Endothelial NOS expression and ischemia-reperfusion in isolated working rat heart from hypoxic and hyperoxic conditions

Induction of endothelial nitric oxide synthase (eNOS) contributes to the mechanism of heart protection against ischemia-reperfusion damage. We analyzed the effects of hypoxia and hyperoxia on eNOS expression in isolated working rat hearts after ischemia-reperfusion damage. Adult male Wistar rats were submitted to chronic hypoxia (2 weeks) and hyperoxia (72 h). The hearts were submitted to 15 min of ischemia and reperfused for 60 min, then we evaluated hemodynamic parameters and creatine phosphokinase (CPK) release. eNOS expression was estimated by RT-PCR; enzyme localization was evaluated by immunohistochemistry and the eNOS protein levels were detected by Western blot. All hemodynamic parameters in hypoxic conditions were better with respect to other groups. The CPK release was lower in hypoxic (P<0.01) than in normoxic and hyperoxic conditions. The eNOS deposition was significantly higher in the hypoxic group versus the normoxic or hyperoxic groups. The eNOS protein and mRNA levels were increased by hypoxia versus both other groups. Chronic hypoxic exposure may decrease injury and increase eNOS protein and mRNA levels in heart subjected to ischemia-reperfusion.     

Prenatal hypoxia induces increased cardiac contractility on a background of decreased capillary density

Background

Chronic hypoxia in utero (CHU) is one of the most common insults to fetal development and may be associated with poor cardiac recovery from ischaemia-reperfusion injury, yet the effects on normal cardiac mechanical performance are poorly understood.

Methods

Pregnant female wistar rats were exposed to hypoxia (12% oxygen, balance nitrogen) for days 10–20 of pregnancy. Pups were born into normal room air and weaned normally. At 10 weeks of age, hearts were excised under anaesthesia and underwent retrograde 'Langendorff' perfusion. Mechanical performance was measured at constant filling pressure (100 cm H₂O) with intraventricular balloon. Left ventricular free wall was dissected away and capillary density estimated following alkaline phosphatase staining. Expression of SERCA2a and Nitric Oxide Synthases (NOS) proteins were estimated by immunoblotting.

Results

CHU significantly increased body mass (P < 0.001) compared with age-matched control rats but was without effect on relative cardiac mass. For incremental increases in left ventricular balloon volume, diastolic pressure was preserved. However, systolic pressure was significantly greater following CHU for balloon volume = 50 μl (P < 0.01) and up to 200 μl (P < 0.05). For higher balloon volumes systolic pressure was not significantly different from control. Developed pressures were correspondingly increased relative to controls for balloon volumes up to 250 μl (P < 0.05). Left ventricular free wall capillary density was significantly decreased in both epicardium (18%; P < 0.05) and endocardium (11%; P < 0.05) despite preserved coronary flow. Western blot analysis revealed no change to the expression of SERCA2a or nNOS but immuno-detectable eNOS protein was significantly decreased (P < 0.001) in cardiac tissue following chronic hypoxia in utero.

Conclusion

These data offer potential mechanisms for poor recovery following ischaemia, including decreased coronary flow reserve and impaired angiogenesis with subsequent detrimental effects of post-natal cardiac performance.     

