Intrauterine programming of urinary calcium and magnesium excretion in children born to mothers with insulin dependent diabetes mellitus

Long-term outcomes and potential mechanisms of offspring exposed to intrauterine hyperglycemia

Diabetes mellitus during pregnancy, which can be classified into pregestational diabetes and gestational diabetes, has become much more prevalent worldwide. Maternal diabetes fosters an intrauterine abnormal environment for fetus, which not only influences pregnancy outcomes, but also leads to fetal anomaly and development of diseases in later life, such as metabolic and cardiovascular diseases, neuropsychiatric outcomes, reproduction malformation, and immune dysfunction. The underlying mechanisms are comprehensive and ambiguous, which mainly focus on microbiota, inflammation, reactive oxygen species, cell viability, and epigenetics. This review concluded with the influence of intrauterine hyperglycemia on fetal structure development and organ function on later life and outlined potential mechanisms that underpin the development of diseases in adulthood. Maternal diabetes leaves an effect that continues generations after generations through gametes, thus more attention should be paid to the prevention and treatment of diabetes to rescue the pathological attacks of maternal diabetes from the offspring.

Hypomagnesaemia and pregnancy

Hypomagnesaemia is common in pregnancy, particularly in developing countries and low-income communities. Despite the frequent therapeutic use of magnesium in pregnancy, and the evidence regarding the association of hypomagnesaemia with adverse pregnancy outcomes in animal studies, it remains unclear whether hypomagnesaemia is associated with complications in human pregnancy. Three case reports of pregnancies complicated by moderate-severe hypomagnesaemia are presented and magnesium physiology in pregnancy is discussed. The evidence as to whether hypomagnesaemia may represent a direct cause, a consequence of other disease processes or an epiphenomenon in adverse pregnancies outcomes is reviewed.

Maternal hypomagnesemia alters renal function but does not program changes in the cardiovascular physiology of adult offspring

Maternal undernutrition is known to adversely impact fetal health and development. Insults experienced in utero alter development of the fetus as it adapts to microenvironment stressors, leading to growth restriction and subsequent low birth weight. Infants born small for gestational age have significantly increased risk of developing cardiovascular and renal disease in later life, an effect that is often characterized by hypertension and reduced glomerular number. Maternal magnesium (Mg2+) deficiency during pregnancy impairs fetal growth, however, the long-term health consequences for the offspring remain unknown. Here, we used a mouse model of dietary Mg2+ deficiency before and during pregnancy to investigate cardiovascular and renal outcomes in male and female adult offspring at 6 months of age. There were no differences between groups in 24-h mean arterial pressure or heart rate as measured by radiotelemetry. Cardiovascular responses to aversive (restraint, dirty cage switch) and non-aversive (feeding response) stressors were also similar in all groups. There were no differences in nephron number, however, Mg2+-deficient offspring had increased urine flow (in both males and females) and reduced Mg2+ excretion (in males only). Despite evidence suggesting that maternal nutrient restriction programs for hypertension in adult offspring, we found that a moderate level of maternal dietary Mg2+ deficiency did not program for a nephron deficit, or alter cardiovascular function at 6 months of age. These data suggest there are no long-term adverse outcomes for the cardiovascular health of offspring of Mg2+ deficient mothers.

Long-term effects of gestational diabetes on offspring health are more pronounced in skeletal growth than body composition and glucose tolerance

Infants of diabetic mothers may have low arachidonic acid (AA) and develop obesity and insulin resistance in adulthood. The present study tested the effect of maternal diabetes and AA supplementation on offspring body composition, bone mass and glucose tolerance from 4 to 12 weeks. Rat dams were randomised into six groups using a 3 × 2 design. The rat dams were treated using the following treatments: saline-placebo, streptozotocin-induced diabetes (STZ) with glucose controlled at < 13 mmol/l (STZ/GC) or poorly controlled at 13-20 mmol/l (STZ/PC) using insulin, and fed either a control or an AA (0.5 % of fat) diet throughout reproduction. Weaned offspring were fed regular chow. Measurements included offspring body composition, bone and oral glucose tolerance testing (OGTT) plus liver fatty acids of dam and offspring. Comparable to saline-placebo offspring, the STZ/GC offspring had greater (P < 0.03) whole body and regional bone area than STZ/PC offspring. Maternal glucose negatively correlated (P < 0.05) with offspring whole body bone area and mineral content at 4 weeks in all offspring, and with tibia area in males at 12 weeks. Maternal liver DHA negatively (P < 0.03) correlated with femur and tibia mineral content and tibia mineral density of female offspring at 12 weeks. Offspring from AA-supplemented dams had higher (P = 0.004) liver AA at 4 weeks. Liver AA at 4 weeks positively (P = 0.05) correlated with lumbar spine mineral density in males. OGTT was not affected by maternal treatment or diet. These results suggest that maternal glucose control has long-term consequences to bone health of adult offspring. Skeletal growth appears more sensitive to maternal hyperglycaemia than glucose tolerance.

Effects of early postnatal hyperglycaemia on renal cortex maturity, endothelial nitric oxide synthase expression and nephron deficit in mice

The influence of hyperglycaemia on nephrogenesis on Swiss mice pups treated with streptozotocin (STZ) (40 mg/kg, i.p.) was studied after birth, at 7 and 21 days. Kidneys were prepared for light microscopy, immunohistochemistry and stereology. In 7-day-old pups, both immature and mature glomeruli were evaluated separately. Proliferating cell nuclear antigen (PCNA) and endothelial nitric oxide synthase (eNOS) immunostaining were performed and quantified. At age 7 days, the immature-to-mature glomeruli ratio (IMGR) was significantly higher in the STZ group than in the control group. There was no difference in the number of glomeruli between the STZ and control groups; however, the number of glomeruli increased by more than 20% in the control group until 21 days of age, but not in the STZ group. STZ pups showed numerous PCNA-positive nuclei mainly in tubular cells, but not control pups. At 21 days, eNOS expression in the outer layer of glomerular endothelial nuclei was strong in control pups, but weaker in STZ pups. Treatment with STZ during the early neonatal period disturbs the normal nephrogenesis occurring at this stage of the rodent's life and causes retardation in renal cortical maturity, as indicated by the increase in both PCNA expression and IMGR, and reduction in eNOS expression.

Diabetes in rat pregnancy alters renal calcium and magnesium reabsorption and bone formation in adult offspring

AIMS/HYPOTHESIS

We tested the hypothesis that diabetes in pregnancy can result in the in-utero reprogramming of renal calcium and magnesium handling and of bone formation in the offspring, which persists into adulthood.

METHODS

Male offspring of streptozotocin-treated diabetic rats (OD rats) and of control non-diabetic animals (OC rats) were investigated as neonates and at 8, 12 and 16 weeks of age.

RESULTS

Compared with OC rats, urinary calcium and magnesium output was significantly reduced in OD rats at every age studied; Na+ and K+ outputs were unaffected. The renal expression of proteins involved in the tubular reabsorption of calcium (calcium ATPase, calbindin-D28k and epithelial calcium channel) was increased in OD animals compared with that in OC animals. Additionally, we observed that adult OD rats had lower trabecular and higher cortical femoral bone volumes, explained by deposition of bone on the endosteal surface.

CONCLUSIONS/INTERPRETATION

These data show that diabetes in pregnancy has profound effects on male offspring in terms of renal tubular calcium and magnesium reabsorption and the normal pattern of bone formation. These effects persist into adulthood. Such long-lasting effects of diabetes on kidney and the skeleton were not suspected and could have important implications for the health of children born to diabetic women.