Adverse events in utero, such as intrauterine growth restriction (IUGR), can permanently alter epigenetic mechanisms leading to the metabolic syndrome, which encompasses a variety of symptoms including augmented cholesterol. The major site for cholesterol homeostasis occurs via the actions of hepatic cholesterol 7α-hydroxylase (Cyp7a1), which catabolizes cholesterol to bile acids. To determine whether posttranslational histone modifications influence the long-term expression of Cyp7a1 in IUGR, we used a protein restriction model in rats. This diet during pregnancy and lactation led to IUGR offspring with decreased liver to body weight ratios, followed by increased circulating and hepatic cholesterol levels in both sexes at d 21 and exclusively in the male offspring at d 130. The augmented cholesterol was associated with decreases in the expression of Cyp7a1. Chromatin immunoprecipitation revealed that this was concomitant with diminished acetylation and enhanced methylation of histone H3 lysine 9 [K9,14], markers of chromatin silencing, surrounding the promoter region of Cyp7a1. These epigenetic modifications originate in part due to dietary-induced decreases in fetal hepatic Jmjd2a expression, a histone H3 [K9] demethylase. Collectively, these findings suggest that the augmented cholesterol observed in low-protein diet-derived offspring is due to permanent repressive posttranslational histone modifications at the promoter of Cyp7a1. Moreover, this is the first study to demonstrate that maternal undernutrition leads to long-term cholesterol dysregulation in the offspring via epigenetic mechanisms.

1 in 5 women report cannabis use during pregnancy, with nausea cited as their primary motivation. Studies show that (-)-△9–tetrahydrocannabinol (Δ9-THC), the major psychoactive ingredient in cannabis, causes fetal growth restriction, though the mechanisms are not well understood. Given the critical role of the placenta to transfer oxygen and nutrients from mother, to the fetus, any compromise in the development of fetal-placental circulation significantly affects maternal-fetal exchange and thereby, fetal growth. The goal of this study was to examine, in rats, the impact of maternal Δ9-THC exposure on fetal development, neonatal outcomes, and placental development. Dams received a daily intraperitoneal injection (i.p.) of vehicle control or Δ9-THC (3 mg/kg) from embryonic (E)6.5 through 22. Dams were allowed to deliver normally to measure pregnancy and neonatal outcomes, with a subset sacrificed at E19.5 for placenta assessment via immunohistochemistry and qPCR. Gestational Δ9-THC exposure resulted in pups born with symmetrical fetal growth restriction, with catch up growth by post-natal day (PND)21. During pregnancy there were no changes to maternal food intake, maternal weight gain, litter size, or gestational length. E19.5 placentas from Δ9-THC-exposed pregnancies exhibited a phenotype characterized by increased labyrinth area, reduced Epcam expression (marker of labyrinth trophoblast progenitors), altered maternal blood space, decreased fetal capillary area and an increased recruitment of pericytes with greater collagen deposition, when compared to vehicle controls. Further, at E19.5 labyrinth trophoblast had reduced glucose transporter 1 (GLUT1) and glucocorticoid receptor (GR) expression in response to Δ9-THC exposure. In conclusion, maternal exposure to Δ9-THC effectively compromised fetal growth, which may be a result of the adversely affected labyrinth zone development. These findings implicate GLUT1 as a Δ9-THC target and provide a potential mechanism for the fetal growth restriction observed in women who use cannabis during pregnancy.

Recent reports indicate that 7% of pregnant mothers in North America use cannabis. This is concerning given that in utero exposure to Δ9-tetrahydrocannabinol (Δ9-THC), the main psychoactive component in cannabis, causes fetal growth restriction and may alter replication and survival of pancreatic β-cells in the offspring. Accordingly, we hypothesized that maternal exposure to Δ9-THC during pregnancy will impair postnatal glucometabolic health of offspring. To test this hypothesis, pregnant Wistar rats were treated with daily intraperitoneal injections of either 3 mg/kg Δ9-THC or vehicle from gestational day 6 to birth. Offspring were subsequently challenged with glucose and insulin at 5 months of age to assess glucose tolerance and peripheral muscle insulin sensitivity. Female offspring exposed to Δ9-THC in utero were glucose intolerant, associated with blunted insulin response in muscle and increased serum insulin concentration 15 minutes after glucose challenge. Additionally, pancreata from male and female offspring were harvested at postnatal day 21 and 5 months of age for assessment of endocrine pancreas morphometry by immunostaining. This analysis revealed that gestational exposure to Δ9-THC reduced the density of islets in female, but not male, offspring at postnatal day 21 and 5 months, culminating in reduced β-cell mass at 5 months. These results demonstrate that fetal exposure to Δ9-THC causes female-specific impairments in glucose homeostasis, raising concern regarding the metabolic health of offspring, particularly females, exposed to cannabis in utero.

