Introduction Very preterm infants (<32 weeks gestation) have an undeveloped primary endogenous circadian rhythm and are deprived abruptly of vital maternal circadian inputs after delivery. Postnatal care in neonatal intensive care units is characterised by constant levels of lighting and noise. Stress arising from disrupted cues for circadian rhythmicity likely disrupts development of coordinated circadian rhythms critical for neurogenesis, organ growth and development. We hypothesise that cycled environmental light and noise commenced soon after birth and continued until discharge home will improve cognitive outcomes compared with infants whose postnatal care comprises constant light (bright or dim) and constant noise.Methods and analysis Australasian multicentre, two-arm, parallel-group, prospective, randomised, open, blinded-endpoint superiority trial in 868 infants born less than 32 weeks’ gestation. Infants are randomised to cycled environmental light and noise or routine care in a non-cycled hospital environment from soon after birth until discharge home. The intervention comprises wearing eye-masks and ear plugs from 20:00 to 6:00, followed by removal of these devices and exposure to normal environmental noise and 300-600 lux light from 6:00 to 20:00. The primary outcome is composite cognitive score on Bayley-4 developmental assessment at 2 years corrected postnatal age.Ethics and dissemination The trial is approved by the Child and Adolescent Health Service Human Research Ethics Committee under the National Mutual Acceptance Scheme in Australia. Infants are randomised to intervention or control group after informed parental consent is obtained. Results of the CIRCA DIEM Study will be disseminated widely via presentations at local, national and international conferences, publication in international peer-reviewed journals and inclusion on the study website. Information about trial findings will also be communicated directly to the parents/guardians of trial participants through the regular study newsletter. The trial investigators will seek opportunities to communicate study results to the lay public through media and social media avenues.Trial registration number ANZCTRN12618000371291.

Adverse prenatal conditions can induce intrauterine growth restriction (IUGR) and increase the risk of adulthood metabolic disease. Mechanisms underlying developmentally programmed metabolic disease remain unclear but may involve disrupted postnatal circadian rhythms and kisspeptin signalling. We investigated the impact of maternal hypoxia-induced IUGR on hypothalamic and hepatic expression of clock genes (Bmal1, Per2 and Reverbα), metabolic genes (Pparα, Pparγ and Pgc1α) and kisspeptin genes (Kiss1 and Kiss1r) in adult offspring. Pregnant BALB/c mice were housed in hypoxic conditions (10.5% oxygen) from gestational day 11 to 17.5 and then returned to normoxic conditions until term (gestational day ∼ 21). Control animals were housed in normoxic conditions throughout pregnancy. Offspring were weighed at birth. At 8 weeks of age, body, liver and brain tissues were collected and weighed. Relative clock gene, metabolic gene and kisspeptin signalling gene expression were measured using qPCR. The IUGR offspring were lighter at birth and remained lighter at 8 weeks but with higher brain relative to body weight. The IUGR offspring had decreased hypothalamic Bmal1 and Reverbα expression, but unchanged hepatic clock gene expression and no change in hypothalamic or hepatic Per2 expression, compared with Control offspring. This tissue-specific change in clock gene expression suggests circadian dysregulation. There were no IUGR-related changes to metabolic gene expression in the hypothalamus or liver, but IUGR offspring had increased hypothalamic Kiss1r expression. These results demonstrate IUGR offspring from hypoxia pregnancies show central circadian misalignment and potentially disrupted hypothalamic Kiss1/Kiss1r signalling, which may contribute to developmentally programmed metabolic disease.

