Breast milk apelin level increases with maternal obesity and high-fat feeding during lactation.

OBJECTIVE: Recent evidence indicates that levels of breast milk (BM) hormones such as leptin can fluctuate with maternal adiposity, suggesting that BM hormones may signal maternal metabolic and nutritional environments to offspring during postnatal development. The hormone apelin is highly abundant in BM but its regulation during lactation is completely unknown. Here, we evaluated whether maternal obesity and overnutrition impacted BM apelin and leptin levels in clinical cohorts and lactating rats. METHODS: BM and plasma samples were collected from normal-weight and obese breastfeeding women, and from lactating rats fed a control or a high fat (HF) diet during lactation. Apelin and leptin levels were assayed by ELISA. Mammary gland (MG) apelin expression and its cellular localization in lactating rats was measured by quantitative RT-PCR and immunofluorescence, respectively. RESULTS: BM apelin levels increased with maternal BMI, whereas plasma apelin levels decreased. BM apelin was also positively correlated with maternal insulin and C-peptide levels. In rats, maternal HF feeding exclusively during lactation was sufficient to increase BM apelin levels and decrease its plasma concentration without changing body weight. In contrast, BM leptin levels increased with maternal BMI in humans, but did not change with maternal HF feeding during lactation in rats. Apelin is highly expressed in the rat MG during lactation and was mainly localized to mammary myoepithelial cells. We found that MG apelin gene expression was up-regulated by maternal HF diet and positively correlated with BM apelin content and maternal insulinemia. CONCLUSIONS: Our study indicates that BM apelin levels increase with long- and short-term overnutrition, possibly via maternal hyperinsulinemia and transcriptional upregulation of MG apelin expression in myoepithelial cells. Apelin regulates many physiological processes, including energy metabolism, digestive function, and development. Further studies are needed to unravel the consequences of such changes in offspring development.

Maternal omega-3 PUFA supplementation prevents hyperoxia-induced pulmonary hypertension in the offspring.

Pulmonary hypertension (PH) and right ventricular hypertrophy (RVH) affect 16-25% of premature infants with bronchopulmonary dysplasia (BPD), contributing significantly to perinatal morbidity and mortality. Omega-3 polyunsaturated fatty acids (PUFA ω-3) can improve vascular remodeling, angiogenesis, and inflammation under pathophysiological conditions. However, the effects of PUFA ω-3 supplementation in BPD-associated PH are unknown. The present study aimed to evaluate the effects of PUFA ω-3 on pulmonary vascular remodeling, angiogenesis, and inflammatory response in a hyperoxia-induced rat model of PH. From embryonic day 15, pregnant Sprague-Dawley rats were supplemented daily with PUFA ω-3, PUFA ω-6, or normal saline (0.2 ml/day). After birth, pups were pooled, assigned as 12 per litter, randomly assigned to either air or continuous oxygen exposure (fraction of inspired oxygen = 85%) for 20 days, and then euthanized for pulmonary hemodynamic and morphometric analysis. We found that PUFA ω-3 supplementation improved survival, decreased right ventricular systolic pressure and RVH caused by hyperoxia, and significantly improved alveolarization, vascular remodeling, and vascular density. PUFA ω-3 supplementation produced a higher level of total ω-3 in lung tissue and breast milk and was found to reverse the reduced levels of VEGFA, VEGF receptor 2, angiopoietin-1 (ANGPT1), endothelial TEK tyrosine kinase, endothelial nitric oxide synthase, and nitric oxide concentrations in lung tissue and the increased ANGPT2 levels in hyperoxia-exposed rats. The beneficial effects of PUFA ω-3 in improving lung injuries were also associated with an inhibition of leukocyte infiltration and reduced expression of the proinflammatory cytokines IL-1ß, IL-6, and TNF-α. These data indicate that maternal PUFA ω-3 supplementation strategies could effectively protect against infant PH induced by hyperoxia.

Intact cord resuscitation in newborns with congenital diaphragmatic hernia: insights from a lamb model.

