretion.

No MeSH data available.


Glucose stimulation of insulin secretion by islets from non-pregnant controls (CN), pregnant controls (CP), low-protein non-pregnant rats (LPNP) and low-protein pregnant rats (LPP). Groups of 5 islets were incubated for 90 min in Krebs-bicarbonate medium containing (A) 5.6 or (B) 8.3 mmol/L glucose. The columns represent the cumulative 90-min insulin secretion and are the means ± SD of 5–9 independent experiments. Columns with different superscript minuscule letters are significantly different by two-way ANOVA followed by a least significant difference (LSD) test (P < 0.05).
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Fig1: Glucose stimulation of insulin secretion by islets from non-pregnant controls (CN), pregnant controls (CP), low-protein non-pregnant rats (LPNP) and low-protein pregnant rats (LPP). Groups of 5 islets were incubated for 90 min in Krebs-bicarbonate medium containing (A) 5.6 or (B) 8.3 mmol/L glucose. The columns represent the cumulative 90-min insulin secretion and are the means ± SD of 5–9 independent experiments. Columns with different superscript minuscule letters are significantly different by two-way ANOVA followed by a least significant difference (LSD) test (P < 0.05).

Mentions: In islets that were administered 5.6 mmol/L glucose, a two-way ANOVA revealed a significant effect of the interaction between the nutritional and physiological status (F1,24 = 8.03, P < 0.01). Thus, insulin secretion in the LPP, CP and CN groups was increased compared to that of the LPNP group (Figure 1A). Insulin secretion in the presence of 8.3 mmol/L glucose was influenced only by the physiological status (F1,36 = 90.13, P < 0.001); i.e., islets from pregnant (LPP and CP) rats released more insulin than islets from non-pregnant (LPNP and CN) rats (Figure 1B).


A low-protein diet during pregnancy prevents modifications in intercellular communication proteins in rat islets.

Marçal-Pessoa AF, Bassi-Branco CL, Salvatierra Cdos S, Stoppiglia LF, Ignacio-Souza LM, de Lima Reis SR, Veloso RV, de Barros Reis MA, Carneiro EM, Boschero AC, Arantes VC, Latorraca MQ - Biol. Res. (2015)

Glucose stimulation of insulin secretion by islets from non-pregnant controls (CN), pregnant controls (CP), low-protein non-pregnant rats (LPNP) and low-protein pregnant rats (LPP). Groups of 5 islets were incubated for 90 min in Krebs-bicarbonate medium containing (A) 5.6 or (B) 8.3 mmol/L glucose. The columns represent the cumulative 90-min insulin secretion and are the means ± SD of 5–9 independent experiments. Columns with different superscript minuscule letters are significantly different by two-way ANOVA followed by a least significant difference (LSD) test (P < 0.05).
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4362834&req=5

Fig1: Glucose stimulation of insulin secretion by islets from non-pregnant controls (CN), pregnant controls (CP), low-protein non-pregnant rats (LPNP) and low-protein pregnant rats (LPP). Groups of 5 islets were incubated for 90 min in Krebs-bicarbonate medium containing (A) 5.6 or (B) 8.3 mmol/L glucose. The columns represent the cumulative 90-min insulin secretion and are the means ± SD of 5–9 independent experiments. Columns with different superscript minuscule letters are significantly different by two-way ANOVA followed by a least significant difference (LSD) test (P < 0.05).
Mentions: In islets that were administered 5.6 mmol/L glucose, a two-way ANOVA revealed a significant effect of the interaction between the nutritional and physiological status (F1,24 = 8.03, P < 0.01). Thus, insulin secretion in the LPP, CP and CN groups was increased compared to that of the LPNP group (Figure 1A). Insulin secretion in the presence of 8.3 mmol/L glucose was influenced only by the physiological status (F1,36 = 90.13, P < 0.001); i.e., islets from pregnant (LPP and CP) rats released more insulin than islets from non-pregnant (LPNP and CN) rats (Figure 1B).

Bottom Line: The low-protein diet reduced the levels of connexin 36 and β-catenin protein in pancreatic islets.The low-protein diet during pregnancy did not alter these mRNA and protein levels, but avoided the increase of levels of phospho-[Ser(279/282)]-connexin 43 in islets.Short-term protein restriction during pregnancy prevented the Cx43 phosphorylation, but this event did not interfer in the insulin secretion.

View Article: PubMed Central - PubMed

Affiliation: Mestrado em Ciências da Saúde, Faculdade de Ciências Médicas, Universidade Federal de Mato Grosso, Cuiabá, Mato Grosso, Brazil. anabiorq@usp.br.

ABSTRACT

Background: Gap junctions between β-cells participate in the precise regulation of insulin secretion. Adherens junctions and their associated proteins are required for the formation, function and structural maintenance of gap junctions. Increases in the number of the gap junctions between β-cells and enhanced glucose-stimulated insulin secretion are observed during pregnancy. In contrast, protein restriction produces structural and functional alterations that result in poor insulin secretion in response to glucose. We investigated whether protein restriction during pregnancy affects the expression of mRNA and proteins involved in gap and adherens junctions in pancreatic islets. An isoenergetic low-protein diet (6% protein) was fed to non-pregnant or pregnant rats from day 1-15 of pregnancy, and rats fed an isocaloric normal-protein diet (17% protein) were used as controls.

Results: The low-protein diet reduced the levels of connexin 36 and β-catenin protein in pancreatic islets. In rats fed the control diet, pregnancy increased the levels of phospho-[Ser(279/282)]-connexin 43, and it decreased the levels of connexin 36, β-catenin and beta-actin mRNA as well as the levels of connexin 36 and β-catenin protein in islets. The low-protein diet during pregnancy did not alter these mRNA and protein levels, but avoided the increase of levels of phospho-[Ser(279/282)]-connexin 43 in islets. Insulin secretion in response to 8.3 mmol/L glucose was higher in pregnant rats than in non-pregnant rats, independently of the nutritional status.

Conclusion: Short-term protein restriction during pregnancy prevented the Cx43 phosphorylation, but this event did not interfer in the insulin secretion.

No MeSH data available.