间歇性低压低氧方式对发育大鼠心脏缺血/再灌注损伤的影响

本研究旨在探讨两种不同形式的间歇性低压低氧（intermittent hypobaric hypoxia,IHH）对发育大鼠心脏缺血,再灌注损伤的影响。雄性Sprague-Dawley（SD）新生大鼠72只,随机分为三组：对照组、IHH3000in组（IHH3000）、IHH5000m组（IHH5000）。低氧组大鼠出生后立即于低压氧舱分别接受28d、42d和56d（海拔5000m、每天6h：海拔3000m、每天5h）的低压低氧处理。应用Langendorff离体心脏灌流技术,给予心脏缺血（停灌30min）／再灌注（复灌60min）处理,分别在缺血前5min及复灌后l、5、10、20、30、60min记录心功能和冠状动脉流量变化,并测定乳酸脱氢酶（1actate dehydrogenase,LDH）活性。实验结束时测定心脏重量。结果显示：（1）IHH3000组大鼠体重增长与对照组无明显差异;IHH5000组大鼠体重增长明显慢于对照组及IHH3000组大鼠（P〈0．01）。（2）IHH3000组人鼠表现明显的心脏保护效应。与对照组相比较,在心脏停灌,再灌注60min时,心功能（LVDP、±LVdp／drmax）恢复增强（P〈0．05）、LDH活性降低（P〈0．05）、冠状动脉流量增多（P〈0．05）;心脏重量与对照组大鼠无差异;IHH42d处理的大鼠心功能恢复明显好于IHH28d处理的大鼠（P〈0．05）。（3）IHH5000组大鼠表现出明显的心脏损伤效应,各项心功能指标（LVDP、±LVdp／dtmax）的恢复均低于对照组（P〈0．05）,复灌过程中LDH活性明显高于相应对照组（P〈0．05）,右心室重量明显高于对照组大鼠（P〈0．05）。结果表明,适当的IHH增强发育大鼠心脏对缺血,再灌注损伤的抵抗能力;间歇性低氧方式是影响其心脏保护作用的重要因素。     

Developmental programming of vascular dysfunction by prenatal and postnatal zinc deficiency in male and female rats

Micronutrient malnutrition during intrauterine and postnatal growth may program cardiovascular diseases in adulthood. We examined whether moderate zinc restriction in male and female rats throughout fetal life, lactation and/or postweaning growth induces alterations that can predispose to the onset of vascular dysfunction in adulthood. Female Wistar rats were fed low- or control zinc diets from pregnancy to offspring weaning. After weaning, offspring were fed either a low- or a control zinc diet until 81 days. We evaluated systolic blood pressure (SBP), thoracic aorta morphology, nitric oxide (NO) system and vascular reactivity in 6- and/or 81-day-old offspring. At day 6, zinc-deficient male and female offspring showed a decrease in aortic NO synthase (NOS) activity accompanied by an increase in oxidative stress. Zinc-deficient 81-day-old male rats exhibited an increase in collagen deposition in tunica media, as well as lower activity of endothelial NOS (eNOS) that could not be reversed with an adequate zinc diet during postweaning life. Zinc deficiency programmed a reduction in eNOS protein expression and higher SBP only in males. Adult zinc-deficient rats of both sexes showed reduced vasodilator response dependent on eNOS activity and impaired aortic vasoconstrictor response to angiotensin-II associated with alterations in intracellular calcium mobilization. Female rats were less sensitive to the effects of zinc deficiency and exhibited higher eNOS activity and/or expression than males, without alterations in SBP or aortic histology. This work strengthens the importance of a balanced intake of micronutrients during perinatal growth to ensure adequate vascular function in adult life.     

Hypoxia inducible factor-1 alpha correlates the expression of heme oxygenase 1 gene in pulmonary arteries of rat with hypoxia-induced pulmonary hypertension

