Effect of electro-acupuncture at ST 36 on maternal food restriction-induced lung phenotype in rat offspring

Maternal food restriction (MFR) during pregnancy leads to pulmonary dysplasia in the newborn period and increases susceptibility to diseases, such as asthma and chronic lung disease, later in life. Previous studies have shown that maternal electro-acupuncture (EA) applied to "Zusanli" (ST 36) could prevent the abnormal expression of key lung developmental signaling pathways and improve the lung morphology and function in perinatal nicotine exposed offspring. There is a significant overlap in lung developmental signaling pathways affected by perinatal nicotine exposure and MFR during pregnancy; however, whether maternal EA at ST 36 also blocks the MFR-induced lung phenotype is unknown. Here, we examined the effects of EA applied to maternal ST 36 on lung morphology and function and the expression of key lung developmental signaling pathways, and the hypercorticoid state associated with MFR during pregnancy. These effects were compared with those of metyrapone, an intervention known to block MFR-induced offspring hypercorticoid state and the resultant pulmonary pathology. Like metyrapone, maternal EA at ST 36 blocked the MFR-induced changes in key developmental signaling pathways and protected the MFR-induced changes in lung morphology and function. These results offer a novel and safe, nonpharmacologic approach to prevent MFR-induced pulmonary dysplasia in offspring.

[Effect of electroacupuncture on lung dysplasia in rats with intrauterine growth restriction induced by maternal food restriction]

OBJECTIVE

To investigate the protective effect of electroacupuncture (EA) at "Zusanli" (ST 36) in pregnant rats on lung dysplasia of newborn rats with intrauterine growth restriction (IUGR) induced by maternal food restriction.

METHODS

Twenty-four female SD rats were randomly divided into a control group, a control+EA group, a model group and a model+EA group, 6 rats in each group. From the 10th day into pregnancy to the time of delivery, the rats in the model group and the model+EA group were given with 50% dietary restriction to prepare IUGR model. From the 10th day into pregnancy to the time of delivery, the rats in the control+EA group and the model+EA group were treated with EA at bilateral "Zusanli" (ST 36), once a day. The body weight of offspring rats was measured at birth, and the body weight and lung weight of offspring rats were measured on the 21st day after birth. The lung function was measured by small animal lung function detection system; the lung tissue morphology was observed by HE staining; the content of peroxisome proliferator activated receptor γ (PPARγ) in lung tissue was detected by ELISA.

RESULTS

Compared with the control group, the body weight at birth as well as the body weight, lung weight, lung dynamic compliance (Cdyn) and PPARγ at 21 days after birth in the model group were significantly decreased (P<0.01), and the peak inspiratory flow (PIF) and inspiratory resistance (RI) were significantly increased (P<0.01); the number of alveoli was significantly decreased, and the alveolar area and alveolar septal thickness were significantly increased, and some alveoli were ruptured and fused. Compared with the model group, the body weight at birth as well as the body weight, lung weight, Cdyn and PPARγ at 21 days after birth in the model+EA group were significantly increased (P<0.01, P<0.05), and the PIF and RI were significantly reduced (P<0.05); the number of alveoli was significantly increased, and the alveolar area and alveolar septal thickness were significantly reduced, and the rupture and fusion of alveolar was improved.

CONCLUSION

EA at "Zusanli" (ST 36) may protect the lung function and lung histomorphology changes by regulating the level of PPARγ of lung in IUGR rats induced by maternal food restriction.

Intergenerational response of steroidogenesis-related genes to maternal malnutrition

We sought to examine whether rat maternal food restriction (MFR) affects the expression of steroidogenesis-related genes Cyp19, Cyp17a1, Insl3 and Gdf-9 in the ovaries of offspring from the first (FRG1) and second (FRG2) generations at pre-pubertal age (week 4) and during adulthood (week 8). At week 4, MFR significantly increased the expression of RNAs for all analyzed genes in both FRG1 and FRG2 females, which may indicate that MFR affects the onset of the reproductive lifespan, by inducing early pubertal onset. At week 8, the Cyp19 gene was still upregulated in MRF-subjected animals (Cyp19: P=0.0049 and P=0.0508 in FRG1 and FRG2, respectively), but MFR induced a significant decrease in Cyp17 and Gdf-9 gene expression in the offspring of both FRG1 and FRG2 females when compared with the controls (Cyp17: P=0.0018 and P=0.0016, respectively; Gdf-9: P=0.0047 and P=0.0023, respectively). This suggests that females at week 8, which should normally be in their optimal reproductive capacity, experience premature ovarian aging. At week 4, the activation of Cyp19 and Cyp17 was higher in the FRG1 ovaries than in the FRG2 ovaries, whereas the extent of Insl3 and Gdf-9 activation was lower in the FRG1 ovaries. This may indicate that FRG2 females were more vulnerable to MFR than their mothers (FRG1) and grandmothers, which is consistent with the 'predictive adaptive response' hypothesis. Our findings reveal that MFR may induce intergenerational ovarian changes as an adaptive response to ensure reproductive success before death.

