High and Low Salt Intake during Pregnancy: Impact on Cardiac and Renal Structure in Newborns

Early-life exposures and long-term health: adverse gestational environments and the programming of offspring renal and vascular disease

According to the Developmental Origins of Health and Disease hypothesis, exposure to certain environmental influences during early life may be a key determinant of fetal development and short- and long-term offspring health. Indeed, adverse conditions encountered during the fetal, perinatal, and early childhood stages can alter normal development and growth, as well as put the offspring at elevated risk of developing long-term health conditions in adulthood, including chronic kidney disease and cardiovascular diseases. Of relevance in understanding the mechanistic basis of these long-term health conditions are previous findings showing low glomerular number in human intrauterine growth restriction and low birth weight-indicators of a suboptimal intrauterine environment. In different animal models, the main suboptimal intrauterine conditions studied relate to maternal dietary manipulations, poor micronutrient intake, prenatal ethanol exposure, maternal diabetes, glucocorticoid and chemical exposure, hypoxia, and placental insufficiency. These studies have demonstrated changes in kidney structure, glomerular endowment, and expression of key genes and signaling pathways controlling endocrine, excretion, and filtration function of the offspring. This review aims to summarize those studies to uncover the effects and mechanisms by which adverse gestational environments impact offspring renal and vascular health in adulthood. This is important for identifying agents and interventions that can prevent and mitigate the long-term consequences of an adverse intrauterine environment on the subsequent generation.NEW & NOTEWORTHY Human data and experimental animal data show that suboptimal environments during fetal development increase the risk of renal and vascular diseases in adult-life. This is related to permanent changes in kidney structure, function, and expression of genes and signaling pathways controlling filtration, excretion, and endocrine function. Uncovering the mechanisms by which offspring renal development and function is impacted is important for identifying ways to mitigate the development of diseases that strain health care services worldwide.

Three-dimensional morphometry of kidney in New Zealand rabbit using unbiased design-based stereology

The rabbit is widely used as a laboratory animal in experimental models of kidney diseases. This species is also important from a veterinary perspective as a companion animal. Stereology has been accepted as an accurate approach to kidney morphometry. The objective of the present project was to provide normal quantitative stereological parameters for adult rabbit kidneys. The left kidneys of five adult male New Zealand rabbits were used. Isotropic sections were obtained using the orientation method. Total kidney volume was calculated by the Cavalieri principle. The volume fraction of the renal structures was estimated using the point counting system. The lengths of the proximal convoluted tubule (PCT) and distal convoluted tubule (DCT) were calculated using counting frames. The total glomerular number was accounted for using the physical/fractionator technique. The mean glomerular volume was obtained by dividing the total volume of glomeruli by their total number. The total volume of rabbit kidneys calculated was 10.39 ± 1.98 cm3. The fractional volume of the kidney cortex and medulla accounted for 57.79 ± 0.65% and 42.2 ± 0.65%, respectively. The total glomerular volume was 2.18 ± 0.32% of the whole kidney. The total number of glomeruli in the rabbit kidney was estimated as 204.68 ± 12 × 103. The mean glomerular volume measured 1.07 ± 0.12 × 106 μm3. The total length of PCT and DCT was 2.96 ± 0.29 km and 1.38 ± 0.24 km, respectively. These findings can be used as a reference in experimental nephrology research and may help to expand the knowledge of nephrology in mammals by comparing with available data on humans and other species. RESEARCH HIGHLIGHTS: Three-dimensional morphometry of adult rabbit kidney structures was analyzed using quantitative stereology. Total volume of kidney, fractional volume of cortex and medulla, length of renal tubules and number of nephrons were estimated. These three-dimensional morphometrical data can be used as a reference in experimental nephrology research and may help to expand the knowledge of nephrology in mammals.

High dietary salt intake attenuates nitric oxide mediated endothelium-dependent vasodilation and increases oxidative stress in pregnancy

OBJECTIVE

This study aimed to investigate the impact of dietary salt intake during normal pregnancy on maternal microvascular and macrovascular endothelium-dependent reactivity and oxidative stress level.

MATERIALS AND METHODS

In this cross-sectional study, based on their 24-h urinary sodium excretion, pregnant women (37-40 weeks of gestation) were divided into three groups: normal salt (<5.75 g/day, N  = 12), high salt (5.75-10.25 g/day, N  = 36), and very high salt (VHS;>10.25 g/day, N  = 17). Forearm skin microvascular reactivity in response to vascular occlusion, local heating (LTH) and iontophoresis of acetylcholine (AChID), as well as brachial artery flow mediated dilation (FMD) were measured. Serum nitric oxide, endocan, 8-iso-prostaglandin F2α (8-iso-PGF2α), thiobarbituric acid reactive substances (TBARS), and ferric-reducing ability of plasma assay were measured as biomarkers of endothelial function/activation and oxidative stress.

RESULTS

Brachial artery FMD, microvascular AChID, and LTH were significantly decreased in VHS compared with NS group, while LTH was also decreased in normal salt compared with high salt group. Nitric oxide was significantly decreased in both high salt and VHS groups compared with normal salt. Endocan, 8-iso-PGF2α, and TBARS were significantly increased in VHS compared with the normal salt group.

