Long-Term Effect of Prolactin Treatment on Glucose-Induced Insulin Secretion in Cultured Neonatal Rat Islets

Crepaldi, S.; Carneiro, E. M.; Boschero, Antônio Carlos

doi:10.1055/s-2007-979025

Cited by 21 publications

(17 citation statements)

References 9 publications

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“…Expression of GLUT2 was further enhanced with the combination of glucose and PRL. The synergistic effect of glucose and PRL treatment on GLUT2 expression correlates well with the increased insulin secretion provoked by glucose in PRL-treated islets compared to control islets (9). These observations indicate that GLUT2 may play an important role in the process of maturation of the glucosesensing mechanism in neonatal islets.…”

supporting

confidence: 58%

Synergistic effect of glucose and prolactin on GLUT2 expression in cultured neonatal rat islets

Crepaldi-Alves

Carneiro²,

Bosqueiro³

et al. 1997

Braz J Med Biol Res

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We studied the synergistic effect of glucose and prolactin (PRL) on insulin secretion and GLUT2 expression in cultured neonatal rat islets. After 7 days in culture, basal insulin secretion (2.8 mM glucose) was similar in control and PRL-treated islets (1.84 ± 0.06% and 2.08 ± 0.07% of the islet insulin content, respectively). At 5.6 and 22 mM glucose, insulin secretion was significantly higher in PRL-treated than in control islets, achieving 1.38 ± 0.15% and 3.09 ± 0.21% of the islet insulin content in control and 2.43 ± 0.16% and 4.31 ± 0.24% of the islet insulin content in PRL-treated islets, respectively. The expression of the glucose transporter GLUT2 in B-cell membranes was dosedependently increased by exposure of the islet to increasing glucose concentrations. This effect was potentiated in islets cultured for 7 days in the presence of 2 µg/ml PRL. At 5.6 and 10 mM glucose, the increase in GLUT2 expression in PRL-treated islets was 75% and 150% higher than that registered in the respective control. The data presented here indicate that insulin secretion, induced by different concentrations of glucose, correlates well with the expression of the B-cell-specific glucose transporter GLUT2 in pancreatic islets. Key wordsThe first step in glucose-induced insulin secretion is the entry of the sugar into the Bcells, which is mediated by the glucose transporter GLUT2, located on the B-cell plasma membrane. Alteration in the expression of GLUT2 has been implicated in the reduction of the secretory response to glucose (1,2). Since growth and differentiation of the endocrine pancreas are controlled by glucose and the somatolactogenic hormones, growth hormone (GH) and prolactin (PRL) (3), we determined the effect of glucose on insulin secretion and GLUT2 expression in neonatal rat islets cultured in the presence or absence of PRL.We have used islets from neonatal rats (2 to 48 h old) obtained by collagenase digestion and cultured for 7 days, as described previously (4). After 7 days, the culture medium was discarded and the islets were incubated for 90 min at 37 o C in a bicarbonatebuffered solution containing different concentrations of glucose. The supernatant was withdrawn for insulin measurements and the

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supporting

confidence: 58%

Synergistic effect of glucose and prolactin on GLUT2 expression in cultured neonatal rat islets

Crepaldi-Alves

Carneiro²,

Bosqueiro³

et al. 1997

Braz J Med Biol Res

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“…Interestingly, insulin has also been reported to stimulate STAT3 serine phosphorylation (Ceresa & Pessin 1996). PRL increases insulin secretion from isolated pancreatic islets , Crepaldi et al 1997, and high serum insulin levels present in late pregnancy return to normal levels on day 1 after delivery (Kawai & Kishi 1999). Thus, the hypothesis that PRL increases STAT3 serine phosphorylation indirectly through the modulation of insulin secretion must also be considered to explain the results showed herein.…”

Section: Discussionmentioning

confidence: 60%

Signal transducer and activator of transcription 3-regulated sarcoendoplasmic reticulum Ca2+-ATPase 2 expression by prolactin and glucocorticoids is involved in the adaptation of insulin secretory response during the peripartum period

