Gestational and Breastfeeding Low-Protein Intake on Blood Pressure, Kidney Structure, and Renal Function in Male Rat Offspring in Adulthood

Mandible development under gestational protein restriction: cellular and molecular mechanisms

Insufficient evidence regarding how maternal undernutrition affects craniofacial bone development persists. With its unique focus on the impact of gestational protein restriction on calvaria and mandible osteogenesis, this study aims to fill, at least in part, this gap. Female mice were mated and randomized into NP (normal protein) or LP (low protein) groups. On the 18th gestational day (GD), male embryos were collected and submitted to microtomography (µCT), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), PCR, and autophagy dynamic analyses. The study shows that the LP offspring exhibited lower body mass than the NP group, with µCT analysis revealing no volumetric differences in fetus's head. EDS analysis showed lower calcium and higher phosphorus percentages in mandibles and calvaria. SEM assessment evidenced higher hydroxyapatite crystal-like (HC) deposition on the calvaria surface in LP fetus. Conversely, lower HC deposition was observed on the mandible surface, suggesting delayed matrix mineralization in LP fetuses with a higher percentage of collagen fibers in the mandible bone. The autophagy process was reduced in the mesenchyme of LP fetuses. PCR array analysis of 84 genes revealed 27 genes with differential expression in the LP progeny-moreover, increased mRNA levels of Akt1, Mtor, Nfkb, and Smad1 in the LP offspring. In conclusion, the results suggest that gestational protein restriction anticipated bone differentiation in utero, before 18GD, where this process is reduced compared to the control, leading to the reduction in bone area at 15 postnatal day previously observed. These findings provide insights into the molecular and cellular mechanisms of mandible development and suggest potential implications for the Developmental Origins of Health and Disease (DOHaD).

Maternal protein restriction combined with postnatal sugar consumption alters liver proteomic profile and metabolic pathways in adult male offspring rats

This study investigated the impact of maternal protein restriction (MPR) and early postnatal sugar consumption (SUG) on the liver health of adult male descendant rats. Male offspring of mothers fed a normal protein diet (NPD) or a low protein diet (LPD) were divided into four groups: Control (CTR), Sugar Control (CTR + SUG), LPD during gestation and lactation (GLLP), and LPD with sugar (GLLP + SUG). Sugar consumption (10% glucose diluted in water) began after weaning on day 21 (PND 21), and at 90 days (PND 90), rats were sacrificed for analysis. Sugar intake reduced food intake and increased water consumption in CTR + SUG and GLLP + SUG compared to CTR and GLLP. GLLP and GLLP + SUG groups showed lower body weight and total and retroperitoneal fat compared to CTR and CTR + SUG. CTR + SUG and GLLP + SUG groups exhibited hepatocyte vacuolization associated with increased hepatic glycogen content compared to CTR and GLLP. Hepatic catalase activity increased in GLLP compared to CTR. Proteomic analysis identified 223 differentially expressed proteins (DEPs) among experimental groups. While in the GLLP group, the DEPs enriched molecular pathways related to cellular stress, glycogen metabolic pathways were enriched in the GLLP + SUG and CTR + SUG groups. The association of sugar consumption amplifies the effects of MPR, deregulating molecular mechanisms related to metabolism and the antioxidant system.

Early morphological and neurochemical changes of the bed nucleus of stria terminalis (BNST) in gestational protein-restricted male offspring

BACKGROUND

The bed nucleus of the stria terminalis (BNST) is a structure with a peculiar neurochemical composition involved in modulating anxietylike behavior and fear.

AIM

The present study investigated the effects on the BNST neurochemical composition and neuronal structure in critical moments of the postnatal period in gestational protein-restricted male rats' offspring.

METHODS

Dams were maintained during the pregnancy on isocaloric rodent laboratory chow with standard protein content [NP, 17%] or low protein content [LP, 6%]. BNST from male NP and age-matched LP offspring was studied using the isotropic fractionator method, Neuronal 3D reconstruction, dendritic-tree analysis, blotting analysis, and high-performance liquid chromatography.

RESULTS

Serum corticosterone levels were higher in male LP offspring than NP rats in 14-day-old offspring, without any difference in 7-day-old progeny. The BNST total cell number and anterodorsal BNST division volume in LP progeny were significantly reduced on the 14th postnatal day compared with NP offspring. The BNST HPLC analysis from 7 days-old LP revealed increased norepinephrine levels compared to NP progeny. The BNST blot analysis from 7-day-old LP revealed reduced levels of GR and BDNF associated with enhanced CRF1 expression compared to NP offspring. 14-day-old LP offspring showed reduced expression of MR and 5HT1A associated with decreased DOPAC and DOPA turnover levels relative to NP rats. In Conclusion, the BNST cellular and neurochemical changes may represent adaptation during development in response to elevated fetal exposure to maternal corticosteroid levels. In this way, gestational malnutrition alters the BNST content and structure and contributes to already-known behavioral changes.

