Joaquim Pombo

Evidence for Sympathetic Origins of Hypertension in Juvenile Offspring of Obese Rats

Maternal obesity in rodents is associated with increased adiposity, impaired glucose tolerance, and hypertension in adult offspring. In this study we investigated the influence of maternal obesity in the rat on blood pressure and blood pressure regulatory pathways in juvenile and adult offspring. Obesity was induced before pregnancy in female Sprague-Dawley rats by feeding a highly palatable energy-dense diet. In juvenile animals (30 days of age), before the onset of obesity and hyperleptinemia, basal nighttime mean arterial pressure was significantly raised in the offspring of obese dams (OffOb) relative to offspring of controls (OffCon; mean arterial pressure, males: OffOb, 121.8±0.6 mm Hg versus OffCon, 115.0±0.5 mm Hg, n=6, P<0.01; females: OffOb, 125.4±0.4 mm Hg versus OffCon, 114.4±0.5 mm Hg, n=6, P<0.001), as was the mean arterial pressure response to restraint stress (P<0.01). The pressor response to a leptin challenge was enhanced in OffOb rats (&Dgr;mean arterial pressure: OffOb, 9.7±0.8 mm Hg versus OffCon, 5.3±1.3 mm Hg; n=8; P<0.05). Renal tissue norepinephrine content (P<0.001) and renin expression (P<0.05) were markedly raised. Analysis of heart rate variability revealed an increased low:high frequency ratio in OffOb versus OffCon rats (P<0.05). At 90 days, hypertension in OffOb rats persisted and was abolished by &agr;1- and &bgr;-adrenergic blockade, and cardiovascular responses to phenylephrine or sodium nitroprusside indicated altered baroreceptor function. The exaggerated pressor response to leptin in OffOb rats was maintained. Hypertension in the offspring of obese rats may arise from persistent sympathoexcitatory hyperresponsiveness acquired in early stages of development.

Maternal obesity programs offspring nonalcoholic fatty liver disease by innate immune dysfunction in mice

The global prevalence of obesity‐induced liver disease (nonalcoholic fatty liver disease; NAFLD) is rising. Suggested causes include a role for in utero influences of maternal obesity compounded by the availability of energy‐dense foods throughout postnatal life. Using a physiologically relevant model, we investigated the role of the innate immune system in liver injury induced by maternal obesity followed by a postnatal obesogenic diet. Female C57BL/6J mice were fed a standard or obesogenic diet before and throughout pregnancy and during lactation. Female offspring were weaned onto a standard or obesogenic diet at 3 weeks postpartum. Biochemical and histological indicators of dysmetabolism, NAFLD and fibrosis, analysis of profibrotic pathways, liver innate immune cells, and reactive oxygen species (ROS) were investigated at 3, 6, and 12 months. Female offspring exposed to a postweaning obesogenic diet (OffCon‐OD) demonstrated evidence of liver injury, which was exacerbated by previous exposure to maternal obesity (OffOb‐OD), as demonstrated by raised alanine aminotransferase, hepatic triglycerides, and hepatic expression of interleukin (IL)‐6, tumor necrosis factor alpha, transforming growth factor beta, alpha smooth muscle actin, and collagen (P < 0.01). Histological evidence of hepatosteatosis and a more‐robust NAFLD phenotype with hepatic fibrosis was observed at 12 months in OffOb‐OD. A role for the innate immune system was indicated by increased Kupffer cell numbers with impaired phagocytic function and raised ROS synthesis (P < 0.01), together with reduced natural killer T cells and raised interleukin (IL)‐12 and IL‐18. Conclusion: Maternal obesity in the context of a postnatal hypercalorific obesogenic diet aggressively programs offspring NAFLD associated with innate immune dysfunction, resulting in a comprehensive phenotype that accurately reflects the human disease. (HEPATOLOGY 2013)

Maternal obesity programmes offspring development of non-alcoholic fatty pancreas disease

