INTRODUCTION:Placental villi include an outer syncytiotrophoblast (STB) layer and an inner layer of cytotrophoblasts (CTBs) that fuse to generate the STB layer in pregnancy. While activation of the locus containing the human (h) placental lactogen (hPL) genes (hPL-A/CSH1 and hPL-B/CSH2) begins in the CTBs, their expression in the STB requires epigenetic modifications and interactions between locus control region (LCR) and gene regulatory sequences. No factor that limits or facilitates hPL LCR/gene interactions for locus activation is reported. The paternally-expressed gene 3 (PEG3/PW1) transcription factor was pursued as a candidate. PEG3 is expressed by villous CTBs but not the STB and putative binding sites were identified in hPL-related sequences. METHODS:PEG3 expression was assessed in multiple cell types including in CTB-like JEG-3 cells. PEG3 binding was also assessed in JEG-3 cells and term placenta samples from women with or without maternal obesity, where chromosomal architecture of the hPL gene locus was also examined. RESULTS:In JEG-3 cells, PEG3 was found to bind to hypersensitive site (HS III-V) sequences within the LCR. Knockdown of PEG3 in these cells resulted in increased hPL gene expression. In term placenta, PEG3 binding at placenta-specific HS IV was increased with maternal obesity, where a decrease in hPL RNA levels is seen, while PEG3 binding was reduced in women with obesity who develop insulin-treated gestational diabetes mellitus (O/GDM + Ins), where increased hPL gene expression is observed. Chromatin conformation capture revealed distinct hPL gene domain interactions that are modified with maternal obesity but largely reversed in O/GDM + Ins, correlating with PEG3 binding. DISCUSSION:Decreased PEG3 binding may be required for hPL domain generation and expression during CTB to STB transition.

The human (h) growth hormone (GH)/placental lactogen (PL) gene family has served as an important model to study tissue-specific expression. The two GH genes (hGH-N/GH1 and GH-V/GH2) and three PL or chorionic somatomammotropin hormone (CSH) genes (hPL-L/CSL1, hPL-A/CSH1 and hPL-B/CSH2) are clustered together at a single locus. Although they share >90% sequence similarity, hGH-N is expressed by somatotrophs of the anterior pituitary while the remaining four hGH/PL genes are expressed by the villous syncytiotrophoblast of the placenta. Efficient pituitary expression depends on a locus control region (LCR) that includes nuclease hypersensitive sites I-V (HS I-V). For activation, data indicate that HS III facilitates the initial access of pituitary-specific transcription factor Pit-1 to the locus, where it is required to bind Pit-1 sites at HS I/II and the hGH-N promoter. This is associated with histone acetylation and tri-methylation modifications that are consistent with active chromatin. However, all five hGH/PL genes share similar nuclease sensitivity in human pituitary chromatin, suggesting similar levels of accessibility and thus potential for transcription. Furthermore, hPL-A and hPL-B promoters contain Pit-1 binding sites, and the hPL-A promoter, like hGH-N, will support expression in transfected pituitary tumor GC cells in culture. These observations suggest the possibility of a transcriptional repressor mechanism that prevents hPL gene expression in the pituitary. P sequences were identified as a candidate. They are located upstream of all four placental hGH/PL genes but not hGH-N, repress hPL-A promoter activity in transfected pituitary GC cells, and bind a forkhead box A1/nuclear factor-1 transcription, which is proposed to act as a repressor complex in human pituitary chromatin. In spite of this, the inability to limit hGH-N expression when tested in transgenic mice brought the role of P sequences in pituitary repression into question. These observations are re-examined here in light of new evidence that the LCR (HS III) interacts with P sequences in the human pituitary.

Growth hormone (GH) signaling is essential for heart development. Both GH deficiency and excess raise cardiovascular risk. Human (h) and mouse (m) GH differ structurally and functionally: hGH binds both the GH receptor (GHR) and prolactin receptor (PRLR), whereas mGH binds only GHR; thus, there is the potential for differential effects. We generated transgenic (hGH-TG) mice that produce pituitary hGH in response to hypothalamic signaling. These mice grow at the same rate as mGH-expressing wild-type (mGH-WT) mice but are smaller and have higher body fat. Echocardiography was used here to compare hGH-TG and mGH-WT mouse hearts. Male hGH-TG mice show a 48% lower left ventricular mass, 36% lower stroke volume, and 48% reduced cardiac output, resembling GH deficiency. Diastolic dysfunction, restrictive ventricular filling, and lower heart rate are suggested in hGH-TG mice. No significant differences in ejection fraction or fractional shortening were observed, even after high-fat diet (HFD) stress. HFD did not affect RNA markers of cardiac damage, although a possible association between B-type natriuretic peptide RNA levels and heart rate was detected. These observations suggest that diastolic dysfunction related to hGH and/or low GH might be offset by a lower heart rate, while structural changes precede functional effects.