AbstractTo test the hypothesis that hypoxia inducible factor-1 alpha (HIF-1α）up-regulated theexpression of heme oxygenase-1 (HO-1) gene in pulmonary arteries of rats with hypoxia-induced pulmonaryhypertension, 8 male Wistar rats in each of 5 groups were exposed to hypoxia for 0, 3, 7, 14 or 21 d, respectively.Mean pulmonary arterial pressure (mPAP), vessel morphometry and right ventricle hypertrophy index weremeasured. Lungs were inflation fixed for immunohistochemistry, in situ hybridization; frozen for latermeasurement of HO-1 enzyme activity, mPAP increased significantly after 7 d of hypoxia [(18.4 ± 0.4)mmHg, P<0.05], reaching its peak after 14 d of hypoxia, then remained stable. Pulmonary artery remodeling became to develop significantly after 14 d of hypoxia. HIF-1αprotein in control was poorly positive (0.05 ±0.01), but was up-regulated in pulmonary arterial tunica intima of all hypoxic rats. In pulmonary arterialtunica media, the levels of HIF-la protein were markedly up-regulated after 3 d and 7 d of hypoxia(0.20±0.02; 0.22 ± 0.02, P<0.05), then declined after 14 d and 21 d of hypoxia. HIF-mRNA stainingwas poorly positive in control, hypoxia for 3 and 7 d, but enhanced significantly after 14 d of hypoxia(0.20±0.02, P<0.05), then remained stable. HO-1 protein increased after 7 d of hypoxia (0.10±0.01,P<0.05), reaching its peak after 14 d of hypoxia (0.21 0.02, P<0.05), then remained stable. HO-1 mRNA increased after 3 d of hypoxia, reaching its peak after 7 d of hypoxia (0.17 ± 0.01, P<0.05), then declined.Linear correlation analysis showed that HIF-lα mRNA, HO-1 protein and mPAP were associatedwith pulmonary remodeling. HIF-1 α protein (tunica intima) was conversely correlated with HIF-1α mRNA(r=0.921, P<0.01), HO-1 protein was conversely correlated with HIF-1α protein (tunica intima)(r=0.821, P<0.01 ). HIF-1αand HO-1 were both involved in the pathogenesis of hypoxia-induced pulmonaryhypertension in rat. Hypoxia inducible factor-1 alpha correlated the expression of heme oxygenase 1 genein pulmonary arteries of rat with hypoxia-induced pulmonary hypertension.     

Increased myogenic tone in 7-month-old adult male but not female offspring from rat dams exposed to hypoxia during pregnancy

Intrauterine growth restriction (IUGR) increases the risk of cardiovascular disease later in life. Vascular dysfunction occurs in adult offspring from animal models of IUGR including maternal undernutrition, but the influence of reduced fetal oxygen supply on adult vascular function is unclear. Myogenic responses, essential for vascular tone regulation, have not been evaluated in these offspring. We hypothesized that 7-mo-old offspring from hypoxic (12% O(2); H) or nutrient-restricted (40% of control; NR) rat dams would show greater myogenic responses than their 4-mo-old littermates or control (C) offspring through impaired modulation by vasodilators. Growth restriction occurred in male H (P < 0.01), male NR (P < 0.01), and female NR (P < 0.02), but not female H, offspring. Myogenic responses in mesenteric arteries from males but not females were increased at 7 mo in H (P < 0.01) and NR (P < 0.05) vs. C offspring. There was less modulation of myogenic responses after inhibition of nitric oxide synthase (P < 0.05), prostaglandin H synthase (P < 0.005), or both enzymes (P < 0.001) in arteries from 7-mo male H vs. C offspring. Thus reduced vasodilator modulation may explain elevated myogenic responses in 7-mo male H offspring. In contrast, there was increased modulation of myogenic responses in arteries from 7-mo female H vs. C or NR offspring after inhibition of both enzymes (P < 0.05). Thus increased vasodilator modulation may maintain myogenic responses in female H offspring at control levels. In summary, vascular responses in adult offspring from adverse intrauterine environments are impaired in a gender-specific, age-dependent, and maternal insult-dependent manner, with males more profoundly affected.     