Maternal Food Restriction during Pregnancy and Lactation Adversely Affect Hepatic Growth and Lipid Metabolism in Three-Week-Old Rat Offspring

Maternal malnutrition influences the early development of foetal adaptive changes for survival. We explored the effects of maternal undernutrition during gestation and lactation on hepatic growth and function. Sprague-Dawley rats were fed a normal or a food-restricted (FR) diet during gestation and/or lactation. We performed analyses of covariance (adjusting for the liver weight/body weight ratio) to compare hepatic growth and lipid metabolism among the offspring. Maternal FR during gestation triggered the development of wide spaces between hepatic cells and increased the expression of mammalian target of rapamycin (mTOR) in three-week-old male offspring compared with controls (both p < 0.05). Offspring nursed by FR dams exhibited wider spaces between hepatic cells and a lower liver weight/body weight ratio than control offspring, and increased mTOR expression (p < 0.05). Interestingly, the significant decrease in expression of lipogenic-related genes was dependent on carbohydrate-responsive element-binding protein, despite the increased expression of sterol regulatory element-binding protein 1 (SREBP1) (p < 0.05). This study demonstrated increased expression of key metabolic regulators (mTOR and SREBP1), alterations in lipid metabolism, and deficits in hepatic growth in the offspring of FR-treated dams.

Metyrapone alleviates deleterious effects of maternal food restriction on lung development and growth of rat offspring

Maternal food restriction (MFR) causes intrauterine growth restriction, a known risk factor for developing chronic lung disease. However, it is unknown whether this negative outcome is gender specific or preventable by blocking the MFR-induced hyperglucocorticoidism. Using a well-established rat model, we used metyrapone (MTP), an inhibitor of glucocorticoid synthesis, to study the MFR-induced lung changes on postnatal day (p) 21 in a gender-specific manner. From embryonic day 10 until delivery, pregnant dams were fed either an ad libitum diet or a 50% caloric restricted diet with or without MTP supplementation. Postnatally, the offspring were fed ad libitum from healthy dams until p21. Morphometric, Western blot, and immunohistochemical analysis of the lungs demonstrated that MTP mitigated the MFR-mediated decrease in alveolar count, decrease in adipogenic protein peroxisome proliferator-activated receptor γ, increase in myogenic proteins (fibronectin, α-smooth muscle actin, and calponin), increase in Wnt signaling intermediates (lymphoid enhancer-binding factor 1 and β-catenin), and increase in glucocorticoid receptor (GR) levels. The MFR-induced lung phenotype and the effects of MTP were similar in both genders. To elucidate the mechanism of MFR-induced shift of the adipogenic-to-myogenic phenotype, lung fibroblasts were used to independently study the effects of (1) nutrient restriction and (2) excess steroid exposure. Nutrient deprivation increased myogenic proteins, Wnt signaling intermediates, and GR, all changes blocked by protein supplementation. MTP also blocked, likely by normalizing nicotinamide adenine dinucleotide phosphate levels, the corticosterone-induced increase in myogenic proteins, but had no effect on GR levels. In summary, protein restriction and increased glucocorticoid levels appear to be the key players in MFR-induced lung disease, affecting both genders.

Metyrapone blocks maternal food restriction-induced changes in female rat offspring lung development

Maternal food restriction (MFR) during pregnancy affects pulmonary surfactant production in the intrauterine growth-restricted (IUGR) offspring through unknown mechanisms. Since pulmonary surfactant production is regulated by maternal and fetal corticosteroid levels, both known to be increased in IUGR pregnancies, we hypothesized that metyrapone (MTP), a glucocorticoid synthesis inhibitor, would block the effects of MFR on surfactant production in the offspring. Three groups of pregnant rat dams were used (1) control dams fed ad libitum; (2) MFR (50% reduction in calories) from days 10 to 22 of gestation; and (3) MFR + MTP in drinking water (0.5 mg/mL), days 11 to 22 of gestation. At 5 months, the MFR offspring weighed significantly more, had reduced alveolar number, increased septal thickness, and decreased surfactant protein and phospholipid synthesis. These MFR-induced effects were normalized by the antiglucocorticoid MTP, suggesting that the stress of MFR causes hypercorticoidism, altering lung structure and function in adulthood.

