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Clinical and experimental studies show that unilateral (1/2Nx) and subtotal nephrectomy (5/6Nx) in adults result in compensatory renal growth without formation of new nephrons. During nephrogenesis, the response to renal mass reduction has not been fully investigated. Ovine fetuses underwent 1/2Nx, 5/6Nx, or sham surgery (sham) at 70 d of gestation (term: 150 d), when nephrogenesis is active. At 134 d, renal function was determined, fetuses were killed, and kidneys were further analyzed at the cellular and molecular levels. Additional fetuses subjected to 5/6Nx were killed at 80 and 90 d of gestation to investigate the kinetics of the renal compensatory process. At 134 d, in 1/2Nx, a significant increase in kidney weight and estimated glomerular number was observed. In 5/6Nx, the early and marked catch-up in kidney weight and estimated glomerular number was associated with a striking butterfly-like remodeling of the kidney that developed within the first 10 d following nephrectomy. In all groups, in utero glomerular filtration rates were similar. Compensatory renal growth was observed after parenchymal reduction in both models; however, the resulting compensatory growth was strikingly different. After 5/6Nx, the remnant kidney displayed a butterfly-like remodeling, and glomerular number was restored.

Background: Intrauterine growth restriction (IUGR) is a risk factor for hypertension (HT) and chronic renal disease (CRD). A reduction in the nephron number is proposed to be the underlying mechanism; however, the mechanism is debated. The aim of this study was to demonstrate that IUGR-induced HT and CRD are linked to the magnitude of nephron number reduction, independently on its cause. Methods: Systolic blood pressure (SBP), glomerular filtration rate (GFR), proteinuria, nephron number, and glomerular sclerosis were compared between IUGR offspring prenatally exposed to a maternal low-protein diet (9% casein; LPD offspring) or maternal administration of betamethasone (from E17 to E19; BET offspring) and offspring with a normal birth weight (NBW offspring). Results: Both prenatal interventions led to IUGR and a similar reduction in birth weight. In comparison to NBW offspring, BET offspring had a severe nephron deficit (-50% in males and -40% in females, p < 0.01), an impaired GFR (-33%, p < 0.05), and HT (SBP+ 17 mmHg, p < 0.05). Glomerular sclerosis was more than twofold higher in BET offspring than in NBW offspring (p < 0.05). Long-term SBP, GFR, and glomerular sclerosis were unchanged in LPD offspring while the nephron number was moderately reduced only in males (-28% vs. NBW offspring, p < 0.05). Conclusion: In this study, the magnitude of nephron number reduction influences long term renal disease in IUGR offspring: a moderate nephron number is an insufficient factor. Extremely long-term follow-up of adults prenatally exposed to glucocorticoids are required.

International audience; Epidemiologic studies have demonstrated that cardiovascular risk is not only determined by conventional risk factors in adulthood, but also by early life events which may reprogram vascular function. To evaluate the effect of maternal diabetes on fetal programming of vas-cular tone in offspring and its evolution during adulthood, we investigated vascular reactivity of third order mesenteric arteries from diabetic mother offspring (DMO) and control mother offspring (CMO) aged 3 and 18 months. In arteries isolated from DMO the relaxation induced by prostacyclin analogues was reduced in both 3-and 18-month old animals although endothelium (acetylcholine)-mediated relaxation was reduced in 18-month old DMO only. Endothelium-independent (sodium nitroprusside) relaxation was not affected. Pressure-induced myogenic tone, which controls local blood flow, was reduced in 18-month old CMO compared to 3-month old CMO. Interestingly, myogenic tone was maintained at a high level in 18-month old DMO even though agonist-induced vasoconstriction was not altered. These perturbations, in 18-months old DMO rats, were associated with an increased pMLC/MLC, pPKA/PKA ratio and an activated RhoA protein. Thus, we highlighted perturbations in the reactivity of resistance mesenteric arteries in DMO, at as early as 3 months of age, followed by the maintenance of high myogenic tone in older rats. These modifications are in favour of excessive vasoconstrictor tone. These results evi-denced a fetal programming of vascular functions of resistance arteries in adult rats exposed in utero to maternal diabetes, which could explain a re-setting of vascular functions and, at least in part, the occurrence of hypertension later in life.

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.

Various antenatal events impair nephrogenesis in humans as well as in several animal models. The consecutive low nephron endowment may contribute to an increased risk for cardiovascular and renal diseases in adulthood. However, little knowledge is available on the influence of the postnatal environment, especially nutrition, on nephrogenesis. Moreover, the consequences of early postnatal nutrition in late adulthood are not clear. We used a model of early postnatal overfeeding (OF) induced by reduction of litter size (3 pups/litter) in rats. Systolic blood pressure (SBP; plethysmography), glomerular filtration rate (clearance of creatinine), glomerular number and volume, and glomerulosclerosis were evaluated in 22-mo-old aging offspring. Early postnatal OF was associated with increased weight gain during the suckling period (+40%, P < 0.01) and a 20% increase in glomerular number ( P < 0.05). However, an increase in SBP at 12 mo by an average of 18 mmHg and an increase in proteinuria (2.6-fold) and glomerulosclerosis at 22 mo of age were observed in OF male offspring compared with controls. In conclusion, early postnatal OF in the rat enhances postnatal nephrogenesis, but elevated blood pressure and glomerulosclerosis are still observed in male adults. Factors other than glomerular number reduction are likely to contribute to the arterial hypertension induced by early postnatal OF.

In this study, low birth weight was induced in rats by feeding the dams with a low-protein diet during pregnancy. Kidneys from the fetuses at the end of gestation were collected and showed a reduction in overall and relative weight, in parallel with other tissues (heart and liver). This reduction was associated with a reduction in nephrons number. To better understand the molecular basis of this observation, a transcriptome analysis contrasting kidneys from control and protein-deprived rats was performed, using a platform based upon long isothermic oligonucleotides, strengthening the robustness of the results. We could identify over 1800 transcripts modified more than twice (772 induced and 1040 repressed). Genes of either category were automatically classified according to functional criteria, making it possible to bring to light a large cluster of genes involved in coagulation and complement cascades. The promoters of the most induced and most repressed genes were contrasted for their composition in putative transcription factor binding sites, suggesting an overrepresentation of the AP1R binding site, together with the transcription induction of factors actually binding to this site in the set of induced genes. The induction of coagulation cascades in the kidney of low-birth-weight rats provides a putative rationale for explaining thrombo-endothelial disorders also observed in intrauterine growth-restricted human newborns. These alterations in the kidneys have been reported as a probable cause for cardiovascular diseases in the adult.

