Rachael C. Crew

Maternal obesity induced by a ‘cafeteria’ diet in the rat does not increase inflammation in maternal, placental or fetal tissues in late gestation

INTRODUCTION Obesity during pregnancy can cause serious complications for maternal and infant health. While this has often been attributed to increased inflammation during obese pregnancy, human and animal studies exhibit variable results with respect to the inflammatory status of the mother, placenta and fetus. Cafeteria (CAF) feeding induces more inflammation than standard high-fat feeding in non-pregnant animal models. This study investigated whether maternal obesity induced by a CAF diet increases maternal, fetal or placental inflammation. METHODS Maternal obesity was established in rats by 8 weeks of pre-pregnancy CAF feeding. Maternal plasma inflammatory markers (IL-1β, IL-6, IL-10, IL-12p40, MCP1, GRO/KC, MIP-2 and TNFα) and expression of inflammatory genes (Tnfα, Il-6, Il-1β, Tlr2, Tlr4, Cox2 and Emr1) in maternal, placental and fetal tissues were measured at day 21 of gestation. RESULTS Despite CAF animals having 63% more central body fat than controls at day 21 of gestation, plasma inflammatory markers were not increased; indeed, levels of IL-6, IL-12p40 and MIP2 were reduced slightly. Similarly, inflammatory gene expression remained largely unaffected by CAF feeding, except for slight reductions to Tlr4 and Emr1 expression in CAF maternal adipose tissue, and reduced Tlr4 expression in male labyrinth zone (LZ). The junctional zone (JZ) displayed increased Il-6 expression in CAF animals when fetal sexes were combined, but no inflammatory genes were affected by the CAF diet in fetal liver. CONCLUSIONS Maternal obesity induced by a CAF diet before and during pregnancy does not increase the inflammatory status of the mother, placenta or fetus in late gestation.

Vitamin D deficiency and impaired placental function: potential regulation by glucocorticoids?

Maternal vitamin D deficiency has been implicated in a range of pregnancy complications including preeclampsia, preterm birth and intrauterine growth restriction. Some of these adverse outcomes arise from alterations in placental function. Indeed, vitamin D appears critical for implantation, inflammation, immune function and angiogenesis in the placenta. Despite these associations, absence of the placental vitamin D receptor in mice provokes little effect. Thus, interactions between maternal and fetal compartments are likely crucial for instigating adverse placental changes. Indeed, maternal vitamin D deficiency elicits changes in glucocorticoid-related parameters in pregnancy, which increase placental and fetal glucocorticoid exposure. As in utero glucocorticoid excess has a well-established role in eliciting placental dysfunction and fetal growth restriction, this review proposes that glucocorticoids are an important consideration when understanding the impact of vitamin D deficiency on placental function and fetal development.

Obesity Disrupts the Rhythmic Profiles of Maternal and Fetal Progesterone in Rat Pregnancy

ABSTRACT Maternal obesity increases the risk of abnormal fetal growth, but the underlying mechanisms remain unclear. Because steroid hormones regulate fetal growth, and both pregnancy and obesity markedly alter circadian biology, we hypothesized that maternal obesity disrupts the normal rhythmic profiles of steroid hormones in rat pregnancy. Obesity was established by cafeteria (CAF) feeding for 8 wk prior to mating and throughout pregnancy. Control (CON) animals had ad libitum access to chow. Daily profiles of plasma corticosterone, 11-dehydrocorticosterone, progesterone, and testosterone were measured at Days 15 and 21 of gestation (term = 23 days) in maternal (both days) and fetal (Day 21) plasma. CAF mothers exhibited increased adiposity relative to CON and showed fetal and placental growth restriction. There was no change, however, in total fetal or placental mass due to slightly larger litter sizes in CAF. Nocturnal declines in progesterone were observed in maternal (39% lower) and fetal (45% lower) plasma in CON animals, but these were absent in CAF animals. CAF mothers were hyperlipidemic at both days of gestation, but this effect was isolated to the dark period at Day 21. CAF maternal testosterone was slightly lower at Day 15 (8%) but increased above CON by Day 21 (16%). Despite elevated maternal testosterone, male fetal testosterone was suppressed by obesity on Day 21. Neither maternal nor fetal glucocorticoid profiles were affected by obesity. In conclusion, obesity disrupts rhythmic profiles of maternal and fetal progesterone, preventing the normal nocturnal decline. Obesity subtly changed testosterone profiles but did not alter maternal and fetal glucocorticoids.