CONCLUSION

High dietary salt intake is associated with decreased nitric oxide mediated endothelium-dependent vasodilation in peripheral microcirculation and macrocirculation of healthy pregnant women due to increased oxidative stress.

Association between dietary intake and symptoms of depression and anxiety in pregnant women: Evidence from a community-based observational study

Dietary intake is considered as a crucial factor affecting mental health symptoms, particularly depression and anxiety symptoms, especially in the case of pregnant women. This study explored the role of dietary intake in depression and anxiety symptoms of pregnant women and provided evidence for primary care interventions. We enrolled 806 pregnant women in their third trimester from 14 communities in Hengyang City, Hunan Province, China, from July 2019 to September 2019. The Chinese version of the Patient Health Questionnaire-9 (PHQ-9) and the Generalized Anxiety Disorder questionnaire-7 (GAD-7) were used to assess depression and anxiety symptoms. Dietary intake, demographic characteristics, BMI, and pregnancy characteristics were collected using a self-designed, structural questionnaire. A covariate-adjusted logistic regression was conducted to examine the relationship between mental health symptoms and dietary intake. The prevalence of anxiety and depression symptoms in our population were 7.7% (95% CI: 5.9%-9.5%) and 9.2% (95% CI: 7.2%-11.2%), respectively. Women consuming eggs and egg products once a week (OR: 3.688, 95% CI: 1.476-9.215) were more likely to have depression symptom than consumed eggs and egg products once or more per day. Consuming green leafy vegetable <2-3 times per month had a significantly greater risk for depression symptoms than consuming the same once or more per day (OR: 3.450, 95% CI: 1.145-10.393). Women who consumed eggs and egg products 2-3 times a week had an increased likelihood of experiencing anxiety symptoms (OR: 2.253, 95% CI: 1.049-4.837). Anxiety symptoms in women consuming green leafy vegetables <2-3 times per month probably increased by 3.988 times (95% CI: 1.327-11.985) compared with women consuming the same once or more per day. Consuming salted and smoked food <2-3 times per month was protective against anxiety symptoms (OR: 0.181, 95% CI: 0.040-0.828) than consuming the same every day. Implementing interventions to promote healthy dietary among pregnant women is crucial due to its association with mental health. However, future researches are warranted to confirm the reliability and causal association obtained in this study.

Inhibition of Maternal c-Src Ameliorates the Male Offspring Hypertension by Suppressing Inflammation and Neurotransmitters in the Paraventricular Nucleus

Long-term maternal salt intake induces the hypertension in offspring. Numerous studies have also indicated that high-salt diet causes the inflammation and an imbalance in neurotransmitters in the paraventricular nucleus (PVN) which increases the blood pressure and sympathetic activity. This study aimed to explore whether maternal salt intake induces hypertension in their male offspring by increasing the inflammation and changing the neurotransmitters balance in the paraventricular nucleus of offspring. This study includes two parts: Part I to explore the effect of high-salt diet on pregnant rats and the changes in inflammation and neurotransmitters in their male offspring PVN; Part II to reveal the influence on their offspring of bilateral PVN infusion of c-Src inhibitor dasatinib (DAS) in pregnant rats fed a high-salt diet. Maternal high-salt diet intake during copulation, pregnancy, and lactation impacted the offspring mean arterial pressure (MAP) and elevated the offspring PVN levels of p-Src, proinflammatory cytokines, and excitatory neurotransmitters. Bilateral PVN infusion of a c-Src inhibitor combined with maternal high-salt diets decreased MAP in the offspring. The infusion was also shown to suppress the Src-induced MAPK/NF-κB signaling pathway (p38 MAPK, JNK, Erk1/2), which attenuates inflammatory reactions. Finally, bilateral PVN infusion of the Src inhibitor in pregnant rat with high-salt diets improved the levels of inhibitory neurotransmitters in offspring PVN, which restored the excitatory-inhibitory neurotransmitter balance in male offspring. High-salt diets increase sympathetic activity and blood pressure in adult offspring, probably by activating the c-Src/MAPKs/NF-κB signaling pathway-induced inflammation. Moreover, NF-κB disrupts the downstream excitatory-inhibitory neurotransmitter balance in the PVN of male offspring.

From Maternal Diet to Neurodevelopmental Disorders: A Story of Neuroinflammation

Providing the appropriate quantity and quality of food needed for both the mother's well-being and the healthy development of the offspring is crucial during pregnancy. However, the macro- and micronutrient intake also impacts the body's regulatory supersystems of the mother, such as the immune, endocrine, and nervous systems, which ultimately influence the overall development of the offspring. Of particular importance is the association between unhealthy maternal diet and neurodevelopmental disorders in the offspring. Epidemiological studies have linked neurodevelopmental disorders like autism spectrum disorders, attention-deficit-hyperactivity disorder, and schizophrenia, to maternal immune activation (MIA) during gestation. While the deleterious consequences of diet-induced MIA on offspring neurodevelopment are increasingly revealed, neuroinflammation is emerging as a key underlying mechanism. In this review, we compile the evidence available on how the mother and offspring are both impacted by maternal dietary imbalance. We specifically explore the various inflammatory and anti-inflammatory effects of dietary components and discuss how changes in inflammatory status can prime the offspring brain development toward neurodevelopmental disorders. Lastly, we discuss research evidence on the mechanisms that sustain the relationship between maternal dietary imbalance and offspring brain development, involving altered neuroinflammatory status in the offspring, as well as genetic to cellular programming notably of microglia, and the evidence that the gut microbiome may act as a key mediator.

