Developmental alcohol exposure alters light-induced phase shifts of the circadian activity rhythm in rats

Sleep Disturbance in Children with Fetal Alcohol Spectrum Disorder and the Relationship to the Neurodevelopmental Profile

OBJECTIVE

Sleep disturbance is an important feature of fetal alcohol spectrum disorder (FASD). We sought to describe sleep patterns in school-aged children with FASD, in comparison with a typically developing community group, and investigate the relationship between sleep and neurodevelopmental profiles.

METHOD

The FASD cohort (N = 36) was recruited from a tertiary Australian FASD diagnostic center, and the typically developing group (N = 36) was previously recruited as a control cohort for a separate study. Sleep disturbance was assessed with the caregiver-completed Sleep Disturbance Scale for Children (SDSC) questionnaire. Neurodevelopmental assessment results for the 10 domains impaired in FASD were used for correlations with sleep disturbance.

RESULTS

In the FASD group, 80% of children scored above the SDSC cutoff, compared with 22% of the control group ( p < 0.001). Statistically significant group differences were seen for all 6 subscales of the SDSC ( p < 0.05). The most frequently affected domains in the FASD group related to difficulties with initiating and maintaining sleep (58%), sleep-wake transition disorders (44%), and disorders of arousal (42%). A statistically significant relationship was not found between sleep and the severity of neurodevelopmental impairment or impairment of a particular domain, acknowledging the limitations of our small sample size. Half of the FASD sample (52%) were taking a pharmaceutical agent to support sleep, which was not associated with lower SDSC scores.

CONCLUSION

In this small study, sleep disturbances were frequently reported by carers of children with FASD, independent of the severity of their neurodevelopmental impairments. Persistent sleep disturbance despite the use of sleep medications highlights the need for prospective studies exploring sleep interventions in this population. Integration of behavioral sleep medicine into management is recommended for all children with FASD.

Home-Cage Sipper Devices Reveal Age and Sex Differences in Ethanol Consumption Patterns

Free-choice paradigms such as two-bottle choice (2BC) are commonly used to characterize ethanol consumption and preference of rodent models used to study alcohol use disorder (AUD). However, these assays are limited by low temporal resolution that misses finer patterns of drinking behavior, including circadian drinking patterns that are known to vary with age and sex and are affected in AUD pathogenesis. Modern, cost-effective tools are becoming widely available that could elucidate these patterns, including open-source, Arduino-based home-cage sipper devices. We hypothesized that adaptation of these home-cage sipper devices would uncover distinct age- and sex-related differences in temporal drinking patterns. To test this hypothesis, we used the sipper devices in a continuous 2BC paradigm using water and ethanol (10%; v/v) for 14 days to measure drinking patterns of male and female adolescent (3-week), young adult (6-week), and mature adult (18-week) C57BL/6J mice. Daily grams of fluid consumption were manually recorded at the beginning of the dark cycle, while home-cage sipper devices continuously recorded the number of sips. Consistent with prior studies, females consumed more ethanol than males, and adolescent mice consumed the most out of any age group. Correlation analyses of manually recorded fluid consumption versus home-cage sipper activity revealed a statistically significant prediction of fluid consumption across all experimental groups. Sipper activity was able to capture subtle circadian differences between experimental groups, as well as distinct individual variation in drinking behavior among animals. Blood ethanol concentrations were significantly correlated with sipper data, suggesting that home-cage sipper devices can accurately determine individual timing of ethanol consumption. Overall, our studies show that augmenting the 2BC drinking paradigm with automated home-cage sipper devices can accurately measure ethanol consumption across sexes and age groups, revealing individual differences and temporal patterns of ethanol drinking behavior. Future studies utilizing these home-cage sipper devices will further dissect circadian patterns for age and sex relevant to the pathogenesis of AUD, as well as underlying molecular mechanisms for patterns in ethanol consumption.

Highlights

Female mice consume more ethanol than males in a continuous access paradigmAdolescent male and female mice consume more ethanol than young or mature adult miceAutomated home-cage sipper devices accurately measure ethanol consumptionDevices reveal sex- and age-dependent differences in circadian drinking patternsDevices reveal distinct individual variation in circadian drinking patterns.

