Programming of the fetal suprachiasmatic nucleus and subsequent adult rhythmicity

Melatonin supplementation in obese mothers reduces hypothalamic inflammation and enhances thermogenesis in mice progeny

Maternal obesity might induce obesity and metabolic alterations in the progeny. The study aimed to determine the effect of supplementing obese mothers with Mel (Mel) on thermogenesis and inflammation. C57BL/6 female mice (mothers) were fed from weaning to 12 weeks control diet (C, 17% kJ as fat) or a high-fat diet (HF, 49% kJ as fat) and then matted with male mice fed the control diet. Melatonin (10 mg/kg daily) was supplemented to mothers during gestation and lactation, forming the groups C, CMel, HF, and HFMel (n = 10/group). Twelve-week male offspring were studied (plasma biochemistry, immunohistochemistry, protein, and gene expressions at the hypothalamus - Hyp, subcutaneous white adipose tissue - sWAT, and interscapular brown adipose tissue - iBAT). Comparing HFMel vs. HF offspring, fat deposits and plasmatic proinflammatory markers decreased. Also, HFMel showed decreased Hyp proinflammatory markers and neuropeptide Y (anabolic) expression but improved proopiomelanocortin (catabolic) expression. Besides, HFMel sWAT adipocytes changed to a beige phenotype with-beta-3 adrenergic receptor and uncoupling protein-1 activation, concomitant with browning genes activation, triggering the iBAT thermogenic activity. In conclusion, compelling evidence indicated the beneficial effects of supplementing obese mothers with Mel on the health of their mature male offspring. Mel led to sWAT browning-related gene enhancement, increased iBAT thermogenis, and mitigated hypothalamic inflammation. Also, principal component analysis of the data significantly separated the untreated obese mother progeny from the progeny of treated obese mothers. If confirmed in humans, the findings encourage a future guideline recommending Mel supplementation during pregnancy and breastfeeding.

Melatonin as a Therapy for Preterm Brain Injury: What Is the Evidence?

Despite significant improvements in survival following preterm birth in recent years, the neurodevelopmental burden of prematurity, with its long-term cognitive and behavioral consequences, remains a significant challenge in neonatology. Neuroprotective treatment options to improve neurodevelopmental outcomes in preterm infants are therefore urgently needed. Alleviating inflammatory and oxidative stress (OS), melatonin might modify important triggers of preterm brain injury, a complex combination of destructive and developmental abnormalities termed encephalopathy of prematurity (EoP). Preliminary data also suggests that melatonin has a direct neurotrophic impact, emphasizing its therapeutic potential with a favorable safety profile in the preterm setting. The current review outlines the most important pathomechanisms underlying preterm brain injury and correlates them with melatonin's neuroprotective potential, while underlining significant pharmacokinetic/pharmacodynamic uncertainties that need to be addressed in future studies.

Beyond sleep: A multidimensional model of chronotype

Chronotype can be defined as an expression or proxy for circadian rhythms of varied mechanisms, for example in body temperature, cortisol secretion, cognitive functions, eating and sleeping patterns. It is influenced by a range of internal (e.g., genetics) and external factors (e.g., light exposure), and has implications for health and well-being. Here, we present a critical review and synthesis of existing models of chronotype. Our observations reveal that most existing models and, as a consequence, associated measures of chronotype have focused solely or primarily on the sleep dimension, and typically have not incorporated social and environmental influences on chronotype. We propose a multidimensional model of chronotype, integrating individual (biological and psychological), environmental and social factors that appear to interact to determine an individual's true chronotype with potential feedback loops between these factors. This model could be beneficial not only from a basic science perspective but also in the context of understanding health and clinical implications of certain chronotypes as well as designing preventive and therapeutic approaches for related illnesses.

Circadian Rhythm Analysis Using Wearable Device Data: Novel Penalized Machine Learning Approach

BACKGROUND

Wearable devices have been widely used in clinical studies to study daily activity patterns, but the analysis remains a major obstacle for researchers.

OBJECTIVE

This study proposes a novel method to characterize sleep-activity rhythms using actigraphy and further use it to describe early childhood daily rhythm formation and examine its association with physical development.

METHODS

We developed a machine learning-based Penalized Multiband Learning (PML) algorithm to sequentially infer dominant periodicities based on the Fast Fourier Transform (FFT) algorithm and further characterize daily rhythms. We implemented and applied the algorithm to Actiwatch data collected from a cohort of 262 healthy infants at ages 6, 12, 18, and 24 months, with 159, 101, 111, and 141 participants at each time point, respectively. Autocorrelation analysis and Fisher test in harmonic analysis with Bonferroni correction were applied for comparison with the PML. The association between activity rhythm features and early childhood motor development, assessed using the Peabody Developmental Motor Scales-Second Edition (PDMS-2), was studied through linear regression analysis.

RESULTS

The PML results showed that 1-day periodicity was most dominant at 6 and 12 months, whereas one-day, one-third-day, and half-day periodicities were most dominant at 18 and 24 months. These periodicities were all significant in the Fisher test, with one-fourth-day periodicity also significant at 12 months. Autocorrelation effectively detected 1-day periodicity but not the other periodicities. At 6 months, PDMS-2 was associated with the assessment seasons. At 12 months, PDMS-2 was associated with the assessment seasons and FFT signals at one-third-day periodicity (P<.001) and half-day periodicity (P=.04), respectively. In particular, the subcategories of stationary, locomotion, and gross motor were associated with the FFT signals at one-third-day periodicity (P<.001).

CONCLUSIONS

The proposed PML algorithm can effectively conduct circadian rhythm analysis using time-series wearable device data. The application of the method effectively characterized sleep-wake rhythm development and identified the association between daily rhythm formation and motor development during early childhood.

Maternal Melatonin Deficiency Leads to Endocrine Pathologies in Children in Early Ontogenesis

The review summarizes the results of experimental and clinical studies aimed at elucidating the causes and pathophysiological mechanisms of the development of endocrine pathology in children. The modern data on the role of epigenetic influences in the early ontogenesis of unfavorable factors that violate the patterns of the formation of regulatory mechanisms during periods of critical development of fetal organs and systems and contribute to the delayed development of pathological conditions are considered. The mechanisms of the participation of melatonin in the regulation of metabolic processes and the key role of maternal melatonin in the formation of the circadian system of regulation in the fetus and in the protection of the genetic program of its morphofunctional development during pregnancy complications are presented. Melatonin, by controlling DNA methylation and histone modification, prevents changes in gene expression that are directly related to the programming of endocrine pathology in offspring. Deficiency and absence of the circadian rhythm of maternal melatonin underlies violations of the genetic program for the development of hormonal and metabolic regulatory mechanisms of the functional systems of the child, which determines the programming and implementation of endocrine pathology in early ontogenesis, contributing to its development in later life. The significance of this factor in the pathophysiological mechanisms of endocrine disorders determines a new approach to risk assessment and timely prevention of offspring diseases even at the stage of family planning.