Obesity-induced changes in hepatic and placental clock gene networks in rat pregnancy

Abstract Maternal obesity induces pregnancy complications and disturbs fetal development, but the specific mechanisms underlying these outcomes are unclear. Circadian rhythms are implicated in metabolic complications associated with obesity, and maternal metabolic adaptations to pregnancy. Accordingly, obesity-induced circadian dysfunction may drive adverse outcomes in obese pregnancy. This study investigated whether maternal obesity alters the rhythmic expression of clock genes and associated nuclear receptors across maternal, fetal, and placental tissues. Wistar rats were maintained on a cafeteria (CAF) diet prior to and throughout gestation to induce maternal obesity. Maternal and fetal liver and placental labyrinth zone (LZ) were collected at four-hourly time points across days 15–16 and 21–22 of gestation (term = 23 days). Gene expression was analyzed by RTqPCR. Expression of the accessory clock gene Nr1d1 was rhythmic in the maternal and fetal liver and LZ of chow-fed controls, but in each case CAF feeding reduced peak Nr1d1 expression. Obesity resulted in a phase advance (approx. 1.5 h) in the rhythms of several clock genes and Ppar-delta in maternal liver. Aside from Nr1d1, expression of clock genes was mostly arrhythmic in LZ and fetal liver, and was unaffected by the CAF diet. In conclusion, maternal obesity suppressed Nr1d1 expression across maternal, fetal, and placental compartments and phase-advanced the rhythms of maternal hepatic clock genes. Given the key role of Nr1d1 in regulating metabolic, vascular, and inflammatory processes, our data suggest that disruptions to rhythmic Nr1d1 expression in utero may contribute to programmed health complications in offspring of obese pregnancies. Summary Sentence Obesity suppresses Nr1d1 expression in maternal, fetal, and placental tissues and phase-advances the rhythms of maternal hepatic clock genes during rat pregnancy.

Maternal-placental-fetal biodistribution of multimodal polymeric nanoparticles in a pregnant rat model in mid and late gestation

Multimodal polymeric nanoparticles have many exciting diagnostic and therapeutic applications, yet their uptake and passage by the placenta, and applications in the treatment of pregnancy complications have not been thoroughly investigated. In this work, the maternal-fetal-placental biodistribution of anionic and cationic multimodal poly(glycidyl methacrylate) (PGMA) nanoparticles in pregnant rats at mid (ED10) and late (ED20) gestation was examined. Fluorescently-labelled and superparamagnetic PGMA nanoparticles functionalized with/without poly(ethyleneimine) (PEI) were administered to pregnant rats at a clinically-relevant dose and biodistribution and tissue uptake assessed. Quantitative measurement of fluorescence intensity or magnetic resonance relaxometry in tissue homogenates lacked the sensitivity to quantify tissue uptake. Confocal microscopy, however, identified uptake by maternal organs and the decidua (ectoplacental cone) and trophoblast giant cells of conceptuses at ED10. At ED20, preferential accumulation of cationic vs. anionic nanoparticles was observed in the placenta, with PGMA-PEI nanoparticles localised mainly within the chorionic plate. These findings highlight the significant impact of surface charge and gestational age in the biodistribution of nanoparticles in pregnancy, and demonstrate the importance of using highly sensitive measurement techniques to evaluate nanomaterial biodistribution and maternal-fetal exposure.

Rhythmic Three-Part Harmony: The Complex Interaction of Maternal, Placental and Fetal Circadian Systems

From the perspective of circadian biology, mammalian pregnancy presents an unusual biological scenario in which an entire circadian system (i.e., that of the fetus) is embodied within another (i.e., that of the mother). Moreover, both systems are likely to be influenced at their interface by a third player, the placenta. Successful pregnancy requires major adaptations in maternal physiology, many of which involve circadian changes that support the high metabolic demands of the growing fetus. A functional role for maternal circadian adaptations is implied by the effects of circadian disruption, which result in pregnancy complications including higher risks for miscarriage, preterm labor, and low birth weight. Various aspects of fetal physiology lead to circadian variation, at least in late gestation, but it remains unclear what drives this rhythmicity. It likely involves contributions from the maternal environment and possibly from the placenta and the developing intrinsic molecular clocks within fetal tissues. The role of the placenta is of particular significance because it serves not only to relay signals about the external environment (via the mother) but may also exhibit its own circadian rhythmicity. This review considers how the fetus may be influenced by dynamic circadian signals from the mother and the placenta during gestation, and how, in the face of these changing influences, a new fetal circadian system emerges. Particular emphasis is placed on the role of endocrine signals, most notably melatonin and glucocorticoids, as mediators of maternal-fetal circadian interactions, and on the expression of the clock gene in the 3 compartments. Further study is required to understand how the mother, placenta, and fetus interact across pregnancy to optimize circadian adaptations that support adequate growth and development of the fetus and its transition to postnatal life in a circadian environment.