Epidemiological studies demonstrate that the link between impaired fetal development and glucose intolerance in later life is exacerbated by postnatal catch-up growth. Maternal protein restriction (MPR) during pregnancy and lactation in the rat has been previously demonstrated to lead to impaired glucose tolerance in adulthood, however the effects of protein restoration during weaning on glucose homeostasis are largely unknown. Recentin vitrostudies have identified that the liver X receptor α (LXRα) maintains glucose homeostasis by inhibiting critical genes involved in gluconeogenesis includingG6pase(G6pc),11β-Hsd1(Hsd11b1) andPepck(Pck1). Therefore, we hypothesized that MPR with postnatal catch-up growth would impair LXRαin vivo, which in turn would lead to augmented gluconeogenic LXRα-target gene expression and glucose intolerance. To examine this hypothesis, pregnant Wistar rats were fed a control (20%) protein diet (C) or a low (8%) protein diet during pregnancy and switched to a control diet at birth (LP). At 4 months, the LP offspring had impaired glucose tolerance. In addition, LP offspring had decreased LXRα expression, while hepatic expression of 11β-HSD1 and G6Pase was significantly higher. This was concomitant with decreased binding of LXRα to the putative LXRE on11β-Hsd1andG6pase. Finally, we demonstrated that the acetylation of histone H3 (K9,14) surrounding the transcriptional start site of hepaticLxrα(Nr1h3) was decreased in LP offspring, suggesting MPR-induced epigenetic silencing of theLxrαpromoter. In summary, our study demonstrates for the first time the important role of LXRα in mediating enhanced hepatic gluconeogenic gene expression and consequent glucose intolerance in adult MPR offspring.

Background: Cannabis use in pregnancy leads to fetal growth restriction (FGR), but the long-term effects on cardiac function in the offspring are unknown, despite the fact that fetal growth deficits are associated with an increased risk of developing postnatal cardiovascular disease. We hypothesize that maternal exposure to Δ9-tetrahydrocannabinol (Δ9-THC) during pregnancy will impair fetal development, leading to cardiac dysfunction in the offspring. Methods: Pregnant Wistar rats were randomly selected and administered 3 mg/kg of Δ9-THC or saline as a vehicle daily via intraperitoneal injection from gestational days 6 to 22, followed by echocardiogram analysis of cardiac function on offspring at postnatal days 1 and 21. Heart tissue was harvested from the offspring at 3 weeks for molecular analysis of cardiac remodelling. Results: Exposure to Δ9-THC during pregnancy led to FGR with a significant decrease in heart-to-body weight ratios at birth. By 3 weeks, pups exhibited catch-up growth associated with significantly greater left ventricle anterior wall thickness with a decrease in cardiac output. Moreover, these Δ9-THC-exposed offsprings exhibited increased expression of collagen I and III, decreased matrix metallopeptidase-2 expression, and increased inactivation of glycogen synthase kinase-3β, all associated with cardiac remodelling. Conclusions: Collectively, these data suggest that Δ9-THC-exposed FGR offspring undergo postnatal catch-up growth concomitant with cardiac remodelling and impaired cardiac function early in life. Impact: To date, the long-term effects of perinatal Δ9-THC (the main psychoactive component) exposure on the cardiac function in the offspring remain unknown. We demonstrated, for the first time, that exposure to Δ9-THC alone during rat pregnancy results in significantly smaller hearts relative to body weight. These Δ9-THC-exposed offsprings exhibited postnatal catch-up growth concomitant with cardiac remodelling and impaired cardiac function. Given the increased popularity of cannabis use in pregnancy along with rising Δ9-THC concentrations, this study, for the first time, identifies the risk of perinatal Δ9-THC exposure on early postnatal cardiovascular health.