Comparison of sleep problems between term and preterm born preschool children

OBJECTIVES

Sleep disorders are common problems among all age groups. If sleep problems detected in childhood are not resolved successfully, they become sleep disorders and a chronic state. In this study, we aimed to compare sleep problems between preterm-born and term-born preschool-age children.

METHODS

In the cross-sectional study, children were grouped according to whether they were born preterm or at term. The preterm group included 137 children aged four to six years. The control group comprised 145 age-matched term-born preschool children. The prenatal, natal, demographical, and clinical characteristics of preterm- and term-born preschool-age children were compared. The Children's Sleep Habits Questionnaire (CSHQ) was used to identify sleep problems. The total score and subscores of the CSHQ were compared between the groups.

RESULTS

The percentage of gastroesophageal reflux (GER) symptoms and obstructive sleep apnea (OSA) symptoms were significantly higher in the preterm group. According to the cutoff point of the CSHQ, 97 children in the preterm group (70.8%) and 88 children in the control group (60.7%) had a sleep disorder. The total score of the CSHQ was significantly higher in the preterm group compared with the control group; however, the scores of the subscales were similar between the groups. In the regression analysis, a significant association was found between being born preterm and having sleep disorder (β = 0.308, OR = 1.36, p = 0.04).

CONCLUSIONS

Our study reported a high percentage of sleep problems in preterm-born preschool children. We suggest that prematurity is associated with sleep problems even if the etiology of sleep problems is heterogeneous. Symptoms regarding GER and OAS should be investigated, and precautions, such as prohibiting maternal cigarette smoking, should be taken in preterm infants.

Melatonin's Impact on Antioxidative and Anti-Inflammatory Reprogramming in Homeostasis and Disease

There is a growing consensus that the antioxidant and anti-inflammatory properties of melatonin are of great importance in preserving the body functions and homeostasis, with great impact in the peripartum period and adult life. Melatonin promotes adaptation through allostasis and stands out as an endogenous, dietary, and therapeutic molecule with important health benefits. The anti-inflammatory and antioxidant effects of melatonin are intertwined and are exerted throughout pregnancy and later during development and aging. Melatonin supplementation during pregnancy can reduce ischemia-induced oxidative damage in the fetal brain, increase offspring survival in inflammatory states, and reduce blood pressure in the adult offspring. In adulthood, disturbances in melatonin production negatively impact the progression of cardiovascular risk factors and promote cardiovascular and neurodegenerative diseases. The most studied cardiovascular effects of melatonin are linked to hypertension and myocardial ischemia/reperfusion injury, while the most promising ones are linked to regaining control of metabolic syndrome components. In addition, there might be an emerging role for melatonin as an adjuvant in treating coronavirus disease 2019 (COVID 19). The present review summarizes and comments on important data regarding the roles exerted by melatonin in homeostasis and oxidative stress and inflammation related pathologies.

The Role of Prenatal Melatonin in the Regulation of Childhood Obesity

There is a growing awareness that pregnancy can set the foundations for an array of diverse medical conditions in the offspring, including obesity. A wide assortment of factors, including genetic, epigenetic, lifestyle, and diet can influence foetal outcomes. This article reviews the role of melatonin in the prenatal modulation of offspring obesity. A growing number of studies show that many prenatal risk factors for poor foetal metabolic outcomes, including gestational diabetes and night-shift work, are associated with a decrease in pineal gland-derived melatonin and associated alterations in the circadian rhythm. An important aspect of circadian melatonin’s effects is mediated via the circadian gene, BMAL1, including in the regulation of mitochondrial metabolism and the mitochondrial melatoninergic pathway. Alterations in the regulation of mitochondrial metabolic shifts between glycolysis and oxidative phosphorylation in immune and glia cells seem crucial to a host of human medical conditions, including in the development of obesity and the association of obesity with the risk of other medical conditions. The gut microbiome is another important hub in the pathoetiology and pathophysiology of many medical conditions, with negative consequences mediated by a decrease in the short-chain fatty acid, butyrate. The effects of butyrate are partly mediated via an increase in the melatoninergic pathway, indicating interactions of the gut microbiome with melatonin. Some of the effects of melatonin seem mediated via the alpha 7 nicotinic receptor, whilst both melatonin and butyrate may regulate obesity through the opioidergic system. Oxytocin, a recently recognized inhibitor of obesity, may also be acting via the opioidergic system. The early developmental regulation of these processes and factors by melatonin are crucial to the development of obesity and many diverse comorbidities.

Programming effects of maternal stress on the circadian system of adult offspring

Maternal stress has long-lasting influences on the brain functions of offspring, and several brain regions have been proposed to mediate such programming. Although perinatal programming of crosstalk between the circadian and stress systems has been proposed, the functional consequences of prenatal stress on the circadian system and the underlying mechanisms remain largely unknown. Therefore, we investigated whether exposing pregnant mice to chronic restraint stress had prolonged effects on the suprachiasmatic nucleus (SCN), which bears the central pacemaker for mammalian circadian rhythms, of offspring. SCN explants from maternally stressed mice exhibited altered cyclic expression patterns of a luciferase reporter under control of the mouse Per1 promoter (mPer1::LUC), which manifested as a decreased amplitude and impaired stability of the rhythm. Bioluminescence imaging at the single-cell level subsequently revealed that impaired synchrony among individual cells was responsible for the impaired rhythmicity. These intrinsic defects appeared to persist during adulthood. Adult male offspring from stressed mothers showed advanced-phase behavioral rhythms with impaired stability as well as altered clock gene expression in the SCN. In addition to affecting the central rhythm, maternal stress also had prolonged influences on the circadian characteristics of the adrenal gland and liver, as determined by circulating corticosterone levels and hepatic glycogen content, and on canonical clock gene mRNA expression in those tissues. Taken together, our findings suggest that the SCN is a key target of the programming effects of maternal stress. The widespread effects of circadian disruptions caused by a misprogrammed clock may have further impacts on metabolic and mental health in later life.

When pregnant mothers are stressed, the fetus’s circadian rhythms are reprogrammed, increasing the risk of health complications later in life. Stress during pregnancy was known to negatively affect the fetus, but how it affected circadian rhythms (day/night patterns of alertness) was poorly understood. Kyungjin Kim (Daegu Gyeongbuk Institute of Science and Technology) and Sooyoung Chung (Ewha Womans University, Seoul), both in South Korea, and co-workers stressed pregnant mice by confining them in small tubes, then measured the effects on their offspring. Pups of stressed mothers showed disturbed circadian rhythms, and the effects persisted into adulthood. Further analysis showed that the rhythms were disrupted because individual cells in the key brain region regulating circadian rhythms were poorly synchronized. These results suggest potential treatments to counteract the negative effects of prenatal stress on circadian rhythms.