Maternal Hypoxia Decreases Capillary Supply and Increases Metabolic Inefficiency Leading to Divergence in Myocardial Oxygen Supply and Demand

Maternal hypoxia is associated with a decrease in left ventricular capillary density while cardiac performance is preserved, implying a mismatch between metabolism and diffusive exchange. We hypothesised this requires a switch in substrate metabolism to maximise efficiency of ATP production from limited oxygen availability. Rat pups from pregnant females exposed to hypoxia (FIO₂=0.12) at days 10-20 of pregnancy were grown to adulthood and working hearts perfused ex vivo. ¹⁴C-labelled glucose and ³H-palmitate were provided as substrates and metabolism quantified from recovery of ¹⁴CO₂ and ³H₂O, respectively. Hearts of male offspring subjected to Maternal Hypoxia showed a 20% decrease in cardiac output (P<0.05), despite recording a 2-fold increase in glucose oxidation (P<0.01) and 2.5-fold increase (P<0.01) in palmitate oxidation. Addition of insulin to Maternal Hypoxic hearts, further increased glucose oxidation (P<0.01) and suppressed palmitate oxidation (P<0.05), suggesting preservation in insulin signalling in the heart. In vitro enzyme activity measurements showed that Maternal Hypoxia increased both total and the active component of cardiac pyruvate dehydrogenase (both P<0.01), although pyruvate dehydrogenase sensitivity to insulin was lost (NS), while citrate synthase activity declined by 30% (P<0.001) and acetyl-CoA carboxylase activity was unchanged by Maternal Hypoxia, indicating realignment of the metabolic machinery to optimise oxygen utilisation. Capillary density was quantified and oxygen diffusion characteristics examined, with calculated capillary domain area increased by 30% (P<0.001). Calculated metabolic efficiency decreased 4-fold (P<0.01) for Maternal Hypoxia hearts. Paradoxically, the decline in citrate synthase activity and increased metabolism suggest that the scope of individual mitochondria had declined, rendering the myocardium potentially more sensitive to metabolic stress. However, decreasing citrate synthase may be essential to preserve local PO₂, minimising regions of hypoxia and hence maximising the area of myocardium able to preserve cardiac output following maternal hypoxia.     

Influence of the estrous cycle on hypoxic failure in the female rat heart

Background: Clinical studies have shown that fluctuation in the plasma concentrations of estrogen during the menstrual cycle has an effect on myocardial health in premenopausal women. When estrogen levels are low, the number of ischemic events experienced is increased.Objective: To determine whether the increased ischemic events reported with low plasma estrogen concentrations in women could be reproduced in an animal model, cardiac function was measured during hypoxia in the female rat at different time points of the estrous cycle.Methods: Hearts from female Sprague-Dawley rats were perfused in the working mode at the diestrous (low estrogen; n = 7) and proestrous (high estrogen; n = 6) phases of the estrous cycle, confirmed by plasma estradiol concentrations. Hearts were perfused under aerobic conditions with 5.5 mM glucose, 100 μU/mL insulin, and 1.2 mM palmitate, followed by a 30-minute period of hypoxia with 95% N₂-5% CO₂ gassing.Results: There were no significant differences in heart function between diestrous and proestrous groups prior to hypoxia. However, hypoxia induced perturbations in function that were dependent on the estrous cycle. Reductions in left ventricular systolic and diastolic pressure occurred with hypoxia, but no significant differences in these pressures were observed between groups. Left ventricular pulse pressure and coronary flow also decreased significantly during hypoxia (both, P < 0.05), but hearts from the proestrous group maintained a significantly higher pulse pressure (P < 0.05). Hearts from the proestrous group also maintained significantly higher rates of coronary flow during hypoxia (P < 0.05), compared with hearts from the diestrous group. However, despite the effect of proestrus, correlation coefficients between plasma estradiol concentrations and indices of cardiac function were not significant.Conclusions: Our findings indicate that the estrous cycle of the female rat affects cardiac function during hypoxia. This model may be useful to study the impact of the estrous cycle on metabolic and cardiovascular function.     

