The islet estrogen receptor-α is induced by hyperglycemia and protects against oxidative stress-induced insulin-deficient diabetes - PubMed (original) (raw)

The islet estrogen receptor-α is induced by hyperglycemia and protects against oxidative stress-induced insulin-deficient diabetes

Gamze Kilic et al. PLoS One. 2014.

Abstract

The female steroid, 17β-estradiol (E2), is important for pancreatic β-cell function and acts via at least three estrogen receptors (ER), ERα, ERβ, and the G-protein coupled ER (GPER). Using a pancreas-specific ERα knockout mouse generated using the Cre-lox-P system and a Pdx1-Cre transgenic line (PERαKO ⁻/⁻), we previously reported that islet ERα suppresses islet glucolipotoxicity and prevents β-cell dysfunction induced by high fat feeding. We also showed that E2 acts via ERα to prevent β-cell apoptosis in vivo. However, the contribution of the islet ERα to β-cell survival in vivo, without the contribution of ERα in other tissues is still unclear. Using the PERαKO ⁻/⁻ mouse, we show that ERα mRNA expression is only decreased by 20% in the arcuate nucleus of the hypothalamus, without a parallel decrease in the VMH, making it a reliable model of pancreas-specific ERα elimination. Following exposure to alloxan-induced oxidative stress in vivo, female and male PERαKO ⁻/⁻ mice exhibited a predisposition to β-cell destruction and insulin deficient diabetes. In male PERαKO ⁻/⁻ mice, exposure to E2 partially prevented alloxan-induced β-cell destruction and diabetes. ERα mRNA expression was induced by hyperglycemia in vivo in islets from young mice as well as in cultured rat islets. The induction of ERα mRNA by hyperglycemia was retained in insulin receptor-deficient β-cells, demonstrating independence from direct insulin regulation. These findings suggest that induction of ERα expression acts to naturally protect β-cells against oxidative injury.

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Conflict of interest statement

Competing Interests: Franck Mauvais-Jarvis received research support from Pfizer Inc. This does not alter the authors' adherence to all the PLOS ONE policies on sharing data and materials.

Figures

Figure 1. ERα expression in PERαKO−/− hypothalamus.

Pdx1-Cre/Lacz mouse and immunofluorescence in frontal brain sections from PERαKO−/− mice. Pdx-1 expression (red) marked by beta galactosidase (β-gal) and ERα (green) show PDX-1 and ERα co-expression in the ventromedial hypothalamus (VMH), the preoptic area and arcuate nucleus (ARC) (A–B). and quantification (C) Bar represents 250 µm. Representative images of immunohistochemical analisys showing ERα expression in frontal brain sections from ERα fl/fl, (D) ERαKO−/− (E) and PERαKO−/− (F) mice Pictures taken at 10X magnification and quantification (G).

Figure 2

No difference in islet vascularization between ERαKO−/−, PERαKO−/− and control female mice. (A) Representative sections showing immunofluorescence staining for insulin (blue) and mouse CD31 (red) positive cells in control, PERαKO−/−, and ERαKO−/− pancreata. (B) Quantification of islets vessel density. Values represent the mean±SEM, n = 3–4/group. Bar represents 100 µm.

Figure 3. Gender dimorphism in alloxan sensitivity.

Comparison of blood glucose values and area under the curve for glucose (AUC) above basal (T0) between male and female C57bl/6J wild type mice. Blood glucose was measured every 48 h for 8 days after injection of 150 mg/kg of alloxan (ALX). Values represent the mean±SEM, n = 4/group.*P<0.05.

Figure 4. Female PERαKO−/− mice are susceptible to ALX-induced diabetes.

(A) Random-fed blood glucose from day 0 to day 11 after injection of either 150 mg/Kg of ALX or saline. (B) Corresponding area under the curve (AUC) for glucose. (C) Ratio of random-fed of insulin (ng/ml) and glucose (mg/dl) at day 11 was used as an index of insulin deficiency. (D) Representative sections showing immunofluorescent histochemical analysis of pancreas sections stained for insulin (green) and glucagon (red) in control ERαlox+/+ and PERαKO−/− mice (E) β-cell mass quantification. (F) Pancreas insulin concentration 11 day after ALX injection. Values represent the mean±SEM, n = 4–13/group. *P<0.05, **P<0.001 ***P<0.01, Bar represents 100 µm.

Figure 5. Male PERαKO−/− mice are susceptible to ALX-induced diabetes.

(A) Random-fed blood glucose from day 0 to day 11 after injection of either 150 mg/Kg of ALX or saline. (B) Corresponding area under the curve (AUC) for glucose. (C) Ratio of random-fed of insulin (ng/ml) and glucose (mg/dl) at day 11 was used as an index of insulin deficiency. (D) Representative sections showing immunofluorescent histochemical analysis of pancreas sections stained for insulin (green) and glucagon (red) in control ERαlox+/+ and PERαKO−/− mice (E) β-cell mass quantification (F) Pancreas insulin concentration 11 day after ALX injection. Values represent the mean±SEM, n = 4–19/group. *P<0.05, ***P<0.001, # = 0.06. Bar represents 100 µm.

Figure 6

Messenger RNA levels of ERα were measured by QT-PCR from (A) 2 and 6 months-old male Wistar rats after 72 h glucose and intralipid co-infusion.(B) C57bl/6J male mice of 8–12 weeks-old after a 4 day glucose infusion. (C) Wistar rat islets cultured for one week in glucose 5, 10 or 30 mM. (D) β-cells cell line from control Lox/Lox and βIRKO mice cultured in 16.7 or 33 mM glucose. Values represent the mean±SEM, n = 4–5/group. *P<0.05, **P<0.01, ***P<0.001.

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The islet estrogen receptor-α is induced by hyperglycemia and protects against oxidative stress-induced insulin-deficient diabetes - PubMed (original) (raw)