High-fat diet (HFD)-induced obesity represents a significant challenge to male reproductive health, affecting approximately 13% of the global adult population. This comprehensive review synthesizes current evidence regarding mulberry (Morus alba L.) fruit extract’s therapeutic potential for HFD-induced male reproductive dysfunction. Through comprehensive analysis of the peer-reviewed literature from multiple databases (PubMed, Web of Science, Scopus, and Google Scholar; 2005–2024), we evaluated mulberry extract’s effects on testicular morphology, spermatogenesis, sperm parameters, and the underlying molecular mechanisms. Mechanistic studies reveal that standardized mulberry extract mediates protective effects through multiple pathways: enhanced antioxidant enzyme activities (SOD: +45%, Catalase: +38%, GPx: +35%), reduced inflammatory markers (TNF-α: −64%, IL-6: −58%), and modulated NF-κB signaling (−42.3%). These effects are facilitated by mulberry’s rich phytochemical profile, particularly anthocyanins (2.92–5.35 mg/g dry weight) and polyphenols (4.23–6.38 mg/g). The extract demonstrates particular efficacy in preserving seminiferous tubule integrity and maintaining blood-testis barrier function, with treated groups maintaining up to 85% of normal tubular architecture compared to HFD controls. Key molecular mechanisms include AMPK/SIRT1 pathway activation (2.3-fold increase), enhanced mitochondrial function (67% increase in mtDNA copy number), and epigenetic regulation of metabolic pathways. Temporal analysis indicates optimal therapeutic effects after 28 days of treatment, with initial improvements observable within 14 days. While current evidence is promising, limitations include predominant reliance on rodent models and lack of standardized extraction protocols. Future research priorities include well-designed human clinical trials, standardization of preparation methods, and investigation of potential synergistic effects with other therapeutic agents. This comprehensive review indicates that mulberry extract is a promising therapeutic candidate for obesity-related male infertility, warranting further clinical investigation.

Unlike embryos that display two pronuclei (2PN), monopronucleated (1PN) embryos are assumed to be haploid and can be routinely discarded. Although there are reports of live births after 1PN embryo transfer, the developmental and clinical prognosis of 1PN embryos has not been systematically evaluated. The aim of this review was to elucidate the developmental, clinical and neonatal outcomes of 1PN embryos compared with 2PN embryos. Twenty-four studies met the inclusion criteria. The blastulation rate was lower in 1PN embryos compared with 2PN embryos [risk ratio (RR) 0.50, 95% CI 0.48-0.51]. The live birth rate was lower in 1PN blastocysts when untested (RR 0.81, 95% CI 0.72-0.90), but was similar after euploidy confirmation by preimplantation genetic testing for aneuploidy (RR 0.85, 95% CI 0.59-1.23). The euploidy rate was comparable in 1PN and 2PN embryos (RR 0.91, 95% CI 0.81-1.02). In a subgroup analysis of untested embryos, 1PN-intracytoplasmic sperm injection (ICSI) blastocysts had a lower live birth rate compared with 2PN-ICSI blastocysts (RR 0.26, 95% CI 0.13-0.50), while no difference was observed with IVF (RR 0.93, 95% CI 0.82-1.06). These results are particularly important for patients with a poor prognosis and limited 2PN embryos, and can aid reproductive professionals to counsel patients on the clinical use of 1PN embryos. Future studies should utilise time-lapse and preimplantation genetic testing technologies for confirmation of diploidy and biparental inheritance. Monopronucleated embryos can be viable, expanding options beyond 2PN embryos.

