Production of a type 2 maternal diabetes rodent model using the combination of high-fat diet and moderate dose of streptozocin.

INTRODUCTION: Pregnancy may be complicated by maternal diabetes. The following experiments were performed in an attempt to produce mouse models of insulin-resistant maternal diabetes. METHODS: CD1 females received 200 mg/kg streptozocin (STZ) to model insulin-dependent diabetes (T1 group). Another group of females (T2 group) was put on a HFD 4 weeks before receiving 100 mg/kg STZ. After 4 additional weeks of HFD, hyperglycemic females were separated and bred. In another experiement, CD1 females were fed a HFD for 4 weeks before receiving an intravenous (GDM1 group) or intraperitoneal (GDM2 group) injection of 100 mg/kg STZ. Females from GDM2 group were bred at the same day of the STZ injection. Females from GDM1 group were bred 4 weeks after the STZ injection. RESULTS AND CONCLUSION: About 25% of the females from T2 group became hyperglycemic after 4 weeks of the injection of STZ. Fifty percent of the females from GDM1 group reached hyperglycemic levels greater than 250 mg/dl during pregnancy. The combination of HFD and moderate STZ in CD1 mice therefore produced hyperglycemic females; however numbers of these mice were somewhat low.

Late-gestation ventricular myocardial reduction in fetuses of hyperglycemic CD1 mice is associated with increased apoptosis.

BACKGROUND: Previous work in our laboratory showed reduced myocardium and dilated ventricular chambers in gestation day (GD) 17 hearts that were collected from hyperglycemic CD1 mouse dams. Pre-breeding maternal immune stimulation, using Freund's complete adjuvant (FCA), diminished the severity of these fetal heart lesions. The following experiments were performed to detect possible changes in fetal heart apoptotic cell death, under hyperglycemic conditions and with or without maternal immune stimulation. METHODS: Female CD1 mice were injected with 200 mg/kg of streptozocin (STZ) to induce insulin-dependent diabetes mellitus. Half of these mice received prior FCA injection. Fetal hearts were collected on GD 17 and myocardial apoptotic cells were quantified using flow cytometry. A panel of apoptosis regulatory genes (Bcl2, p53, Casp3, Casp9, PkCe) was then examined in the fetal myocardium using RT-PCR. RESULTS: Early apoptotic cells and late apoptotic/necrotic cells were significantly increased in fetal hearts from STZ or STZ+FCA dams. Pre-treatment with FCA reduced late apoptotic/necrotic cells to control level, suggesting some cell death protection was rendered by FCA. Paradoxically in the face of such increased cell death, the expression of pro-apoptotic genes Casp3 and Casp9 was decreased by diabetes, while the anti-apoptotic gene Bcl2 was increased. CONCLUSIONS: Maternal hyperglycemia causes dys-regulated apoptosis of fetal myocardial cells. Such effect may be prevented by maternal immune stimulation.