Introduction: Congenital diaphragmatic hernia (CDH) is a rare condition characterized by pulmonary hypoplasia, vascular dystrophy, and pulmonary hypertension at birth. Validation of the lamb model as an accurate representation of human CDH is essential to translating research findings into clinical practice and understanding disease mechanisms. This article emphasizes the importance of validating the lamb model to study CDH pathogenesis and develop innovative therapeutics. Material and methods: At 78 days of gestation, the fetal lamb's left forelimb was exposed through a midline laparotomy and hysterotomy, and a supra diaphragmatic thoracotomy was performed to allow the digestive organs to ascend into the thoracic cavity. At 138 ± 3 days of gestation, lambs were delivered via a cesarean section; then, with umbilical cord intact during 1 hour, the lambs were mechanically ventilated with gentle ventilation in a pressure-controlled mode for 2 h. Results: CDH lambs exhibited a lower left lung-to-body weight ratio of 5.3 (2.03), p < 0.05, and right lung-to-body weight ratio of 8.2 (3.1), p < 0.05. They reached lower Vt/kg (tidal volume per kg) during the course of the resuscitation period with 1.2 (0.7) ml/kg at 10 min and 3 (1.65) ml/kg at 60 min (p < 0.05). Compliance of the respiratory system was lower in CDH lambs with 0.5 (0.3) ml/cmH2O at 60 min (p < 0.05) and 0.9 (0.26) ml/cmH2O at 120 min (p < 0.05). Differences between pre- and postductal SpO2 were higher with 15.1% (21.4%) at 20 min and 6.7% (14.5%) at 80 min (p < 0.05). CDH lambs had lower differences between inspired and expired oxygen fractions with 4.55% (6.84%) at 20 min and 6.72% (8.57%) at 60 min (p < 0.05). CDH lamb had lower left ventricle [2.73 (0.5) g/kg, p < 0.05] and lower right ventricle [0.69 (0.8), p < 0.05] to left ventricle ratio. Discussion: CDH lambs had significantly lower tidal volume than control lambs due to lower compliance of the respiratory system and higher airway resistance. These respiratory changes are characteristic of CDH infants and are associated with higher mortality rates. CDH lambs also exhibited pulmonary hypertension, pulmonary hypoplasia, and left ventricle hypoplasia, consistent with observations in human newborns. To conclude, our lamb model successfully provides a reliable representation of CDH and can be used to study its pathophysiology and potential interventions.

Respiratory toxicity of buprenorphine results from the blockage of P-glycoprotein-mediated efflux of norbuprenorphine at the blood-brain barrier in mice.

OBJECTIVES: Deaths due to asphyxia as well as following acute poisoning with severe respiratory depression have been attributed to buprenorphine in opioid abusers. However, in human and animal studies, buprenorphine exhibited ceiling respiratory effects, whereas its metabolite, norbuprenorphine, was assessed as being a potent respiratory depressor in rodents. Recently, norbuprenorphine, in contrast to buprenorphine, was shown in vitro to be a substrate of human P-glycoprotein, a drug-transporter involved in all steps of pharmacokinetics including transport at the blood-brain barrier. Our objectives were to assess P-glycoprotein involvement in norbuprenorphine transport in vivo and study its role in the modulation of buprenorphine-related respiratory effects in mice. SETTING: University-affiliated research laboratory, INSERM U705, Paris, France. SUBJECTS: Wild-type and P-glycoprotein knockout female Friend virus B-type mice. INTERVENTIONS: Respiratory effects were studied using plethysmography and the P-glycoprotein role at the blood-brain barrier using in situ brain perfusion. MEASUREMENTS AND MAIN RESULTS: Norbuprenorphine(≥ 1 mg/kg) and to a lesser extent buprenorphine (≥ 10 mg/kg) were responsible for dose-dependent respiratory depression combining increased inspiratory (TI) and expiratory times (TE). PSC833, a powerful P-glycoprotein inhibitor, significantly enhanced buprenorphine-related effects on TI (p < .01) and TE (p < .05) and norbuprenorphine-related effects on minute volume (VE, p < .05), TI, and TE (p < .001). In P-glycoprotein-knockout mice, buprenorphine-related effects on VE (p < .01), TE (p < .001), and TI (p < .05) and norbuprenorphine-related effects on VE (p < .05) and TI (p < .001) were significantly enhanced. Plasma norbuprenorphine concentrations were significantly increased in PSC833-treated mice (p < .001), supporting a P-glycoprotein role in norbuprenorphine pharmacokinetics. Brain norbuprenorphine efflux was significantly reduced in PSC833-treated and P-glycoprotein-knockout mice (p < .001), supporting P-glycoprotein-mediated norbuprenorphine transport at the blood-brain barrier. CONCLUSIONS: P-glycoprotein plays a key-protective role in buprenorphine-related respiratory effects, by allowing norbuprenorphine efflux at the blood-brain barrier. Our findings suggest a major role for drug-drug interactions that lead to P-glycoprotein inhibition in buprenorphine-associated fatalities and respiratory depression.

Maternal obesity reduces apelin level in cord blood without altering the placental apelin/elabela-APJ system.

The APJ receptor and its two endogenous ligands, apelin and elabela, exert key roles in fetoplacental development. In adult, this system is altered by obesity but no data are available during pregnancy. We measured apelin and elabela levels in maternal plasma and cord blood and quantified placental gene expression of apelin, elabela and APJ in obese and non-obese mothers. We found that obesity reduced apelin level in cord blood without affecting maternal and cord blood elabela levels as well as placental gene expression of this system. Our data suggest that obesity alters fetal apelinemia in humans.

Long-Lasting Analgesia With Transdermal Fentanyl: A New Approach in Rat Neonatal Research.