Gestational protein restriction alters early amygdala neurochemistry in male offspring

BACKGROUND

Gestational protein intake restriction-induced long-lasting harmful outcomes in the offspring's organs and systems. However, few studies have focused on this event's impact on the brain's structures and neurochemical compounds.

AIM

The present study investigated the effects on the amygdala neurochemical composition and neuronal structure in gestational protein-restricted male rats' offspring.

METHODS

Dams were maintained on isocaloric standard rodent laboratory chow with regular protein [NP, 17%] or low protein content [LP, 6%]. Total cells were quantified using the Isotropic fractionator method, Neuronal 3D reconstruction, and dendritic tree analysis using the Golgi-Cox technique. Western blot and high-performance liquid chromatography performed neurochemical studies.

RESULTS

The gestational low-protein feeding offspring showed a significant decrease in birth weight up to day 14, associated with unaltered brain weight in youth or adult progenies. The amygdala cell numbers were unchanged, and the dendrites length and dendritic ramifications 3D analysis in LP compared to age-matched NP progeny. However, the current study shows reduced amygdala content of norepinephrine, epinephrine, and dopamine in LP progeny. These offspring observed a significant reduction in the amygdala glucocorticoid (GR) and mineralocorticoid (MR) receptor protein levels. Also corticotrophin-releasing factor (CRF) amygdala protein content was reduced in 7 and 14-day-old LP rats.

CONCLUSION

The observed amygdala neurochemical changes may represent adaptation during embryonic development in response to elevated fetal exposure to maternal corticosteroid levels. In this way, gestational malnutrition stress can alter the amygdala's neurochemical content and may contribute to known behavioral changes induced by gestational protein restriction.

Impact of maternal protein restriction on Hypoxia-Inducible Factor (HIF) expression in male fetal kidney development

BACKGROUND

Kidney developmental studies have demonstrated molecular pathway changes that may be related to decreased nephron numbers in the male 17 gestational days (17GD) low protein (LP) intake offspring compared to normal protein intake (NP) progeny. Here, we evaluated the HIF-1 and components of its pathway in the kidneys of 17-GD LP offspring to elucidate the molecular modulations during nephrogenesis.

METHODS

Pregnant Wistar rats were allocated into two groups: NP (regular protein diet-17%) or LP (Low protein diet-6%). Taking into account miRNA transcriptome sequencing previous study (miRNA-Seq) in 17GD male offspring kidneys investigated predicted target genes and proteins related to the HIF-1 pathway by RT-qPCR and immunohistochemistry.

RESULTS

In the present study, in male 17-GD LP offspring, an increased elF4, HSP90, p53, p300, NFκβ, and AT2 gene encoding compared to the NP progeny. Higher labeling of HIF-1α CAP cells in 17-DG LP offspring was associated with reduced elF4 and phosphorylated elF4 immunoreactivity in LP progeny CAP cells. In 17DG LP, the NFκβ and HSP90 immunoreactivity was enhanced, particularly in the CAP area.

DISCUSSION AND CONCLUSION

The current study supported that the programmed reduced nephron number in the 17-DG LP offspring may be related to changes in the HIF-1α signaling pathway. Factors that facilitate the transposition of HIF-1α to progenitor renal cell nuclei, such as increased NOS, Ep300, and HSP90 expression, may have a crucial role in this regulatory system. Also, HIF-1α changes could be associated with reduced transcription of elF-4 and its respective signaling path.

Cardiovascular and renal profiles in rat offspring that do not undergo catch-up growth after exposure to maternal protein restriction

Maternal protein restriction is often associated with structural and functional sequelae in offspring, particularly affecting growth and renal-cardiovascular function. However, there is little understanding as to whether hypertension and kidney disease occur because of a primary nephron deficit or whether controlling postnatal growth can result in normal renal-cardiovascular phenotypes. To investigate this, female Sprague-Dawley rats were fed either a low-protein (LP, 8.4% protein) or normal-protein (NP, 19.4% protein) diet prior to mating and until offspring were weaned at postnatal day (PN) 21. Offspring were then fed a non 'growth' (4.6% fat) which ensured that catch-up growth did not occur. Offspring growth was determined by weight and dual energy X-ray absorptiometry. Nephron number was determined at PN21 using the disector-fractionator method. Kidney function was measured at PN180 and PN360 using clearance methods. Blood pressure was measured at PN360 using radio-telemetry. Body weight was similar at PN1, but by PN21 LP offspring were 39% smaller than controls (P_diet < 0.001). This difference was due to proportional changes in lean muscle, fat, and bone content. LP offspring remained smaller than NP offspring until PN360. In LP offspring, nephron number was 26% less in males and 17% less in females, than NP controls (P_diet < 0.0004). Kidney function was similar across dietary groups and sexes at PN180 and PN360. Blood pressure was similar in LP and NP offspring at PN360. These findings suggest that remaining on a slow growth trajectory after exposure to a suboptimal intrauterine environment does not lead to the development of kidney dysfunction and hypertension.

