Effects of subtotal pancreatectomy and long-term glucose and lipid overload on insulin secretion and glucose homeostasis in minipigs

Abstract

Introduction: Nowadays, there are no strong diabetic pig models, yet they are required for various types of diabetes research. Using cutting-edge techniques, we attempted to develop a type 2 diabetic minipig model in this study by combining a partial pancreatectomy (Px) with an energetic overload administered either orally or parenterally.

Methods: Different groups of minipigs, including Göttingen-like (GL, n = 17) and Ossabaw (O, n = 4), were developed. Prior to and following each intervention, metabolic assessments were conducted. First, the metabolic responses of the Göttingen-like (n = 3) and Ossabaw (n = 4) strains to a 2-month High-Fat, High-Sucrose diet (HFHSD) were compared. Then, other groups of GL minipigs were established: with a single Px (n = 10), a Px combined with a 2-month HFHSD (n = 6), and long-term intraportal glucose and lipid infusions that were either preceded by a Px (n = 4) or not (n = 4).

Results: After the 2-month HFHSD, there was no discernible change between the GL and O minipigs. The pancreatectomized group in GL minipigs showed a significantly lower Acute Insulin Response (AIR) (18.3 ± 10.0 IU/mL after Px vs. 34.9 ± 13.7 IU/mL before, p < .0005). In both long-term intraportal infusion groups, an increase in the Insulinogenic (IGI) and Hepatic Insulin Resistance Indexes (HIRI) was found with a decrease in the AIR, especially in the pancreatectomized group (IGI: 4.2 ± 1.9 after vs. 1.5 ± 0.8 before, p < .05; HIRI (×10^-5 ): 12.6 ± 7.9 after vs. 3.8 ± 4.3 before, p < .05; AIR: 24.4 ± 13.7 µIU/mL after vs. 43.9 ± 14.5 µIU/mL before, p < .005). Regardless of the group, there was no fasting hyperglycemia.

Conclusions: In this study, we used pancreatectomy followed by long-term intraportal glucose and lipid infusions to develop an original minipig model with metabolic syndrome and early signs of glucose intolerance. We reaffirm the pig's usefulness as a preclinical model for the metabolic syndrome but without the fasting hyperglycemia that characterizes diabetes mellitus.

Keywords: energetic overload; hyperglycemia; minipig model; pancreatectomy; type 2 diabetes.

FIGURE 1

Overall study design for each group of animals. CVC, Central Venous Catheter; HFHSD, High‐Fat High‐Sucrose diet; Px, Pancreatectomy. The fully black minipig represents the Ossabaw strain, while the pink and black ones indicate the Göttingen‐like strain. A Mixed Meal Test (MMT) and an Intravenous Glucose Tolerance Test constitute metabolic assessments (IVGTT). Metabolic tests were performed on all minipigs (n = 10) with subtotal pancreatectomy 2 weeks after the intervention.

FIGURE 2

Comparison of the Ossabaw and Göttingen‐like minipig strains' metabolic responses to a 2‐month High‐Fat, High‐Sucrose diet. (A–D) Mean curves (Mean ± SEM; n = 3) of Blood Glucose (A) and Plasma Insulin (B) during Mixed Meal Test (MMT) and Blood Glucose (C) and Plasma Insulin (D) during Intravenous Glucose Tolerance Test (IVGTT) in the Göttingen‐like (GL) strain, with the baseline characteristics represented in black and after 2‐month High‐Fat High‐Sucrose diet (HFHSD) in orange. (E–H) Mean curves (Mean ± SEM; n = 4) of Blood Glucose (E) and Plasma Insulin (F) during MMT and Blood Glucose (G) and Plasma Insulin (H) during IVGTT in the Ossabaw (O) strain, with the baseline characteristics represented in black and after HFHSD in blue. (I) Mean Fasting Blood Glucose (Mean ± SD) measured during MMT before (in black) and after (in colour) HFHSD in the Göttingen‐like (GL, in orange; n = 3) and in the Ossabaw (O, blue; n = 4) strains. (J, K) Mean Insulinogenic Index (J) and Hepatic Insulin Resistance Index (K) (Mean ± SD) calculated during MMT before (in black) and after (in colour) HFHSD in the Göttingen‐like (GL, in orange; n = 3) and in the Ossabaw (O, blue; n = 4) strains. (L) Mean Acute Insulin Response (Mean ± SD) calculated during IVGTT before (in black) and after (in colour) HFHSD in the Göttingen‐like (GL, in orange; n = 3) and in the Ossabaw (O, blue; n = 4) strains. (M) Fasting plasma lipid profile (Mean ± SD) assessed before (in black) and after (in colour) HFHSD in the Göttingen‐like (GL, in orange; n = 3) and in the Ossabaw (O, blue; n = 4) strains. HDL, high‐density lipoprotein; LDL, low‐density lipoprotein; TG, triglycerides; Total Chol, total cholesterol. Two‐Way ANOVA test for repeated measures and Sidak post‐hoc test; Paired or unpaired t‐test; *p < .05, **p < .01, ***p < .001.