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Maternal obesity is a serious health concern because it increases risks of neurological disorders, including anxiety and peripartum depression. In mice, a high fat diet (HFD) in pregnancy can negatively affect placental structure and function as well as maternal behavior reflected by impaired nest building and pup-retrieval. In humans, maternal obesity in pregnancy is associated with reduced placental lactogen (PL) gene expression, which has been linked to a higher risk of depression. PL acting predominantly through the prolactin receptor maintains energy homeostasis and is a marker of placenta villous trophoblast differentiation during pregnancy. Impaired neurogenesis and low serum levels of brain-derived neurotrophic factor (BDNF) have also been implicated in depression. Augmented neurogenesis in brain during pregnancy was reported in the subventricular zone (SVZ) of mice at gestation day 7 and linked to increased prolactin receptor signaling. Here, we used transgenic CD-1 mice that express human (h) PL during pregnancy to investigate whether the negative effects of diet on maternal behavior are mitigated in these (CD-1[hGH/PL]) mice. Specifically, we examined the effect of a HFD on nest building prepartum and pup retrieval postpartum, as well as on brain BDNF levels and neurogenesis. In contrast to wild-type CD-1[WT]mice, CD-1[hGH/PL] mice displayed significantly less anxiety-like behavior, and showed no impairment in prepartum nest building or postpartum pup-retrieval when fed a HFD. Furthermore, the HFD decreased prepartum and increased postpartum BDNF levels in CD-1[WT] but not CD-1[hGH/PL] mice. Finally, neurogenesis in the SVZ as well as phosphorylated mitogen-activated protein kinase, indicative of lactogenic signaling, appeared unaffected by pregnancy and diet at gestation day 7 in CD-1[hGH/PL] mice. These observations indicate that CD-1[hGH/PL] mice are resistant to the negative effects of HFD reported for CD-1[WT] mice, including effects on maternal behaviors and BDNF levels, and potentially, neurogenesis. This difference probably reflects a direct or indirect effect of the products of the hGH/PL transgene.

The objective was to assess the potential differential effects of human versus mouse growth hormone in vivo, given that human unlike mouse growth hormone can bind prolactin as well as the growth hormone receptor. To this end, a transgenic CD-1 mouse expressing human but not mouse growth hormone was generated, and the phenotypes of male mice fed with a regular chow or high-fat diet were assessed. Pancreas and epididymal white adipose tissue gene expression and/or related function were targeted as the pancreas responds to both prolactin and growth hormone receptor signaling, and catabolic effects like lipolytic activity are more directly attributable to growth hormone and growth hormone receptor signaling. The resulting human growth hormone-expressing mice are smaller than wild-type CD-1 mice, despite higher body fat and larger adipocytes, but both mouse types grow at the same rate with similar bone densities. Unlike wild-type mice, there was no significant delay in glucose clearance in human growth hormone-expressing mice when assessed at 8 versus 24 weeks on a high-fat diet. However, both mouse types showed signs of hepatic steatosis that correlated with elevated prolactin but not growth hormone RNA levels. The larger adipocytes in human growth hormone-expressing mice were associated with modified leptin (higher) and adiponectin (lower) RNA levels. Thus, while limited to observations in the male, the human growth hormone-expressing mice exhibit signs of growth hormone insufficiency and adipocyte dysfunction as well as an initial resistance to the negative effects of high-fat diet on glucose clearance.