Background and aims The prevalence of pancreatic adenocarcinoma (PAC) parallels rising rates of obesity and dysmetabolism, a possible link being non-alcoholic fatty pancreas disease (NAFPD). We have recently shown that maternal obesity programmes the development of a dysmetabolic and fatty liver (non-alcoholic fatty liver disease, NAFLD) phenotype in adult offspring. Since the pancreas and liver originate from the same embryonic bud, it is plausible that maternal obesity may similarly programme the development of NAFPD. Our objective was to determine the effect of maternal obesity on development of NAFPD in offspring and ascertain contributions of the intra/extra-uterine periods. Methods Female C57BL/6J mice were fed either a standard chow (3% fat, 7% sugar) or a hypercalorific diet (16% fat, 33% sugar) for six weeks prior to mating and throughout pregnancy and lactation. Female offspring were cross-fostered for suckling to dams on the same or opposite diet to yield four groups: offspring of lean suckled by lean dams (n = 6), offspring of obese suckled by obese dams (n = 6), offspring of lean suckled by obese dams (n = 5) and offspring of obese suckled by lean dams (n = 6). All offspring were weaned onto a standard chow diet at 21 days and sacrificed at 3 months post-partum for tissue collection. Results Offspring subjected to an adverse suckling environment showed significant increases in body weight, pancreatic triglyceride content, TGF-β, collagen gene expression and SBP at rest along with an enhanced restraint stress response, indicating a dysmetabolic and NAFPD phenotype. Conclusions Developmental programming is involved in the pathogenesis of NAFPD and appears to be largely dependent on an adverse extra-uterine environment.

Fostering in mice induces cardiovascular and metabolic dysfunction in adulthood

Non‐technical summary  Cross‐fostering of newborn pups to different dams is a method widely used in rodent studies of developmental ‘programming’ to determine whether pregnancy or the suckling period is more important in determining adult characteristics following changes to the maternal environment. We have investigated whether the process of fostering per se influences cardiovascular and metabolic development in mice. Compared with mice reared by their biological mother, fostered mice showed increased appetite, body weight, abdominal fatness and altered blood sugar metabolism. A marked increase in blood pressure was also apparent. This study demonstrates that the process of fostering can lead to profound effects in cardiovascular and metabolic function in otherwise normal mice. The findings have implications both for the interpretation of previous cross‐fostering studies in mice and for studies investigating the hypothesis of developmental programming, in which early postnatal manipulation of litters is common practice.

Experimental hyperleptinemia in neonatal rats leads to selective leptin responsiveness, hypertension, and altered myocardial function

The prevalence of obesity among pregnant women is increasing. Evidence from human cohort studies and experimental animals suggests that offspring cardiovascular and metabolic function is compromised through early life exposure to maternal obesity. Previously, we reported that juvenile offspring of obese rats develop sympathetically mediated hypertension associated with neonatal hyperleptinemia. We have now addressed the hypothesis that neonatal exposure to raised leptin in the immediate postnatal period plays a causal role. Pups from lean Sprague-Dawley rats were treated either with leptin (3 mg/kg IP) or with saline twice daily from postnatal day 9 to 15 to mimic the exaggerated postnatal leptin surge observed in offspring of obese dams. Cardiovascular function was assessed by radiotelemetry at 30 days, and 2 and 12 months. In juvenile (30 days) leptin-treated rats, hearts were heavier and night-time (active period) systolic blood pressure was raised (mm Hg; mean±SEM: male leptin-treated, 132±1 versus saline-treated, 119±1, n=6, P<0.05; female leptin-treated, 132±2 versus saline-treated, 119±1, n=6, P<0.01), and the pressor response to restraint stress and leptin challenge increased compared with saline-treated rats. Heart rate variability demonstrated an increased low:high frequency ratio in 30-day leptin-treated animals, indicative of heightened sympathetic efferent tone. Echocardiography showed altered left ventricular structure and systolic function in 30-day female leptin versus saline-treated rats. These disorders persisted to adulthood. In isolated hearts, contractile function was impaired at 5 months in male leptin-treated rats. Exogenously imposed hyperleptinemia in neonatal rats permanently influences blood pressure and cardiac structure and function.

Non-Alcoholic Fatty Pancreas Disease Pathogenesis: A Role for Developmental Programming and Altered Circadian Rhythms