Background and Aims: Acute renal failure (ARF) remains a major healthcare problem. Although modern medical therapy has improved its outcome, the syndrome still has high mortality and morbidity rates [Xue et al.: J Am Soc Nephrol 2006;17:1135–1142]. Recently, stem cell (SC) therapies have been proposed as an alternative for the treatment of ARF on the basis of the damaged cells’ replacement or enhanced recovery or regeneration. The aims of this study were to investigate the engraftment of autologous mesenchymal stem cells (MSC) injected into the renal artery in an ovine model of ischemia reperfusion injury (IRI) and to assess the consequence of the delay between injury and cell transplantation on the engraftment. Material and Methods: MSC were transplanted in animals submitted to IRI or in healthy animals not submitted to IRI. Sheep with IRI were grafted at two different time points after injury. Unilateral renal IRI was performed by percutaneous transluminal placement of a balloon catheter in the renal artery. MSC were isolated from bone marrow, cultured, labeled and injected into the renal artery. Results: All ewes showed renal engraftment by MSC, both in tubules and glomeruli. MSC expressed tubular epithelial cell markers and podocyte phenotype. There was a significant increase of engraftment of tubules by MSC when cells were injected early after injury indicating that the delay for cell transplantation after ischemic insult should be short. Conclusions: This is the first report of intra-arterial autologous transplantation of MSC in the kidney, resulting in a successful engraftment into tubular and glomerular structures. The results strongly suggest that the optimal time window for stem cell therapy is during the early phase of the ischemic injury.

The National Institute of Health and Medical Research (Inserm), the Society of Nephrology, and the French Kidney Foundation recognized the need to create a National Research Program for kidney and urinary tract diseases. They organized a conference gathering 80 researchers to discuss the state-of-the art and evaluate the strengths and weaknesses of kidney and urinary tract disease research in France, and to identify research priorities. From these priorities emerged 11 of common interest: 1) conducting epidemiologic studies; 2) conducting large multicenter cohorts of well-phenotyped patients with blood, urine and biopsy biobanks; 3) developing large scale approach: transcriptomics, proteomics, metabolomics; 4) developing human and animal functional imaging techniques; 5) strengthening the expertise in renal pathology and electrophysiology; 6) developing animal models of kidney injury; 7) identifying nontraumatic diagnostic and prognostic biomarkers; 8) increasing research on the fetal programming of adult kidney diseases; 9) encouraging translational research from bench to bedside and to population; 10) creating centers grouping basic and clinical research workforces with critical mass and adequate logistic support; 11) integrating and developing european research programs.

Background: The kidney development involves a wide variety of developmental processes requiring a lot of genes expressed in a sequential manner. The aim of the present study is to identify new genes involved in these processes. Methods: To obtain a view of the mouse embryonic kidney transcriptome we used the SADE method, which allows large-scale quantitative gene expression measurements. Results: 7,689 tags were sequenced from our library. Among the 4,507 unique transcripts yielded, 64% correspond to known genes, 22% ESTs, 12% unidentified genes. 472 genes were differentially expressed as compared to published adult kidney library. Among these, we identified several candidate genes and focused on a particular one: thymosin β4 (Tβ4), an actin-sequestering protein more highly expressed in fetal kidney. First we studied the in vivo expression patterns of Tβ4 transcript during kidney development. Tβ4 increases throughout the kidney development and remains high during active nephrogenesis. Moreover, the spatial distribution of Tβ4 mRNA was analysed and reveals that during active nephrogenesis (i.e., 18 dpc) Tβ4 is localised in differentiating glomeruli. In adult kidney, Tβ4 remains expressed in podocytes and collecting ducts. Conclusion: Our results provide the first demonstration of Tβ4 production in vivo by embryonic kidney and further show that Tβ4 is implicated in kidney organogenesis.

The goal of this study was to validate high-frequency (24 MHz) ultrasound imaging techniques for early detection and follow-up of renal tumors in a murine Wilms’ tumor model (n = 26). For 11 mice, maximum tumor dimensions were estimated from images along three orthogonal axes for comparison with posteuthanasia caliper and histologic measurements. Tumor size in the 15 remaining mice was checked biweekly. The mice were then euthanized and histologic study assessed tumor position and nature. Tumors were detected in vivo between 7 to 14 days after injection of tumor-inducing cells. Tumor maximum cross-sectional area varied from 0.07 mm2 to 5.7 mm2 at the time of initial detection. The relative r.m.s. error between ultrasonic and histologic estimations of maximum cross-sectional area was estimated to be 19%. Results demonstrate feasibility of noninvasive ultrasound biomicroscopy early detection and characterization of renal tumor development for longitudinal monitoring of the same animal. (E-mail: bridal@lip.bhdc.jussieu.fr )

In the kidney, in which development depends on epithelial-mesenchymal interactions, it has been shown that retinoids modulate nephrogenesis in a dose-dependent manner in vivo and in vitro. Midkine (MK) is a retinoic acid responsive gene for a heparin-binding growth factor. The aim of the present study was therefore to quantify the expression of MK mRNA during renal development in the rat, to analyze the regulation of MK expression by retinoids in vivo and in vitro, and, finally, to study the role of MK in rat metanephric organ cultures. The spatiotemporal expression of MK in fetal kidney was studied. In control rats, MK expression is ubiquitous at gestational day 14, i.e., at the onset of nephrogenesis. On day 16, MK is expressed in the condensed mesenchyme and in early epithelialized mesenchymal derivatives. On gestational day 21, MK is rather localized in the nonmature glomeruli of the renal cortex. In utero exposure to vitamin A deficiency did not modify the specific spatial and temporal expression pattern of MK gene in the metanephros, although a decrease in mRNA expression occurred. In metanephroi explanted from 14-d-old fetuses and cultured in a defined medium, expression of MK mRNA was found to be stimulated when retinoic acid (100 nM) was added in the culture medium. Finally, in vitro nephrogenesis was strongly inhibited in the presence of neutralizing antibodies for MK: the number of nephrons formed in vitro was reduced by approximately 50% without changes in ureteric bud branching morphogenesis. These results indicated that MK is implicated in the regulation of kidney development by retinoids. These results also suggested that MK plays an important role in the molecular cascade of the epithelial conversion of the metanephric blastema.