Desipramine restores the alterations in circadian entrainment induced by prenatal exposure to glucocorticoids

Alterations in circadian rhythms are closely linked to depression, and we have shown earlier that progressive alterations in circadian entrainment precede the onset of depression in mice exposed in utero to excess glucocorticoids. The aim of this study was to investigate whether treatment with the noradrenaline reuptake inhibitor desipramine (DMI) could restore the alterations in circadian entrainment and prevent the onset of depression-like behavior. C57Bl/6 mice were exposed to dexamethasone (DEX-synthetic glucocorticoid analog, 0.05 mg/kg/day) between gestational day 14 and delivery. Male offspring aged 6 months (mo) were treated with DMI (10 mg/kg/day in drinking water) for at least 21 days before behavioral testing. We recorded spontaneous activity using the TraffiCage™ system and found that DEX mice re-entrained faster than controls after an abrupt advance in light-dark cycle by 6 h, while DMI treatment significantly delayed re-entrainment. Next we assessed the synchronization of peripheral oscillators with the central clock (located in the suprachiasmatic nucleus-SCN), as well as the mechanisms required for entrainment. We found that photic entrainment of the SCN was apparently preserved in DEX mice, but the expression of clock genes in the hippocampus was not synchronized with the light-dark cycle. This was associated with downregulated mRNA expression for arginine vasopressin (AVP; the main molecular output entraining peripheral clocks) in the SCN, and for glucocorticoid receptor (GR; required for the negative feedback loop regulating glucocorticoid secretion) in the hippocampus. DMI treatment restored the mRNA expression of AVP in the SCN and enhanced GR-mediated signaling by upregulating GR expression and nuclear translocation in the hippocampus. Furthermore, DMI treatment at 6 mo prevented the onset of depression-like behavior and the associated alterations in neurogenesis in 12-mo-old DEX mice. Taken together, our data indicate that DMI treatment enhances GR-mediated signaling and restores the synchronization of peripheral clocks with the SCN and support the hypothesis that altered circadian entrainment is a modifiable risk factor for depression.

Developmental pathways towards mood disorders in adult life: Is there a role for sleep disturbances?

INTRODUCTION

Mood disorders are among the most prevalent and serious mental disorders and rank high among to the leading global burdens of disease. The developmental psychopathology framework can offer a life course perspective on them thus providing a basis for early prevention and intervention. Sleep disturbances, are considered risk factors for mood disorders across childhood, adolescence and adulthood. Assuming that sleep disturbances may play a pivotal role in the pathogenesis of mood disorders from a life course point of view, we reviewed the data on developmental pathways towards mood disorders in adult life in relation to sleep disturbances.

METHOD

From February 2017, a systematic search was conducted in PubMed, PsycINFO and Embase electronic databases for literature on developmental pathways to mood disorders in adult life in relation to sleep disturbances and to 1) pre-natal stress, 2) early brain developmental processes, and 3) temperaments, character and attachment style.

RESULTS

Eleven, 54 and 15 articles were respectively selected.

CONCLUSIONS

Experimental and clinical studies revealed that exposure to prenatal/early life stress results in sleep disturbances such as poor sleep and altered circadian regulation phases and may predict or even precipitate mood disorders in adulthood. Chronic sleep disruption may interfere with neuronal plasticity, connectivity and the developing brain thus contributing to the development of mood disorders. In addition sleep and circadian dysregulations have been shown to be related to those temperaments, character and attachment styles which are considered precursors of mood disorders. Sleep and circadian behaviours may serve as early targets regarding mood disorders.

Sleep Characteristics and Temperament in Preterm Children at Two Years of Age

STUDY OBJECTIVES

We aimed to compare 2-year-old children born preterm with children born full term regarding: (1) sleep characteristics, (2) temperament, and (3) relations between sleep pattern and habits and temperament.

METHODS

The study included 51 preterm children with normal cognitive, language, and motor development (mean = 20.94 months, standard deviation [SD] = 4.08) and 57 full-term children (mean = 21.19, SD = 4.32). To assess sleep-related difficulties and habits and child temperament, mothers completed the following questionnaires: the (1) Sleep Disturbance Scale for Children-adapted (SDSC); (2) Brief Infant Sleep Questionnaire (BISQ); and (3) Italian Temperament Questionnaires-version 12-36 months (QUIT).

RESULTS

Preterm children needed less support to fall asleep and fell asleep more often alone in their own bed compared to those born at full term; however, preterm children showed more frequent sleep difficulties, such as restlessness and breathing problems during the night. In addition, preterm children had lower scores in the temperamental dimension of attention and higher scores in negative emotionality than full-term children. Finally, sleep problems were correlated with higher motor activity, lower social orientation and attention, and increased negative emotionality; a shorter nocturnal sleep duration was related to higher motor activity and lower inhibition to novelty whereas an earlier rise time was associated with lower attention and social orientation.

CONCLUSIONS

Preterm children showed sleep pattern problems and disturbance, predominance of attention problems, and negative emotionality related to sleep disruption.

Effects of intrauterine growth restriction on sleep and the cardiovascular system: The use of melatonin as a potential therapy?

Intrauterine growth restriction (IUGR) complicates 5-10% of pregnancies and is associated with increased risk of preterm birth, mortality and neurodevelopmental delay. The development of sleep and cardiovascular control are closely coupled and IUGR is known to alter this development. In the long-term, IUGR is associated with altered sleep and an increased risk of hypertension in adulthood. Melatonin plays an important role in the sleep-wake cycle. Experimental animal studies have shown that melatonin therapy has neuroprotective and cardioprotective effects in the IUGR fetus. Consequently, clinical trials are currently underway to assess the short and long term effects of antenatal melatonin therapy in IUGR pregnancies. Given melatonin's role in sleep regulation, this hormone could affect the developing infants' sleep-wake cycle and cardiovascular function after birth. In this review, we will 1) examine the role of melatonin as a therapy for IUGR pregnancies and the potential implications on sleep and the cardiovascular system; 2) examine the development of sleep-wake cycle in fetal and neonatal life; 3) discuss the development of cardiovascular control during sleep; 4) discuss the effect of IUGR on sleep and the cardiovascular system and 5) discuss the future implications of melatonin therapy in IUGR pregnancies.

Mother-infant circadian rhythm: development of individual patterns and dyadic synchrony

BACKGROUND

Mutual circadian rhythm is an early and essential component in the development of maternal-infant physiological synchrony.

AIMS

The aim of this to examine the longitudinal pattern of maternal-infant circadian rhythm and rhythm synchrony as measured by rhythm parameters.

STUDY DESIGN

In-home dyadic actigraphy monitoring at infant age 4, 8, and 12 weeks.

SUBJECTS

Forty-three healthy mother-infant pairs.

OUTCOME MEASURES

Circadian parameters derived from cosinor and non-parametric analysis including mesor, magnitude, acrophase, L5 and M10 midpoints (midpoint of lowest 5 and highest 10h of activity), amplitude, interdaily stability (IS), and intradaily variability (IV).

RESULTS

Mothers experienced early disruption of circadian rhythm, with re-establishment of rhythm over time. Significant time effects were noted in increasing maternal magnitude, amplitude, and IS and decreasing IV (p<.001). Infants demonstrated a developmental trajectory of circadian pattern with significant time effects for increasing mesor, magnitude, amplitude, L5, IS, and IV (p<.001). By 12 weeks, infant phase advancement was evidenced by mean acrophase and M10 midpoint occurring 60 and 43 min (respectively) earlier than at 4 weeks. While maternal acrophase remained consistent over time, infants became increasingly phase advanced relative to mother and mean infant acrophase at 12 weeks occurred 60 min before mother. Mother-infant synchrony was evidenced in increasing correspondence of acrophase at 12 weeks (r=0.704), L5 (r=0.453) and M10 (r=0.479) midpoints.

