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<p>Aim/hypothesis:In utero exposure to maternal diabetes increases the risk of developing hypertension and cardiovascular disorders during adulthood. We have previously shown that this is associated with changes in vascular tone in favor of a vasoconstrictor profile, which is involved in the development of hypertension. This excessive constrictor tone has also a strong impact on vascular structure. Our objective was to study the impact of in utero exposure to maternal diabetes on vascular structure and remodeling induced by chronic changes in hemodynamic parameters.</p><p>Methods and Results: We used an animal model of rats exposed in utero to maternal hyperglycemia (DMO), which developed hypertension at 6 months of age. At a pre-hypertensive stage (3 months of age), we observed deep structural modifications of the vascular wall without any hemodynamic perturbations. Indeed, in basal conditions, resistance arteries of DMO rats are smaller than those of control mother offspring (CMO) rats; in addition, large arteries like thoracic aorta of DMO rats have an increase of smooth muscle cell attachments to elastic lamellae. In an isolated perfused kidney, we also observed a leftward shift of the flow/pressure relationship, suggesting a rise in renal peripheral vascular resistance in DMO compared to CMO rats. In this context, we studied vascular remodeling in response to reduced blood flow by in vivo mesenteric arteries ligation. In DMO rats, inward remodeling induced by a chronic reduction in blood flow (1 or 3 weeks after ligation) did not occur by contrast to CMO rats in which arterial diameter decreased from 428 ± 17 μm to 331 ± 20 μm (at 125 mmHg, p = 0.001). In these animals, the transglutaminase 2 (TG2) pathway, essential for inward remodeling development in case of flow perturbations, was not activated in low-flow (LF) mesenteric arteries. Finally, in old hypertensive DMO rats (18 months of age), we were not able to detect a pressure-induced remodeling in thoracic aorta.</p><p>Conclusions: Our results demonstrate for the first time that in utero exposure to maternal diabetes induces deep changes in the vascular structure. Indeed, the early narrowing of the microvasculature and the structural modifications of conductance arteries could be a pre-emptive adaptation to fetal programming of hypertension.</p

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

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

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

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

Nighttime (NT) and daylight (DL) spontaneous locomotor activity.

<p>Activity was measured in standard cages (BL) and during 14 days (d1–d14) for control (<b>A</b>), isolated-control (<b>B</b>), isolated (<b>C</b>), attached (<b>D</b>), and unloaded (<b>E</b>) rats. Data are given as a mean ± SEM. *- P < 0.05 <i>versus</i> basal level (BL).</p

Design of the experimental cages.

<p>Control (<b>A</b>), isolated-control (<b>B</b>), isolated (<b>C</b>), attached (<b>D</b>), and unloaded (<b>E</b>) rats.</p

Heart rate and blood pressure during treadmill running.

<p>Heart rate (left) and mean arterial pressure (right) during a treadmill running test before (<b>PRE</b>) and after (<b>POST</b>) 14-days of control (<b>A</b>), isolation-control (<b>B</b>), isolation (<b>C</b>), attachment (<b>D</b>), and unloading (<b>E</b>). Cage: in experimental cage. TM1: in the treadmill cage, at rest, before exercise. EX: during treadmill running. TM2: in the treadmill cage, at rest, after exercise. Data are given as a mean ± SEM. *and # - P < 0.05 <i>versus</i> respective TM1 level.</p

Heart rate changes.

<p>Nighttime (NT) and daylight (DL) heart rate measured in standard cages (BL) and during 14 days (d1–d14) for control (<b>A</b>), isolated-control (<b>B</b>), isolated (<b>C</b>), attached (<b>D</b>), and unloaded (<b>E</b>) rats. Data are given as a mean ± SEM. *- P < 0.05 <i>versus</i> basal level (BL).</p

Body weight and food consumption.

<p>Values are group means for 7 days ± SEM, *<i>P</i> < 0.05, **<i>P</i> < 0.01 ***<i>P</i> < 0.001 <i>vs.</i> control group.</p