Overweight, hypertension and renal dysfunction in adulthood of neonatally overfed rats

Postnatally overfed mice display cardiac function alteration following myocardial infarction

BACKGROUND

Cardiovascular (CV) pathologies remain a leading cause of death worldwide, often associated with common comorbidities such as overweight, obesity, type 2 diabetes or hypertension. An innovative mouse model of metabolic syndrome induced by postnatal overfeeding (PNOF) through litter size reduction after birth was developed experimentally. This study aimed to evaluate the impact of PNOF on cardiac remodelling and the development of heart failure following myocardial infarction.

METHODS

C57BL/6 male mice were raised in litter adjusted to 9 or 3 pups for normally-fed (NF) control and PNOF group respectively. After weaning, all mice had free access to standard diet and water. At 4 months, mice were subjected to myocardial infarction (MI). Echocardiographic follows-up were performed up to 6-months post-surgery and biomolecular analyses were carried-out after heart collection.

FINDINGS

At 4 months, PNOF mice exhibited a significant increase in body weight, along with a basal reduction in left ventricular ejection fraction (LVEF) and an increase in left ventricular end-systolic area (LVESA), compared to NF mice. Following MI, PNOF mice demonstrated a significant decrease in stroke volume and an increased heart rate compared to their respective initial values, as well as a notable reduction in cardiac output 4-months after MI. After 6-months, left ventricle and lung masses, fibrosis staining, and mRNA expression were all similar in the NF-MI and PNOF-MI groups.

INTERPRETATION

After MI, PNOF mice display signs of cardiac function worsening as evidenced by a decrease in cardiac output, which could indicate an early sign of heart failure decompensation.

Swimming training prevents obesity installation and normalizes hypothalamic expressions of GLP1 and leptin receptors in adult offspring born in small litters

OBJECTIVE

Glucagon-like peptide-1 (GLP1) and leptin (Lep) are afferent signals that regulate energy metabolism. Lactational hypernutrition results in hyperphagia and adiposity in adult life, and these events can be prevented by exercise. We evaluated the effects of swimming training on hypothalamic (GLP1-R) and Lep receptor (Lep-R) gene expressions in lactational hypernutrition-induced obesity.

METHODS

On the 3rd postnatal day, the litter sizes of lactating dams were adjusted to small litters (SL; 3 pups/dams) or normal litters (NL; 9 pups/dams). After weaning (21 days), NL and SL male rats were randomly distributed to sedentary (Sed) and exercised (Exe) groups. Exercised mice swam (30 min/3 times/week) for 68 days. Food intake and body weight gain were registered. At 92 days, intraperitoneal glucose and insulin tolerance tests were performed and rats were euthanized at 93 days; adipose tissue depots were weighed, and blood counts and plasma biochemical analyses performed. Hypothalamus were isolated to evaluate Lep-R and GLP1-R gene expressions.

RESULTS

Small litters sedentary rats presented increased body weight gain, adiposity, insulin sensibility and higher fasting values of glucose and triglycerides, besides higher hypothalamic gene expressions of Lep-R and GLP1-R, compared to NLSed animals. SLExe rats did not develop obesity or metabolic abnormalities and Lep-R and GLP1-R hypothalamic gene expressions were normalized.

CONCLUSION

Lactational hypernutrition induces obesity and metabolic dysfunction in adult life, in association with higher hypothalamic expressions of the Lep-R and GLP1-R genes. Exercise prevented obesity and improved metabolic state in SL overnourished rats, and normalized their hypothalamic Lep-R and GLP1-R gene expressions.

Can breastfeeding affect the rest of our life?

The breastfeeding period is one of the most important critical windows in our development, since milk, our first food after birth, contains several compounds, such as macronutrients, micronutrients, antibodies, growth factors and hormones that benefit human health. Indeed, nutritional, and environmental alterations during lactation, change the composition of breast milk and induce alterations in the child's development, such as obesity, leading to the metabolic dysfunctions, cardiovascular diseases and neurobehavioral disorders. This review is based on experimental animal models, most of them in rodents, and summarizes the impact of an adequate breast milk supply in view of the developmental origins of health and disease (DOHaD) concept, which has been proposed by researchers in the areas of epidemiology and basic science from around the world. Here, experimental advances in understanding the programming during breastfeeding were compiled with the purpose of generating knowledge about the genesis of chronic noncommunicable diseases and to guide the development of public policies to deal with and prevent the problems arising from this phenomenon. This review article is part of the special issue on "Cross talk between periphery and brain".