Parent-reported sleep problems in school-aged children with fetal alcohol spectrum disorder: association with child behaviour, caregiver, and family functioning

OBJECTIVE/BACKGROUND

Sleep problems are a common clinically reported area of concern for children and adolescents with fetal alcohol spectrum disorder (FASD). However, limited empirical research has been undertaken investigating sleep problems for children with FASD. The current study aimed to examine the associations between parent-reported sleep problems in children with FASD and child behaviour, caregiver mental health and health-related quality of life and family functioning.

PARTICIPANTS

163 caregivers of children diagnosed with FASD aged 5-17 years were included in the current study.

METHOD

Cross-sectional online survey that collected information pertaining to child sleep problems (difficulty falling asleep, difficulty staying asleep and/or frequent waking during the night and waking early in the morning) and standardised caregiver reported measures of child behaviour, caregiver mental wellbeing, caregiver health-related quality of life, and family functioning.

RESULTS

Sleep problems were common, affecting 65.6% (n = 107) of participants. Difficulty falling asleep (56.4%) was the most common sleep problem encountered, followed by difficulty staying asleep (44.8%) and waking early (29.4%). Sleep problems were associated with increased rates of child behaviour problems and caregiver anxiety and negative impacts on caregiver and family quality of life.

CONCLUSION

Sleep problems in children and adolescents with FASD are common and associated with poorer child, caregiver and family outcomes. Future research needs to determine whether effective identification and management of sleep problems can reduce adverse outcomes.

The Demographic and Neurocognitive Profile of Clients Diagnosed With Fetal Alcohol Spectrum Disorder in PATCHES Paediatrics Clinics Across Western Australia and the Northern Territory

BACKGROUND

Fetal alcohol spectrum disorder (FASD) is a diagnosis relating to neurocognitive impairments associated with prenatal alcohol exposure. A key aspect of improving FASD diagnostic processes and management is understanding the demographic and neurocognitive profile of those living with FASD. The aim of this study was to describe the demographic and neurocognitive profile of the first 199 individuals diagnosed with FASD in PATCHES Paediatrics clinics.

METHODS

A retrospective cross-sectional descriptive study design was conducted with individuals diagnosed with FASD between 2013 and 2018 through a multidisciplinary team according to the Australian FASD Diagnostic Guidelines.

RESULTS

Participants were primarily male 133 (66.8%) and Aboriginal Australian 147 (73.9%), aged 2 to 31 (mean 10.5), with 94 (47.3%) from remote or very remote parts of Western Australia. Participants came from low 119 (59.8%), medium 48 (24.1%), and high 32 (16.1%) socioeconomic (SE) backgrounds. Low SE background was found to be a predictor of number of sentinel facial features (Wald χ2 (1) = 4.03, p < 0.05). Most received a diagnosis of FASD with <3 sentinel features 165 (82.9%). Participants either had 6 or more 46 (23.1%), 5 44 (22.1%), 4 55 (27.6%), or 3 (27.1%) neurodevelopmental domains impaired. Executive functioning was the most commonly impaired neurodevelopmental domain 158 (79.4%), and 31 (61%) reported sleep disturbance. ADHD was the most observed comorbid condition (41.7%).

CONCLUSIONS

This study improves our current understanding of neurocognitive and demographic profiles in individuals with FASD that have been clinically referred for diagnosis within Western Australia and the Northern Territory, and highlights the importance of prevention and early assessment/diagnosis as well as guidance regarding more targeted interventions. FASD affects individuals from all cultural and SE backgrounds. Individuals from middle to higher SE groups are at risk of FASD with prevention efforts needing to target these sectors of society. Suggestions for future research directions are also provided.

Sleep in Infants and Children with Prenatal Alcohol Exposure

Prenatal exposure to alcohol can result in a range of neurobehavioral impairments and physical abnormalities. The term "fetal alcohol spectrum disorders (FASD)" encompasses the outcomes of prenatal alcohol exposure (PAE), the most severe of which is fetal alcohol syndrome. These effects have lifelong consequences, placing a significant burden on affected individuals, caregivers, and communities. Caregivers of affected children often report that their child has sleep problems, and many symptoms of sleep deprivation overlap with the cognitive and behavioral deficits characteristic of FASD. Alcohol-exposed infants and children demonstrate poor sleep quality based on measures of electroencephalography, actigraphy, and questionnaires. These sleep studies indicate a common theme of disrupted sleep pattern, more frequent awakenings, and reduced total sleep time. However, relatively little is known about circadian rhythm disruption and the neurobehavioral correlates of sleep disturbance in individuals with PAE. Furthermore, there is limited information available to healthcare providers about identification and treatment of sleep disorders in patients with FASD. This review consolidates the findings from studies of infant and pediatric sleep in this population, providing an overview of typical sleep characteristics, neurobehavioral correlates of sleep disruption, and potential avenues for intervention in the context of PAE.