Mild vitamin A deficiency leads to inborn nephron deficit in the rat. Background Vitamin A plays a critical role in fetal organogenesis, and its severe deficiency during pregnancy is known to result in malformations of several organs, including the kidney. However, the consequences of mild vitamin A deficiency (VAD) has received little attention. In the present study, we examined the effect of in utero exposure to mild VAD on renal organogenesis. Methods A rat model of mild VAD compatible with normal gestation was developed. Plasma retinol was determined by reverse phase HPLC in mothers and fetuses. Nephron counting was performed in kidneys of fetuses and pups issued from control and VAD mothers. Metanephroi explanted from 14-day-old fetuses from both groups were cultured in the presence or absence of retinoic acid (RA), and growth and differentiation were assessed. c-ret expression was analyzed from fetuses exposed in utero to VAD or to normal vitamin A status and also in metanephroi grown in culture with or without RA using RT-PCR. Results The 50% reduction in circulating vitamin A levels induced by vitamin A deprivation in pregnant rats did not affect the overall fetal development. However, the number of nephrons was reduced by 20% in 21-day-old VAD fetuses. The number of nephrons was closely correlated with circulating vitamin A level in both VAD and control fetuses. Metanephroi taken from VAD fetuses developed to a lesser extent in vitro , but their capacity to respond to exogenous retinoic acid was not altered. Finally, we found that the expression of the proto-oncogene c-ret was modulated according to the retinoid environment. Conclusion We conclude that vitamin A supply to the fetus is critical in determining the number of nephrons. Data available thus far on the frequency of mild VAD during pregnancy and on the long-term consequences of inborn nephron deficit highlight the clinical relevance of the present study.

1. Prevention of weaning prevents the increase in the carrier affinity for Na(+)-cotransported phosphate (Pi) and the normal elevation of plasma 3,5,3'-triiodothyronine (T3) which occur between postnatal days 14 and 21. 2. This study examines the possible role of T3 in the control of the maturation process of Pi transport. Clearance experiments and brush-border membrane studies were performed on 14-day-old rats given T3. 3. The fractional excretion of Pi of T3-treated rats was 33% lower compared with controls (P < 0.01). After Pi perfusion, it remained at a lower level, and the amount of Pi reabsorbed per minute, corrected for the glomerular filtration rate (RPi/GFR), was higher. 4. The membrane vesicles from 14-day-old rats given T3 showed a 30% increase in carrier affinity for Na(+)-cotransported Pi. In addition to this maturational effect of T3, a 46% increase in Vmax was also observed. 5. The amount of immunoreactive Pi transporter, detected using anti-(NaPi-2) antiserum, was increased in T3-treated rats. 6. Glucose transport, another Na(+)-dependent transport system, was not altered by T3. 7. It is concluded that exogenous T3 given before the third postnatal week specifically induced precocious maturation of renal Pi transport in 14-day-old rats, suggesting that thyroid hormone is normally involved in this maturation.

Renal phosphate transport matures via an increase in the carrier affinity for phosphate during the 3rd post-natal week in the rat. This study examines whether weaning, which normally takes place during this period, plays a role in phosphate transport maturation. Early weaning (EW) and prevention of weaning (PW) both increased the fractional excretion of phosphate (EW 26.5±4.9, PW 26.7±2.2, controls 11.3±2.8,P

The renal phosphate (Pi)-transporting capacity normally increases, due to increased carrier system affinity, during the third postnatal week in rats. However, the tubular Pi reabsorption of rat pups born from gentamicin-treated mothers does not increase during this period. This study determines whether exposure to gentamicin in utero selectively alters the postnatal maturation of the carrier affinity for Pi. Pi and glucose transports by proximal tubule brush-border membrane (BBM) were studied. The maximal rate of uptake (Vmax) of Na-Pi cotransport was significantly lower (536 +/- 169 pmol.mg protein-1.10 s-1; n = 6, P < 0.01) in gentamicin-exposed rats than in controls (1,021 +/- 167 pmol.mg protein-1.10 s-1, n = 6), whereas the Michaelis constant (Km) values were the same. Gentamicin exposure had no effect on plasma parathyroid hormone concentration or on BBM glucose transport activity. The total phospholipid content of BBM, their phospholipid composition, cholesterol content, and cholesterol-to-total phospholipid mole ratio were unaltered, suggesting that membrane fluidity was unchanged. The Vmax of BBM alkaline phosphatase was lower in gentamicin-exposed rats than in controls.

Aim Recent evidence shows that adult metabolic disease may originate from an adverse fetal environment that can alter organ development and function in postnatal life. This study aimed to analyze the effect of exposure in utero to maternal diabetes on the development of the metabolic syndrome in the offspring. Methods Pregnant rats were made diabetic (blood glucose was 20mM) with a single streptozotocin injection on day 0 of gestation. Offspring from diabetic mothers (DMO) and control mothers (CMO) were followed from birth to 12 months of age. In these animals, metabolic parameters, such as glucose tolerance, insulin sensitivity and plasma lipid levels, as well as pancreatic insulin and morphology were studied. Results Compared with controls, DMO offspring had normal birth weights, but impaired postnatal growth that persisted throughout life. Metabolic tests revealed that DMO offspring also showed impaired glucose tolerance at six months associated with decreased insulin sensitivity and low insulin secretion. In older animals (12 months old), this phenotype persisted, but to a lesser extent. The DMO offspring also presented with high blood pressure and decreased levels of fasting plasma triglycerides, but normal plasma NEFA, and HDL and total cholesterol. Conclusion Altogether, these results show that our model of exposure in utero to maternal diabetes led to normal birth weights, and induced transient glucose intolerance and increased blood pressure with no major effects on lipid metabolism. It also suggests that a hyperglycaemic fetal environment may be able to ‘programme' hypertension and glucose intolerance, but not alter lipid metabolism.