Searchable abstracts of presentations at key conferences in endocrinology ISSN 1470-3947 (print) | ISSN 1479-6848 (online)

In order to maintain maternal behavior, it is important that the maternal rodent brain promotes neurogenesis. Maternal neurogenesis is altered by the dynamic shifts in reproductive hormone levels during pregnancy. Thus, lifestyle events such as gestational stress and obesity that can affect hormone production will affect neuroendocrine control of maternal neurogenesis. However, there is a lack of information about the regulation of maternal neurogenesis by placental hormones, which are key components of the reproductive hormonal profile during pregnancy. There is also little known about how maternal neurogenesis can be affected by health concerns such as gestational stress and obesity, and its relationship to peripartum mental health disorders. This review summarizes the changing levels of neurogenesis in mice and rats during gestation and postpartum as well as regulation of neurogenesis by pregnancy-related hormones. The influence of neurogenesis on maternal behavior is also discussed while bringing attention to the effect of health-related concerns during gestation, such as stress and obesity on neuroendocrine control of maternal neurogenesis. In doing so, this review identifies the gaps in the literature and specifically emphasizes the importance of further research on maternal brain physiology to address them.

Fibroblast growth factor 2 (FGF2), produced as high (Hi-) and low (Lo-) molecular weight isoforms, is implicated in cardiac response to injury. The role of endogenous FGF2 isoforms during chronic stress is not well defined. We investigated the effects of endogenous Hi-FGF2 in a mouse model of simulated pressure-overload stress achieved by transverse aortic constriction (TAC) surgery. Hi-FGF2 knockout mice, expressing only Lo-FGF2, FGF2(Lo), and wild-type mice, FGF2(WT), expressing both Hi-FGF2 and Lo-FGF2, were used. By echocardiography, a decline in systolic function was observed in FGF2(WT) but not FGF2(Lo) mice compared to corresponding sham-operated animals at 4–8 weeks post-TAC surgery. TAC surgery increased markers of myocardial stress/damage including B-type natriuretic peptide (BNP) and the pro-cell death protein BCL2/adenovirus E1B 19 kDa protein-interacting protein-3 (Bnip3) in FGF2(WT) but not FGF2(Lo) mice. In FGF2(Lo) mice, cardiac levels of activated FGF receptor 1 (FGFR1), and downstream signals, including phosphorylated mTOR and p70S6 kinase, were elevated post-TAC. Finally, NR1D1 (nuclear receptor subfamily 1 group D member 1), implicated in cardioprotection from pressure-overload stress, was downregulated or upregulated in the presence or absence, respectively, of Hi-FGF2 expression, post-TAC surgery. In wild-type cardiomyocyte cultures, endothelin-1 (added to simulate pressure-overload signals) caused NR1D1 downregulation and BNP upregulation, similar to the effect of TAC surgery on the FGF2(WT) mice. The NR1D1 agonist SR9009 prevented BNP upregulation, simulating post-TAC findings in FGF2(Lo) mice. We propose that elimination of Hi-FGF2 is cardioprotective during pressure-overload by increasing FGFR1-associated signaling and NR1D1 expression.

Obesity in puberty, already a time of insulin resistance, increases the risk of developing type 2 diabetes. Human (h) growth hormone (GH) levels also peak during puberty, where it contributes to growth and energy homeostasis through positive effects on maintaining pancreatic β cell mass. Thus, it is important to understand the effects of overeating and obesity on hGH production in puberty. Three days of overeating in young male adults or high-fat diet (HFD) in pubescent male transgenic (171hGH/CS) CD-1 mice containing the hGH gene (hGH-N) results in excess insulin and a decrease in hGH production. This reduction in these mice occurred during the light phase of the daily cycle, and was associated with decreased availability of the clock-related transcription factor Brain and Muscle ARNT-Like 1 (Bmal1). However, the HFD-induced decrease in hGH-N expression was blocked by forced daily swim activity, which is expected to increase glucocorticoid (GC) levels. The aim of the study was to assess whether GCs, specifically daily injections with a pharmacological dose of dexamethasone (DEX) in the light or dark phase of the daily cycle, can limit the negative effect of HFD for 3 days on hGH-N expression in male 171hGH/CS mice. DEX treatment increased or rescued hGH-N RNA levels, and was associated with elevated Bmal1 transcripts when assessed 12 h after final treatment, and at a time when serum corticosterone levels were suppressed >90%. In addition, a diet-dependent effect on hGH-N RNA levels was observed at 36 h after final treatment, but only in the light stage, presumably due to residual effects of DEX treatment and/or recovery of endogenous corticosterone levels. This is the first evidence for a direct effect of GCs on hGH-N expression in vivo and the ability to potentially limit the negative effect of overeating/obesity on hGH production in puberty.