Challenging sleep-wake behaviors reported in informal, conversational interviews of caregivers of children with fetal alcohol spectrum disorder

Objective: Sleep complaints are clinically expected in children exposed to alcohol during pregnancy. We aim to reveal patterns of association among sleep-wake behaviors that are challenging in the life of children with fetal alcohol spectrum disorders (FASD). Methods: Through text-mining analyses, we numericized the transcripts of 59 caregiver's informal, conversational interviews. That is, the relative frequencies-of-occurrences of words as well as their semantic specificities (italic) were clustered, categorized, and visualized for patterns. Results: A total of 4008 words were indexed where sleep took the 91st place of most important words. Sleep and wake were however not associatively conversed throughout the interviews. Sleep-related words conversed were: night, nap, apnea, asleep, awake, bed, bedroom, bedtime, mattress, melatonin, overnight, and wake-up. Among some FASD-characteristic words describing the challenges were: huge, alcohol, manage*, stop, adopt, crazy*. The semantic space reflecting these challenges experienced in caring for children with FASD was divided into two axes: child-oriented vs. other-oriented words, and day-related and night-related words. The position of sleep shows that problematic sleep was expressed as a 'family' issue. Clumsy* was interrelated with problematic sleeping and waking. Despite that mostly night was associatively conversed, the association of Routines, Managing, and Planning with sleep underscores the challenges faced. Conclusion: When conversing caregivers of children with FASD seldom interrelate 'sleep' but rather 'night' with FASD-characteristics. Increased sleep awareness combined with educational initiatives regarding sleep are advocated.

Circadian rhythms and addiction: mechanistic insights and future directions

Circadian rhythms are prominent in many physiological and behavioral functions. Circadian disruptions either by environmental or molecular perturbation can have profound health consequences, including the development and progression of addiction. Both animal and humans studies indicate extensive bidirectional relationships between the circadian system and drugs of abuse. Addicted individuals display disrupted rhythms, and chronic disruption or particular chronotypes may increase the risk for substance abuse and relapse. Moreover, polymorphisms in circadian genes and an evening chronotype have been linked to mood and addiction disorders, and recent efforts suggest an association with the function of reward neurocircuitry. Animal studies are beginning to determine how altered circadian gene function results in drug-induced neuroplasticity and behaviors. Many studies suggest a critical role for circadian rhythms in reward-related pathways in the brain and indicate that drugs of abuse directly affect the central circadian pacemaker. In this review, we highlight key findings demonstrating the importance of circadian rhythms in addiction and how future studies will reveal important mechanistic insights into the involvement of circadian rhythms in drug addiction.

"They silently live in terror…" why sleep problems and night-time related quality-of-life are missed in children with a fetal alcohol spectrum disorder

Children and adolescents with a Fetal Alcohol Spectrum Disorder (FASD) are at high-risk for developing sleep problems (SPs) triggering daytime behavioral co-morbidities such as inattention, hyperactivity, and cognitive and emotional impairments. However, symptoms of sleep deprivation are solely associated with typical daytime diagnosis, such as attention deficit hyperactivity disorder (ADHD) and treated with psychotropic medications. To understand how and why SPs are missed, we conducted qualitative interviews (QIs) with six parents and seven health care professionals (HCPs), and performed comprehensive clinical sleep assessments (CCSAs) in 27 patients together with their caregivers referred to our clinic for unresolved SPs. We used narrative schema and therapeutic emplotment in conjunction with analyzes of medical records to appropriately diagnose SPs and develop treatment strategies. The research was conducted at British Columbia Children's Hospital in Vancouver (Canada) between 2008 and 2011. In the QIs, parents and HCPs exhibited awareness of the significance of SPs and the effects of an SP on the daytime behaviors of the child and the associated burdens on the parents. HCPs' systemic inattention to the sequelae of SPs and the affected family's wellbeing appears due to an insufficient understanding of the various factors that contribute to nighttime SPs and their daytime sequelae. In the CCSAs, we found that the diagnostic recognition of chronic SPs in children and adolescents was impaired by the exclusive focus on daytime presentations. Daytime behavioral and emotional problems were targets of pharmacological treatment rather than the underlying SP. Consequently, SPs were also targeted with medications, without investigating the underlying problem. Our study highlights deficits in the diagnostic recognition of chronic SPs among children with chronic neurodevelopmental disorders/disabilities and proposes a clinical practice strategy, based on therapeutic emplotment that incorporates patients and parents' contributions in recognizing SPs and related sequelae in designing appropriate treatment and care.