Background: With advances in neonatal care, management of prolonged pain in newborns is a daily concern. In addition to ethical considerations, pain in early life would have long-term effects and consequences. However, its treatment remains inadequate. It was therefore important to develop an experimental model of long-lasting analgesia for neonatal research. Materials and Methods: Experiments were performed in six groups of rats with transdermal fentanyl 0, 3, 12, 50, 100, or 200 µg/kg/h from second postnatal day (P2) until weaning. Assessment of analgesia was carried out at P21, with behavioral scores (ranging from 0 to 3) using a 4% formalin test. Plasma levels of fentanyl were determined by UPLC/TQD at P22. Growth rate was investigated. Results: Fentanyl 100 and 200 µg/kg/h reduced scores of formalin-evoked behavioral pain. They increased time spent in pain score 0 (8 min 55 s and 6 min 34 s versus 23 s in controls) as in low pain scores 1 and 2, and decreased time in the most severe pain score 3 (19 min 56 s and 17 min 39 s versus 44 min 15 s). Fentanylemia increased in a dose-dependent manner from 50 µg/kg/h (2.36 ± 0.64 ng/ml) to 200 µg/kg/h (8.66 ± 1.80 ng/ml). Concerning growth, no difference was observed except weaker growth from P17 to P22 with 200 µg/kg/h. Clinically, we noticed no visible side effect from 3 to 100 µg/kg/h. Concomitantly, 200 µg/kg/h was responsible for ophthalmological side effects with appearance of corneal bilateral clouding in 90% pups. No difference was observed between male and female rats. Conclusion: Altogether, results indicate that transdermal fentanyl 100 µg/kg/h is an efficient therapeutic for long-lasting analgesia in lactating pups. This new model provides a useful tool for protection and welfare, and future opportunity for studying long-term health consequences of sustainable neonatal analgesia.

Changes in Umbilico-Placental Circulation during Prolonged Intact Cord Resuscitation in a Lamb Model.

Some previous studies reported a benefit to cardiopulmonary transition at birth when starting resuscitation maneuvers while the cord was still intact for a short period of time. However, the best timing for umbilical cord clamping in this condition is unknown. The aim of this study was to explore the duration of effective umbilico-placental circulation able to promote cardiorespiratory adaptation at birth during intact cord resuscitation. Umbilico-placental blood flow and vascular resistances were measured in an experimental neonatal lamb model. After a C-section delivery, the lambs were resuscitated ventilated for 1 h while the cord was intact. The maximum and mean umbilico-placental blood flow were respectively 230 ± 75 and 160 ± 12 mL·min-1 during the 1 h course of the experiment. However, umbilico-placental blood flow decreased and vascular resistance increased significantly 40 min after birth (p < 0.05). These results suggest that significant cardiorespiratory support can be provided by sustained placental circulation for at least 1 h during intact cord resuscitation.

Maternal obesity alters the apelinergic system at the feto-maternal interface.

Apelin and its receptor APJ have been implicated in pathologies including cardiovascular disease, diabetes and obesity. Little is known about the function of the apelinergic system during gestation. We evaluated in mice this system at the feto-maternal interface in insulin-resistant obese female (HF) mice. Maternal apelinemia was decreased at term and fetal apelinemia was sixfold higher than maternal level. Ex-vivo, the placenta releases apelin at E12.5 and E18.5. In HF pregnant mice at term, apelinemia as well as placental apelin and APJ mRNA levels were increased whereas placental release of apelin was drastically reduced compared to controls.

ABCG2- and ABCG4-mediated efflux of amyloid-ß peptide 1-40 at the mouse blood-brain barrier.

The accumulation of amyloid-ß peptide (Aß) in the brain is a critical hallmark of Alzheimer's disease. This high cerebral Aß concentration may be partly caused by impaired clearance of Aß across the blood-brain barrier (BBB). The low-density lipoprotein receptor-related protein-1 (LRP-1) and the ATP-binding cassette (ABC) protein ABCB1 (P-glycoprotein) are involved in the efflux of Aß across the BBB. We hypothesized that other ABC proteins, such as members of the G subfamily, are also involved in the BBB clearance of Aß. We therefore investigated the roles of ABCG2 (BCRP) and ABCG4 in the efflux of [3H] Aß1-40 from HEK293 cells stably transfected with human ABCG2 or mouse abcg4. We showed that ABCG2 and Abcg4 mediate the cellular efflux of [3H] Aß1-40. In addition, probucol fully inhibited the efflux of [3H] Aß1-40 from HEK293-abcg4 cells. Using the in situ brain perfusion technique, we showed that GF120918 (dual inhibitor of Abcb1 and Abcg2) strongly enhanced the uptake (Clup, µl/g/s) of [3H] Aß1-40 by the brains of Abcb1-deficient mice, but not by the brains of Abcb1/Abcg2-deficient mice, suggesting that Abcg2 is involved in the transport of Aß at the mouse BBB. Perfusing the brains of Abcb1/Abcg2- and Abca1-deficient mice with [3H] Aß1-40 plus probucol significantly increased the Clup of Aß. This suggests that a probucol-sensitive transporter that is different from Abca1, Abcb1, and Abcg2 is involved in the brain efflux of Aß. We suggest that this probucol-sensitive transporter is Abcg4. We conclude that Abcg4 acts in concert with Abcg2 to efflux Aß from the brain across the BBB.