STUDY QUESTION Do embryos displaying abnormal cleavage (ABNCL) up to Day 3 have compromised live birth rates and neonatal outcomes if full blastulation has been achieved prior to transfer? SUMMARY ANSWER ABNCL is associated with reduced full blastulation rates but does not impact live birth rates and neonatal outcomes once full blastulation has been achieved. WHAT IS KNOWN ALREADY? It is widely accepted that ABNCL is associated with reduced implantation rates of embryos when transferred at the cleavage stage. However, evidence is scarce in the literature reporting birth outcomes from blastocysts arising from ABNCL embryos, likely because they are ranked low priority for transfer. STUDY DESIGN, SIZE, DURATION This retrospective cohort study included 1562 consecutive autologous in vitro fertilization cycles (maternal age 35.1 ± 4.7 years) performed at Fertility North, Australia between January 2017 and June 2022. Fresh transfers were performed on Day 3 or 5, with remaining embryos cultured up to Day 6 before vitrification. A total of 6019 embryos were subject to blastocyst culture, and a subset of 664 resulting frozen blastocysts was included for live birth and neonatal outcome analyses following single transfers. PARTICIPANTS/MATERIALS, SETTING, METHODS ABNCL events were annotated from the first mitotic division up to Day 3, including direct cleavage (DC), reverse cleavage (RC) and <6 intercellular contact points at the 4-cell stage (<6ICCP). For DC and RC in combination, the ratios of affected blastomeres over the total number of all blastomeres up to Day 3 were also recorded. All pregnancies were followed up until birth with gestational age, birthweight, and sex of the baby being recorded. MAIN RESULTS AND THE ROLE OF CHANCE Full blastulation rates for embryos showing DC (19.5%), RC (41.7%), <6ICCP (58.8%), and mixed (≥2) ABNCL types (26.4%) were lower than the rates for those without ABNCL (67.2%, P < 0.01 respectively). Subgroup analysis showed declining full blastulation rates with increasing ratios of combined DC/RC affected blastomeres over all blastomeres up to the 8-cell stage (66.2% when 0 affected, 47.0% when 0.25 affected, 27.4% when 0.5 affected, 14.5% when 0.75 affected, and 7.7% when all affected, P < 0.01). However, once full blastulation had been achieved, no difference was detected between DC, RC, <6ICCP, and no ABNCL blastocysts following single frozen transfers in subsequent live birth rates (25.9%, 33.0%, 36.0% versus 30.8%, P > 0.05, respectively), gestational age (38.7 ± 1.6, 38.5 ± 1.2, 38.3 ± 3.5 versus 38.5 ± 1.8 weeks, P > 0.05, respectively) and birthweight (3343.0 ± 649.1, 3378.2 ± 538.4, 3352.6 ± 841.3 versus 3313.9 ± 509.6 g, P > 0.05, respectively). Multiple regression (logistic or linear as appropriate) confirmed no differences in all of the above measures after accounting for potential confounders. LIMITATIONS, REASONS FOR CAUTION Our study is limited by its retrospective nature, making it impossible to control every known or unknown confounder. Embryos in our dataset, being surplus after selection for fresh transfer, may not represent the general embryo population. WIDER IMPLICATIONS OF THE FINDINGS Our findings highlight the incremental impact of ABNCL, depending on the ratio of affected blastomeres up to Day 3, on subsequent full blastulation. The reassuring live birth and neonatal outcomes of ABNCL blastocysts imply a potential self-correction mechanism among those embryos reaching the blastocyst stage, which provides valuable guidance for clinical practice and patient counseling. STUDY FUNDING/COMPETTING INTEREST(S) This research is supported by an Australian Government Research Training Program (RTP) Scholarship. All authors report no conflict of interest. TRIAL REGISTRATION NUMBER N/A.

Abstract Background Dysferlinopathies are a clinically heterogeneous group of muscular dystrophies caused by gene mutations resulting in deficiency of the membrane-associated protein dysferlin. They manifest post-growth and are characterised by muscle wasting (primarily in the limb and limb-gridle muscles), inflammation, and replacement of myofibres with adipose tissue. The precise pathomechanism for dysferlinopathy is currently unclear; as such there are no treatments currently available. Glucocorticoids (GCs) are widely used to reduce inflammation and treat muscular dystrophies, but when administered to patients with dysferlinopathy, they have unexpected adverse effects, with accelerated loss of muscle strength. Methods To investigate the mechanistic basis for the adverse effects of GCs in dysferlinopathy, the potent GC dexamethasone (Dex) was administered for 4–5 weeks (0.5–0.75 µg/mL in drinking water) to dysferlin-deficient BLA/J and normal wild-type (WT) male mice, sampled at 5 (Study 1) or 10 months (Study 2) of age. A wide range of analyses were conducted. Metabolism- and immune-related gene expression was assessed in psoas muscles at both ages and in quadriceps at 10 months of age. For the 10-month-old mice, quadriceps and psoas muscle histology was assessed. Additionally, we investigated the impact of Dex on the predominantly slow and fast-twitch soleus and extensor digitorum longus (EDL) muscles (respectively) in terms of contractile function, myofibre-type composition, and levels of proteins related to contractile function and metabolism, plus glycogen. Results At both ages, many complement-related genes were highly expressed in BLA/J muscles, and WT mice were generally more responsive to Dex than BLA/J. The effects of Dex on BLA/J mice included (i) increased expression of inflammasome-related genes in muscles (at 5 months) and (ii) exacerbated histopathology of quadriceps and psoas muscles at 10 months. A novel observation was pronounced staining for glycogen in many myofibres of the damaged quadriceps muscles, with large pale vacuolated myofibres, suggesting possible myofibre death by oncosis. Conclusion These pilot studies provide a new focus for further investigation into the adverse effects of GCs on dysferlinopathic muscles.