Low birth weight is associated with an increased risk of hypertension and renal dysfunction at adulthood. Such an association has been shown to involve a reduction of nephron endowment and to be enhanced by accelerated postnatal growth in humans. However, while low-birth-weight infants often undergo catch-up growth, little is known about the long-term vascular and renal effects of accelerated postnatal growth. We surimposed early postnatal overfeeding (OF; reduction of litter size during the suckling period) to appropriate-birth-weight (NBW+OF) and intrauterine growth restriction (IUGR; IUGR+OF) pups, obtained after a maternal gestational low-protein diet. Blood pressure (systolic blood pressure; SBP) and renal function (glomerular filtration rate; GFR) were measured in young and aging offspring. Glomerulosclerosis and nephron number were determined in aging offspring (22 mo). Nephron number was reduced in both IUGR and IUGR+OF male offspring (by 24 and 26%). GFR was reduced by 40% in 12-mo-old IUGR+OF male offspring, and both NBW+OF and IUGR+OF aging male offspring had sustained hypertension (+25 mmHg) and glomerulosclerosis, while SBP and renal function were unaffected in IUGR aging offspring. Female offspring were unaffected. In conclusion, in this experimental model, early postnatal OF in the neonatal period has major long-lasting effects. Such effects are gender dependent. Reduced nephron number alone, associated with IUGR, may not be sufficient to induce long-lasting physiological alterations, and early postnatal OF acts as a “second hit.” Early postnatal OF is a suitable model with which to study the long-term effects of postnatal growth in the pathogenesis of vascular disorders and renal disease.

Renal clearance studies and morphologic observations were performed in rats aged 14, 21, and 28 d and 3, 6, 9, and 12 mo born with a 20% reduction in nephron number after administration of 75 mg/kg/d of gentamicin to their mothers during the second half of gestation. Gentamicin was still present in urine 3 mo after birth. Morphologic damage characteristic of gentamicin accumulation was observed in the kidney on d 14 and 21. Adequate compensatory adaptation to oligonephronia occurred for glomerular function within 14 d of birth, but tubular phosphate reabsorption was significantly low on d 21. On d 28, no evidence of histologic or functional damage to the kidney was observed. At 3 mo, mesangial lesions were observed in rats of the gentamicin group, whereas they were rarely present in 6-mo-old control rats. Furthermore, glomerular sclerotic lesions were already evident in about 5% of the juxtamedullary nephrons. The same percentage of injured nephrons was not observed before 12 mo in controls. Complementary morphologic data obtained in 24-mo-old rats showed that glomerulosclerosis involved 40% of the juxtamedullary nephron population at this age in animals of the gentamicin group versus 21% in controls. It is concluded that in the young rats born with oligonephronia of gentamicin-treated mothers neither the gentamicin remaining in the kidney cells nor the injuries it caused them prevented compensatory adaptation of the kidney to a reduced number of nephrons. However, although this oligonephronia was mild, it might have been sufficient to cause early development of glomerular sclerosis in the adults.

OBJECTIVE—Epidemiological and experimental studies have led to the hypothesis of fetal origin of adult diseases, suggesting that some adult diseases might be determined before birth by altered fetal development. We have previously demonstrated in the rat that in utero exposure to maternal diabetes impairs renal development leading to a reduction in nephron number. Little is known on the long-term consequences of in utero exposure to maternal diabetes. The aim of the study was to assess, in the rat, long-term effects of in utero exposure to maternal diabetes on blood pressure and renal function in adulthood. RESEARCH DESIGN AND METHODS—Diabetes was induced in Sprague-Dawley pregnant rats by streptozotocin on day 0 of gestation. Systolic blood pressure, plasma renin activity, and renal function were measured in the offspring from 1 to 18 months of age. High-salt diet experiments were performed at the prehypertensive stage, and the abundance of tubular sodium transporters was evaluated by Western blot analysis. Kidney tissues were processed for histopathology and glomerular computer-assisted histomorphometry. RESULTS AND CONCLUSIONS—We demonstrated that in utero exposure to maternal diabetes induces a salt-sensitive hypertension in the offspring associated with a decrease in renal function in adulthood. High-salt diet experiments show an alteration of renal sodium handling that may be explained by a fetal reprogramming of tubular functions in association or as a result of the inborn nephron deficit induced by in utero exposure to maternal diabetes.

Aminoglycoside antibiotics, like gentamicin, given to pregnant females cross the placenta and accumulate in the fetal kidney, which, like the adult kidney, was found to be the major site of deposition. In young guinea-pigs whose mothers were given gentamicin during the week following nephrogenesis in the fetus, nephron growth was found to be retarded temporarily. In rats whose mothers were given gentamicin during the period of fetal nephrogenesis, the final number of nephrons was reduced by about 20%. In both cases, renal development was impaired, although the concentration of gentamicin in the fetal kidney was lower than that measured in the kidney of human fetuses whose mothers had received a single injection of aminoglycoside. In rats exposed to gentamicin in utero, cellular damage of the undifferentiated and differentiating renal tissues was observed. It is, there are likely that the oligonephronia observed in animals born of gentamicin-treated mothers resulted from a direct effect of the drug at early stages of nephrogenesis. When gentamicin administration to the mother was prolonged, part of the oligonephronia observed at birth might have also resulted from fetal growth retardation, secondary to adverse effects of the drug on the mother. Providing it was not associated with fetal growth retardation, the presence of high gentamicin concentrations in the fetal kidney at late stages of nephrogenesis did not affect nephron differentiation. Long-term studies of rats born with gentamicin-induced oligonephronia showed that neither the antibiotic still present in kidney several weeks after birth, nor the injuries it caused, prevented renal growth and morphological adaptation of the nephrons to their reduced number.(ABSTRACT TRUNCATED AT 250 WORDS)