Transcriptome and morphological analysis on the heart in gestational protein-restricted aging male rat offspring

Background: Adverse factors that influence embryo/fetal development are correlated with increased risk of cardiovascular disease (CVD), type-2 diabetes, arterial hypertension, obesity, insulin resistance, impaired kidney development, psychiatric disorders, and enhanced susceptibility to oxidative stress and inflammatory processes in adulthood. Human and experimental studies have demonstrated a reciprocal relationship between birthweight and cardiovascular diseases, implying intrauterine adverse events in the onset of these abnormalities. In this way, it is plausible that confirmed functional and morphological heart changes caused by gestational protein restriction could be related to epigenetic effects anticipating cardiovascular disorders and reducing the survival time of these animals. Methods: Wistar rats were divided into two groups according to the protein diet content offered during the pregnancy: a normal protein diet (NP, 17%) or a Low-protein diet (LP, 6%). The arterial pressure was measured, and the cardiac mass, cardiomyocytes area, gene expression, collagen content, and immunostaining of proteins were performed in the cardiac tissue of male 62-weeks old NP compared to LP offspring. Results: In the current study, we showed a low birthweight followed by catch-up growth phenomena associated with high blood pressure development, increased heart collagen content, and cardiomyocyte area in 62-week-old LP offspring. mRNA sequencing analysis identified changes in the expression level of 137 genes, considering genes with a p-value < 0.05. No gene was. Significantly changed according to the adj-p-value. After gene-to-gene biological evaluation and relevance, the study demonstrated significant differences in genes linked to inflammatory activity, oxidative stress, apoptosis process, autophagy, hypertrophy, and fibrosis pathways resulting in heart function disorders. Conclusion: The present study suggests that gestational protein restriction leads to early cardiac diseases in the LP progeny. It is hypothesized that heart dysfunction is associated with fibrosis, myocyte hypertrophy, and multiple abnormal gene expression. Considering the above findings, it may suppose a close link between maternal protein restriction, specific gene expression, and progressive heart failure.

Kidney Injuries and Evolution of Chronic Kidney Diseases Due to Neonatal Hyperoxia Exposure Based on Animal Studies

Preterm birth interrupts the development and maturation of the kidneys during the critical growth period. The kidneys can also exhibit structural defects and functional impairment due to hyperoxia, as demonstrated by various animal studies. Furthermore, hyperoxia during nephrogenesis impairs renal tubular development and induces glomerular and tubular injuries, which manifest as renal corpuscle enlargement, renal tubular necrosis, interstitial inflammation, and kidney fibrosis. Preterm birth along with hyperoxia exposure induces a pathological predisposition to chronic kidney disease. Hyperoxia-induced kidney injuries are influenced by several molecular factors, including hypoxia-inducible factor-1α and interleukin-6/Smad2/transforming growth factor-β, and Wnt/β-catenin signaling pathways; these are key to cell proliferation, tissue inflammation, and cell membrane repair. Hyperoxia-induced oxidative stress is characterized by the attenuation or the induction of multiple molecular factors associated with kidney damage. This review focuses on the molecular pathways involved in the pathogenesis of hyperoxia-induced kidney injuries to establish a framework for potential interventions.

Impact of Zinc Deficiency During Prenatal and/or Postnatal Life on Cardiovascular and Metabolic Diseases: Experimental and Clinical Evidence

This review summarizes the latest findings, from animal models and clinical studies, regarding the cardiovascular and metabolic consequences in adult life of zinc deficiency (ZD) during prenatal and early postnatal life. The effect of zinc supplementation (ZS) and new insights about sex differences in the phenotype and severity of cardiovascular and metabolic alterations are also discussed. Zinc has antioxidant, anti-inflammatory, and antiapoptotic properties and regulates the activity of enzymes involved in regulation of the metabolic, cardiovascular, and renal systems. Maternal ZD is associated with intrauterine growth restriction and low birth weight (LBW). Breast-fed preterm infants are at risk of ZD due to lower zinc uptake during fetal life and reduced gut absorption capacity. ZS is most likely to increase growth in preterm infants and survival in LBW infants in countries where ZD is prevalent. Studies performed in rats revealed that moderate ZD during prenatal and/or early postnatal growth is a risk factor for the development of hypertension, cardiovascular and renal alterations, obesity, and diabetes in adult life. An adequate zinc diet during postweaning life does not always prevent the cardiovascular and metabolic alterations induced by zinc restriction during fetal and lactation periods. Male rats are more susceptible to this injury than females, and some of the mechanisms involved include: 1) alterations in organogenesis, 2) activation of oxidative, apoptotic, and inflammatory processes, 3) dysfunction of nitric oxide and renin-angiotensin-aldosterone systems, 4) changes in glucose and lipid metabolism, and 5) adipose tissue dysfunction. Safeguarding body zinc requirements during pregnancy, lactation, and growth periods could become a new target in the prevention and treatment of cardiovascular and metabolic disorders. Further research is needed to elucidate the efficacy of ZS during early stages of growth to prevent the development of these diseases later in life.