Objectives Emerging evidence suggests that maternal obesity (MO) predisposes offspring to obesity and the recently described non-alcoholic fatty pancreas disease (NAFPD) but involved mechanisms remain unclear. Using a pathophysiologically relevant murine model, we here investigated a role for the biological clock - molecular core circadian genes (CCG) in the generation of NAFPD. Design Female C57BL6 mice were fed an obesogenic diet (OD) or standard chow (SC) for 6 weeks, prior to pregnancy and throughout gestation and lactation: resulting offspring were subsequently weaned onto either OD (Ob_Ob and Con_Ob) or standard chow (Ob_Con and Con_Con) for 6 months. Biochemical, pro-inflammatory and pro-fibrogenic markers associated with NAFPD were then evaluated and CCG mRNA expression in the pancreas determined. Results Offspring of obese dams weaned on to OD (Ob_Ob) had significantly increased (p≤0.05): bodyweight, pancreatic triglycerides, macrovesicular pancreatic fatty-infiltration, and pancreatic mRNA expression of TNF-α, IL-6, α-SMA, TGF-β and increased collagen compared to offspring of control dams weaned on to control chow (Con_Con). Analyses of CCG expression demonstrated a phase shift in CLOCK (−4.818, p<0.01), REV-ERB-α (−1.4,p<0.05) and Per2 (3.27,p<0.05) in association with decreased amplitude in BMAL-1 (−0.914,p<0.05) and PER2 (1.18,p<0.005) in Ob_Ob compared to Con_Con. 2-way ANOVA revealed significant interaction between MO and post-weaning OD in expression of CLOCK (p<0.005), PER1 (p<0.005) and PER2 (p<0.05) whilst MO alone influenced the observed rhythmic variance in expression of all 5 measured CCG. Conclusions Fetal and neonatal exposure to a maternal obesogenic environment interacts with a post-natal hyper-calorific environment to induce offspring NAFPD through mechanisms involving perturbations in CCG expression.

Central role for melanocortin-4 receptors in offspring hypertension arising from maternal obesity

Significance Obesity is increasing in pregnant women worldwide. Independent associations have been reported between maternal obesity and metabolic cardiorenal disorders in the offspring, including hypertension. In this study, using genetically modified mice, we have identified a role for the hypothalamic paraventricular nucleus (PVH) melanocortin system in the etiology of hypertension. We show that maternal obesity permanently resets the responsiveness of the central sympathetic nervous system via this pathway. We conclude that neonatal leptin exposure is the primary mediator, because exogenous neonatal leptin administration to pups of lean mice leads to the same phenotype mediated by PVH melanocortin-4 receptors. Thus, primary hypertension of sympathetic origin can result from early-life exposure to maternal obesity, and the melanocortin pathway presents a target for intervention. Melanocortin-4 receptor (Mc4r)–expressing neurons in the autonomic nervous system, particularly in the paraventricular nucleus of the hypothalamus (PVH), play an essential role in blood pressure (BP) control. Mc4r-deficient (Mc4rKO) mice are severely obese but lack obesity-related hypertension; they also show a reduced pressor response to salt loading. We have previously reported that lean juvenile offspring born to diet-induced obese rats (OffOb) exhibit sympathetic-mediated hypertension, and we proposed a role for postnatally raised leptin in its etiology. Here, we test the hypothesis that neonatal hyperleptinemia due to maternal obesity induces persistent changes in the central melanocortin system, thereby contributing to offspring hypertension. Working on the OffOb paradigm in both sexes and using transgenic technology to restore Mc4r in the PVH of Mc4rKO (Mc4rPVH) mice, we have now shown that these mice develop higher BP than Mc4rKO or WT mice. We have also found that experimental hyperleptinemia induced in the neonatal period in Mc4rPVH and WT mice, but not in the Mc4rKO mice, leads to heightened BP and severe renal dysfunction. Thus, Mc4r in the PVH appears to be required for early-life programming of hypertension arising from either maternal obesity or neonatal hyperleptinemia. Early-life exposure of the PVH to maternal obesity through postnatal elevation of leptin may have long-term consequences for cardiovascular health.

Developmental Programming of Obesity and Liver Metabolism by Maternal Perinatal Nutrition Involves the Melanocortin System

Maternal obesity predisposes offspring to metabolic dysfunction and Non-Alcoholic Fatty Liver Disease (NAFLD). Melanocortin-4 receptor (Mc4r)-deficient mouse models exhibit obesity during adulthood. Here, we aim to determine the influence of the Mc4r gene on the liver of mice subjected to perinatal diet-induced obesity. Female mice heterozygous for Mc4r fed an obesogenic or a control diet for 5 weeks were mated with heterozygous males, with the same diet continued throughout pregnancy and lactation, generating four offspring groups: control wild type (C_wt), control knockout (C_KO), obese wild type (Ob_wt), and obese knockout (Ob_KO). At 21 days, offspring were genotyped, weaned onto a control diet, and sacrificed at 6 months old. Offspring phenotypic characteristics, plasma biochemical profile, liver histology, and hepatic gene expression were analyzed. Mc4r_ko offspring showed higher body, liver and adipose tissue weights respect to the wild type animals. Histological examination showed mild hepatic steatosis in offspring group C_KO. The expression of hepatic genes involved in regulating inflammation, fibrosis, and immune cell infiltration were upregulated by the absence of the Mc4r gene. These results demonstrate that maternal obesogenic feeding during the perinatal period programs offspring obesity development with involvement of the Mc4r system.