Background Studies have found an association between obesity and an increased risk for peripartum depression, which has also been linked to decreased placental lactogen levels. In addition, women with obesity treated for gestational diabetes with insulin were found to have increased levels of placental lactogen. Treatment options exist for perinatal and postpartum depression however they pose a risk to the developing offspring. Thus, prevention as well as markers for early identification of peripartum depression are needed. Therefore, our study objective is to identify the association between insulin treatment in pregnancy and the risk of postpartum psychological distress (abbreviated here as PPD) among cohorts of women with and without obesity. Methods Administrative health data (2002/03–2018/19) were used to identify a cohort of women (age 15+ years) who gave birth (N = 250,746) and had no pre-existing mood/anxiety disorders or diabetes (N = 222,863 excluded). Women were then divided into two groups: lean (N = 17,975) and with obesity (N = 9908), which was identified by a recorded maternal weight of > 38 to < 65.6 kg and ≥ 85 to < 186 kg (respectively). The risk of PPD within one year after delivery with and without insulin treatment was assessed by Poisson regression analysis. Models were adjusted for maternal age group (at pregnancy start date) and area-level income (at delivery). Results The unadjusted risk of PPD was higher in the obesity group (8.56%; 95% CI 8.00–9.15) than in the lean group (6.93%; 95% CI 6.56–7.33). When no insulin treatment was given during pregnancy, mothers with obesity had a significantly higher risk of PPD than the lean group (aRR 1.27; 95% CI 1.17–1.39; p < 0.0001). However, when women with obesity and insulin treatment were compared to the lean group with no insulin treatment, no significant difference in the risk of PPD was observed between the groups (aRR 1.30; 95% CI 0.83–2.02; p = 0.248). Conclusion This is the first study to demonstrate a positive association between insulin treatment in pregnancy among women with obesity and reduced PPD rates, suggesting insulin as a possible preventative measure. However, the biological mechanism behind the observed positive effect of insulin on PPD rates remains to be investigated.

Obesity before and during pregnancy negatively affects the mental and physical health of the mother. A diet high in fat also increases the risk for anxiety, depression and cognitive dysfunction. We examined the effects of high fat diet (HFD)-induced obesity and pregnancy on maternal behavior, cognitive function and anxiety-and depression-like behaviors in mice. Four-week-old female CD-1 mice were placed on a HFD or regular chow diet (RCD) for 5 weeks. Mice were maintained on either diet as non-pregnant HFD and RCD groups, or allowed to breed, and then fed these diets throughout gestation, lactation and after weaning, as pregnant HFD and RCD groups. Mice on HFD but not on RCD for 5 weeks pre-pregnancy significantly gained weight and had impaired glucose clearance. Maternal behavior was assessed by nest building prepartum and pup-retrieval postpartum. Anxiety-like behavior was evaluated both prepartum and postpartum by elevated plus maze and cognitive function was assessed by the novel object recognition test postpartum. Anhedonia, a measure of impaired reward function, is an endophenotype of depression and was assessed by sucrose preference test pre-and post-weaning in dams. Mice on HFD in pregnancy exhibited both impaired maternal behavior and cognitive function in the postpartum period. We did not detect measurable differences between the HFD and RCD groups in anxiety-like behavior in the prepartum period. In contrast, HFD was also associated with anhedonia in pregnant mice pre weaning, and anxiety-like behavior post-weaning. Thus, HFD has a negative effect on maternal behavior in the outbred CD-1 mouse, which provides a model to study associated outcomes and related mechanisms.

