Understanding diabetic teratogenesis: where are we now and where are we going?

Maternal pregestational diabetes (type 1 or type 2) poses an increased risk for a broad spectrum of birth defects. To our knowledge, this problem first came to the attention of the Teratology Society at the 14th Annual Meeting in Vancouver, B.C. in 1974, with a presentation by Lewis Holmes, "Etiologic heterogeneity of neural tube defects". Although advances in the control of diabetes in the decades since the discovery of insulin in the 1920's have reduced the risk for birth defects during diabetic pregnancy, the increasing incidence of diabetes among women of childbearing years indicates that this cause of birth defects is a growing public health concern. Major advances in understanding how a disease of maternal fuel metabolism can interfere with embryogenesis of multiple organ systems have been made in recent years. In this review, we trace the history of the study of diabetic teratogenesis and discuss a model in which tissue-specific developmental control genes are regulated at specific times in embryonic development by glucose metabolism. The major function of such genes is to suppress apoptosis, perhaps to preserve proliferative capability, and inhibit premature senescence.

SOD1 deficiency causes salt sensitivity and aggravates hypertension in hydronephrosis.

Hydronephrosis causes renal dysfunction and salt-sensitive hypertension, which is associated with nitric oxide deficiency and abnormal tubuloglomerular feedback (TGF) response. We investigated the role of oxidative stress for salt sensitivity and for hypertension in hydronephrosis. Hydronephrosis was induced in superoxide dismutase 1-transgenic (SOD1-tg), SOD1-deficient (SOD1-ko), and wild-type mice and in rats. In mice, telemetric measurements were performed during normal (0.7% NaCl) and high-sodium (4% NaCl) diets and with chronic tempol supplementation. The 8-iso-prostaglandin-F(2alpha) (F2-IsoPs) and protein excretion profiles and renal histology were investigated. The acute effects of tempol on blood pressure and TGF were studied in rats. In hydronephrosis, wild-type mice developed salt-sensitive hypertension (114 +/- 1 to 120 +/- 2 mmHg), which was augmented in SOD1-ko (125 +/- 3 to 135 +/- 4 mmHg) but abolished in SOD1-tg (109 +/- 3 to 108 +/- 3 mmHg). SOD1-ko controls displayed salt-sensitive blood pressure (108 +/- 1 to 115 +/- 2 mmHg), which was not found in wild types or SOD1-tg. Chronic tempol treatment reduced blood pressure in SOD1-ko controls (-7 mmHg) and in hydronephrotic wild-type (-8 mmHg) and SOD1-ko mice (-16 mmHg), but had no effect on blood pressure in wild-type or SOD1-tg controls. SOD1-ko controls and hydronephrotic wild-type and SOD1-ko mice exhibited increased fluid excretion associated with increased F2-IsoPs and protein excretion. The renal histopathological changes found in hydronephrotic wild-type were augmented in SOD1-ko and diminished in SOD-tg mice. Tempol attenuated blood pressure and normalized TGF response in hydronephrosis [DeltaP(SF): 15.2 +/- 1.2 to 9.1 +/- 0.6 mmHg, turning point: 14.3 +/- 0.8 to 19.7 +/- 1.4 nl/min]. Oxidative stress due to SOD1 deficiency causes salt sensitivity and plays a pivotal role for the development of hypertension in hydronephrosis. Increased superoxide formation may enhance TGF response and thereby contribute to hypertension.

Maternal blood glucose levels determine the severity of diabetic embryopathy in mice with different expression of copper-zinc superoxide dismutase (CuZnSOD).

Excess oxygen radical formation is suggested to be involved in the etiology of diabetic embryopathy. We aimed to investigate the effects of altered maternal antioxidative status in conjunction with a varied severity of the maternal diabetic state on embryonic development by using mice with different gene expression of CuZn superoxide dismutase (CuZnSOD). The mice were wild-type (WT), transgenic (TG), or knockout (KO) with regard to CuZnSOD. Alloxan was used to induce diabetes (DWT, DTG, DKO) in female mice before pregnancy and, noninjected mice served as controls (NWT, NTG, NKO). The minimum alloxan dose required to induce diabetes was 80 mg/kg for WT, 100 mg/kg for TG, and 65 mg/kg for KO mice. When KO mice were made diabetic with 80 mg/kg alloxan, they produced no living offspring. The pregnancies were interrupted on gestational day 18, when maternal diabetic state, that is, blood glucose concentration, as well as fetal outcome, genotype and hepatic isoprostane levels were assessed. The mean maternal blood glucose levels were positively associated with the alloxan dose, that is, the DWT and DTG groups had higher blood glucose concentration than the DKO group, and the DWT and DTG fetuses increased their hepatic isoprostane levels, whereas the DKO fetuses did not. However, in all diabetic groups, increased maternal blood glucose concentration was associated with higher resorption and malformation rates as well as lowered fetal and placental weight. Furthermore, diabetes increased the fraction of WT offspring in the TG and KO groups. We conclude that both fetal antioxidative capacity and maternal diabetic state affect the development of the offspring. However, the maternal diabetic state is the major teratogenic factor and overrides the influence of fetal antioxidative capacity.