Programming of Cardiovascular Dysfunction by Postnatal Overfeeding in Rodents

Nutritional environment in the perinatal period has a great influence on health and diseases in adulthood. In rodents, litter size reduction reproduces the effects of postnatal overnutrition in infants and reveals that postnatal overfeeding (PNOF) not only permanently increases body weight but also affects the cardiovascular function in the short- and long-term. In addition to increased adiposity, the metabolic status of PNOF rodents is altered, with increased plasma insulin and leptin levels, associated with resistance to these hormones, changed profiles and levels of circulating lipids. PNOF animals present elevated arterial blood pressure with altered vascular responsiveness to vasoactive substances. The hearts of overfed rodents exhibit hypertrophy and elevated collagen content. PNOF also induces a disturbance of cardiac mitochondrial respiration and produces an imbalance between oxidants and antioxidants. A modification of the expression of crucial genes and epigenetic alterations is reported in hearts of PNOF animals. In vivo, a decreased ventricular contractile function is observed during adulthood in PNOF hearts. All these alterations ultimately lead to an increased sensitivity to cardiac pathologic challenges such as ischemia-reperfusion injury. Nevertheless, caloric restriction and physical exercise were shown to improve PNOF-induced cardiac dysfunction and metabolic abnormalities, drawing a path to the potential therapeutic correction of early nutritional programming.

Size Does Matter: Litter Size Strongly Determines Adult Metabolism in Rodents

In this essay, we highlight how litter size in rodents is a strong determinant of neonatal growth and long-term metabolic health. Based on these effects, we strongly advise that scientific articles that utilize rodent models for obesity and metabolic research should include information on the litter sizes in the study to increase the data transparency of such reports.

Renal Programming by Transient Postnatal Overfeeding: The Role of Senescence Pathways

Background

Early nutrition influences the risk of chronic kidney diseases (CKDs) development in adulthood. Mechanisms underlying the early programming of altered renal function remain incompletely understood. This study aims at characterizing the role of cell senescence pathways in early programming of CKD after transient postnatal overfeeding.

Materials and Methods

Reduced litters of 3 mice pups and standard litters of 9 mice pups were obtained to induce overfed animals during lactation and control animals, respectively. Animals were sacrificed at 24 days (weaning) or at 7 months of life (adulthood). Body weight, blood pressure, kidney weight, and glomerular count were assessed in both groups. Senescence pathways were investigated using β-Galactosidase staining and Western blotting of P16, P21, P53, P-Rb/Rb, and Sirtuin 1 (Sirt1) proteins.

Results

Early overfed animals had a higher body weight, a higher blood pressure at adulthood, and a higher glomerular number endowment compared to the control group. A higher β-Galactosidase activity, a significant increase in P53 protein expression (p = 0.0045) and a significant decrease in P-Rb/Rb ratio (p = 0.02), were observed at weaning in animals who underwent early postnatal overfeeding. Protein expression of Sirt1, a protective factor against accelerated stress-induced senescence, was significantly decreased (p = 0.03) at weaning in early overfed animals.

Conclusion

Early postnatal overfeeding by litter size reduction is associated with increased expression of factors involved in cellular senescence pathways, and decreased expression of Sirt 1 in the mouse kidney at weaning. These alterations may contribute to CKD programming after early postnatal overfeeding.

Effect of early postnatal nutrition on chronic kidney disease and arterial hypertension in adulthood: a narrative review

Intrauterine growth restriction (IUGR) has been identified as a risk factor for adult chronic kidney disease (CKD), including hypertension (HTN). Accelerated postnatal catch-up growth superimposed to IUGR has been shown to further increase the risk of CKD and HTN. Although the impact of excessive postnatal growth without previous IUGR is less clear, excessive postnatal overfeeding in experimental animals shows a strong impact on the risk of CKD and HTN in adulthood. On the other hand, food restriction in the postnatal period seems to have a protective effect on CKD programming. All these effects are mediated at least partially by the activation of the renin-angiotensin system, leptin and neuropeptide Y (NPY) signaling and profibrotic pathways. Early nutrition, especially in the postnatal period has a significant impact on the risk of CKD and HTN at adulthood and should receive specific attention in the prevention of CKD and HTN.