Remodeling of extracellular matrix (ECM) is an important physiological feature of normal growth and development. Recent studies have emphasized the role of matrix metalloproteinases (MMP-2 and MMP-9) in normal mouse nephrogenesis. We have demonstrated previously in the rat that in utero exposure to maternal diabetes impairs renal development leading to a 30% reduction in the nephron number. Transforming growth factor-beta1 (TGF-beta1) and connective tissue growth factor (CTGF) are known to mediate high glucose effects on matrix degradation. The aim of the present study was to address the expression of type IV collagenase and TGF-beta1/CTGF systems in rat kidney during normal development and after in utero exposure to maternal diabetes. Both MMP-2 and MMP-9 mRNA metanephric expressions and activities were dramatically downregulated in kidneys issued from diabetic fetuses and in metanephros cultured in the presence of high glucose concentration. TGF-beta1 and CTGF expressions were significantly enhanced in diabetic fetal kidneys and in high glucose cultured metanephroi. Conditioned media obtained from metanephroi grown with high glucose concentration upregulated functional TGF-beta activity in transfected ATDC5 cells. In conclusion, in impaired nephrogenesis resulting from in utero exposure to maternal diabetes, alteration of both type IV collagenase and TGF-beta1/CTGF systems may lead to abnormal remodeling of ECM, which may, in turn, induce defects in ureteral bud branching leading to the observed reduction in the nephron number with consequences later in life: progression of chronic renal disease and hypertension.

Introduction Des donnees recentes ont montre que les maladies metaboliques adultes peuvent etre programmees par un environnement fœtal deletere qui altere le developpement et la fonction de certains organes. Notamment, l’environnement maternel hyperglycemique a des consequences nefastes sur la fonction insulino-secretoire (par les cellules beta pancreatiques) et la sensibilite a l’insuline (par le foie, le tissu adipeux et les muscles). Des modeles animaux ont ete developpes et permettent de mieux comprendre les mecanismes sous-jacents et plus specifiquement comment la masse et / ou la fonction des cellules beta pancreatiques sont modifiees par l’exposition a un environnement intra-uterin hyperglycemique. Materiels et methodes Une revue de la litterature sur l’impact de l’environnement hyperglycemique sur les cellules beta ainsi que les resultats obtenus au laboratoire sont presentes. Notre modele repose sur un diabete modere induit chez des rates gestantes (glycemie a 20 mM) par une injection unique de streptozotocine (toxine detruisant les cellules beta) au jour 0 de gestation. Les animaux issus de meres diabetiques et de meres temoins ont ete suivis depuis la naissance jusqu’a l’âge de 12 mois. La tolerance au glucose, la sensibilite a l’insuline et les niveaux plasmatiques de lipides ont ete analyses. Resultats La revue de la litterature montre que l’hyperglycemie maternelle moderee altere la fonction beta tandis que l’hyperglycemie severe a des atteintes massives sur la masse et fonction beta. Ces anomalies sont ensuite transmises a la seconde generation. Concernant nos resultats, les animaux issus de meres diabetiques ont un poids de naissance normal puis une croissance postnatale reduite compares aux temoins. A six mois, ils presentent une intolerance au glucose, leur sensibilite a l’insuline est alteree et leur secretion d’insuline est diminuee. A 12 mois, ce phenotype persiste mais dans une moindre mesure. Ces animaux issus des meres diabetiques presentent egalement une hypertension arterielle et une concentration basse de triglycerides. Conclusion L’hyperglycemie maternelle a des consequences deleteres sur la fonction et masse des cellules beta dans la descendance. Ces anomalies sont transmissibles a la seconde generation, placant l’hyperglycemie maternelle a l’origine de troubles metaboliques intergenerationnels et confirmant l’hypothese de la programmation fœtale des maladies metaboliques adultes.

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.

Exposure to hyperglycemia in utero impairs rat nephrogenesis. The effect of maternal diabetes on insulin-like growth factors and their receptors in the fetal kidney is associated with an increase in both mRNA and protein of the insulin-like growth factor II/mannose 6-phosphate receptor. However, this receptor has never been localized in the fetal kidney. The spatial and temporal distribution of the three insulin-like growth factor receptors (insulin-like growth factor I receptor, insulin-like growth factor II/mannose 6-phosphate receptor and insulin receptor) in rat metanephros during both normal and streptozotocin-induced diabetic renal development was investigated using in situ hybridization and immunohistochemistry. All receptors were found in the fetal kidney from the start of nephrogenesis. Insulin-like growth factor I receptor expression was ubiquitous and continuously present during metanephric development. Insulin receptor expression was developmentally regulated during kidney maturation with an enhanced expression in proximal tubules at the late stages of development. Insulin-like growth factor II/mannose 6-phosphate receptor expression was ubiquitous in the early stages of development and was dramatically decreased at the late stages of normal kidney development. Insulin receptor and insulin-like growth factor I receptor expressions were unchanged in diabetic metanephroi. Although the spatial expression of insulin-like growth factor II/mannose 6-phosphate receptor was unaffected by hyperglycemia, its expression was not downregulated in the mesenchyme of the nephrogenic zone of diabetic fetuses on gestational day 20. This study suggests a crucial role of insulin-like growth factor II/mannose 6-phosphate receptor in the pathogenesis of the impaired nephrogenesis in fetuses of diabetic mothers.

We have recently demonstrated that the exposure to hyperglycemia in utero impairs nephrogenesis in rat fetuses (Amri K et al., Diabetes 48:2240–2245, 1999). Diabetic pregnancy is commonly associated with alterations in the IGF system in fetal tissues. It has also been shown that both IGF-I and IGF-II are produced within developing metanephros and promote renal organogenesis. Therefore, we investigated the effect of maternal diabetes on IGFs and their receptors in developing fetal rat kidney. Diabetes was induced in pregnant rats by a single injection of streptozotocin on day 0 of gestation. We measured the amounts of IGF and their receptors, both proteins and mRNAs, in the metanephroi of fetuses issued from diabetic subjects and in age-matched fetuses from control subjects (14–20 days of gestation). IGF-II was produced throughout fetal nephrogenesis, whereas IGF-I protein was not detected, suggesting a critical role of IGF-II in kidney development. Fetal exposure to maternal diabetes caused no change in IGF production in the early stages of nephrogenesis. Similarly, the amounts of IGF-I receptor and insulin receptor were not altered. By contrast, there was an increase in production of IGF-II/mannose-6-phosphate receptor throughout nephrogenesis. Because this receptor plays an essential role in regulating the action of IGF-II, the altered nephrogenesis in fetuses exposed to maternal diabetes may be linked to a decrease in IGF-II bioavailability.