In examining maternal depression, placental 11β-HSD2 mRNA expression and offspring cortisol regulation as a potential fetal programming pathway in relation to later child emotional disorders, it has become clear that sex differences may be important to consider. This study reports on data obtained from 209 participants in the Mercy Pregnancy and Emotional Wellbeing Study (MPEWS) recruited before 20 weeks of pregnancy. Maternal depressive disorders were diagnosed using the SCID-IV and maternal childhood trauma using the Childhood Trauma Questionnaire. Placental 11β-HSD2 mRNA was measured using qRT-PCR. For assessment of stress-induced cortisol reactivity, salivary cortisol samples were taken at 12 months of age. At 4 years of age, measurement of Childhood Emotional Disorders (depression and anxiety) was based on maternal report using the Preschool Age Psychiatric Assessment (PAPA) and internalizing symptoms using the Child Behavior Checklist (CBCL). Maternal depression in pregnancy and postpartum, and infant cortisol reactivity, was associated with internalizing symptoms for females only. For female offspring only, increased 12-month cortisol reactivity was also associated with increased emotional disorders at 4 years of age; however, there was no association with placental 11β-HSD2 mRNA expression. In females only, the combination of lower placental 11β-HSD2 mRNA expression and higher cortisol reactivity at 12 months of age predicted increased internalising problems. These findings suggest there may be sex differences in prenatal predictors and pathways for early childhood depression and anxiety symptoms and disorder.

Temperature rhythms can act as potent signals for the modulation of the amplitude and phase of clock gene expression in peripheral organs in vitro, but the relevance of the circadian rhythm of core body temperature (Tc) as a modulating signal in vivo has not yet been investigated. Using calorie restriction and cafeteria feeding, we induced a larger and a dampened Tc amplitude, respectively, in male Wistar rats, and investigated the circadian expression profile of the core clock genes Bmal1, Per2, Cry1, and Rev-erbα, the heat-responsive genes heat shock protein 90 (Hsp90) and cold-inducible RNA binding protein (Cirbp), and Pgc1α, Pparα/γ/δ, Glut1/4, and Chop10 in the liver, skeletal muscle, white adipose tissue (WAT), and adrenal glands. Diet-altered Tc rhythms differentially affected the profiles of clock genes, Hsp90, and Cirbp expression in peripheral tissues. Greater Tc amplitudes elicited by calorie restriction were associated with large amplitudes of Hsp90 and Cirbp expression in the liver and WAT, in which larger amplitudes of clock gene expression were also observed. The amplitudes of metabolic gene expression were greater in the WAT, but not in the liver, in calorie-restricted rats. Conversely, diet-altered Tc rhythms were not translated to distinct changes in the amplitude of Hsp90, Cirbp, or clock or metabolic genes in the skeletal muscle or adrenal glands. While it was not possible to disentangle the effects of diet and temperature in this model, taken together with previous in vitro studies, our study presents novel data consistent with the notion that the circadian Tc rhythm can modulate the amplitude of circadian gene expression in vivo. The different responses of Hsp90 and Cirbp in peripheral tissues may be linked to the tissue-specific responses of peripheral clocks to diet and/or body temperature rhythms, but the association with the amplitude of metabolic gene expression is limited to the WAT.