Genetic Contributions to Childhood Obesity: Association of Candidate Gene Polymorphisms and Overweight/Obesity in Korean Preschool Children

This study was aimed to investigate the association of candidate gene polymorphisms and obesity or overweight in young Korean children. A total of 190 Korean preschool children (96 control, 48 overweight, and 46 obese children) were genotyped for the angiotensin converting enzyme (ACE) insertion (I)/deletion (D), angiotensin II type 2 receptor (AT2) C3123A, transforming growth factor (TGF)-β1 T869C, vascular endothelial growth factor (VEGF) T460C, and tumor necrosis factor (TNF)-α G308A polymorphisms. No differences were found among the groups with respect to age, sex, birth weight, blood pressure levels, and serum concentrations of glucose and total cholesterol. Obese children showed a higher incidence of ACE DD genotype and D allelic frequency compared to the controls (odds ratio [OR], 2.7, 95% confidence interval [CI], 1.01-7.21; OR, 2.5, 95% CI, 1.49-4.19; all P < 0.05). The frequency of TC genotype and C allele in the TGF-β1 T869C polymorphism (OR, 2.08, 95% CI, 1.01-4.27; OR, 1.93, 95% CI, 1.15-3.21) and that in the VEGF T460C polymorphism (OR, 2.5, 95% CI, 1.19-5.28; OR, 2.15, 95% CI, 1.26-3.68) was also higher in obese children than in control subjects (all P < 0.05). Overweight children exhibited a higher frequency of the A allele in the AT2 C3123A polymorphism compared to the controls (OR, 1.72, 95% CI, 1.03-2.88, P < 0.05). There were no differences in the TNF-α G308A polymorphism among the groups. The ACE I/D, AT2 C3123A, TGF-β1 T869C, and VEGF T460C polymorphisms can affect susceptibility to obesity or overweight in Korean children.

Renoprotective effect of berberine on type 2 diabetic nephropathy in rats

Inflammation, fibrosis, and lipid disorder are essential promoters in the pathogenesis of diabetic kidney injury in diabetes mellitus type 2. Berberine (BBR) has been reported to have beneficial effects on diabetic nephropathy, but its action mechanism is still unclear. The present study was designed to elucidate the therapeutic mechanism of BBR in a type 2 diabetic nephropathy rat model induced by a high-fat diet and low-dose streptozotocin injection. The diabetic rats were treated with or without BBR by gavage for 20 weeks and examined by serology, 24-h albuminuria, histology, immunohistochemistry, and molecular analyses. Results showed that treatment with BBR significantly reduced serum levels of blood glucose and lipids, inhibited urinary excretion of albumin, and attenuated renal histological injuries in diabetic rats. Berberine treatment also inhibited renal inflammation, which was associated with inactivation of nuclear factor kappa-light-chain-enhancer of activated B-cell signalling. As a result, the upregulation of pro-inflammatory cytokines (interleukin-1β, tumour necrosis factor-α) and chemokine (monocyte chemotactic protein-1) was blocked. In addition, BBR treatment also inactivated transforming growth factor-β/Smad3 signalling and suppressed renal fibrosis, including expression of fibronectin, collagen I, and collagen IV. The present study reveals that BBR is a therapeutic agent for attenuating type 2 diabetic nephropathy by inhibiting nuclear factor kappa-light-chain-enhancer of activated B cell-driven renal inflammation and transforming growth factor-β/Smad3 signalling pathway.

Early life obesity and chronic kidney disease in later life

The prevalence of chronic kidney disease (CKD) has increased considerably with a parallel rise in the prevalence of obesity. It is now recognized that early life nutrition has life-long effects on the susceptibility of an individual to develop obesity, diabetes, cardiovascular disease and CKD. The kidney can be programmed by a number of intrauterine and neonatal insults. Low birth weight (LBW) is one of the most identifiable markers of a suboptimal prenatal environment, and the important intrarenal factors sensitive to programming events include decreased nephron number and altered control of the renin-angiotensin system (RAS). LBW complicated by accelerated catch-up growth is associated with an increased risk of obesity, hypertension and CKD in later life. High birth weight and exposure to maternal diabetes or obesity can enhance the risk for developing CKD in later life. Rapid postnatal growth per se may also contribute to the subsequent development of obesity and CKD regardless of birth weight and prenatal nutrition. Although the mechanisms of renal risks due to early life nutritional programming remain largely unknown, experimental and clinical studies suggest the burdening role of early life obesity in longstanding cardiovascular and renal diseases.