Several lines of evidence, mostly derived from animal studies, indicate that changes in the fetal environment may affect the renal development. Fetal growth retardation is associated with a nephron deficit in both humans and animals. Changes in the supply of vitamin A to the fetus may be responsible for the variations in the number of nephrons in the human kidney. In utero exposure to hyperglycemia or drugs may also cause a nephron deficit.

Congenital malformations occur more frequently in the offspring of diabetic mothers. These in vivo and in vitro studies investigate the potential adverse effects of hyperglycemia on kidney development in the rat. Female rats were made hyperglycemic throughout gestation with a single injection of streptozotocin (STZ) on day 0 of gestation, or for a short period encompassing the early stage of renal organogenesis by infusing glucose from gestational days 12-16. Kidney development in the pups was assessed by determining the total number of nephrons formed in the kidney. The number of nephrons was significantly reduced (10-35%) in the pups from STZ-treated dams, as a function of hyperglycemia. There were also fewer nephrons in pups from dams given glucose infusion whose hyperglycemia was transiently higher on day 13 of gestation. The in vitro experiments were done on metanephroi removed from 14-day-old fetuses and grown for 6 days in medium containing 0, 6.9, 13.8, or 27.5 mmol/l glucose. The development of explants grown in 0, 13.8, and 27.5 mmol/l glucose was impaired compared with that of explants grown in the 6.9 mmol/l control medium, showing that the glucose concentration must be closely controlled to ensure optimum in vitro metanephros development. Thus, exposure to hyperglycemia in utero can cause a nephron deficit, which in turn may have renal consequences later in life.

During late pregnancy, the fetal lung stores surfactant in preparation for extrauterine life. Surfactant deficiency, most often due to prematurity, precipitates respiratory distress syndrome (RDS) of the neonate. Although vitamin A (retinol) and retinoic acid have been shown to enhance the synthesis of phospholipid surfactant components, their effect on surfactant-specific proteins is unclear. No attempt has been made to evaluate the consequences of vitamin A restriction on surfactant phospholipid storage or on the expression of the life-essential surfactant protein-B (SP-B). We induced in rats a partial vitamin A deficiency leading to a 30-60% reduction in blood retinol, a status compatible with maintenance of gestation and absence of gross abnormalities in offspring. At term, lung surfactant phospholipids were reduced by 21%, and the major surfactant phospholipid, disaturated phosphatidylcholine (DSPC), was reduced by 27% in vitamin A-deficient (VAD) fetuses. The decrease in surfactant phospholipids and DSPC correlated linearly with plasma retinol, and reached about 50% in fetuses with the lowest retinol concentrations; it was accompanied by reduced expression of the gene for fatty acid synthase, a key enzyme in the synthetic pathway for surfactant-phospholipid lipid precursors. The amounts of SP-A, SP-B, and SP-C messenger RNAs were decreased by 46%, 32%, and 28%, respectively, in VAD fetuses. Consistently, amounts of SP-A and SP-B proteins were diminished as assessed by Western blotting. The proportion of type II cells determined after SP-B labeling was unchanged in VAD as compared with control lungs. Vitamin A deficiency is therefore a cause of lung maturational delay. In view of its rather large incidence in human populations, it may represent an increased risk for RDS and an aggravating factor for prematurity.

Vitamin A closely modulates nephron endowment at birth. It is also required for the development of renal vasculature. Fetal vitamin A status may thus be responsible for most of the variations in nephron number found in the general population, and may play a major role in the intrauterine programming of chronic renal disease and hypertension.

Vitamin A and its derivatives have been shown to promote kidney development in vitro in a dose-dependent fashion. To address the molecular mechanisms by which all- trans-retinoic acid (RA) may regulate the nephron mass, rat kidneys were removed on embryonic day 14( E14) and grown in organ culture under standard or RA-stimulated conditions. By using RT-PCR, we studied the expression of the glial cell line-derived neurotrophic factor (GDNF), its cell surface receptor-α (GDNFR-α), and the receptor tyrosine kinase c-ret, known to play a major role in renal organogenesis. Expression of GDNF and GDNFR-α transcripts was high at the time of explantation and remained unaffected in culture with or without RA. In contrast, c-ret mRNA level, which was low in E14 metanephros and dropped rapidly in vitro, was increased by RA in a dose-dependent manner. The same is true at the protein level. Exogenous GDNF barely promotes additional nephron formation in vitro. Thus the present data establish c-ret as a key target of retinoids during kidney organogenesis.

The plasma concentration of T3 increases during the third postnatal week in rats when the young are weaned. Renal phosphate (Pi) transport matures during this period, with increases in the carrier affinity for Na-cotransported Pi(1/K(m)) and in the maximal transport rate (Vmax). As prevention of weaning prevents the normal increase in the plasma T3 concentration and blocks the maturation of Pi transport, this study examines the influence of T3 on Pi transport maturation. The brush border membranes from 21-day-old rats rendered hypothyroid with 6-n-propyl-2-thiouracil (PTU) or prevented from weaning (PW) were examined. These two treatments effectively prevented normal maturation, as the apparent K(m) was significantly higher in the PTU (0.243 +/- 0.04) and PW (0.159 +/- 0.008) rats than in controls [0.111 +/- 0.032 (n = 6; P < 0.05) and 0.104 +/- 0.005 (n = 6; P < 0.05)], and the Vmax was significantly lower [3192 +/- 170 vs. 4269 +/- 343 (n = 6; P < 0.01) and 3479 +/- 478 vs. 4184 +/- 368 (n = 6; P < 0.05)]. Administration of T3 to PTU and PW rats restored the apparent K(m) and V(max) to control values. The amounts of Na-Pi co-transporter messenger RNA and protein were also determined. The amounts of NaPi-2 messenger RNA and protein were decreased about 5-fold in PTU and PW rats, and T3 restored them to control levels. The effect of T3 on the maturation of Pi transport was independent of PTH, GH, or glucocorticoids. Thus, thyroid hormone helps control the maturation of Pi transport in the rat during weaning, and thyroid hormone may be a dominant triggering factor in this process.