Synergistic effects of prenatal hypoxia and postnatal high-fat diet in the development of cardiovascular pathology in young rats

We have previously shown that adult offspring exposed to a prenatal hypoxic insult leading to intrauterine growth restriction (IUGR) are more susceptible to cardiovascular pathologies. Our objectives were to evaluate the interaction between hypoxia-induced IUGR and postnatal diet in the early development of cardiovascular pathologies. Furthermore, we sought to determine whether the postnatal administration of resveratrol could prevent the development of cardiovascular disorders associated with hypoxia-induced IUGR. On day 15 of pregnancy, Sprague-Dawley rats were randomly assigned to hypoxia (11.5% oxygen), to induce IUGR, or normal oxygen (control) groups. For study A, male offspring (3 wk of age) were randomly assigned a low-fat (LF, <10% fat) or a high-fat (HF, 45% fat) diet. For study B, offspring were randomized to either HF or HF+resveratrol diets. After 9 wk, cardiac and vascular functions were evaluated. Prenatal hypoxia and HF diet were associated with an increased myocardial susceptibility to ischemia. Blood pressure, in vivo cardiac function, and ex vivo vascular function were not different among experimental groups; however, hypoxia-induced IUGR offspring had lower resting heart rates. Our results suggest that prenatal insults can enhance the susceptibility to a second hit such as myocardial ischemia, and that this phenomenon is exacerbated, in the early stages of life by nutritional stressors such as a HF diet. Supplementing HF diets with resveratrol improved cardiac tolerance to ischemia in offspring born IUGR but not in controls. Thus we conclude that the additive effect of prenatal (hypoxia-induced IUGR) and postnatal (HF diet) factors can lead to the earlier development of cardiovascular pathology in rats, and postnatal resveratrol supplementation prevented the deleterious cardiovascular effects of HF diet in offspring exposed to prenatal hypoxia.     

Age impairs Flk-1 signaling and NO-mediated vasodilation in coronary arterioles

Impairment of flow-induced vasodilation in coronary resistance arterioles may contribute to the decline in coronary vasodilatory reserve that occurs with advancing age. This study investigated the effects of age on flow-induced signaling and activation of nitric oxide (NO)-mediated vasodilation in coronary resistance arterioles. Coronary arterioles were isolated from young (approximately 6 mo) and old (approximately 24 mo) male Fischer-344 rats to assess vasodilation to flow, vascular endothelial growth factor (VEGF), and ACh. Flow- and VEGF-induced vasodilation of coronary arterioles was impaired with age (P相似文献   

Early postnatal chronic intermittent hypoxia modifies hypoxic respiratory responses and long-term phrenic facilitation in adult rats

Acute isocapnic intermittent hypoxia elicits time-dependent, serotonin-dependent enhancement of phrenic motor output in anesthetized rats (phrenic long-term facilitation, pLTF). In adult rats, pLTF is enhanced by chronic intermittent hypoxia (CIH). To test the hypothesis that early postnatal CIH induces persistent modifications of ventilation and pLTF, we exposed male Sprague-Dawley rat pups on their first day of life to a CIH profile consisting of alternating room air and 10% oxygen every 90 s for 30 days during daylight hours (RAIH) or to comparable exposures consisting of room air throughout (RARA). One month after cessation of CIH, respiratory responses were recorded using whole body plethysmography, and integrated phrenic nerve activity was recorded in urethane-anesthetized, vagotomized, paralyzed, and ventilated rats at baseline and after exposures to three 5-min hypoxic episodes [inspired O2 fraction (FiO2)=0.11] separated by 5 min of hyperoxia (FiO2=0.5). RAIH rats displayed greater normoxic ventilation and also increased burst frequency compared with RARA rats (P<0.01). Ventilatory responses to hypoxia and short-term phrenic responses during acute hypoxic challenges were reduced in RAIH rats (P<0.01). Although pLTF was present in both RAIH and RARA rats, it was diminished in RAIH rats (minute activity: 74+/-2% in RARA vs. 55+/-5% in RAIH at 60 min; P<0.01). Thus we conclude that early postnatal CIH modifies normoxic and hypoxic ventilatory and phrenic responses that persist at 1 mo after cessation of CIH (i.e., metaplasticity) and markedly differ from previously reported increased neural plasticity changes induced by CIH in adult rats.     

