Back ground Cigarette smoking/nicotine exposure during pregnancy is one of the major perinatal insults resulting in an increased risk of cardiovascular diseases in offspring. However, the fetal nicotine exposure‐induced programming of adult cardiovascular dysfunction remains largely elusive. The present study tested the hypothesis that perinatal nicotine exposure caused gender‐dependent increase in heart vulnerability to ischemia‐reperfusion injury and cardiac dysfunction in adult male rat offspring through up‐regulation of miRNA‐181a (miR‐181a)‐mediated signaling pathway. Methods Nicotine or saline was administered to pregnant rats via subcutaneous osmotic minipumps from gestational day 4 until postnatal day 10. The adult (~ 3 month old) offspring were treated with miR‐181a antisense (LNA‐miR‐181a) (10 mg/kg × 2 every 5 day, i.p.) or saline. After 10 days of treatment, the rats underwent the cardiac ischemia/reperfusion (I/R) procedure and echocardiography analysis, and the left ventricle (LV) tissues were isolated for molecular biological studies. Results Perinatal nicotine exposure enhanced I/R‐induced cardiac infraction and dysfunction in adult male but not in female offspring. The miR‐181a levels in LV tissues were significantly higher in the nicotine‐treated group than the saline control group. In addition, nicotine exposure decreased global DNA methylation levels but enhanced AT1 and AT2 receptor protein expression, and ROS production in LV tissues in the male offspring. Furthermore, the nicotine exposure up‐regulated autophagy‐related proteins (Atg‐5, beclin‐1, LC3 II) expressions as compared to controls in the male offspring. The most importance, treatment with LNA‐miR‐181a reversed nicotine‐mediated I/R‐induced cardiac infarction and dysfunction in male offspring, which was associated with an elimination of the nicotine’s effects on miR‐181a expression, DNA methylation, AT1R/AT2R protein, ROS, and autophagy‐related proteins expressions in the male offspring. Conclusion Our data demonstrated that perinatal nicotine exposure could cause a gender‐dependent fetal programing of adult heart ischemia‐sensitive phenotype. Our findings further suggest that miR‐181a plays a casual role in nicotine‐mediated up‐regulation of oxidative stress, renin‐angiotensin system (RAS) and autophagic flux, which may contribute to the development of ischemia‐sensitive phenotype in adult male rats. Support or Funding Information Supported in part by the NIH grants: R01HL135623, R03DA041492, and R01HD088039; TRDRP grants: 29IR0437 and T30FT0936
With the increase of satellite power, the current-carrying and heat dissipation of power cable is increasing significantly and the thermal safety problem becomes prominent. Therefore, the need for accurate modeling and fine design of power cable becomes increasingly urgent. In this paper, the thermal analysis modeling method for high-power cable bundle is proposed based on ground test data, and the heat transfer parameters at the installation and bundling points are obtained. At the same time, the thermal effect of cable bundling is quantitatively analyzed by simulating the splitting and binding power cable bundle. The result indicates that enhancing the radiation heat transfer between cables and the surrounding environment is the most effective means to improve the heat dissipation condition of cable bundles. The thermal model of high-power satellite power cable proposed in this paper can be used as an important basis for the prediction of on-orbit temperature and fine laying design of the power cable.
Maternal cigarette smoking is a major perinatal insult that contributes to an increased risk of cardiovascular and neurodevelopmental diseases in offspring. Our previous studies revealed that perinatal nicotine exposure reprograms a sensitive phenotype in neonatal hypoxic-ischemic encephalopathy (HIE), yet the underlying molecular mechanisms remain largely elusive. The present study tested the hypothesis that perinatal nicotine exposure impacts autophagy signaling in the developing brain, resulting in enhanced susceptibility to neonatal HIE. Nicotine was administered to pregnant rats via subcutaneous osmotic minipumps. Neonatal HIE was conducted in 9-day-old male rat pups. Protein kinase B/glycogen synthase kinase-3β/mammalian target of rapamycin (Akt/GSK-3β/mTOR) signaling and key autophagy markers were determined by Western blotting analysis. Rapamycin and MK2206 were administered via intracerebroventricular injection. Nicotine exposure significantly inhibited autophagy activities in neonatal brain tissues, characterized by an increased ratio of phosphoylated (p-) to total mTOR protein expression but reduced levels of autophagy-related 5, Beclin 1, and LC3βI/II. Treatment with mTOR inhibitor rapamycin effectively blocked nicotine-mediated autophagy deficiency and, more importantly, reversed the nicotine-induced increase in HI brain infarction. In addition, nicotine exposure significantly upregulated p-Akt and p-GSK-3β. Treatment with the Akt selective inhibitor MK2206 reversed the enhanced p-Akt and p-GSK-3β, restored basal autophagic flux, and abolished nicotine-mediated HI brain injury. These findings suggest that perinatal nicotine-mediated alteration of Akt/GSK-3β/mTOR signaling plays a key role in downregulation of autophagic flux, which contributes to the development of hypoxia/ischemia-sensitive phenotype in the neonatal brain.
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