Introduction L’epidemie actuelle d’obesite et de diabete de type II augmente la probabilite de diabete chez la femme enceinte. Si les complications maternelles, obstetricales et fœtales d’une grossesse diabetique sont bien connues, peu d’informations sont disponibles sur le devenir a long terme des enfants nes de meres diabetiques, notamment en terme de pathologie cardiovasculaire. Materiels et methodes Nous avons donc developpe un modele d’exposition in utero au diabete maternel. Le suivi postnatal des rats issus de ces meres diabetiques (DMO) a permis de mettre en evidence une programmation de l’hypertension arterielle (HTA) des l’âge de 6 mois ainsi qu’un profil d’expression genique aortique specifique des rats DMO au stade pre-hypertensif (3 mois) favorisant un phenotype vasoconstricteur. En effet, nous avons montre que differents acteurs du metabolisme de l’acide arachidonique - systeme clef dans la physiologie vasculaire - etaient differentiellement exprimes par rapport aux animaux temoins, avec une baisse de 50% de l’expression du gene du recepteur de la prostacycline et une augmentation de l’expression de plusieurs sous-unites du cytochrome P450. Notre objectif etait ensuite de determiner si la re-programmation vasculaire observee pouvait etre impliquee dans le developpement de l’HTA en comparant la reactivite vasculaire des vaisseaux de resistance des DMO et des rats controles mâles et femelles aux stades pre - (3 mois) et post-hypertensifs (18 mois) et en analysant leur structure histomorphometrique. Resultats Les premiers resultats ne montrent pas, a 18 mois comme a 3 mois, de modification de reactivite vasculaire aux agents pharmacologiques classiques (phenylephrine, achetylcholine…) mais une diminution de la reponse vasodilatatrice a un analogue de la prostacycline (beraprost) aussi bien chez les mâles que chez les femelles En revanche une augmentation du tonus myogenique n’est observe que chez les mâles. Conclusion Ces resultats montrent que la re-programmation vasculaire chez les rats issus de meres diabetiques serait impliquee dans la physiopathologie de l’HTA dans ce modele.

Intrauterine growth retardation (IUGR) was induced in Sprague-Dawley rats by partial artery ligation of one uterine horn in the mother on day 17 of gestation or by feeding the mother a 5% protein diet from day 8 of gestation. The controls were pups of the contralateral uterine horn or pups born to mothers fed a normal (22%) protein diet. The number of nephrons present at birth and the final number of nephrons in 2-week-old rats were counted throughout the entire kidney. The number of nephrons present at birth and the final number of nephrons were significantly correlated with birth weight for growth-retarded rats of both groups and their corresponding controls (P

The renal phosphate (Pi) transport system matures during the 3rd postnatal wk in the rat by an increase in the carrier affinity for sodium-cotransported phosphate. This study examines the ability of pups to adapt their renal Pi transport to the dietary phosphorus content during this period of carrier affinity maturation, corresponding to the weaning period in the rat. Clearance experiments and brush border membrane studies were performed on 21-d-old rats weaned early on d 16 onto a low phosphate diet (LPD, 0.19 g/100 g), a normal phosphate diet (control, 0.78 g/100 g), or a high phosphate diet (HPD, 1.5 g/100 g). In LPD rats, the Pi fractional excretion (0.3 +/- 0.1%) was lower than in controls (18 +/- 3%, p < 0.001). It remained very low (0.21 +/- 0.05% in LPD rats versus 40.5 +/- 6.3% in controls, p < 0.001) after Pi perfusion (1.5 mumol.min-1.100 g-1) and the reabsorbed Pi per min, corrected for the glomerular filtration rate, was higher than in the two other groups. The calcium fractional excretion (12.6 +/- 1.02%) in the LPD rats was much higher than in the controls (0.42 +/- 0.2%, p < 0.001). In contrast, HPD rats had an elevated Pi fractional excretion (41 +/- 4%, p < 0.001), whereas reabsorbed phosphate per min corrected for the glomerular filtration rate was not increased by a Pi load.(ABSTRACT TRUNCATED AT 250 WORDS)

Introduction Des etudes epidemiologiques et experimentales ont conduit a proposer l'hypothese de l'origine foetale des maladies de l'adulte. Nous avons montre que, chez le rat, l'exposition in utero au diabete maternel altere le developpement renal induisant un deficit nephronique d'environ 30 %. L'objectif de notre etude a ete d'evaluer, chez le rat, les consequences a long terme de l'exposition in utero au diabete maternel sur la pression arterielle et la fonction arterielle et renale. Materiels et methodes Le diabete a ete induit chez les femelles gestantes par administration de streptozotocine le premier jour de la gestation. Chez les rats, de 1 a 18 mois, issus de meres temoins (Te) et diabetiques (D), nous avons realise des mesures de la pression arterielle (PA), de l'activite renine plasmatique (ARP) et de la proteinurie. Chez ces memes rats, une analyse de la structure et des proprietes elastiques arterielles, de la fonction renale, et de l'histopathologie et l'histomorphometrie renales a egalement ete realisee. Enfin le profil d'expression genique (puces d'oligonucleotides, 22 000 genes) a ete etudie chez des rats de 3 mois des groupes Te et D. Resultats Des l'âge de 6 mois, les rats D developpent une hypertension arterielle, la clairance de la creatinine est alteree et associee a une proteinurie. Au stade pre-hypertensif de 3 mois, l'ARP n'est pas differente dans les deux groupes de rats, en revanche, elle est diminuee chez les rats D hypertendus. L'administration d'un regime hypersode au stade pre-hypertensif induit une augmentation de la pression arterielle systolique chez les rats D. Dans les aortes abdominales des rats D, la sur-expression desgenes codant differentes sous-unites du cytochrome P450 (Cyp4f4, Cyp4f2, Cyp8b1) et la sous-expression du recepteur de la prostacycline pourraient etre responsable d'une vasoconstriction arterielle. De facon etonnante, aucune difference de structure arterielle n'a ete mise en evidence entre les deux groupes. Ceci pourrait etre du a la sous-expression de genes codant pour des proteines interagissant avec les myofibrilles (Evl, Ckap4, Dcamkl1). Conclusion Les rats exposes in utero au diabete maternel developpent, a l'âge adulte, une hypertension sel-sensible et presentent une alteration de la fonction renale. Ces alterations pourraient resulter, chez ces animaux, du deficit nephronique induit par l'exposition in utero au diabete maternel mais aussi a une programmation fœtale vasculaire anormale.