Exercise early in life in rats born small does not normalize reductions in skeletal muscle PGC-1α in adulthood

We have previously shown that 4 wk of exercise training early in life normalizes the otherwise greatly reduced pancreatic β-cell mass in adult male rats born small. The aim of the current study was to determine whether a similar normalization in adulthood of reduced skeletal muscle mitochondrial biogenesis markers and alterations in skeletal muscle lipids of growth-restricted male rats occurs following early exercise training. Bilateral uterine vessel ligation performed on day 18 of gestation resulted in Restricted offspring born small (P < 0.05) compared with both sham-operated Controls and a sham-operated Reduced litter group. Offspring remained sedentary or underwent treadmill running from 5-9 (early exercise) or 20-24 (later exercise) wk of age. At 24 wk of age, Restricted and Reduced litter offspring had lower (P < 0.05) skeletal muscle peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α) protein expression compared with Control offspring. Early exercise training had the expected effect of increasing skeletal muscle markers of mitochondrial biogenesis, but, at this early age (9 wk), there was no deficit in Restricted and Reduced litter skeletal muscle mitochondrial biogenesis. Unlike our previous observations in pancreatic β-cell mass, there was no "reprogramming" effect of early exercise on adult skeletal muscle such that PGC-1α was lower in adult Restricted and Reduced litter offspring irrespective of exercise training. Later exercise training increased mitochondrial biogenesis in all groups. In conclusion, although the response to exercise training remains intact, early exercise training in rats born small does not have a reprogramming effect to prevent deficits in skeletal muscle markers of mitochondrial biogenesis in adulthood.     

Effects of ET-A receptor blockade on eNOS gene expression in chronic hypoxic rat lungs

We tested the hypothesis that pulmonary endothelial nitric oxide synthase (eNOS) gene expression is primarily regulated by hemodynamic factors and is thus increased in rats with chronic hypoxic pulmonary hypertension. Furthermore, we examined the role of endothelin (ET)-1 in this regulatory process, since ET-1 is able to induce eNOS via activation of the ET-B receptor. Therefore, chronic hypoxic rats (10% O(2)) were treated with the selective ET-A receptor antagonist LU-135252 (50 mg x kg(-1) x day(-1)). Right ventricular systolic pressure and cross-sectional medial vascular wall area of pulmonary arteries rose significantly, and eNOS mRNA levels increased 1.8- and 2.6-fold after 2 and 4 wk of hypoxia, respectively (each P < 0.05). Pulmonary ET-1 mRNA and ET-1 plasma levels increased significantly after 4 wk of hypoxia (each P < 0.05). LU-135252 reduced right ventricular systolic pressure, vascular remodeling, and eNOS gene expression in chronic hypoxic rats (each P < 0.05), whereas ET-1 production was not altered. We conclude that eNOS expression in chronic hypoxic rat lungs is modified predominantly by hemodynamic factors, whereas the ET-B receptor-mediated pathway and hypoxia seem to be less important.     

Endothelin-1 and angiotensin II contribute to BNP but not c-fos gene expression response to elevated load in isolated mice hearts

The early events in the cardiac hypertrophic process induced by hemodynamic load include activation of B-type natriuretic peptide (BNP) and c-fos gene expression. However, it is unknown whether stretch acts directly or through local paracrine factors to trigger changes in cardiac gene expression. Herein we studied the involvement of endothelin-1 (ET-1) and angiotensin II (Ang II) in load-induced activation of left ventricular BNP and c-fos gene expression using an in vitro stretch model in isolated perfused adult mice hearts. Two-hour stretch induced by increasing coronary flow rate from 2 to 5 ml/min increased the expression of BNP and c-fos genes by 1.9- and 1.5-fold, respectively (P<0.001 and P<0.05). A mixed ET(A/B) receptor antagonist bosentan attenuated the BNP gene expression response to load by 58% (P<0.005). A similar 53% inhibition was observed with the selective ET(A) receptor blocker BQ-123 (P<0.05). Type 1 Ang II receptor antagonist CV-11974 decreased the activation of BNP gene expression by 50% (P<0.05). In contrast, the activation of c-fos gene expression was not inhibited by antagonists of ET(A/B) and AT(1) receptors. Our results show that ET-1 and Ang II play a key role in the induction of BNP, but not c-fos gene expression in response to load in intact adult murine hearts.     

