Maternal high-fat diet regulates glucose metabolism and pancreatic β cell phenotype in mouse offspring at weaning

Abstract

Background: Maternal malnutrition is a critical factor in determining the risk of obesity and glucose intolerance in offspring. However, little is known about the effects of a maternal high-fat diet (HFD) on the β cell phenotype in offspring, which is a major factor in glucose homeostasis, especially during the early life of offspring.

Methods: Dams were randomly fed a HFD (60% kcal from fat) or a chow diet before pregnancy and during gestation and lactation. Glucose metabolism and the β cell phenotype were assessed in male offspring at weaning.

Results: Dams fed a HFD showed impaired glucose tolerance. A HFD predisposed the offspring to increased impairment of metabolic health, including obesity, glucose intolerance and insulin resistance, compared with offspring from chow diet-fed dams. Furthermore, increased islet sizes and islet densities were observed in male offspring from HFD-fed dams at weaning. There were increases in the insulin-positive area, β cell mass and β cell proliferation in male offspring from HFD-fed dams at weaning age. Next, we further determined whether a maternal HFD could affect β cell apoptosis in mouse offspring and found that there was no significant change in β cell apoptosis between the HFD and control groups.

Conclusion: Our study is novel in showing that a maternal HFD predisposes offspring to impaired glucose metabolism and has a profound effect on β cell mass and proliferation in offspring mice, which is observed in mice as early as at weaning age. However, further study to clarify the underlying mechanisms is warranted.

Keywords: Glucose metabolism; Maternal high-fat diet; Offspring; Weaning; β cell.

Figure 1. Effects of diets on metabolic profile in dams.

(A) Body weight gain during 3 weeks before pregnancy; (B) Pre-gestational body weight; (C) Food intake; (D) Intraperitoneal glucose tolerance test (IPGTT) of dams; (E) AUC during the glucose tolerance test of dams; (F) Insulin tolerance test (ITT) of dams; (G) AUC during the insulin tolerance test of dams. AUC: area under the curve, HFD: high-fat diet; Dams were noted as F0; Data represented as the mean ±  SEM. **P < 0.01, ***P < .001 vs. Chow, n = 12 to 16, per group.

Figure 2. Impaired glucose metabolism in male offspring from HFD-fed dams at weaning.

(A) Body weight at weaning; (B) Fasting blood glucose (FBG); (C) Fasting insulin concentration; (D) Intraperitoneal glucose tolerance test (IPGTT) of male offspring at weaning; (E) AUC during the glucose tolerance test; (F) Insulin tolerance test (ITT) of male offspring at weaning; (G) AUC during the insulin tolerance test of offspring. AUC: area under the curve, HFD: high-fat diet; Data represented as the mean ± SEM. *P < 0.05, **P < 0.01, ***P < .001 vs. Chow, n = 6 − 8 litters in each group, one male offspring per litter.

Figure 3. Effect of maternal over-nutrition on islet morphology in male offspring at weaning.

(A–B) Representative images of HE staining in pancreatic cross sections. Scale: 200 um. (C) Quantitative analysis of islets size. The islet size was calculated by the average of the longest and shortest diameters of each islet. (D) Total islet area (% pancreas areas). (E) Islet density (calculated by total number of islets/pancreas areas (mm2)). HFD: high-fat diet. Data represented as the mean ± SEM. *P < 0.05 vs. Chow, n = 6 − 8 litters in each group, one male offspring per litter.

Figure 4. Higher β cell mass in male offspring from HFD-fed dams at weaning.

(A–B) Representative images of insulin-positive areas in pancreatic cross sections immunostained with anti-insulin antibody. (C) β cell mass quantification. HFD: high-fat diet. Data represented as the mean ± SEM. *P < 0.05 vs. Chow, n = 6 − 8 litters in each group, one male offspring per litter.

Figure 5. Maternal HFD predisposes higher β cell proliferation in male offspring at weaning.

(A–H) Representative images of proliferating cells in pancreatic sections immunostained with insulin/Ki67/DAPI in Chow and HFD groups. (I–P) Representative images of proliferating cells in pancreatic sections immunostained with insulin/BrdU/DAPI in Chow and HFD groups. HFD: high-fat diet. Feel free to contact me if you have any questions

Figure 6. Effect of maternal over-nutrition on β cell proliferation and apoptosis in offspring at weaning age.

(A) Quantification of Ki67(+) insulin(+) cells: at least 5,000 insulin(+) cells were counted for each mouse. (B) Quantification of BrdU(+) insulin(+) cells: at least 5,000 insulin(+) cells were counted for each mouse. (C) Quantification of TUNEL(+) insulin(+) cells: at least 5,000 insulin(+) cells were counted for each mouse. HFD: high-fat diet. Data represent mean ± SEM. ^∗P < 0.05 vs. Chow, n = 6–8 litters in each group, one male offspring per litter.