Effect of repeated fasting/refeeding on obesity development and health complications in rats arising from reduced nest

BACKGROUND

Overnutrition during postnatal life represents a risk factor for later obesity and associated metabolic disorders.

AIM

We investigated the interaction between postnatal and later-life nutrition on body composition, blood pressure and the jejunal enzyme activities in male Sprague-Dawley rats.

METHODS

From birth, we adjusted the number of pups in the nest to 4 (small litters-SL; overfeeding) or to 10 pups (normal litters-NL; controls), and from day 50 until 70, the SL (SL-R) and NL (NL-R) rats were subjected to 1 day fasting and 1 day refeeding cycles (RFR). Their body composition was determined by magnetic resonance imaging, and enzyme activity was assayed histochemically.

RESULTS

At 50 and 70 days, SL rats were found to be overweight (p < 0.001), with higher adiposity (p < 0.001) and blood pressure (p < 0.01). Moreover, despite significantly decreased daily food intake during RFR (SL-R 39 %, NL-R 23 %), higher fat deposition (p < 0.001) and blood pressure (p < 0.05) was detected in SL-R rats. Activity of alkaline phosphatase (AP) functionally involved in lipid absorption was significantly higher in SL than NL rats (p < 0.001) but substantially decreased in RFR groups (SL-R p < 0.001, NL-R p < 0.01). However, despite these enzymatic adaptations to reduced food intake, the SL-R rats displayed significantly higher AP activity in comparison with NL-R rats (p < 0.01) on day 70.

CONCLUSIONS

Our results demonstrate that postnatal overfeeding predisposes the ontogeny of intestinal function, which may promote the probability of obesity risk. Accordingly, in these animals, efficient fat deposition and elevated blood pressure were not diminished in response to dietary restrictions in later life.

Differential modification of enalapril in the kidneys of lean and 'programmed' obese male young rats

OBJECTIVE

We investigated whether enalapril treatment could have beneficial effects on nutritionally-programmed renal changes in postnatally overfed young rats.

METHODS

Three or 10 male pups per mother were assigned to either the Obese or Lean groups during the first 21 days of life. These pups were treated with enalapril (Obese enalapril, OE; Lean enalapril, LE) or vehicle (Obese control, OC; Lean control, LC) between 15 and 28 days. All pups had their kidneys examined at 29 days.

RESULTS

OC pups weighed more than those in the LC group between 7 and 28 days of age (P<0.05). Enalapril reduced body weights in rats from both the Obese and Lean groups between 22 and 28 days (P<0.05). Renal cell proliferation and apoptosis, glomerulosclerosis, and tubulointerstitial fibrosis were all increased by enalapril (P<0.05). Among the groups, renal cell apoptosis and serum creatinine were the highest in OE pups (P<0.05). Enalapril treatment resulted in contrasting molecular expression profiles involved in renal maturation and repair in the kidneys of the rats from the Lean and Obese groups.

CONCLUSION

Enalapril can differentially modulate renal molecular alterations in lean and postnatally overfed rats and may be not beneficial in obese young male rats.

Postnatal early overnutrition causes long-term renal decline in aging male rats

BACKGROUND

We evaluated the influence of postnatal early overnutrition on renal pathophysiological changes in aging rats.

METHODS

Three or 10 male pups per mother were assigned to either the small litter (SL) or normal litter (control) groups, respectively, during the first 21 d of life. The effects of early postnatal overnutrition were determined at 12 mo.

RESULTS

SL rats weighed more than controls between 4 d and 6 mo of age (P < 0.05). However, between 6 and 12 mo, body weights in both groups were not different. In the SL group, at 12 mo, systolic blood pressure was higher and creatinine clearance was lower than the same in controls (P < 0.05). Numbers of CD68 (ED1)-positive macrophages and apoptotic cells in renal cortex were higher in SL rats (P < 0.05). Furthermore, index scores for glomerulosclerosis and tubulointerstitial fibrosis were higher in the SL group (P < 0.05). Significantly less glomeruli per section area were found in aging SL rats (P < 0.05). Immunoblotting and immunohistochemistry showed decreased intrarenal renin expression in SL rats (P < 0.05).

CONCLUSION

Early postnatal overnutrition can potentiate structural and functional abnormalities in the aging kidney and can lead to systolic hypertension with reduced intrarenal renin activity.