Effects of maternal food restriction on offspring lung extracellular matrix deposition and long term pulmonary function in an experimental rat model

Intrauterine growth restriction (IUGR) increases the risk of respiratory compromise throughout postnatal life. However, the molecular mechanism(s) underlying the respiratory compromise in offspring following IUGR is not known. We hypothesized that IUGR following maternal food restriction (MFR) would affect extracellular matrix deposition in the lung, explaining the long-term impairment in pulmonary function in the IUGR offspring. Using a well-established rat model of MFR during gestation to produce IUGR pups, we found that at postnatal day 21, and at 9 months (9M) of age the expression and abundance of elastin and alpha smooth muscle actin (αSMA), two key extracellular matrix proteins, were increased in IUGR lungs when compared to controls (P < 0.05, n = 6), as determined by both Western and immunohistochemistry analyses. Compared to controls, the MFR group showed no significant change in pulmonary resistance at baseline, but did have significantly decreased pulmonary compliance at 9M (P < 0.05 vs. control, n = 5). In addition, MFR lungs exhibited increased responsiveness to methacholine challenge. Furthermore, exposing cultured fetal rat lung fibroblasts to serum deprivation increased the expression of elastin and elastin-related genes, which was blocked by serum albumin supplementation, suggesting protein deficiency as the predominant mechanism for increased pulmonary elastin deposition in IUGR lungs. We conclude that accompanying the changes in lung function, consistent with bronchial hyperresponsiveness, expression of the key alveolar extracellular matrix proteins elastin and αSMA increased in the IUGR lung, thus providing a potential explanation for the compromised lung function in IUGR offspring.

Effect of maternal food restriction on fetal rat lung lipid differentiation program

Although "fetal programming" has been extensively studied in many organs, there is only limited information on pulmonary effects in the offspring following intrauterine growth restriction (IUGR). We aimed to determine the effects of nutrient restriction on the lung structure and lung lipid differentiation programs in offspring using an animal mode of maternal food restriction (MFR). We utilized a rodent model of 50% MFR from day 10 of gestation to term and then using lung morphology, Western blotting, Real Time RT-PCR and Oil Red O staining, lung structure and development of the offspring were examined at postnatal days (p) 1, p21, and 9 months (9M). At postnatal day 1, MFR pups weighed significantly less compared to control pups, but at p21 and 9M, they weighed significantly more. However, lung weight, expressed as a percentage of body weight between the two groups was not different at all time-points examined. The MFR group had significantly decreased alveolar number and significantly increased septal thickness at p1 and 9M, indicating significantly altered lung structure in the MFR offspring. Furthermore, although at p1, compared to the control group, lung lipid accumulation was significantly decreased in the MFR group, at 9M, it was significantly increased. There were significant temporal changes in the parathyroid hormone-related protein/peroxisome proliferator-activated receptor gamma signaling pathway and surfactant synthesis. We conclude that MFR alters fetal lung lipid differentiation programming and lung morphometry by affecting specific epithelial-mesenchymal signaling pathways, offering the possibility for specific interventions to overcome these effects.

Mechanisms of impaired nephrogenesis with fetal growth restriction: altered renal transcription and growth factor expression

OBJECTIVE

Maternal food restriction during pregnancy results in growth-restricted newborns and reduced glomerular number, contributing to programmed offspring hypertension. We investigated whether reduced nephrogenesis may be programmed by dysregulation of factors controlling ureteric bud branching and mesenchyme to epithelial transformation.

STUDY DESIGN

At 10 to 20 days' gestation, Sprague Dawley pregnant rats (n = 6/group) received ad libitum food; food-restricted rats were 50% food restricted. At embryonic day 20, messenger ribonucleic acid (mRNA) and protein expression of Wilms' tumor 1 gene product (WT1), paired box transcription factor (Pax)-2, fibroblast growth factor (FGF)-2, glial cell line-derived neurotrophic factor (GDNF), cRET, wingless-type mouse mammary tumor virus integration site (WNT)4, WNT11, bone morphogenetic protein (BMP)-4, BMP7, and FGF7 were determined by real-time polymerase chain reaction and Western blotting.

RESULTS

Maternal food restriction resulted in up-regulated mRNA expression for WT1, FGF2, and BMP7, whereas Pax2, GDNF, FGF7, BMP4, WNT4, and WNT11 mRNAs were down-regulated. Protein expression was concordant for WT1, GDNF, Pax2, FGF7, BMP4, and WNT4.

CONCLUSION

Maternal food restriction altered gene expression of fetal renal transcription and growth factors and likely contributes to development of offspring hypertension.