BackgroundAbout a third of pregnant women of age 20–39 are obese, which carries significant risks for the mother and fetus, and adversely impacts pregnancy outcome. Specifically, women with obesity are at increased risk for peripartum depression. Maternal behaviour in mice is influenced by changes in hormone signaling in pregnancy, which is associated with effects on adult neurogenesis in the brain. Thus, we used mouse as a model system to gain further insight into the possible relationship between overeating/obesity and brain physiology and maternal behaviour.ObjectiveTo assess the ability of a high‐fat diet (HFD) versus a regular chow diet (CD), starting up to 10 weeks pre‐pregnancy, to modify glucose clearance before and during pregnancy and affect maternal behaviour in the CD1 mouse.ApproachTwo groups of 3–4 week‐old female CD1 mice were fed a HFD (fat=60 kcal%; carbohydrate=20 kcal%; protein=20 kcal%) or CD (fat=14 kcal%; carbohydrate=60 kcal%; protein=26 kcal%) and maintained on their respective diets throughout the study and weighed periodically. After at least 4 weeks of feeding on their diets, mice were allowed to breed. Glucose tolerance was tested using 2 g/kg of i.p. glucose at gestational day (GD) ‐1) after fasting (16 hours‐overnight) as well as during pregnancy at GD16.5. An even number of pregnant and non‐pregnant females were selected for each diet for maternal behaviour testing. Tests include an assessment of nest building at GD16.5–17 (use of nesting material and nest quality), and after birth pup retrieval at postpartum day (PD) 3, 4 and 5 (time of retrieval of each of the four pups within six minutes) using video capture.ResultsThe HFD led to a significant increase in weight relative to mice fed a CD. HFD impaired glucose‐load clearances at GD ‐1 and 16.5 (p<0.05) compared to mice fed a CD. Mice fed on HFD performed poorly in the nest building task (p<0.01) as well as demonstrated a reduced completion rate on the pup retrieval test on PD3 (CD=8/10 vs. HFD 2/9 mice) but their retrieval response latency was improved by PD4 (CD=8/10 vs. HFD 8/9 mice) and PD5 (CD=7/10 vs. HFD 7/9 mice).ConclusionsInitial observations suggest that a HFD for at least 4 weeks before and during pregnancy results in overweight CD1 mice with impaired glucose clearance, and a negative effect on maternal behaviour as assessed by nest‐building during pregnancy and pup retrieval postpartum; however, with regard to the latter, mice on the HFD show the ability to learn. Additional behavioural tests for locomotion, anxiety, risk avoidance and object recognition memory during or after pregnancy, as well as associated changes in hormonal signaling and adult neurogenesis are also currently under investigation.

Abstract Background: About a third of pregnant women of age 20-39 are obese, which carries significant risks for the mother and fetus, and adversely impacts pregnancy outcome. Specifically, women with obesity are at increased risk for peripartum depression. Maternal behaviour in mice is influenced by changes in hormone signaling in pregnancy, which is associated with effects on adult neurogenesis in the brain. Thus, we used mouse as a model system to gain further insight into the possible relationship between overeating/obesity and brain physiology and maternal behaviour. Objective: To assess the ability of a high-fat diet (HFD) versus a regular chow diet (CD), starting up to 10 weeks pre-pregnancy, to modify glucose clearance before and during pregnancy and affect maternal behaviour in the CD1 mouse. Study Design: Two groups of 3-4 week-old female CD1 mice were fed a HFD (fat=60 kcal%; carbohydrate=20 kcal%; protein=20 kcal%) or CD (fat=14 kcal%; carbohydrate=60 kcal%; protein=26 kcal%) and maintained on their respective diets throughout the study and weighed periodically. After at least 4 weeks of feeding on their diets, mice were allowed to breed. Glucose tolerance was tested using 2 g/kg of i.p. glucose at gestational day (GD) -1) after fasting (16 hours-overnight) as well as during pregnancy at GD16.5. An even number of pregnant and non-pregnant females were selected for each diet for maternal behaviour testing. Tests include an assessment of nest building at GD16.5-17 (use of nesting material and nest quality), and after birth pup retrieval at postpartum day (PD) 3, 4 and 5 (time of retrieval of each of the four pups within six minutes) using video capture. Results: The HFD led to a significant increase in weight relative to mice fed a CD. HFD impaired glucose-load clearances at GD -1 and 16.5 (p<0.05) compared to mice fed a CD. Mice fed on HFD performed poorly in the nest building task (p<0.01) as well as demonstrated a reduced completion rate on the pup retrieval test on PD3 (CD=8/10 vs. HFD 2/9 mice) but their retrieval response latency was improved by PD4 (CD=8/10 vs. HFD 8/9 mice) and PD5 (CD=7/10 vs. HFD 7/9 mice). Conclusions: Initial observations suggest that a HFD for at least 4 weeks before and during pregnancy results in overweight CD1 mice with impaired glucose clearance, and a negative effect on maternal behaviour as assessed by nest-building during pregnancy and pup retrieval postpartum; however, with regard to the latter, mice on the HFD show the ability to learn. Additional behavioural tests for locomotion, anxiety, risk avoidance and object recognition memory during or after pregnancy, as well as associated changes in hormonal signaling and adult neurogenesis are also currently under investigation.