FIGURE 3

Evaluation of the effect of a subtotal pancreatectomy on glucose metabolism in Göttingen‐like minipigs. (A) Mean Fasting Blood Glucose (Mean ± SD; n = 10) measured during MMT before (in black) and after (in blue) subtotal pancreatectomy. (B, C) Mean curves (Mean ± SEM; n = 10) of Blood Glucose (B) and Plasma Insulin (C) during MMT before (in black) and after (in blue) subtotal pancreatectomy. (D) Mean Insulinogenic Index (Mean ± SD; n = 10) calculated during MMT before (in black) and after (in blue) subtotal pancreatectomy. (E, F) Mean curves (Mean ± SEM; n = 10) of Blood Glucose (E) and Plasma Insulin (F) during IVGTT before (in black) and after (in blue) subtotal pancreatectomy. (G) Mean Acute Insulin Response (Mean ± SD; n = 10) calculated during IVGTT before (in black) and after (in blue) subtotal pancreatectomy. (H) Fasting plasma lipid profile (Mean ± SD; n = 10) assessed before (in black) and after (in blue) subtotal pancreatectomy. HDL, high‐density lipoprotein; LDL, low‐density lipoprotein; TG, triglycerides; Total Chol, total cholesterol. Two‐Way ANOVA test for repeated measures and Sidak post‐hoc test; Paired t‐test; *p < .05, ***p < .0005 between baseline and after pancreatectomy.

FIGURE 4

Effect of the combination of a subtotal pancreatectomy followed by a 2‐month High‐Fat High‐Sucrose diet on glucose metabolism in Göttingen‐like minipigs. (A) Mean Fasting Blood Glucose (Mean ± SD; n = 6) measured during MMT before (in black) and after (in orange) subtotal pancreatectomy followed by a 2‐month High‐Fat High‐Sucrose diet (HFHSD). (B, C) Mean curves (Mean ± SEM; n = 6) of Blood Glucose (A) and Plasma Insulin (B) during MMT before (in black) and after (in orange) subtotal pancreatectomy followed by a 2‐month HFHSD. (D, E) Mean Insulinogenic Index (D) and Hepatic Insulin Resistance Index (E) (Mean ± SD; n = 6) calculated during MMT before (in black) and after (in orange) subtotal pancreatectomy followed by a 2‐month HFHSD. (F, G) Mean curves (Mean ± SEM; n = 6) of Blood Glucose (F) and Plasma Insulin (G) during IVGTT before (in black) and after (in orange) subtotal pancreatectomy followed by a 2‐month HFHSD. (H) Mean Acute Insulin Response (Mean ± SD; n = 6) calculated during IVGTT before (in black) and after (in orange) subtotal pancreatectomy followed by a 2‐month HFHSD. (I) Fasting plasma lipid profile (Mean ± SD; n = 6) assessed before (in black) and after (in orange) subtotal pancreatectomy followed by a 2‐month HFHSD. HDL, high‐density lipoprotein; LDL, low‐density lipoprotein; TG, triglycerides; Total Chol, total cholesterol. Two‐Way ANOVA test for repeated measures and Sidak post‐hoc test; Paired t‐test; *p < .05.

FIGURE 5

Effect of long‐term intraportal glucose and lipid infusions on glucose metabolism in Göttingen‐like minipigs, whether or not they are preceded by a subtotal pancreatectomy. (A–D) Mean curves (Mean ± SEM; n = 4) of Blood Glucose (A) and Plasma Insulin (B) during Mixed Meal Test (MMT) and Blood Glucose (C) and Plasma Insulin (D) during Intravenous Glucose Tolerance Test (IVGTT) before (in black) and after (in blue) 3 weeks of long‐term intraportal glucose and lipids infusions. (E–H) Mean curves (Mean ± SEM; n = 4) of Blood Glucose (E) and Plasma Insulin (F) during Mixed Meal Test (MMT) and Blood Glucose (G) and Plasma Insulin (H) during Intravenous Glucose Tolerance Test (IVGTT) before (in black) and after (in orange) the combination of a subtotal pancreatectomy followed by 3 weeks of long‐term intraportal glucose and lipid infusions. (I) Mean Fasting Blood Glucose (Mean ± SD; n = 4 per group) measured during MMT at the baseline for Group 1 (in light grey) and Group 2 (in dark grey) and after 3 weeks of long‐term intraportal glucose and lipid infusions (Group 1, in blue) and after subtotal pancreatectomy followed by 3 weeks of long‐term intraportal glucose and lipid infusions (Group 2, in orange). (J, K) Mean Insulinogenic Index (J) and Hepatic Insulin Resistance Index (K) (Mean ± SD; n = 4 per group) calculated during MMT at the baseline for Group 1 (in light grey) and Group 2 (in dark grey) and after 3 weeks of long‐term intraportal glucose and lipid infusions (Group 1, in blue) and after subtotal pancreatectomy followed by 3 weeks of long‐term intraportal glucose and lipid infusions (Group 2, in orange). (L) Mean Acute Insulin Response (Mean ± SD; n = 4 per group) calculated during IVGTT at the baseline for Group 1 (in light grey) and Group 2 (in dark grey) and after 3 weeks of long‐term intraportal glucose and lipid infusions (Group 1, in blue) and after subtotal pancreatectomy followed by 3 weeks of long term intraportal glucose and lipid infusions (Group 2, in orange). (M) Fasting plasma lipid profile (Mean ± SD; n = 4 per group) assessed at the baseline for Group 1 (in light grey) and Group 2 (in dark grey) and after 3 weeks of long‐term intraportal glucose and lipid infusions (Group 1, in blue) and after subtotal pancreatectomy followed by 3 weeks of long‐term intraportal glucose and lipid infusions (Group 2, in orange). HDL, high‐density lipoprotein; LDL, low‐density lipoprotein; TG, triglycerides; Total Chol, total cholesterol. Two‐Way ANOVA test for repeated measures and Sidak post‐hoc test; Paired t‐test; *p < .05, **p < .01.