Fetal Undernutrition Programming, Sympathetic Nerve Activity, and Arterial Hypertension Development

A wealth of evidence showed that low birth weight is associated with environmental disruption during gestation, triggering embryotic or fetal adaptations and increasing the susceptibility of progeny to non-communicable diseases, including metabolic and cardiovascular diseases, obesity, and arterial hypertension. In addition, dietary disturbance during pregnancy in animal models has highlighted mechanisms that involve the genesis of arterial hypertension, particularly severe maternal low-protein intake (LP). Functional studies demonstrated that maternal low-protein intake leads to the renal decrease of sodium excretion and the dysfunction of the renin-angiotensin-aldosterone system signaling of LP offspring. The antinatriuretic effect is accentuated by a reduced number of nephron units and glomerulosclerosis, which are critical in establishing arterial hypertension phenotype. Also, in this way, studies have shown that the overactivity of the central and peripheral sympathetic nervous system occurs due to reduced sensory (afferent) renal nerve activity. As a result of this reciprocal and abnormal renorenal reflex, there is an enhanced tubule sodium proximal sodium reabsorption, which, at least in part, contributes directly to arterial hypertension development in some of the programmed models. A recent study has observed that significant changes in adrenal medulla secretion could be involved in the pathophysiological process of increasing blood pressure. Thus, this review aims to compile studies that link the central and peripheral sympathetic system activity mechanisms on water and salt handle and blood pressure control in the maternal protein-restricted offspring. Besides, these pathophysiological mechanisms mainly may involve the modulation of neurokinins and catecholamines pathways.

IL-6/STAT3 signaling activation exacerbates high fructose-induced podocyte hypertrophy by ketohexokinase-A-mediated tristetraprolin down-regulation

Glomerular hypertrophy is a crucial factor of severe podocyte damage and proteinuria. Our previous study showed that high fructose induced podocyte injury. The current study aimed to explore a novel molecular mechanism underlying podocyte hypertrophy induced by high fructose. Here we demonstrated for the first time that high fructose significantly initiated the hypertrophy in rat glomeruli and differentiated human podocytes (HPCs). Consistently, it induced inflammatory response with the down-regulation of anti-inflammatory factor zinc-finger protein tristetraprolin (TTP) and the activation of interleukin-6 (IL-6)/signal transducer and activator of transcription 3 (STAT3) signaling in these animal and cell models. Subsequently, high-expression of microRNA-92a-3p (miR-92a-3p) and its target protein cyclin-dependent kinase inhibitor p57 (P57) down-regulation, representing abnormal proliferation and apoptosis, were observed in vivo and in vitro. Moreover, high fructose increased ketohexokinase-A (KHK-A) expression in rat glomeruli and differentiated HPCs. Exogenous IL-6 stimulation up-regulated IL-6/STAT3 signaling and miR-92a-3p, reduced P57 expression and promoted podocyte proliferation, apoptosis and hypertrophy in vitro. The data from anti-inflammatory agent maslinic acid treatment or TTP siRNA transfection showed that high fructose may decrease TTP to activate IL-6/STAT3 signaling in podocyte overproliferation and apoptosis, causing podocyte hypertrophy. Whereas, KHK-A siRNA transfection remarkably restored high fructose-induced TTP down-regulation, IL-6/STAT3 signaling activation, podocyte overproliferation, apoptosis and hypertrophy in differentiated HPCs. Taken together, these results suggested that high fructose possibly increased KHK-A expression to down-regulate TTP, subsequently activated IL-6/STAT3 signaling to interfere with podocyte proliferation and apoptosis by up-regulating miR-92a-3p to suppress P57 expression, causing podocyte hypertrophy. Therefore, the inactivation of IL-6/STAT3 to relieve podocyte hypertrophy mediated by inhibiting KHK-A to increase TTP may be a novel strategy for high fructose diet-associated podocyte injury and proteinuria.