Prenatal diet determines susceptibility to cardiac ischaemia-reperfusion injury following treatment with diethylmaleic acid and N-acetylcysteine

Fetal undernutrition programmes increased risk of developing cardiovascular disease in adult life. We hypothesized that prenatal protein restriction would impair recovery in post-ischaemic cardiac function in adult offspring through antioxidant-mediated processes. Pregnant Wistar rats were fed control or maternal low protein diets (MLP) throughout gestation. The offspring of these rats were treated with either saline, N-acetylcysteine (NAC), diethylmaleate (DEM), or both NAC and DEM to manipulate glutathione status at 6 months of age. Hearts were rapidly excised and retro-perfused (Langendorff) to assess isolated cardiac function before (baseline), and during 30 min global ischaemia and 60 min reperfusion. Hearts from adult rats exposed to a MLP diet in utero suffered greater cardiac dysfunction than those from controls following 30 min ischaemia. Left ventricular developed pressure (LVDP) was significantly reduced upon early reperfusion (p<0.042) in MLP rats compared to controls. NAC pre-treatment had no effect on LVDP of hearts from control animal hearts but improved the revival of MLP hearts to the same level as controls. DEM treatment did not affect control hearts but significantly reduced recovery of LVDP of MLP hearts during early (p<0.008) and late reperfusion (0.035). Combined NAC and DEM treatment had no effect on LVDP between control and MLP fed offspring. Prenatal protein restriction throughout pregnancy increases the susceptibility of the adult rat heart to suffer a functional deficit following ischaemia-reperfusion injury. Pharmacologically improving antioxidant status prevented this injury. A nutritionally-imbalanced developmental environment may increase susceptibility to coronary heart disease through the programming of myocardial glutathione metabolism.     

Quercetin intake during lactation modulates the AMP-activated protein kinase pathway in the livers of adult male rat offspring programmed by maternal protein restriction

Quercetin, a naturally occurring flavonoid, has been reported to possess numerous biological activities including activation of adenosine-5’-monophosphate-activated protein kinase (AMPK). We investigated the effects of quercetin intake during lactation on the AMPK activation in the livers of adult offspring programmed by maternal protein restriction during gestation. Pregnant Wistar rats were fed control and low-protein diets during gestation. Following delivery, each dam received a control or 0.2% quercetin-containing control diet during lactation as follows: control on control (CC), control on restricted (LPC) and 0.2% quercetin-containing control on restricted (LPQ). At weaning (week 3), some of the pups from each dam were killed, and the remaining pups (CC, n= 8; LPC, n= 10; LPQ, n= 13) continued to receive a standard laboratory diet and were killed at week 23. Blood chemistry and phosphorylation levels of AMPKα, acetyl-CoA carboxylase (ACC), endothelial nitric oxide synthase (eNOS) and mammalian target of rapamycin (mTOR) in the livers of male offspring were examined. At week 3, the level of phosphorylated AMPK protein in LPQ increased about 1.5- and 2.1-fold compared with LPC and CC, respectively, and the level in LPQ at week 23 increased about 1.9- and 2.9-fold, respectively. A significant increase in phosphorylated ACC and eNOS levels was found in LPQ. There was no significant difference among the three groups in the level of phosphorylated mTOR protein. In conclusion, quercetin intake during lactation up-regulates AMPK activation in the adult offspring of protein-restricted dams and modulates the AMPK pathway in the liver.