Introduction: Epidemiological and experimental studies demonstrate that low birth weight is associated with increased risk of arterial hypertension and metabolic diseases in adulthood. Rapid postnatal catch-up growth may constitute an additional risk factor.

Introduction: Low birth weight is associated with increased risk of arterial hypertension and metabolic diseases in adulthood. Rapid postnatal catch-up growth may constitute an additional risk factor. Aim: To investigate the effects of postnatal overfeeding (OF) after intrauterine growth restriction (IUGR) in 12 month old, adult rats. Methods: 4 groups of animals were investigated: group I, controls: offspring of dams fed normal diet (NP, casein 22 %); group II: offspring of dams fed isocaloric low-protein diet (LP, casein 9 %); group III: postnatal OF (obtained by reduction of litter size); group IV: LP rats exposed to postnatal OF. Systolic blood pressure (SBP), glomerular number, renal function, fasting glycaemia and intraperitoneal glucose tolerance test were obtained Results: (mean +/- SEM). Offspring of dams fed LP diet had a 20 % birth weight and 38 % glomerular number reduction (p < 0.01). Catch-up growth was associated with an elevated SBP from the age of 4 weeks (110 +/-3; 117 +/- 2; 116 +/- 3; 127 +/- 2 mmHg in groups NP, LP, OF, LP+OF rats respectively; p < 0.05). But the difference in SBP between LP and controls rats disappeared at the age of 12 months. Creatinine clearance decreased with age in LP+OF rats but reached statistical significance in males at 12 months (3.34 +/- 0.2; 4.26 +/-0.3; 4.61+/-1.6; 5.48 +/-1.6 ml/min/kg in LP+OF, LP, OF, controls respectively). Proteinuria was significantly higher in LP+OF rats than in controls at 4 months. At the age of 12 months, glucose tolerance was significantly altered in OF and LP+OF rats. Conclusion: Early catch-up growth in IUGR rats enhances alteration of SBP, glucose tolerance and renal function in adulthood. Early postnatal overfeeding may amplify single nephron hyperfiltration, and insulin-resistance associated with IUGR, resulting in cardiovascular and metabolic diseases at adulthood.

Introduction: Intrauterine growth restriction (IUGR) is associated with increased risk of cardiovascular and metabolic diseases in adulthood. Nephron number reduction has been proposed as a key mechanism for later hypertension. Aim: To compare the long term effects of two models of IUGR on arterial systolic blood pressure (SBP) and renal function in adult rats. Methods: 3 groups of animals were investigated: group I, controls: offspring of dams fed normal diet (NP, casein 22 %); group II: offspring of dams fed isocaloric low-protein diet (LP, casein 9 %); group III: offspring of dams that received 3 daily intramuscular injections of betamethasone (0.25 mg/kg) on gestational days 17,18, 19 (BET). SBP, glomerular number, and renal function were obtained in 12 months old animals. Results: (mean +/- SEM). Glomerular number was significantly reduced in IUGR rats (38 % in LP rats and 50 % in BET rats vs. controls p

Objectifs Les techniques d’evaluation dans un modele murin de cancer renal de l’enfance (frequence 1/10,000) restent limitees a la palpation et a des etudes histologiques post-mortem. Pour detecter et suivre de maniere non invasive le developpement des tumeurs par ultrasonographie un protocole a ete mis en place sur 7 souris. Materiels et methodes Des echographies a 25MHz du rein controlateral et tumoral ont ete acquises in vivo tous les 4 jours. Ensuite, la souris a ete sacrifiee et echographiee avec un systeme d’acquisition 3D a 40-50MHz. La position de la tumeur, sa nature et ses dimensions ont ete caracterisees a l’aide d’une etude histologique. Resultats La detection ultrasonore precoce de petites tumeurs ( Conclusion Cette etude montre la faisabilite et l’interet de l’echographie a haute frequence, dans le suivi d’un meme animal, lors d’une etude longitudinale de l’evaluation d’une therapie.

The number of nephrons at birth is normally quite fixed in any species. Severe renal hypoplasia is readily detected because of functional insufficiency, but moderate inborn nephron deficits may exist, yeat remain undetected. A systematic anatomical study revealed a large quantitative variation of the number of nephrons at birth in man (600000-1400000). Inborn nephron deficits were found to correlate very strongly with birth weight in the rat

Aminoglycoside antibiotics used to treat severe bacterial infection during pregnancy can cross the placenta. The effects of in utero exposure to these compounds is receiving increasing attention. It was shown that in the foetal animal, as in the adult, the kidney was the major site of gentamicin accumulation (1). In foetal guinea-pigs whose mothers were given daily 4 mg/kg of gentamicin for the seven days immediately following the period of nephrogenesis, intrarenal gentamicin concentration was found to be about 2 ug/g of tissue. More than two weeks after the treatment to the mother has ceased, the antibiotic released from all maternal and foetal tissues continued to accumulate in the developing kidney, especially as the renal blood flow and glomerular filtration rate increased with age (2). In pups born of gentamicin-treated mothers, impairments of the growth and the function of the proximal tubules were observed, but the damage was transitory (2).