Fibroblast growth factor 2 (FGF2) is produced as high (>20 kDa, Hi‐) and low molecular weight (18 kDa, Lo) isoforms in the heart. While administered Lo‐FGF2 has been established as a cardioprotective agent in multiple models of cardiac injury, there is limited information about the role of Hi‐FGF2 in the heart. To investigate the effect of endogenous Hi‐FGF2 we compared cardiac transcriptome (35240 targets, GeneChip™ Mouse Gene 2.0 ST Array (Affymetrix, 902119)) and systolic function between Hi‐FGF2 knock‐out mice, FGF2(Lo), expressing only Lo‐FGF2, and wild type mice, FGF2(WT), expressing both Hi‐FGF2 and Lo‐FGF2, under ‘normal’ (sham‐operated) and “stress” (pressure overload) conditions. Transaortic constriction surgery (TAC) was used to induce pressure overload. Echocardiography was done at baseline and at 4–8 weeks post‐surgery. Microarray analysis showed that under normal conditions, the absence of Hi‐FGF2 promoted changes in relative levels of 118 transcripts, including those associated with circadian rhythm regulation and heat shock protein (HSP70)‐associated apoptosis regulation. Comparative analysis of TAC surgery‐induced gene expression changes showed that 275 transcripts were differentially affected by the presence or absence of Hi‐FGF2 expression, most prominently the orphan nuclear receptor NR1D1 which is linked to regulation of circadian rhythm and metabolism. Under non‐stress conditions, systolic function was unaffected by endogenous Hi‐FGF2 expression. Pressure overload stress caused a decline in systolic function in the presence of endogenous Hi‐FGF2, at 4–8 weeks post‐TAC surgery, accompanied by increases in markers of myocardial stress/damage including B‐type natriuretic peptide (BNP) and the pro‐cell death protein BCL2/adenovirus E1B 19 kDa protein‐interacting protein‐3, Bnip3. In the absence of endogenous Hi‐FGF2, mice were protected from stress‐induced loss of systolic function and increases in BNP and Bnip3. TAC surgery induced Hi‐FGF2‐independent increases in: cardiac mass (heart weight/tibia length); cardiac fibrosis; transcripts linked to exracellular matrix remodeling. Increased cardiomyocyte size, however, was only observed in FGF2(WT) but not FGF2(Lo) hearts post‐TAC. It is suggested that elimination of endogenous Hi‐FGF2 elicits cardioprotection by increasing cardiac HSP70 (pre‐TAC surgery); and NR1D1, after TAC surgery.Support or Funding InformationFunding (EK, PAC, DJ) was provided by the Canadian Institutes for Health Research (FRN‐74733) and the Molson Women’s Heart Health Foundation (EK). MPC was supported by a CIHR Open Operating Grant (MOP136862). NK and RSN were the recipients of a Bank of Montreal studentship award via the St. Boniface Hospital Albrechtsen Research Centre and University of Manitoba funding to PAC.

The four genes coding for placental members of the human (h) growth hormone (GH) family include two that code independently for placental lactogen (PL), also known as chorionic somatomammotrophin hormone, one that codes for placental growth hormone (PGH) and a pseudogene for which RNA but no protein product is reported. These genes are expressed preferentially in the villus syncytiotrophoblast of the placenta in pregnancy. In higher primates, the placental members, including hPL and PGH, are the result of multiple duplication events of the GH gene. This contrasts with rodents and ruminants, where PLs result from duplication of the prolactin (PRL) gene. Thus, unlike their mouse counterparts, the hPL and PGH hormones bind both lactogenic and somatogenic receptors with varying affinity. Roles influenced by nutrient availability in both metabolic control in pregnancy and maternal behaviour are supported. However, the effect maternal obesity has on the activation of placental members of the hGH gene family, particularly the expression and function of those genes, is poorly understood. Evidence from partially humanised hGH/PL transgenic mice indicates that both the remote upstream hPL locus control region (LCR) and more gene‐related regulatory regions are required for placental expression in vivo. Furthermore, a specific pattern of interactions between the LCR and hPL gene promoter regions is detected in term placenta chromatin from women with a normal body mass index (BMI) in the range 18.5–25 kg m‐2 by chromosome conformation capture assay. This pattern is disrupted with maternal obesity (class II BMI > 35 kg m‐2) and associated with a > 40% decrease in term hPL RNA levels, as well as serum hPL but not PRL levels, during pregnancy. The relative importance of the chromosomal architecture and predicted properties for transcription factor participation in terms of hPL production and response to obesity are considered, based on comparison with components required for efficient human pituitary GH gene expression.