CONCLUSIONS

Development of mother-infant synchrony reflects shared elements of circadian rhythm.

Advanced sleep phase in adolescents born preterm

The objective of this article is to evaluate whether sleep patterns and quality differed between adolescents born preterm and term, and to further explore whether differences in sleep patterns were explained by differences in mediating factors such as mood, behavior, or socioeconomic status. Five hundred and one 16- to 19-year-old children in the longitudinal Cleveland Children's Sleep and Health Study cohort underwent overnight polysomnography (PSG), wore wrist actigraphs, and completed sleep logs for 1 week. The modified Epworth Sleepiness Scale, the Adolescent Sleep Hygiene Scale, and the Adolescent Sleep-Wake Scale were used to further assess sleep. Adolescents born preterm demonstrated significantly (p < .05) earlier bed and wake times and sleep midpoints (approximately 22 min after adjusting for demographic and psychosocial factors) by actigraphy. They also had significantly fewer arousals (by PSG), and reported being more rested and alert in the morning, as well as less sleepiness and fatigue. These findings support a growing body of evidence that perinatal factors may influence sleep phenotypes later in life. These factors may reflect developmental influences, as well as the influence of parenting styles on children's sleep.

Exposure to dim light at night during early development increases adult anxiety-like responses

Early experiences produce effects that may persist throughout life. Therefore, to understand adult phenotype, it is important to investigate the role of early environmental stimuli in adult behavior and health. Artificial light at night (LAN) is an increasingly common phenomenon throughout the world. However, animals, including humans, evolved under dark night conditions. Many studies have revealed affective, immune, and metabolic alterations provoked by aberrant light exposure and subsequent circadian disruption. Pups are receptive to entraining cues from the mother and then light early during development, raising the possibility that the early life light environment may influence subsequent behavior. Thus, to investigate potential influences of early life exposure to LAN on adult phenotype, we exposed mice to dim (~5 lux; full spectrum white light) or dark (~0 lux) nights pre- and/or postnatally. After weaning at 3 weeks of age, all mice were maintained in dark nights until adulthood (9 weeks of age) when behavior was assessed. Mice exposed to dim light in early life increased anxiety-like behavior and fearful responses on the elevated plus maze and passive avoidance tests. These mice also displayed reduced growth rates, which ultimately normalized during adolescence. mRNA expression of brain derived neurotrophic factor (BDNF), a neurotrophin previously linked to early life environment and adult phenotype, was not altered in the prefrontal cortex or hippocampus by early life LAN exposure. Serum corticosterone concentrations were similar between groups at weaning, suggesting that early life LAN does not elicit a long-term physiologic stress response. Dim light exposure did not influence behavior on the open field, novel object, sucrose anhedonia, or forced swim tests. Our data highlight the potential deleterious consequences of low levels of light during early life to development and subsequent behavior. Whether these changes are due to altered maternal behavior or persistent circadian abnormalities incurred by LAN remains to be determined.

Designing artificial environments for preterm infants based on circadian studies on pregnant uterus

Using uterine explants from Per1::Luc rats and in situ hybridization, we recently reported that the circadian property of the molecular clock in the uterus and placenta is stably maintained from non-pregnancy, right through to the end stage of pregnancy under regular light-dark (LD) cycles. Despite long-lasting increases in progesterone during gestation and an increase in estrogen before delivery, the uterus keeps a stable Per1::Luc rhythm throughout the pregnancy. The study suggests the importance of stable circadian environments for fetuses to achieve sound physiology and intrauterine development. This idea is also supported by epidemiological and animal studies, in which pregnant females exposed to repeated shifting of the LD cycles have increased rates of reproductive abnormalities and adverse pregnancy outcomes. Leading from this, we introduced artificial circadian environments with controlled lighting conditions to human preterm infants by developing and utilizing a specific light filter which takes advantage of the unique characteristics of infants' developing visual photoreceptors. In spite of growing evidence of the physiological benefits of nighttime exposure to darkness for infant development, many Japanese Neonatal Intensive Care Units (NICUs) still prefer to maintain constant light in preparation for any possible emergencies concerning infants in incubators. To protect infants from the negative effects of constant light on their development in the NICU, we have developed a new device similar to a magic mirror, by which preterm infants can be shielded from exposure to their visible wavelengths of light even in the constant light conditions of the NICU while simultaneously allowing medical care staff to visually monitor preterm infants adequately. The device leads to significantly increased infant activity during daytime than during night time and better weight gains.

Influence of gestational diabetes on circadian rhythms of children and their association with fetal adiposity

OBJECTIVE

To analyse the circadian rhythm maturation of temperature, activity and sleep during the first year of life in offspring of diabetic mothers (ODM) and its relationship with obesity markers.

METHODS

A prospective analysis of the children of 63 pregnant women (23 controls, 21 gestational diabetes mellitus (GDM) controlled with diet and 19 GDM with insulin). Fetal abdominal circumference was evaluated ecographically during gestation. Skin temperature and rest-activity rhythms were monitored for 3 consecutive days in children at 15 days and 1, 3 and 6 months. Anthropometrical parameters of the children were evaluated during the first year of life.

RESULTS

Children from the GDM groups tended to higher fetal abdominal circumference z-score than controls at the beginning of the last trimester (p = 0.077) and at delivery (p = 0.078). Mean skin temperature or activity was not different among the groups. The I < O sleep index pointed to increasing concordance with parental sleeping at 3 and 6 months but no significant GDM-dependent differences. However, some of the parameters that define temperature maturation and also the circadian function index from the temperature-activity variable were significantly lower at 6 months in the GDM + insulin group. Fetal abdominal circumference z-score, as a predictor of fetal adiposity, correlated negatively with parameters related to circadian rhythm maturation as the circadian/ultradian rhythm (P1 /Pult ratio).

CONCLUSIONS

Fetal adiposity correlated with a worse circadian rhythm regulation in ODM. In addition, ODM insulin-treated showed a disturbed pattern of the circadian function index of temperature activity at 6 months of age.

Roles of melatonin in fetal programming in compromised pregnancies

Compromised pregnancies such as those associated with gestational diabetes mellitus, intrauterine growth retardation, preeclampsia, maternal undernutrition, and maternal stress may negatively affect fetal development. Such pregnancies may induce oxidative stress to the fetus and alter fetal development through the epigenetic process that may affect development at a later stage. Melatonin is an oxidant scavenger that reverses oxidative stress during the prenatal period. Moreover, the role of melatonin in epigenetic modifications in the field of developmental programming has been studied extensively. Here, we describe the physiological function of melatonin in pregnancy and discuss the roles of melatonin in fetal programming in compromised pregnancies, focusing on its involvement in redox and epigenetic mechanisms.