Placental 11β-HSD2 has been a focus of research for understanding potential fetal programming associated with maternal emotional disorders. This study examined the pathway from antenatal mental health via placental 11β-HSD2 mRNA to cortisol regulation in the infant offspring. This study reports on data obtained from 236 participants in the Mercy Pregnancy and Emotional Wellbeing Study (MPEWS). At term, placental tissue was collected within 30 min of birth from 52 participants meeting current criteria for a depressive disorder, and 184 control participants. Depressive disorders were diagnosed using the SCID-IV. In addition, antidepressant use, depressive and anxiety symptoms were measured in early and late pregnancy. Placental 11β-HSD2 mRNA expression was measured using qRT-PCR. Infant salivary cortisol samples were taken at 12 months of age. Women on antidepressant medication and with higher trait anxiety had higher placental 11β-HSD2 expression compared to women not taking medication. Furthermore, the offspring of women taking an antidepressant and who also had a current depressive disorder and high trait anxiety had high cortisol reactivity at 12 months of age and this was mediated through 11β-HSD2 mRNA expression. In contrast, offspring of women not taking antidepressant medication with depressive disorder and high anxiety there was low cortisol reactivity observed. Our findings suggest that the relationship between maternal antenatal depression and anxiety and infant cortisol reactivity is mediated through placental 11β-HSD2 mRNA expression. Furthermore, the direction differed for women taking antidepressants, where infant cortisol reactivity was high whereas when compared to those with unmedicated depression and anxiety, where infant cortisol reactivity was low.

ABSTRACT Circadian rhythms optimize health by coordinating the timing of physiological processes to match predictable daily environmental challenges. The circadian rhythm of body temperature is thought to be an important modulator of molecular clocks in peripheral tissues, but how daily temperature cycles affect physiological function is unclear. Here, we examined the effect of constant temperature (Tcon, 25°C) and cycling temperature (Tcyc, 28°C:22°C during light:dark) paradigms on lifespan of Drosophila melanogaster, and the expression of clock genes, heat shock protein 83 (Hsp83), Frost (Fst) and senescence marker protein-30 (smp-30). Male and female D. melanogaster housed at Tcyc had longer median lifespans than those housed at Tcon. Tcyc induced robust Hsp83 rhythms and rescued the age-related decrease in smp-30 expression that was observed in flies at Tcon, potentially indicating an increased capacity to cope with age-related cellular stress. Ageing under Tcon led to a decrease in the amplitude of expression of all clock genes in the bodies of male flies, except for cyc, which was non-rhythmic, and for per and cry in female flies. Strikingly, housing under Tcyc conditions rescued the age-related decrease in amplitude of all clock genes, and generated rhythmicity in cyc expression, in the male flies, but not the female flies. The results suggest that ambient temperature rhythms modulate D. melanogaster lifespan, and that the amplitude of clock gene expression in peripheral body clocks may be a potential link between temperature rhythms and longevity in male D. melanogaster. Longevity due to Tcyc appeared predominantly independent of clock gene amplitude in female D. melanogaster.

Circadian rhythms, primarily entrained through the light–dark cycle, play significant roles in the endocrine system. Fetal circadian rhythms develop through maternal rhythmic secretion of the hormones, melatonin and cortisol. This feto-maternal connection drives the development of the fetal circadian system until birth, to prepare the newborn for the postnatal environment. Conditions that affect maternal circadian rhythms (i.e. shift work and sleep disorders) can affect fetal circadian rhythmicity development, and thus the development of the offspring endocrine system. Furthermore, infants born preterm are hospitalised in neonatal intensive care units where constant light, loud noise and persistent handling disrupts infant sleep and circadian development. The consequences of circadian disruption include melatonin and glucocorticoid dysregulation, which can impact growth, development and other health outcomes.