Larval ethanol exposure alters adult circadian free-running locomotor activity rhythm in Drosophila melanogaster

Alcohol consumption causes disruptions in a variety of daily rhythms, including the sleep-wake cycle. Few studies have explored the effect of alcohol exposure only during developmental stages preceding maturation of the adult circadian clock, and none have examined the effects of alcohol on clock function in Drosophila. This study investigates developmental and behavioral correlates between larval ethanol exposure and the adult circadian clock in Drosophila melanogaster, a well-established model for studying circadian rhythms and effects of ethanol exposure. We reared Drosophila larvae on 0%, 10%, or 20% ethanol-supplemented food and assessed effects upon eclosion and the free-running period of the circadian rhythm of locomotor activity. We observed a dose-dependent effect of ethanol on period, with higher doses resulting in shorter periods. We also identified the third larval instar stage as a critical time for the developmental effects of 10% ethanol on circadian period. These results demonstrate that developmental ethanol exposure causes sustainable shortening of the adult free-running period in Drosophila melanogaster, even after adult exposure to ethanol is terminated, and suggests that the third instar is a sensitive time for this effect.

Dim light melatonin onset in alcohol-dependent men and women compared with healthy controls

Sleep disturbances in alcohol-dependent (AD) individuals may persist despite abstinence from alcohol and can influence the course of the disorder. Although the mechanisms of sleep disturbances of AD are not well understood and some evidence suggests dysregulation of circadian rhythms, dim light melatonin onset (DLMO) has not previously been assessed in AD versus healthy control (HC) individuals in a sample that varied by sex and race. The authors assessed 52 AD participants (mean ± SD age: 36.0 ± 11.0 yrs of age, 10 women) who were 3-12 wks since their last drink (abstinence: 57.9 ± 19.3 d) and 19 age- and sex-matched HCs (34.4 ± 10.6 yrs, 5 women). Following a 23:00-06:00 h at-home sleep schedule for at least 5 d and screening/baseline nights in the sleep laboratory, participants underwent a 3-h extension of wakefulness (02:00 h bedtime) during which salivary melatonin samples were collected every 30 min beginning at 19:30 h. The time of DLMO was the primary measure of circadian physiology and was assessed with two commonly used methodologies. There was a slower rate of rise and lower maximal amplitude of the melatonin rhythm in the AD group. DLMO varied by the method used to derive it. Using 3 pg/mL as threshold, no significant differences were found between the AD and HC groups. Using 2 standard deviations above the mean of the first three samples, the DLMO in AD occurred significantly later, 21:02 ± 00:41 h, than in HC, 20:44 ± 00:21 h (t = -2.4, p = .02). Although melatonin in the AD group appears to have a slower rate of rise, using well-established criteria to assess the salivary DLMO did not reveal differences between AD and HC participants. Only when capturing melatonin when it is already rising was DLMO found to be significantly delayed by a mean 18 min in AD participants. Future circadian analyses on alcoholics should account for these methodological caveats.