Conserved expression of the glutamate NMDA receptor 1 subunit splice variants during the development of the Siberian hamster suprachiasmatic nucleus

Glutamate neurotransmission and the N-methyl-D-aspartate receptor (NMDAR) are central to photic signaling to the master circadian pacemaker located in the hypothalamic suprachiasmatic nucleus (SCN). NMDARs also play important roles in brain development including visual input circuits. The functional NMDAR is comprised of multiple subunits, but each requiring the NR1 subunit for normal activity. The NR1 can be alternatively spliced to produce isoforms that confer different functional properties on the NMDAR. The SCN undergoes extensive developmental changes during postnatal life, including synaptogenesis and acquisition of photic signaling. These changes are especially important in the highly photoperiodic Siberian hamster, in which development of sensitivity to photic cues within the SCN could impact early physiological programming. In this study we examined the expression of NR1 isoforms in the hamster at different developmental ages. Gene expression in the forebrain was quantified by in situ hybridization using oligonucleotide probes specific to alternatively spliced regions of the NR1 heteronuclear mRNA, including examination of anterior hypothalamus, piriform cortex, caudate-putamen, thalamus and hippocampus. Gene expression analysis within the SCN revealed the absence of the N1 cassette, the presence of the C2 cassette alone and the combined absence of C1 and C2 cassettes, indicating that the dominant splice variants are NR1-2a and NR1-4a. Whilst we observe changes at different developmental ages in levels of NR1 isoform probe hybridization in various forebrain structures, we find no significant changes within the SCN. This suggests that a switch in NR1 isoform does not underlie or is not produced by developmental changes within the hamster SCN. Consistency of the NR1 isoforms would ensure that the response of the SCN cells to photic signals remains stable throughout life, an important aspect of the function of the SCN as a responder to environmental changes in quality/quantity of light over the circadian day and annual cycle.

Developmental programming of adult obesity and cardiovascular disease in rodents by maternal nutrition imbalance

Studies on fetal undernutrition have generated the hypothesis that fetal programming corresponds to an attempt of the fetus to adapt to adverse conditions encountered in utero. These adaptations would be beneficial if these conditions prevail later in life, but they become detrimental in the case of normal or plentiful nutrition and favor the appearance of the metabolic syndrome. In this article, the discussion is limited to the developmental programming of obesity and cardiovascular disorders caused by an early mismatched nutrition, particularly intrauterine growth retardation followed by postnatal catch-up growth. Selected data in humans are reviewed before evoking some mechanisms revealed or suggested by experiments in rodents. A variety of physiologic mechanisms are implicated in obesity programming, 2 of which are detailed. In some, but not all observations, hyperphagia resulting namely from perturbed development of the hypothalamic circuitry devoted to appetite regulation may contribute to obesity. Another contribution may be the developmental changes in the population of fat cell precursors in adipose tissue. Even if the link between obesity and cardiovascular disease is well established, alteration of blood pressure regulation may appear independently of obesity. A loss of diurnal variation in heart rate and blood pressure in adulthood has resulted from maternal undernutrition followed by postnatal overnutrition. Further research should clarify the effect of mismatched early nutrition on the development of brain centers regulating energy intake, energy expenditure, and circadian rhythms.

Assessment of circadian rhythms of both skin temperature and motor activity in infants during the first 6 months of life

The authors developed a method useful for home measurement of temperature, activity, and sleep rhythms in infants under normal-living conditions during their first 6 mos of life. In addition, parametric and nonparametric tests for assessing circadian system maturation in these infants were compared. Anthropometric parameters plus ankle skin temperature and activity were evaluated in 10 infants by means of two data loggers, Termochron iButton (DS1291H, Maxim Integrated Products, Sunnyvale, CA) for temperature and HOBO Pendant G (Hobo Pendant G Acceleration, UA-004-64, Onset Computer Corporation, Bourne, MA) for motor activity, located in special baby socks specifically designed for the study. Skin temperature and motor activity were recorded over 3 consecutive days at 15 days, 1, 3, and 6 mos of age. Circadian rhythms of skin temperature and motor activity appeared at 3 mos in most babies. Mean skin temperature decreased significantly by 3 mos of life relative to previous measurements (p = .0001), whereas mean activity continued to increase during the first 6 mos. For most of the parameters analyzed, statistically significant changes occurred at 3-6 mos relative to 0.5-1 mo of age. Major differences were found using nonparametric tests. Intradaily variability in motor activity decreased significantly at 6 mos of age relative to previous measurements, and followed a similar trend for temperature; interdaily stability increased significantly at 6 mos of age relative to previous measurements for both variables; relative amplitude increased significantly at 6 mos for temperature and at 3 mos for activity, both with respect to previous measurements. A high degree of correlation was found between chronobiological parametric and nonparametric tests for mean and mesor and also for relative amplitude versus the cosinor-derived amplitude. However, the correlation between parametric and nonparametric equivalent indices (acrophase and midpoint of M5, interdaily stability and Rayleigh test, or intradaily variability and P(1)/P(ultradian)) despite being significant, was lower for both temperature and activity. The circadian function index (CFI index), based on the integrated variable temperature-activity, increased gradually with age and was statistically significant at 6 mos of age. At 6 mos, 90% of the infants' rest period coincided with the standard sleep period of their parents, defined from 23:00 to 07:00 h (dichotomic index I < O; when I < O = 100%, there is a complete coincidence between infant nocturnal rest period and the standard rest period), whereas at 15 days of life the coincidence was only 75%. The combination of thermometry and actimetry using data loggers placed in infants' socks is a reliable method for assessing both variables and also sleep rhythms in infants under ambulatory conditions, with minimal disturbance. Using this methodological approach, circadian rhythms of skin temperature and motor activity appeared by 3 mos in most babies. Nonparametric tests provided more reliable information than cosinor analysis for circadian rhythm assessment in infants.

A survey of molecular details in the human pineal gland in the light of phylogeny, structure, function and chronobiological diseases

The human pineal gland is a neuroendocrine transducer that forms an integral part of the brain. Through the nocturnally elevated synthesis and release of the neurohormone melatonin, the pineal gland encodes and disseminates information on circadian time, thus coupling the outside world to the biochemical and physiological internal demands of the body. Approaches to better understand molecular details behind the rhythmic signalling in the human pineal gland are limited but implicitly warranted, as human chronobiological dysfunctions are often associated with alterations in melatonin synthesis. Current knowledge on melatonin synthesis in the human pineal gland is based on minimally invasive analyses, and by the comparison of signalling events between different vertebrate species, with emphasis put on data acquired in sheep and other primates. Together with investigations using autoptic pineal tissue, a remnant silhouette of premortem dynamics within the hormone's biosynthesis pathway can be constructed. The detected biochemical scenario behind the generation of dynamics in melatonin synthesis positions the human pineal gland surprisingly isolated. In this neuroendocrine brain structure, protein-protein interactions and nucleo-cytoplasmic protein shuttling indicate furthermore a novel twist in the molecular dynamics in the cells of this neuroendocrine brain structure. These findings have to be seen in the light that an impaired melatonin synthesis is observed in elderly and/or demented patients, in individuals affected by Alzheimer's disease, Smith-Magenis syndrome, autism spectrum disorder and sleep phase disorders. Already, recent advances in understanding signalling dynamics in the human pineal gland have significantly helped to counteract chronobiological dysfunctions through a proper restoration of the nocturnal melatonin surge.