Extravascular renal denervation ameliorates juvenile hypertension and renal damage resulting from experimental hyperleptinemia in rats

Background: Material obesity in rodents is associated with neonatal hyperleptinemia and hypertension of sympathetic origin in adult offspring. Previously, we reported that experimentally induced hyperleptinemia in rat pups results in adulthood hypertension. Here, we addressed the hypothesis that experimental neonatal hyperleptinemia, through renal nerve activation, adversely affects adult renal function. Method: Sprague-Dawley male and female pups were treated with neonatal leptin (3 mg/kg, intraperitoneal) or neonatal saline, twice daily from postnatal day 9–14. Juvenile (1 month) neonatal leptin and neonatal saline rats were subjected to either bilateral renal denervation, unilateral renal denervation or Sham surgery. Arterial pressure was telemetrically monitored. Results: Juvenile neonatal leptin rats with intact renal nerves demonstrated increased mean arterial pressure (MAP) accompanied by local renin–angiotensin system overactivity and reduced glomerular filtration rate. Bilateral renal denervation in rats protected against neonatal leptin-induced MAP, renal renin–angiotensin system and impaired glomerular filtration rate. A two-fold increase in sympathetically mediated tubulointerstitial damage in young adult (2 months) neonatal leptin females, was suppressed by unilateral renal denervation, independent of MAP. Neonatal leptin rats also demonstrated increases in urinary protein, neutrophil gelatinase-associated lipocalin, and kidney injury molecule-1. Raised blood pressure was associated with increased salt sensitivity and with sustained renal dysfunction in adulthood. Conclusion: We propose that neonatal hyperleptinemia programmes long-term renal structural and functional damage, through renal sympathetic nerve activation.

[OP.5D.03] CHRONIC INFLAMMATION DURING PREGNANCY INFLUENCE THE PROGRESSION OF EARLY SYMPATHETIC-MEDIATED HYPERTENSION IN OFFSPRING ARISING FROM MATERNAL OBESITY.

Objective: Mounting evidence suggests that an overactive immune response during pregnancy may alter the development of the central nervous system in the foetus. An increased concentration of pro-inflammatory cytokines has been demonstrated in amniotic fluid of obese pregnancy. This study investigate if low-chronic inflammation, during brain development may have enduring effects on hypothalamic immune response leading to autonomic disturbances and sympathetic mediated hypertension arising from maternal obesity. Design and method: C57BL/6J female mice were fed either a standard chow (7% simple sugars,3% fat) or a highly palatable obesogenic diet (33% simple sugars, 16% fat) 6 weeks prior to mating and throughout gestation and lactation. Offspring were then weaned onto standard chow. Serum samples were collected at gestational day 18 (GD 18), postnatal day 21 and 3 months of age for multiplex cytokine assay. At 3 months of age, blood pressure and pressor response to acute restraint stress were recorded by radiotelemetry. Renal norephinephrine was measured by ELISA. Hypothalamic Interleukin-6 (IL-6) mRNA expression was monitored in juvenile (pre-hypertensive) offspring using QPCR. Results: Diet-induced obese dams demonstrated an enhanced serum pro-inflammatory cytokine profile at GD 18. Serum IL-6 and necrosis factor alpha (TNF- &agr;) concentrations were twice as high in offspring of obese dams (OffOb) as neonates (P < 0.05, n = 6) and adult (P < 0.05, n = 10). Heightened hypothalamic IL-6 mRNA expression was obtained in juvenile OffOb compared with OffCon mice. At 3 months of age, OffOb mice demonstrated sympathetic mediated hypertension with a heightened pressure response to stress and renal norephineprine concentration. Conclusions: Low-chronic inflammation in obese pregnancy have enduring effects on hypothalamic immune populations in the offspring leading to autonomic disturbances and an early onset sympathetic mediated hypertension.