In Utero Exposure to Maternal Diabetes Impairs Vascular Expression of Prostacyclin Receptor in Rat Offspring

International audienc

Effects of mild vitamin a deficiency on lung maturation in newborn rats: a morphometric and morphologic study

OBJECTIVE To evaluate the effects of a 60% vitamin A deficiency (VAD) on the two postnatal stages of lung development: alveolarization and microvascular maturation. Lungs from deficient rats were compared to age-matched controls. STUDY DESIGN Starting at 3 weeks before mating, female rats were maintained under a diet lacking vitamin A. Due to the slow depletion of the vitamin A liver stores the pregnant rats carried to term and delivered pups under mild VAD conditions. Mothers and offspring were then kept under the same diet what resulted in a mean reduction of vitamin A plasma concentration of about 60% vs. controls during the whole experimental period. Pups were sacrificed on days 4, 10 and 21 and their lungs fixed and analyzed by means of a combined morphologic and morphometric investigation at light and electron microscopic levels. RESULTS During the whole experiment, body weights of VAD animals were lower than controls with a significant decrease on day 10. On days 4, 10 and 21 the pulmonary structure was in a comparable gross morphologic state in both groups. Despite this morphologic normality, quantitative alterations in some functional parameters could be detected. On day 4, lung volume and the volume and surface area of air spaces were decreased, while the arithmetic mean barrier thickness and type 2 pneumocyte volume were increased in the VAD group. On day 21, some changes were again manifest mainly consisting in an augmentation of the vascularization and a decrease in interstitial volume in deficient animals. CONCLUSIONS Mild VAD causes no gross disturbances in the postnatal phases of lung development in rats. However, a body weight-related transient retardation of lung maturation was detectable in the first postnatal week. At 3 weeks, the VAD lungs showed a more mature vascular system substantiated by an increase in volume of both capillary volume and the large non-parenchymal vessels. In view of these quantitative alterations, we suspect that mild VAD deregulates the normal phases of body and lung growth, but does not induce serious functional impairments

MMP9 Limits Apoptosis and Stimulates Branching Morphogenesis During Kidney Development

Early events in kidney organogenesis involve reciprocal interactions between the ureteric bud and the metanephric mesenchyme, which lead to remodeling of the extracellular matrix. This remodeling involves matrix metalloproteases (MMPs), but the specific roles of individual MMPs in kidney development are not completely understood. Here, we analyzed MMP9-deficient mice at the first step of kidney development and found that MMP9 deficiency delayed embryonic kidney maturation and increased apoptosis ex vivo by 2.5-fold. These early defects resulted in a 30% decrease in nephron number, a 20% decrease in adult kidney weight, and altered kidney function and morphology at 12 mo. The membrane form of stem cell factor (SCF) increased, whereas the activated form of the SCF receptor, c-kit, decreased in MMP9-deficient embryonic kidneys. In organotypic culture, MMP9-deficient kidneys failed to secrete SCF, and addition of recombinant SCF partially rescued both apoptosis and the branching defect. In conclusion, these data show that MMP9 protects mesenchymal cells from apoptosis during kidney development and stimulates ureteric bud branching morphogenesis, most likely by releasing the soluble form of SCF, suggesting that normal renal development requires MMP9

Vascular relaxation of mesenteric arteries in control (CMO) and diabetic (DMO) mother offspring.

<p>Concentration-response curve to acetylcholine (ACh, A) and sodium nitroprusside (SNP, B). Bar graphs represent the level of pre-contraction induced by 10^-6M phenylephrine. Values are mean ± SEM (n = 7 minimum per group). * p<0.05 and ** p<0.01 DMO vs. CMO.</p

Vascular contraction and histomorphological parameters of mesenteric arteries from control (CMO) and diabetic (DMO) mother offspring.

<p>(A) Concentration–response curve to phenylephrine (PE); (B) KCl-induced contraction; (C) passive arterial diameter measured in response to increased pressure; (D) myogenic tone and (E) lumen diameter, media cross-sectional area (MCSA), intima-media thickness (IMT) and remodelling index (media/lumen ratio). Values are mean ± SEM (n = 5 minimum per group). ** p<0.01 DMO vs. CMO at 18 months of age; ### p<0.001 CMO 18 vs. CMO 3.</p

Western blot analysis of contractile proteins.

<p>(A) Activity of MLC reflected by the pMLC/MLC ratio; (B) activity of PKA reflected by the pPKA/PKA ratio; (C) activity of RhoA reflected by the RhoA-GTP/RhoA ratio; (D) activity of MAP kinase P38 reflected by the ratio of pP38/P38 and protein expression levels of (E) filamin-1 and (F) profilin-1, normalised to β-actin were measured in mesenteric arteries from 3- and 18-month old CMO and DMO. Values are mean ± SEM (n = 5 minimum per group). * p<0.05 and ** p<0.01 DMO vs. CMO at the same age, ## p<0.05 18 vs. 3 months of age.</p

Prostacyclin-mediated relaxation and receptor expression level in control (CMO) and diabetic (DMO) mother offspring.

<p>(A) Relative protein expression of the prostacyclin receptor (IP receptor) was analysed by Western-blot in mesenteric arteries of CMO (open bars, n = 5) and DMO (solid bars, n = 5); each value was normalised to β-actin protein expression. (B) Left panel represents phenylephrine (PE)-induced pre-contraction level; right panel shows concentration-relaxation response curve to beraprost of mesenteric arteries in CMO and DMO (n = 5 at 3 months and n = 7 at 18 months of age for each group). Values are mean ± SEM. (C) Measurement of serum 6-keto-PGF1-α (prostacyclin metabolite) in CMO (n = 6) and DMO (n = 6). Each bar graph represents mean ± SEM. * p<0.05 DMO vs. CMO and ## p<0.01 18 vs. 3 months-old animals.</p