Abstract BACKGROUND: Pregnant women with obesity are at increased risk for peripartum depression. Maternal obesity is also associated with reduced human placental lactogen (hPL) levels, and decreased hPL transcripts were reported in women with clinical depression. In addition, hPL production may be rescued in women with obesity that were subsequently diagnosed with gestational diabetes and treated with insulin (INS). Objective: Study the effect of INS treatment in pregnancy on the risk for postpartum psychological distress (PPD) in women with and without obesity. Study Design: Using data housed at the Manitoba Centre for Health Policy (2002–2017), cohorts of women (ages 15+) with a single live birth with and without obesity were developed using weight (≥85 and <65.6 kg, respectively) and an average (1.63 m) height. Pre-existing mood and anxiety disorders within 5 years preceding delivery as well as gestational hypertension were excluded. After randomly selecting 1 birth per mother, cohorts were stratified by INS treatment during the gestational period. The risk of PPD within 1 year of delivery was assessed by Poisson regression analysis. Models were adjusted for maternal age and area-level income at delivery. Results: The risk of PPD was 27% greater among women with obesity versus without (adjusted rate ratio (aRR)=1.27, 95% CI 1.16–1.4, p<0.0001). However, women with obesity treated with INS did not have a significantly different risk of PPD compared to women without obesity whether treated with INS (aRR=0.99, 95%CI 0.48–2.02, p=0.974) or not (aRR=1.16, 95%CI 0.86–1.56, p=0.328). This suggests that the risk of PPD among women with obesity may be reduced by INS treatment; however, our ability to detect a significant difference may be limited by small cohort numbers (46 women with obesity received INS in pregnancy) or confounders for receiving INS in pregnancy. Direct comparison of INS treatment within weight groups faced the same limitations but trended toward a reduction in women with obesity who received INS (aRR=0.91, 95%CI 0.68–1.22, p=0.531). The positive association between INS treatment in pregnancy and decreased risk of PPD in women with obesity was lost when pre-existing mood and anxiety disorder was not excluded. Inclusion of pre-existing diabetes in the adjusted models did not improve model fit or contribute significantly to the differences in PPD rates. Conclusions: Maternal obesity increases the risk for PPD but this risk may be reduced by gestational INS treatment in the absence of a pre-existing mood and anxiety disorders. This correlates with the decrease and increase in hPL levels reported previously with maternal obesity without and with INS treatment (for diabetes) in pregnancy, respectively. Thus, hPL levels may serve as a possible indicator of PPD risk and a potential target for gestational INS treatment.

Human (h) growth hormone (GH) production studies are largely limited to effects on secretion. How pituitary hGH gene (hGH-N/GH1) expression is regulated is important in our understanding of the role hGH plays in physiology and disease. Here we assess for the first time the effect of sleep deprivation (SD) and high-fat diet (HFD) on hGH-N expression in vivo using partially humanized 171hGH/CS transgenic (TG) mice, and attempted to elucidate a role for DNA methylation. Activation of hGH-N expression requires interactions between promoter and upstream locus control region (LCR) sequences including pituitary-specific hypersensitive site (HS) I/II. Both SD and diet affect hGH secretion, but the effect of SD on hGH-N expression is unknown. Mice fed a HFD or regular chow diet for 3 days underwent SD (or no SD) for 6 h at Zeitgeber time (ZT) 3. Serum and pituitaries were assessed over 24 h at 6-h intervals beginning at ZT 14. SD and HFD caused significant changes in serum corticosterone and insulin, as well as hGH and circadian clock-related gene RNA levels. No clear association between DNA methylation and the negative effects of SD or diet on hGH RNA levels was observed. However, a correlation with increased methylation at a CpG (cytosine paired with a guanine) in a putative E-box within the hGH LCR HS II was suggested in situ. Methylation at this site also increased BMAL1/CLOCK-related nuclear protein binding in vitro. These observations support an effect of SD on hGH synthesis at the level of gene expression.