Nitric oxide deficiency and increased adenosine response of afferent arterioles in hydronephrotic mice with hypertension.

Afferent arterioles were used to investigate the role of adenosine, angiotensin II, NO, and reactive oxygen species in the pathogenesis of increased tubuloglomerular feedback response in hydronephrosis. Hydronephrosis was induced in wild-type mice, superoxide dismutase-1 overexpressed mice (superoxide-dismutase-1 transgenic), and deficient mice (superoxide dismutase-1 knockout). Isotonic contractions in isolated perfused arterioles and mRNA expression of NO synthase isoforms, adenosine, and angiotensin II receptors were measured. In wild-type mice, N(G)-nitro-L-arginine methyl ester (L-NAME) did not change the basal arteriolar diameter of hydronephrotic kidneys (-6%) but reduced it in control (-12%) and contralateral arterioles (-43%). Angiotensin II mediated a weaker maximum contraction of hydronephrotic arterioles (-18%) than in control (-42%) and contralateral arterioles (-49%). The maximum adenosine-induced constriction was stronger in hydronephrotic (-19%) compared with control (-8%) and contralateral kidneys (+/-0%). The response to angiotensin II became stronger in the presence of adenosine in hydronephrotic kidneys and attenuated in contralateral arterioles. L-NAME increased angiotensin II responses of all of the groups but less in hydronephrotic kidneys. The mRNA expression of endothelial NO synthase and inducible NO synthase was upregulated in the hydronephrotic arterioles. No differences were found for adenosine or angiotensin II receptors. In superoxide dismutase-1 transgenic mice, strong but similar L-NAME response (-40%) was observed for all of the groups. This response was totally abolished in arterioles of hydronephrotic superoxide dismutase-1 knockout mice. In conclusion, hydronephrosis is associated with changes in the arteriolar reactivity of both hydronephrotic and contralateral kidneys. Increased oxidative stress, reduced NO availability, and stronger reactivity to adenosine of the hydronephrotic kidney may contribute to the enhanced tubuloglomerular feedback responsiveness in hydronephrosis and be involved in the development of hypertension.

Folic acid supplementation affects ROS scavenging enzymes, enhances Vegf-A, and diminishes apoptotic state in yolk sacs of embryos of diabetic rats.

We aimed to investigate the extent to which maternal diabetes with or without folic acid (FA) supplementation affects mRNA levels and protein distribution of ROS scavenging enzymes, vascular endothelial growth factor-A (Vegf-A), folate binding protein-1 (Folbp-1), and apoptosis-associated proteins in the yolk sacs of rat embryos on gestational days 10 and 11. Commencing at conception and throughout pregnancy, half of the streptozotocin-diabetic and half of the control rats received daily FA injections. Maternal diabetes impaired vascular morphology and decreased CuZnSOD and GPX-1 gene expression in yolk sacs. Maternal diabetes also increased the levels of CuZnSOD protein, increased the Bax/Bcl-2 protein ratio and decreased Vegf-A protein distribution. FA treatment normalized vascular morphology, decreased mRNA levels of all three SOD isoforms and increased Vegf-A mRNA levels, rectified CuZnSOD protein distribution and Bax/Bcl-2 ratio. A teratogenic diabetic environment produces a state of vasculopathy, oxidative stress, and mild apoptosis in the yolk sac. FA administration normalizes vascular morphology, diminishes apoptotic rate, and increases Vegf-A gene expression and protein distribution in the yolk sac of diabetic rats.

Metastasis-associated S100A4 (Mts1) protein is expressed in subpopulations of sensory and autonomic neurons and in Schwann cells of the adult rat.

S100A4 (Mts1) is a member of a family of calcium-binding proteins of the EF-hand type, which are widely expressed in the nervous system, where they appear to be involved in the regulation of neuron survival, plasticity, and response to injury or disease. S100A4 has previously been demonstrated in astrocytes of the white matter and rostral migratory stream of the adult rat. After injury, S100A4 is markedly up-regulated in affected central nervous white matter areas as well as in the periventricular area and rostral migratory stream. Here, we show that S100A4 is expressed in a subpopulation of dorsal root, trigeminal, geniculate, and nodose ganglion cells; in a subpopulation of postganglionic sympathetic and parasympathetic neurons; in chromaffin cells of the adrenal medulla; and in satellite and Schwann cells. In dorsal root ganglia, S100A4-positive cells appear to constitute a subpopulation of small ganglion neurons, a few of which coexpressed calcitonin gene-related peptide (CGRP) and Griffonia simplicifolia agglutinin (GSA) isolectin B4 (B4). S100A4 protein appears to be transported from dorsal root ganglia to the spinal cord, where it is deposited in the tract of Lissauer. After peripheral nerve or dorsal root injury, a few S100A4-positive cells coexpress CGRP, GSA, or galanin. Peripheral nerve or dorsal root injury induces a marked up-regulation of S100A4 expression in satellite cells in the ganglion and in Schwann cells at the injury site and in the distal stump. This pattern of distribution partially overlaps that of the previously studied S100B and S100A6 proteins, indicating a possible functional cooperation between these proteins. The presence of S100A4 in sensory neurons, including their processes in the central nervous system, suggests that S100A4 is involved in propagation of sensory impulses in specific fiber types.