A low intensity dietary intervention for reducing excessive gestational weight gain in an overweight and obese pregnant cohort

PURPOSE

Excessive gestational weight gain is associated with detrimental outcomes to both the mother and baby. Currently, the best approach to prevent excessive gestational weight gain in overweight and obese women is undetermined. The present study aimed to evaluate the effectiveness of a group-based outpatient dietary intervention in pregnancy to reduce excessive gestational weight gain.

METHODS

In this retrospective study, overweight and obese pregnant women who attended a single 90-min group education session were compared to women who received standard care alone. Total gestational weight gain, maternal and neonatal outcomes were compared between the intervention and control groups. Data were analysed using Student t, Mann-Whitney and Chi-squared tests as appropriate. A 24-h dietary recall was analysed and compared to the Australian National Nutrition Survey.

RESULTS

A significant reduction in gestational weight gain was observed with this intervention (P = 0.010), as well as in the rate of small for gestational age births (P = 0.043). Those who attended the intervention had saturated fat and sodium intake levels that exceeded recommendations. Intake of pregnancy-specific micronutrients including folate, calcium and iron were poor from diet alone.

CONCLUSIONS

A low-intensity antenatal dietary intervention may be effective in reducing excessive gestational weight gain, although multi-disciplinary interventions yield the best success. Further research is required to identify the optimal modality and frequency to limit excessive gestational weight gain. Dietary interventions tailored to ethnicity should also be explored.

LEVEL OF EVIDENCE

Level II, controlled trial without randomization.

Cat Kidney Glomeruli and Tubules Evaluated by Design-Based Stereology

Renal function is related to its structure and three-dimensional structural parameters correlate better with the kidney function than two-dimensional structural parameters. Stereology is the current gold-standard technique for the morphometrical evaluation of kidney structures. This study describes morphometric features of the kidney of the cat using design-based stereological techniques aimed to introduce the cat as a translational model in nephrology and provide basic findings for diagnosis and treatment of kidney diseases in this species. Left kidneys of four cats were included in the present study. The kidney volume, volume fraction of cortex and medulla, glomerular volume, glomerular mean volume, glomerular number, and proximal convoluted tubule (PCT) and distal convoluted tubule (DCT) length were estimated. The kidney volume was estimated to 11.4 ± 1.3 cm³ . The volume fraction of cortex and medulla was 65.6 ± 2% and 34.2 ± 2%, respectively. The total number of glomeruli was estimated to be 186 ± 11 × 10³ using the physical disector/fractionator method. The mean glomerular volume was estimated to be 1.54 ± 0.06 × 10⁶ μm³ and the glomerular volume was covering 2.13 ± 0.34% of the whole kidney. The total length of PCT and DCT was estimated to be 2.26 ± 0.48 km and 505 ± 43 m, respectively. Our data might contribute to the knowledge of kidneys in mammals and provide a comparison with available data on human and other mammals. Anat Rec, 302:1846-1854, 2019. © 2019 American Association for Anatomy.

Maternal high-salt diet alters redox state and mitochondrial function in newborn rat offspring's brain

Excessive salt intake is a common feature of Western dietary patterns, and has been associated with important metabolic changes including cerebral redox state imbalance. Considering that little is known about the effect on progeny of excessive salt intake during pregnancy, the present study investigated the effect of a high-salt diet during pregnancy and lactation on mitochondrial parameters and the redox state of the brains of resulting offspring. Adult female Wistar rats were divided into two dietary groups (n 20 rats/group): control standard chow (0·675 % NaCl) or high-salt chow (7·2 % NaCl), received throughout pregnancy and for 7 d after delivery. On postnatal day 7, the pups were euthanised and their cerebellum, hypothalamus, hippocampus, prefrontal and parietal cortices were dissected. Maternal high-salt diet reduced cerebellar mitochondrial mass and membrane potential, promoted an increase in reactive oxygen species allied to superoxide dismutase activation and decreased offspring cerebellar nitric oxide levels. A significant increase in hypothalamic nitric oxide levels and mitochondrial superoxide in the hippocampus and prefrontal cortex was observed in the maternal high-salt group. Antioxidant enzymes were differentially modulated by oxidant increases in each brain area studied. Taken together, our results suggest that a maternal high-salt diet during pregnancy and lactation programmes the brain metabolism of offspring, favouring impaired mitochondrial function and promoting an oxidative environment; this highlights the adverse effect of high-salt intake in the health state of the offspring.