Pancreatic beta-cell failure is characterized by compromised insulin secretion in response to glucose, which ultimately results in hyperglycemia, the clinical hallmark of type 2 diabetes mellitus (T2DM). Acute exposure to plasma free fatty acids (FFAs) potentiates glucose stimulated insulin secretion (GSIS), while chronic exposure impairs GSIS, and the latter has been associated with the mechanism of beta cell failure in obesity linked T2DM. By contrast, growth hormone (GH) signaling has been linked positively to GSIS in beta cells. Numerous studies have examined chronic exposure of beta cells to elevated FFAs both with in vivo cohorts and in vitro models. Little attention, however, has been given to the fluctuation of plasma FFA levels due to rhythmic effects that are affected by daily diet and fat intake. Mouse insulinoma Min6 cells were exposed to cyclic/daily palmitate treatment over 2 and 3 days to assess effects on GSIS. Cyclic/daily palmitate treatment with a period of recovery negatively affected GSIS in a dose-dependent manner. Removal of palmitate after two cycles/day resulted in reversal of the effect on GSIS, which was also reflected by relative gene expression involved in insulin biosynthesis (Ins1, Ins2, Pdx1, and MafA) and GSIS (glucose 2 transporter and glucokinase). Modest positive effects on GSIS and glucokinase transcript levels were also observed when Min6 cells were cotreated with human GH and palmitate. These observations indicate that like continuous palmitate treatment, cyclic exposure to palmitate can acutely impair GSIS over 48 and 72 h. However, they also suggest that the negative effects of short periods of exposure to FFAs on beta cell function remain reversible.

Cardiac fibroblast growth factor 2 (FGF2) exerts multiple paracrine activities related to cardiac response to injury. Endogenous FGF2 is composed of a mixture of 70% high- and 30% low-molecular-weight isoforms (Hi-FGF2 and Lo-FGF2, respectivley); although exogenously added Lo-FGF2 is cardioprotective, the roles of endogenous Hi-FGF2 or Lo-FGF2 have not been well defined. Therefore, we investigated the effect of elimination of Hi-FGF2 expression on susceptibility to acute cardiac damage in vivo caused by an injection of the genotoxic drug doxorubicin (Dox). Mice genetically depleted of endogenous Hi-FGF2 and expressing only Lo-FGF2 [FGF2(Lo) mice] were protected from the Dox-induced decline in ejection fraction displayed by their wild-type FGF2 [FGF2(WT)] mouse counterparts, regardless of sex, as assessed by echocardiography for up to 10 days post-Dox treatment. Because cardiac FGF2 is produced mainly by nonmyocytes, we next addressed potential contribution of fibroblast-produced FGF2 on myocyte vulnerability to Dox. In cocultures of neonatal rat cardiomyocytes (r-cardiomyocytes) with mouse fibroblasts from FGF2(WT) or FGF2(Lo) mice, only the FGF2(Lo)-fibroblast cocultures protected r-cardiomyocytes from Dox-induced mitochondrial and cellular damage. When r-cardiomyocytes were cocultured with or exposed to conditioned medium from human fibroblasts, neutralizing antibodies for human Hi-FGF-2, but not total FGF2, mitigated Dox-induced injury of cardiomyocytes. We conclude that endogenous Hi-FGF2 reduces cardioprotection by endogenous Lo-FGF2. Antibody-based neutralization of endogenous Hi-FGF2 may offer a prophylactic treatment against agents causing acute cardiac damage. NEW & NOTEWORTHY Cardiomyocytes, in vivo and in vitro, were protected from the deleterious effects of the anticancer drug doxorubicin by the genetic elimination or antibody-based neutralization of endogenous paracrine high-molecular-weight fibroblast growth factor 2 isoforms. These findings have a translational potential for mitigating doxorubicin-induced cardiac damage in patients with cancer by an antibody-based treatment.