Melatonin in experimental seizures and epilepsy

Although melatonin is approved only for the treatment of jet-lag syndrome and some types of insomnia, clinical data suggest that it is effective in the adjunctive therapy of osteoporosis, cataract, sepsis, neurodegenerative diseases, hypertension, and even cancer. Melatonin also modulates the electrical activity of neurons by reducing glutamatergic and enhancing GABA-ergic neurotransmission. The indoleamine may also be metabolized to kynurenic acid, an endogenous anticonvulsant. Finally, the hormone and its metabolites act as free radical scavengers and antioxidants. The vast majority of experimental data indicates anticonvulsant properties of the hormone. Melatonin inhibited audiogenic and electrical seizures, as well as reduced convulsions induced by pentetrazole, pilocarpine, L-cysteine and kainate. Only a few studies have shown direct or indirect proconvulsant effects of melatonin. For instance, melatonin enhanced low Mg2+-induced epileptiform activity in the hippocampus, whereas melatonin antagonists delayed the onset of pilocarpine-induced seizures. However, the relatively high doses of melatonin required to inhibit experimental seizures can induce some undesired effects (e.g., cognitive and motor impairment and decreased body temperature). In humans, melatonin may attenuate seizures, and it is most effective in the treatment of juvenile intractable epilepsy. Its additional benefits include improved physical, emotional, cognitive, and social functions. On the other hand, melatonin has been shown to induce electroencephalographic abnormalities in patients with temporal lobe epilepsy and increase seizure activity in neurologically disabled children. The hormone showed very low toxicity in clinical practice. The reported adverse effects (nightmares, hypotension, and sleep disorders) were rare and mild. However, more placebo-controlled, double-blind randomized clinical trials are needed to establish the usefulness of melatonin in the adjunctive treatment of epilepsy.

Synergistic effects of genetic beta cell dysfunction and maternal glucose intolerance on offspring metabolic phenotype in mice

AIMS/HYPOTHESIS

Diabetes in pregnancy is linked to development of obesity in the offspring, but the mechanisms are not fully understood. Gestational diabetes mellitus (GDM) occurs when beta cells are unable to compensate for the normal insulin resistance of late pregnancy. In this study, we used a murine model of beta cell dysfunction to examine the effects of maternal GDM on phenotype in male offspring with and without an inherited predisposition for beta cell dysfunction.

METHODS

Beta cell-specific aryl-hydrocarbon receptor nuclear translocator-null (βArnt) mice develop GDM from beta cell dysfunction. βArnt and control female mice were used to induce GDM and non-diabetic pregnancies, respectively.

RESULTS

Offspring from GDM pregnancies became spontaneously obese on a normal-chow diet. They were heavier than offspring from non-diabetic pregnancies, with increased body fat. Respiratory exchange ratio (RER) was higher, indicating decreased capacity to switch to lipid oxidation. Metabolic rate in GDM offspring was decreased prior to onset of obesity. The phenotype was more pronounced in βArnt GDM offspring than in GDM offspring of control genotype, demonstrating an interaction between genotype and pregnancy exposure. βArnt GDM offspring had increased hypothalamic neuropeptide Y (Npy) and decreased pro-opiomelanocortin (Pomc) expression. Weight, body fat, insulin sensitivity and RER in all mice, and hypothalamic Npy in βArnt mice were significantly correlated with AUC of maternal late pregnancy glucose tolerance tests (p < 0.01), but not with litter size, maternal weight, triacylglycerol or pre-pregnancy glycaemia.

CONCLUSIONS/INTERPRETATION

In βArnt mice, exposure to GDM and inheritance of genetic beta cell dysfunction had additive effects on male offspring obesity; severity of the offspring phenotype correlated with maternal glycaemia.

Epigenomics: maternal high-fat diet exposure in utero disrupts peripheral circadian gene expression in nonhuman primates

The effect of in utero exposure to a maternal high-fat diet on the peripheral circadian system of the fetus is unknown. Using mRNA copy number analysis, we report that the components of the peripheral circadian machinery are transcribed in the nonhuman primate fetal liver in an intact phase-antiphase fashion and that Npas2, a paralog of the Clock transcription factor, serves as the rate-limiting transcript by virtue of its relative low abundance (10- to 1000-fold lower). We show that exposure to a maternal high-fat diet in utero significantly alters the expression of fetal hepatic Npas2 (up to 7.1-fold, P<0.001) compared with that in control diet-exposed animals and is reversible in fetal offspring from obese dams reversed to a control diet (1.3-fold, P>0.05). Although the Npas2 promoter remains largely unmethylated, differential Npas2 promoter occupancy of acetylation of fetal histone H3 at lysine 14 (H3K14ac) occurs in response to maternal high-fat diet exposure compared with control diet-exposed animals. Furthermore, we find that disruption of Npas2 is consistent with high-fat diet exposure in juvenile animals, regardless of in utero diet exposure. In summary, the data suggest that peripheral Npas2 expression is uniquely vulnerable to diet exposure.

Improving the quality of infant sleep through the inclusion at supper of cereals enriched with tryptophan, adenosine-5'-phosphate, and uridine-5'-phosphate

The present study evaluated whether the administration of cereals enriched with nutrients that are facilitators of sleep could help improve the sleep of infants who had sleep disorders at night time. Thirty infants aged 8-16 months with sleep disorders involving at least three nocturnal waking episodes took part in the study. They were given a night-time 'sleep facilitating cereal' product containing 225 mg tryptophan, 5.3 mg adenosine-5'-P, and 6.3 mg uridine-5'-P per 100 g of product. These cereals were given in a double-blind procedure lasting 5 weeks, with ingestion of the cereal between 18:00 and 06:00. In the control week, the children received a standard cereal (75 mg tryptophan/100 g product without nucleotides) dissolved in a standard formula milk (231.5 mg tryptophan, 2.6 mg adenosine-5'-P, 5 mg uridine-5'-P, per 100 g product). In one experimental week, the children received the night-time sleep facilitating cereal together with the standard formula milk. In another week, they received the sleep facilitating cereal together with a night milk specially formulated to attain the sleep rhythm (480 mg tryptophan, 8.8 mg uridine-5'-P, and 7.6 mg adenosine-5'-P per 100 g product). The three experimental weeks were separated by two wash-out weeks in which the milk and cereal administered was identical in composition to that of the control week. All the infants received a programmed writer actimeter which they wore continually, attached to their ankles, to record their motor activity. The recorded activity was used to calculate information about the time in bed, assumed sleep, actual sleep, sleep efficiency, sleep latency, immobility, and total activity. The infants receiving the enriched cereal during the time of darkness showed improvements in their sleep parameters, regardless of whether the milk they took at night was standard or enriched with tryptophan, adenosine-5'-P, and uridine-5'-P. In summary, the administration of enriched cereals led to an improvement in sleep, regardless of the type of infant milk used. These results support the concept of chrononutrition since they confirm that the sleep/wake rhythm can be influenced by diet.

