Angiotensin receptor blockade in juvenile male rat offspring: Implications for long-term cardio-renal health

Melatonin Use during Pregnancy and Lactation Complicated by Oxidative Stress: Focus on Offspring's Cardiovascular-Kidney-Metabolic Health in Animal Models

Cardiovascular-kidney-metabolic (CKM) syndrome has emerged as a major global public health concern, posing a substantial threat to human health. Early-life exposure to oxidative stress may heighten vulnerability to the developmental programming of adult diseases, encompassing various aspects of CKM syndrome. Conversely, the initiation of adverse programming processes can potentially be thwarted through early-life antioxidant interventions. Melatonin, originally recognized for its antioxidant properties, is an endogenous hormone with diverse biological functions. While melatonin has demonstrated benefits in addressing disorders linked to oxidative stress, there has been comparatively less focus on investigating its reprogramming effects on CKM syndrome. This review consolidates the current knowledge on the role of oxidative stress during pregnancy and lactation in inducing CKM traits in offspring, emphasizing the underlying mechanisms. The multifaceted role of melatonin in regulating oxidative stress, mediating fetal programming, and preventing adverse outcomes in offspring positions it as a promising reprogramming strategy. Currently, there is a lack of sufficient information in humans, and the available evidence primarily originates from animal studies. This opens up new avenues for novel preventive intervention in CKM syndrome.

Brief Early Life Angiotensin Converting Enzyme Inhibition Offers Reno-Protection in Sheep with a Solitary Functioning Kidney at 8 Months of Age

Background: Children born with a solitary functioning kidney (SFK) are predisposed to develop hypertension and kidney injury. Glomerular hyperfiltration and hypertrophy contribute to the pathophysiology of kidney injury. Angiotensin converting enzyme inhibitors (ACEi) can mitigate hyperfiltration and may be therapeutically beneficial in reducing progression of kidney injury in SFK. Methods: SFK was induced in male sheep fetuses at 100 days gestation (term=150 day). Between 4-8 weeks of age, SFK lambs received enalapril (SFK+ACEi; 0.5mg/kg/day, once daily, orally) or vehicle (SFK). At 8 months we examined whether SFK+ACEi reduced elevation in blood pressure (BP) and improved basal kidney function, renal functional reserve (RFR; glomerular filtration rate (GFR) response to combined amino acid and dopamine infusion), GFR response to nitric oxide synthase (NOS) inhibition and basal nitric oxide (NO) bioavailability (basal urinary total nitrate+nitrite (NOx)). Results: SFK+ACEi prevented albuminuria, resulted in lower basal GFR (16%), higher renal blood flow (~22%), and lower filtration fraction ( 35%), but similar BP compared to ~ vehicle-treated SFK sheep. Together with greater recruitment of RFR (~14%) in SFK+ACEi animals than SFK, this indicates reduction in glomerular hyperfiltration-mediated kidney dysfunction. During NOS inhibition, the decrease in GFR ( 14%) was greater among SFK+ACEi than among SFK animals. Increased ( 85%) basal urinary total NOx in SFK+ACEi animals compared to SFK indicates elevated NO bioavailability likely contributing to improvements in kidney function and prevention of albuminuria. Conclusions: Brief and early ACEi in SFK is associated with reduced glomerular hyperfiltration-mediated kidney disease up to 8 months of age in a sheep model.

N-Acetyl-L-Cysteine Reduces Fibrosis and Improves Muscle Function After Acute Compartment Syndrome Injury

INTRODUCTION

Upon injury, skeletal muscle undergoes a multiphase process beginning with degeneration of the damaged tissue, which is accompanied by inflammation and finally regeneration. One consequence of an injured microenvironment is excessive production of reactive oxygen species, which results in attenuated regeneration and recovery of function ultimately leading to fibrosis and disability. The objective of this research was to test the potential of the antioxidant, N-Acetyl-L-Cysteine (NAC), as a mediator of reactive oxygen species damage that results from traumatic muscle injury in order to support repair and regeneration of wounded muscle tissue and improve function recovery.