Aims/hypothesis Exposure to sunlight has the potential to suppress metabolic dysfunction and obesity. We previously demonstrated that regular exposure to low-doses of ultraviolet radiation (UVR) reduced weight gain and signs of diabetes in male mice fed a high-fat diet, in part via release of nitric oxide from skin. Here, we explore further mechanistic pathways through which low-dose UVR exerts these beneficial effects. Methods We fed mice with a luciferase-tagged Ucp1 gene (which encodes uncoupling protein-1 [UCP-1]), referred to here as the Ucp1 luciferase transgenic mouse ('Thermomouse') a high-fat diet and examined the effects of repeated exposure to low-dose UVR on weight gain and development of metabolic dysfunction as well as UCP-1-dependent thermogenesis in interscapular brown adipose tissue (iBAT). Results Repeated exposure to low-dose UVR suppressed the development of glucose intolerance and hepatic lipid accumulation via dermal release of nitric oxide while also reducing circulating IL-6 (compared with mice fed a high-fat diet only). Dietary nitrate supplementation did not mimic the effects of low-dose UVR. A single low dose of UVR increased UCP-1 expression (by more than twofold) in iBAT of mice fed a low-fat diet, 24 h after exposure. However, in mice fed a high-fat diet, there was no effect of UVR on UCP-1 expression in iBAT (compared with mock-treated mice) when measured at regular intervals over 12 weeks. More extensive circadian studies did not identify any substantial shifts in UCP-1 expression in mice exposed to low-dose UVR, although skin temperature at the interscapular site was reduced in UVR-exposed mice. The appearance of cells with a white adipocyte phenotype ('whitening') in iBAT induced by consuming the high-fat diet was suppressed by exposure to low-dose UVR in a nitric oxide-dependent fashion. Significant shifts in the expression of important core gene regulators of BAT function (Dio2, increased more than twofold), fatty acid transport (increased Fatp2 [also known as Slc27a2]), lipolysis (decreased Atgl [also known as Pnpla2]), lipogenesis (decreased Fasn) and inflammation (decreased Tnf), and proportions of macrophages (increased twofold) were observed in iBAT of mice exposed to low-dose UVR. These effects were independent of nitric oxide released from skin. Conclusions/interpretation Our results suggest that non-burning (low-dose) UVR suppresses the BAT 'whitening', steatotic and pro-diabetic effects of consuming a high-fat diet through skin release of nitric oxide, with some metabolic and immune pathways in iBAT regulated by UVR independently of nitric oxide.

In the fast lane of chronobiology, ultradian events are short-term rhythms that have been observed since the beginning of modern biology and were quantified about a century ago. They are ubiquitous in all biological systems and found in all organisms, from unicellular organisms to mammals, and from single cells to complex biological functions in multicellular animals. Since these events are aperiodic and last for a few minutes to a few hours, they are better classified as episodic ultradian events (EUEs). Their origin is unclear. However, they could have a molecular basis and could be controlled by hormonal inputs-in vertebrates, they originate from the activity of the central nervous system. EUEs are receiving increasing attention but their aperiodic nature requires specific sampling and analytic tools. While longer scale rhythms are adaptations to predictable changes in the environment, in theory, EUEs could contribute to adaptation by preparing organisms and biological functions for unpredictability.

Nutritional disturbances during in utero life can disrupt fetal development and thereby "program' the subsequent metabolic phenotype in adulthood. Maternal nutritional status is thus a key determinant of the intrauterine environment quality. Offspring born to nutritionally compromised pregnancies, such as those complicated by maternal obesity, undernutrition, or micronutrient deficiencies, often experience developmental aberrations and associated metabolic pathologies in adulthood. A growing body of evidence indicates that these nutritionally programmed metabolic complications are mediated via fetal epigenetic changes, including shifts in DNA methylation, histone structure and non-coding RNA activity. Moreover, because metabolic processes are intimately linked to circadian biology, clock gene networks have emerged as potential mediators of the programmed metabolic phenotype. In this chapter, we explore the evidence supporting a role for nutritional signals in utero affecting fetal clock and clock-controlled systems via permanent effects on the fetal epigenome, thereby leading to metabolic health complications in postnatal life.

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.

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 (T-c) regulation in nonpregnant rodents; however, it is unknown whether obesity alters normal maternal T-c adaptations to pregnancy. Since T-c 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 T-c 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 T-c 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 T-c (by up to 0.29 degrees C) across the estrous cycle and most of pregnancy; however, T-c for CAF and CON animals converged toward the end of gestation. Obesity reduced the amplitude of T-c 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 T-c exclusively in the light period during pre-pregnancy but only during the dark period in late gestation. In conclusion, obesity alters rhythmic T-c profiles and reduces the magnitude of the T-c decline late in rat gestation, which may have implications for maternal health and fetal development.

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.