Prenatal origins of poor sleep in children

STUDY OBJECTIVES

We examined whether small body size at birth and prenatal tobacco or alcohol exposure predict poor sleep and more sleep disturbances in children.

DESIGN

An epidemiologic cohort study of 289 eight-year-old children born at term.

MEASUREMENTS AND RESULTS

Sleep duration and efficiency were measured by actigraphy for 7 consecutive nights (mean = 7.1, SD = 1.2). We used both continuous measures of poor sleep and binary variables of short sleep and low sleep efficiency ( < or = 10th percentiles). Parents completed the Sleep Disturbance Scale for Children. Lower birth weight and shorter length at birth were associated with lower sleep efficiency. For every 1-SD decrease in weight and length at birth, the odds for low sleep efficiency increased by 1.7 fold (95% confidence interval [CI]: 1.1 to 2.7) and 2.2 fold (95% CI: 1.3 to 3.7), respectively. For every 1-SD decrease in ponderal index at birth, the risk of parent-reported sleep disorders increased by 1.4 fold (95% CI: 1.0 to 2.0). Moreover, children exposed prenatally to alcohol had a 2.9-fold (95% CI: 1.1 to 7.6) and 3.6-fold (95% CI: 1.3 to 10.0) increased risk for having short sleep and low sleep efficiency, respectively. The associations were not confounded by sex, gestational length, prenatal and perinatal complications, body mass index at 8 years, asthma, allergies, or parental socioeconomic status.

CONCLUSIONS

Poor sleep in children may have prenatal origins. Possible mechanisms include alcohol consumption during pregnancy and other conditions associated with small body size at birth.

A newly proposed disease condition produced by light exposure during night: asynchronization

The bedtime of preschoolers/pupils/students in Japan has become progressively later with the result sleep duration has become progressively shorter. With these changes, more than half of the preschoolers/pupils/students in Japan recently have complained of daytime sleepiness, while approximately one quarter of junior and senior high school students in Japan reportedly suffer from insomnia. These preschoolers/pupils/students may be suffering from behaviorally induced insufficient sleep syndrome due to inadequate sleep hygiene. If this diagnosis is correct, they should be free from these complaints after obtaining sufficient sleep by avoiding inadequate sleep hygiene. However, such a therapeutic approach often fails. Although social factors are often involved in these sleep disturbances, a novel clinical notion--asynchronization--can further a deeper understanding of the pathophysiology of these disturbances. The essence of asynchronization is a disturbance in various aspects (e.g., cycle, amplitude, phase and interrelationship) of the biological rhythms that normally exhibit circadian oscillation, presumably involving decreased activity of the serotonergic system. The major trigger of asynchronization is hypothesized to be a combination of light exposure during the night and a lack of light exposure in the morning. In addition to basic principles of morning light and an avoidance of nocturnal light exposure, presumable potential therapeutic approaches for asynchronization involve both conventional ones (light therapy, medications (hypnotics, antidepressants, melatonin, vitamin B12), physical activation, chronotherapy) and alternative ones (kampo, pulse therapy, direct contact, control of the autonomic nervous system, respiration (qigong, tanden breathing), chewing, crawling). A morning-type behavioral preference is described in several of the traditional textbooks for good health. The author recommends a morning-type behavioral lifestyle as a way to reduce behavioral/emotional problems, and to lessen the likelihood of falling into asynchronization.

Season of birth, gender, and social-cultural effects on sleep timing preferences in humans

STUDY OBJECTIVE

The present study aimed to analyze season of birth effects on preferred sleep-wake cycle timing as assessed by Morningness-Eveningness Questionnaire (MEQ).

PARTICIPANTS AND MEASUREMENTS

The MEQ was administered to a sample of 5,720 university students (3,851 Italians and 1,869 Spaniards; 3,877 female and 1,843 male; mean age 22.23 +/- 2.98 years).

RESULTS

Females preferred to go to bed significantly earlier and sleep longer than males, regardless of season of birth and nationality. Subjects born in spring and summer went to bed and reached midpoint of sleep later than subjects born in fall and winter. Nationality significantly affected all the sleep parameters considered except duration.

CONCLUSION

Overall, the effect of the season of birth on sleep preference timing was significant but quantitatively small. We suggest an evolutionary context for the different contributions of genetic and environmental factors in modulating sleep-wake cycles in humans.

Maternal feeding controls fetal biological clock

Background

It is widely accepted that circadian physiological rhythms of the fetus are affected by oscillators in the maternal brain that are coupled to the environmental light-dark (LD) cycle.

Methodology/Principal Findings

To study the link between fetal and maternal biological clocks, we investigated the effects of cycles of maternal food availability on the rhythms of Per1 gene expression in the fetal suprachiasmatic nucleus (SCN) and liver using a transgenic rat model whose tissues express luciferase in vitro. Although the maternal SCN remained phase-locked to the LD cycle, maternal restricted feeding phase-advanced the fetal SCN and liver by 5 and 7 hours respectively within the 22-day pregnancy.

Conclusions/Significance

Our results demonstrate that maternal feeding entrains the fetal SCN and liver independently of both the maternal SCN and the LD cycle. This indicates that maternal-feeding signals can be more influential for the fetal SCN and particular organ oscillators than hormonal signals controlled by the maternal SCN, suggesting the importance of a regular maternal feeding schedule for appropriate fetal molecular clockwork during pregnancy.

Prenatal ethanol exposure alters core body temperature and corticosterone rhythms in adult male rats

Ethanol's effects on the developing brain include alterations in morphology and biochemistry of the hypothalamus. To examine the potential functional consequences of ethanol's interference with hypothalamic differentiation, we studied the long-term effects of prenatal ethanol exposure on basal circadian rhythms of core body temperature (CBT) and heart rate (HR). We also examined the late afternoon surge in corticosterone (CORT). Core body temperature and HR rhythms were studied in separate groups of animals at 4, 8, and 20 months of age. The normal late afternoon rise in plasma CORT was examined in freely moving male rats at 6 months of age via an indwelling right atrial cannula. Results showed that the CBT circadian rhythm exhibited an earlier rise after the nadir of the rhythm in fetal alcohol-exposed (FAE) males at all ages compared to controls. At 8 months of age, the amplitude of the CBT circadian rhythm in FAE males was significantly reduced to the level observed in controls at 20 months. No significant effects of prenatal ethanol exposure were observed on basal HR rhythm at any age. The diurnal rise in CORT secretion was blunted and prolonged in 6-month-old FAE males compared to controls. Both control groups exhibited a robust surge in CORT secretion around the onset of the dark phase of the light cycle, which peaked at 7:30 p.m. Whereas FAE males exhibited a linear rise beginning in mid afternoon, which peaked at 9:30 p.m. These results indicate that exposure to ethanol during the period of hypothalamic development can alter the long-term regulation of circadian rhythms in specific physiological systems.