MATERIALS AND METHODS

Adult female Lewis rats were subjected to compartment syndrome injury as previously published by our group. Rats received intramuscular injections of NAC or vehicle at 24, 48, and 72 hours postinjury. Muscle function, tissue fibrosis, and the expression of myogenic and angiogenic markers were measured.

RESULTS

Muscle function was significantly improved, and tissue fibrosis was significantly decreased in NAC-treated muscles.

CONCLUSIONS

These results suggest that NAC treatment of skeletal muscle after injury may be a viable option for the prevention of long-term fibrosis and scar formation, facilitating recovery of muscle function.

Intrarenal Renin Angiotensin System Imbalance During Postnatal Life Is Associated With Increased Microvascular Density in the Mature Kidney

Environmental stress during early life is an important factor that affects the postnatal renal development. We have previously shown that male rats exposed to maternal separation (MatSep), a model of early life stress, are normotensive but display a sex-specific reduced renal function and exacerbated angiotensin II (AngII)-mediated vascular responses as adults. Since optimal AngII levels during postnatal life are required for normal maturation of the kidney, this study was designed to investigate both short- and long-term effect of MatSep on (1) the renal vascular architecture and function, (2) the intrarenal renin-angiotensin system (RAS) components status, and (3) the genome-wide expression of genes in isolated renal vasculature. Renal tissue and plasma were collected from male rats at different postnatal days (P) for intrarenal RAS components mRNA and protein expression measurements at P2, 6, 10, 14, 21, and 90 and microCT analysis at P21 and 90. Although with similar body weight and renal mass trajectories from P2 to P90, MatSep rats displayed decreased renal filtration capacity at P90, while increased microvascular density at both P21 and P90 (p < 0.05). MatSep increased renal expression of renin, and angiotensin type 1 (AT1) and type 2 (AT2) receptors (p < 0.05), but reduced ACE2 mRNA expression and activity from P2-14 compared to controls. However, intrarenal levels of AngII peptide were reduced (p < 0.05) possible due to the increased degradation to AngIII by aminopeptidase A. In isolated renal vasculature from neonates, Enriched Biological Pathways functional clusters (EBPfc) from genes changed by MatSep reported to modulate extracellular structure organization, inflammation, and pro-angiogenic transcription factors. Our data suggest that male neonates exposed to MatSep could display permanent changes in the renal microvascular architecture in response to intrarenal RAS imbalance in the context of the atypical upregulation of angiogenic factors.

Impact of early life AT1 blockade on adult cardiac morpho-functional changes and the renin-angiotensin system in a model of neonatal high oxygen-induced cardiomyopathy

We previously reported that neonatal blockade of angiotensin II AT₁ receptor prevents cardiac changes in 4 weeks rats with neonatal hyperoxia-induced cardiomyopathy, a recognized model of prematurity-related deleterious conditions. Considering the importance of AT₁ receptor and the renin angiotensin system (RAS) in normal development, the present study aimed to investigate the adult effects of neonatal AT₁ blockade on left ventricle (LV) in rats exposed to neonatal hyperoxia. Sprague-Dawley pups were exposed to 80% O₂ or room air from days 3-10. AT₁ blocker (losartan) or H₂O were given by gavage from day 8-10. LV function (echo and intraventricular pressure), histology and expression of RAS components were examined in 15-16 weeks old adult males. Losartan treatment prevented myocardial fibrosis, LV wall thickening and stroke volume reduction in rats exposed to high O₂ in the neonatal period. However, Losartan treatment of O₂-exposed pups led to reduced ejection fraction (EF) and fractional shortening (FS), and did not prevent changes in diastolic function. Losartan also did not prevent increased LV AT₂ and decreased angiotensin-(1-7) Mas receptors expression observed in high O₂-exposed rats. Neonatal Losartan attenuated long-term impact of neonatal hyperoxia but also led to decreased EF and FS. Increased AT₂ and decreased Mas receptor expression observed in O₂-exposed group were unaffected by Losartan treatment. Our results show that early life Losartan treatment aimed at preventing cardiac consequences of neonatal deleterious conditions may also comprise detrimental effects that require further investigation prior to clinical translation in developing children.