Anhê

Nogueira

Nicoletti-Carvalho

et al. 2007

Journal of Endocrinology

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During pregnancy, the maternal endocrine pancreas undergoes, as a consequence of placental lactogens and prolactin (PRL) action, functional changes that are characterized by increased glucose-induced insulin secretion. After delivery, the maternal endocrine pancreas rapidly returns to nonpregnant state, which is mainly attributed to the increased serum levels of glucocorticoids (GCs). Although GCs are known to decrease insulin secretion and counteract PRL action, the mechanisms for these effects are poorly understood. We have previously demonstrated that signal transducer and activator of transcription 3 (STAT3) is increased in islets treated with PRL. In the present study, we show that STAT3 expression and serine phosphorylation are increased in pancreatic islets at the end of pregnancy (P19). STAT3 serine phosphorylation rapidly returned to basal levels 3 days after delivery (L3). The expression of the sarcoendoplasmic reticulum Ca 2C -ATPase 2 (SERCA2), a crucial protein involved in the regulation of calcium handling in b-cells, was also increased in P19, returning to basal levels at L3. PRL increased SERCA2 and STAT3 expressions and STAT3 serine phosphorylation in RINm5F cells. The upregulation of SERCA2 by PRL was abolished after STAT3 knockdown. Moreover, PRL-induced STAT3 serine phosphorylation and SERCA2 expression were inhibited by dexamethasone (DEX). Insulin secretion from islets of P19 rats pre-incubated with thapsigargin and L3 rats showed a dramatic suppression of first phase of insulin release. The present results indicate that PRL regulates SERCA2 expression by a STAT3-dependent mechanism. PRL effect is counteracted by DEX and might contribute to the adaptation of maternal endocrine pancreas during the peripartum period.

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“…The effect of lactation on insulin secretion could be mediated by direct prolactin action as levels increase with lactation (32). Prolactin has been shown to stimulate insulin secretion (32) through stimulation of b-cell proliferation by downregulating the expression of menin (33).…”

Section: Discussionmentioning

confidence: 99%

Relationship between lactation duration and insulin and glucose response among women with prior gestational diabetes

Chouinard-Castonguay

Weisnagel

Tchernof

et al. 2013

European Journal of Endocrinology

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Background: Few studies have investigated whether favorable effects of lactation persist after weaning and protect women with prior gestational diabetes mellitus (GDM) against later development of insulin resistance and insulin secretion defects. Objective: To investigate the impact of lactation duration on insulin and glucose response among women with prior GDM. Design/methods: The study group comprised 144 women with a history of GDM between 2003 and 2010. Plasma insulin and glucose concentrations were obtained from a 75 g oral glucose tolerance test (OGTT). Total lactation duration (exclusive breastfeeding and breast and bottle-feeding) for all infants was self-reported in months. Results: Mean age was 36.5G5.0 years. Time between delivery and metabolic testing was 4.0G1.9 years. Women breastfed for an average of 13.9G16.8 months. Most women (80.6%) reported a history of lactation. Women who lactated had higher homeostasis model assessment for insulin sensitivity (HOMA-IS) and Matsuda indices and lower fasting and 2-h post-OGTT insulin concentrations as well as area under the curve (AUC) for insulin (P%0.01 for all). Compared with women who lactated for !10 months, women who lactated for R10 months had improved insulin sensitivity-secretion index, higher HOMA-IS and Matsuda indices, lower fasting and 2-h post-OGTT insulin concentrations as well as AUC for insulin, and lower incidence of impaired glucose intolerance (P%0.05 for all). In multiple linear regression analyses, lactation duration emerged as an independent predictor of fasting insulin concentrations (bZK0.02) and insulin sensitivity indices (bZ0.02) (P%0.05 for all). Conclusions: These results suggest that longer duration of lactation is associated with improved insulin and glucose response among women with prior GDM.

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Long-Term Effect of Prolactin Treatment on Glucose-Induced Insulin Secretion in Cultured Neonatal Rat Islets

Cited by 21 publications

References 9 publications

Synergistic effect of glucose and prolactin on GLUT2 expression in cultured neonatal rat islets

Synergistic effect of glucose and prolactin on GLUT2 expression in cultured neonatal rat islets

Signal transducer and activator of transcription 3-regulated sarcoendoplasmic reticulum Ca2+-ATPase 2 expression by prolactin and glucocorticoids is involved in the adaptation of insulin secretory response during the peripartum period

Relationship between lactation duration and insulin and glucose response among women with prior gestational diabetes

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