Vitamin D is crucial for maternal care and offspring social behaviour in rats

Early life vitamin D plays a prominent role in neurodevelopment and subsequent brain function, including schizophrenic-like outcomes and increasing evidence for an association with autism spectrum disorder (ASD). Here, we investigate how early life vitamin D deficiency during rat pregnancy and lactation alters maternal care and influences neurodevelopment and affective, cognitive and social behaviours in male adult offspring. Sprague-Dawley rats were placed on either a vitamin D control (2195 IU/kg) or deficient diet (0 IU/kg) for five weeks before timed mating, and diet exposure was maintained until weaning of offspring on postnatal day (PND) 23. MRI scans were conducted to assess brain morphology, and plasma corticosterone levels and neural expression of genes associated with language, dopamine and glucocorticoid exposure were characterised at PND1, PND12 and 4 months of age. Compared to controls, vitamin D-deficient dams exhibited decreased licking and grooming of their pups but no differences in pup retrieval. Offspring neurodevelopmental markers were unaltered, but vitamin D-deficient pup ultrasonic vocalisations were atypical. As adults, males that had been exposed to vitamin D deficiency in early life exhibited decreased social behaviour, impaired learning and memory outcomes and increased grooming behaviour, but unaltered affective behaviours. Accompanying these behavioural changes was an increase in lateral ventricle volume, decreased cortical FOXP2 (a protein implicated in language and communication) and altered neural expression of genes involved in dopamine and glucocorticoid-related pathways. These data highlight that early life levels of vitamin D are an important consideration for maternal behavioural adaptations as well as offspring neuropsychiatry.

Obesity Disrupts Rhythmic Clock Gene Expression in Maternal Adipose Tissue during Rat Pregnancy

Obesity during pregnancy causes numerous maternal and fetal health complications, but the underlying mechanisms remain unclear. Adipose tissue dysfunction in obesity has previously been linked to disruption of the intrinsic adipose clock gene network that is crucial for normal metabolic function. This adipose clock also undergoes major change as part of the maternal metabolic adaptation to pregnancy, but whether this is affected by maternal obesity is unknown. Consequently, in this study we tested the hypothesis that obesity disturbs rhythmic gene expression in maternal adipose tissue across pregnancy. A rat model of maternal obesity was established by cafeteria (CAF) feeding, and adipose expression of clock genes and associated nuclear receptors (Ppars and Pgc1α) was measured across days 15-16 and 21-22 of gestation (term = 23 days). CAF feeding suppressed the mesor and/or amplitude of adipose tissue clock genes (most notably Bmal1, Per2, and Rev-erbα) relative to chow-fed controls (CON) across both days of gestation. On day 15, the CAF diet also induced adipose Pparα, Pparδ, and Pgc1α rhythmicity but repressed that of Pparγ, while expression of Pparα, Pparδ, and Pgc1α was reduced at select time points. CAF mothers were hyperleptinemic at both stages of gestation, and at day 21 this effect was time-of-day dependent. Fetal plasma leptin exhibited clear rhythmicity, albeit with low amplitude, but interestingly these levels were unaffected by CAF feeding. Our data show that maternal obesity disrupts rhythmic expression of clock and metabolic genes in maternal adipose tissue and leads to maternal but not fetal hyperleptinemia.

Diet-induced obesity reduces core body temperature across the estrous cycle and pregnancy in the rat

ABSTRACT Obesity during pregnancy causes adverse maternal and fetal health outcomes and programs offspring for adult-onset diseases, including cardiovascular disease. Obesity also disrupts core body temperature (Tc) regulation in nonpregnant rodents; however, it is unknown whether obesity alters normal maternal Tc adaptations to pregnancy. Since Tc is influenced by the circadian system, and both obesity and pregnancy alter circadian biology, it was hypothesized that obesity disrupts the normal rhythmic patterns of Tc before and during gestation. Obesity was induced by cafeteria (CAF) feeding in female Wistar rats for 8 weeks prior to and during gestation, whereas control (CON) animals had free access to chow. Intraperitoneal temperature loggers measured daily Tc profiles throughout the study, while maternal body composition and leptin levels were assessed near term. Daily temperature profiles were examined for rhythmic features (mesor, amplitude and acrophase) by cosine regression analysis. CAF animals exhibited increased fat mass (93%) and associated hyperleptinemia (3.2-fold increase) compared to CON animals. CAF consumption reduced the average Tc (by up to 0.29°C) across the estrous cycle and most of pregnancy; however, Tc for CAF and CON animals converged toward the end of gestation. Obesity reduced the amplitude of Tc rhythms at estrus and proestrus and on day 8 of pregnancy, but increased the amplitude at day 20 of pregnancy. Photoperiod analysis revealed that obesity reduced Tc exclusively in the light period during pre-pregnancy but only during the dark period in late gestation. In conclusion, obesity alters rhythmic Tc profiles and reduces the magnitude of the Tc decline late in rat gestation, which may have implications for maternal health and fetal development.