Prenatal mood disturbance predicts sleep problems in infancy and toddlerhood

BACKGROUND

Experimental animal data link prenatal stress with sleep disturbance in offspring, but the link in humans is unclear.

AIMS

To investigate the link between prenatal maternal anxiety and depression and infant sleep disturbance from 6 to 30 months of age.

STUDY DESIGN

Longitudinal prospective study of a large birth cohort from pregnancy to 30 months. Questionnaire measures of anxiety and depression were completed by mothers at 18 and 32 weeks gestation and at 8 weeks and 8 months postpartum.

SUBJECTS

The ALSPAC cohort, a prospective community study of women in the UK who have been followed since pregnancy.

OUTCOME MEASURES

Measures of total sleep time, number of awakenings, and broadly defined sleep problems were available on children at ages 6, 18, and 30 months.

RESULTS

Reliable measures of total sleep time, nighttime awakenings, and sleep problems were identified at 6, 18, and 30 months. Higher levels of prenatal maternal anxiety and depression predicted more sleep problems at 18 and 30 months, after controlling for postnatal mood and obstetric and psychosocial covariates; the association was not restricted to clinical extremes. No link with total sleep time was observed.

CONCLUSIONS

Mood disturbance in pregnancy has persisting effects on sleep problems in the child, a finding that is consistent with experimental animal research. The findings add to a growing literature showing that maternal prenatal stress, anxiety, and depression may have lasting effects on child development.

The mammalian pineal gland: known facts, unknown facets

In the mammalian pineal gland, information on environmental lighting conditions that is neuronally encoded by the retina is converted into nocturnally elevated synthesis of the hormone melatonin. Evolutionary pressure has changed the morphology of vertebrate pinealocytes, eliminating direct photoreception and the endogenous clock function. Despite these changes, nocturnally elevated melatonin synthesis has remained a reliable indicator of time throughout evolution. In the photo-insensitive mammalian pineal gland this message of darkness depends on the master circadian pacemaker in the hypothalamic suprachiasmatic nuclei. The dramatic change in vertebrate pinealocytes has received little attention; here, we therefore link the known evolutionary morphodynamics and well-investigated biochemical details responsible for rhythmic synthesis of melatonin with recently characterized patterns of gene expression in the pineal gland. We also address the enigmatic function of clockwork molecules in mammalian pinealocytes.

Prenatal melatonin and its interaction with tachykinins in the hypothalamic-pituitary-gonadal axis

The pineal gland, through its hormone melatonin, influences the function of the hypothalamic-pituitary-gonadal axis. Tachykinins are bioactive peptides whose presence has been demonstrated in the pineal gland, hypothalamus, anterior pituitary gland and the gonads, in addition to other central and peripheral structures. Tachykinins have been demonstrated to influence the function of the hypothalamic-pituitary-gonadal axis, acting as paracrine factors at each of these levels. In the present review, we examine the available evidence supporting a role for melatonin in the regulation of reproductive functions, the possible role of tachykinins in pineal function and the possible interactions between melatonin and tachykinins in the hypothalamic-pituitary-gonadal axis. Evidence is presented showing that melatonin, given to pregnant rats, influences the developmental pattern of tachykinins in the hypothalamus and the anterior pituitary gland of the offspring during postnatal life. In the gonads, the effects of melatonin on the tachykinin developmental pattern were rather modest. In particular, in the present review, we have included a summary of our own work performed in the past few years on the effect of melatonin on tachykinin levels in the hypothalamic-pituitary-gonadal axis.

Cerebrospinal fluid monoamine metabolite levels in human newborn infants born in winter differ from those born in summer

An earlier study has shown significant differences in the CSF monoamine metabolite levels in adults born during different seasons of the year. We study here the relationship between season of birth and CSF monoamine metabolite levels in 283 newborn febrile infants without neurological abnormalities, with an age distribution ranging from birth to about 3 months, adjusting for the confounding variables age and time at lumbar puncture, weight at birth, estimated gestational age at birth, gender, race, and medicaid status. Each of the three metabolite levels as well as their ratios HVA/5-HIAA and 5-HIAA/MHPG showed significant month-of-birth variations, but not the ratio HVA/MHPG. For HVA and MHPG levels, the maximum was obtained around the winter birth months November-December, whereas for 5-HIAA level, the maximum was obtained around the summer birth months June-July. The correlations between HVA and 5-HIAA were, in general, significantly positive within the different birth seasons and races. Among summer-born Caucasian infants, MHPG was significantly positively correlated with HVA and with 5-HIAA, whereas among winter-born Black infants, MHPG was significantly positively correlated with HVA. Season of birth is an unspecific environmental factor that may be proxy for several possible seasonally varying environmental circumstances such as the length of photoperiod, temperature, infections, nutrition, stress and lifestyle. Studies relating season of birth to monoaminergic turnover at different stages of life may yield important clues about the gestational and perinatal origins of neurodevelopment.

Alterations in circadian rhythm phase shifting ability in rats following ethanol exposure during the third trimester brain growth spurt

BACKGROUND

Disruptions in sleep and feeding rhythms are among the consequences of prenatal alcohol exposure. Previously, we reported that ethanol exposure during the second trimester equivalent in rats produces long-lasting impairments in circadian system functioning. In the present study, we examined the effects of ethanol exposure during the third trimester equivalent brain growth spurt on the development of the circadian clock system.

METHODS

Sprague-Dawley male rat pups were exposed to 6.0 g/kg/d ethanol via an artificial rearing procedure on postnatal days (PD) 4 through 9 (EtOH). An artificially reared gastrostomized control group and a normally reared suckle control group were also included. At 10 to 12 weeks of age, wheel-running behavior was measured continuously under a 12-hour/12-hour light/dark (LD) cycle. Thereafter, subjects were exposed to a 6-hour phase delay of the LD cycle, and the ability to adjust to the new LD cycle was evaluated.

RESULTS

Before the phase delay, onset time of activity and acrophases of activity in all 3 groups were not significantly different from one another. After the 6-hour LD cycle delay, EtOH subjects were slower to adapt to the new cycle compared with both control groups, as measured by both activity onset and acrophase. Throughout the experiment, activity levels of EtOH subjects tended to be higher compared to both controls.

CONCLUSIONS

These data demonstrate that ethanol exposure during the third trimester disrupts the ability to synchronize circadian rhythm to light cues. Disruptions in circadian regulation may cause abnormal behavioral rhythmicity, such as disrupted sleep and feeding patterns, as seen in individuals prenatally exposed to ethanol.

The hypothalamic H1 receptor: a novel therapeutic target for disrupting diurnal feeding rhythm and obesity

Histamine-containing neurons and histamine H1 receptors are distributed within the brain and peripheral tissues. The results of physiological and pharmacological studies have revealed that brain histamine and H1 receptors are involved in the regulation of feeding and obesity in rodents. The adipocytokine leptin regulates feeding and obesity, partially through brain histamine. Furthermore, recent studies have provided evidence that regulation of the diurnal rhythm of feeding through H1 receptors is a crucial factor in the development of obesity. Thus, the regulation of H1 receptors is important for the control of energy metabolism, feeding rhythms and obesity in rodents.