Effects of neonatal alcohol exposure on vasoactive intestinal polypeptide neurons in the rat suprachiasmatic nucleus

Neonatal alcohol exposure produces long-term changes in the suprachiasmatic nucleus (SCN) that are presumably responsible for disturbances in the light-dark regulation of circadian behavior in adult rats, including the pattern of photoentrainment, rate of re-entrainment to shifted light-dark cycles, and phase-shifting responses to light. Because SCN neurons containing vasoactive intestinal polypeptide (VIP) receive direct photic input via the retinohypothalamic tract and thus play an important role in the circadian regulation of the SCN clock mechanism by light, the present study examined the long-term effects of neonatal alcohol exposure on VIP neuronal populations within the SCN of adult rats. Male Sprague-Dawley rat pups were exposed to alcohol (EtOH; 3.0, 4.5, or 6.0 g/kg/day) or isocaloric milk formula (gastrostomy control; GC) on postnatal days 4-9 using artificial-rearing methods. At 2-3 months of age, animals from the suckle control (SC), GC, and EtOH groups were exposed to constant darkness (DD) and SCN tissue was harvested for subsequent analysis of either VIP mRNA expression by quantitative polymerase chain reaction (PCR) and in situ hybridization or of VIP-immunoreactive (ir) neurons using stereological methods. Neonatal alcohol exposure had no impact on VIP mRNA expression but dramatically altered immunostaining of neurons containing this peptide within the SCN of adult rats. The relative abundance of VIP mRNA and anatomical distribution of neurons expressing this transcript were similar among all control- and EtOH-treated groups. However, the total number and density of VIP-ir neurons within the SCN were significantly decreased by about 35% in rats exposed to alcohol at a dose of 6.0 g/kg/day relative to that observed in both control groups. These results demonstrate that VIP neuronal populations in the SCN are vulnerable to EtOH-induced insult during brain development. The observed alterations in SCN neurons containing VIP may have an impact upon clock responses to light input and thus contribute to the long-term effects of neonatal alcohol exposure on the photic regulation of circadian behavior.

Sleep fragmentation and evidence for sleep debt in alcohol-exposed infants

BACKGROUND

Infants exposed prenatally to alcohol are at increased risk for poor neurodevelopmental outcome including Sudden Infant Death Syndrome.

AIM

To examine the relationship between prenatal alcohol exposure, sleep, arousal and sleep-related spontaneous motor movements in early infancy.

STUDY DESIGN

Low-income women (N=13) were interviewed regarding pre- and pregnancy rates of alcohol, cigarette smoking and other substance use in the perinatal period. Infants were examined in a laboratory nap study using EEG, videography and actigraphy at 6-8 weeks of age. Estimates of maternal pre- and pregnancy alcohol use were used to divide infants into high vs. low maternal alcohol use groups.

SUBJECTS

Mother-infant dyads recruited from a family practice clinic.

OUTCOME MEASURES

Sleep-related spontaneous movements, behavioral state, and maternal assessments of infant alertness and irritability.

RESULTS

Pre-pregnancy rates of alcohol consumption including binge drinking correlated with maternal report of poor infant alertness, and increased irritability. High maternal exposure groups showed increased sleep fragmentation, e.g., frequency and duration of wakefulness following sleep onset and decreased active sleep. Bout analysis of the temporal structure of sleep-related spontaneous movements showed significantly reduced bout duration associated with high maternal alcohol use.

CONCLUSION

These results present evidence that prenatal alcohol exposure disrupts postnatal sleep organization and suppresses spontaneous movements during sleep, and increased sleep fragmentation promotes sleep deprivation. Results are consistent with the SIDS model of chronic sleep debt and suggest that attenuated sleep-related movements should be examined as an important modulator of cardiorespiratory functions during sleep in high-risk groups.

Perinatal alcohol exposure leads to prolonged upregulation of hypothalamic GABA A receptors and increases behavioral sensitivity to gaboxadol

Prenatal alcohol exposure (AE) is associated with lasting abnormalities of sleep and motor development, but the underlying mechanisms are unknown. We hypothesized that AE alters development of GABAergic signaling in the hypothalamic regions important for the control of sleep and motor activity. Alcohol (5.25 g/(kg day)) was administered intragastrically to male rats on postnatal days (PD) 4-9, a period of brain development equivalent to the human third trimester (AE group). Control pups were sham-intubated (S group). Motor activity was monitored on PD27 and 28. On PD29 and 30, GABA A receptor subunit mRNA levels and alpha4 and delta subunit proteins were quantified by RT-PCR and immunoblotting, respectively, in the wake- and motor activity-promoting perifornical (PF) region of the posterior hypothalamus and the sleep-promoting ventrolateral preoptic (VLPO) region of the anterior hypothalamus. Then, in 47-52-day-old rats, motor activity was quantified following administration of GABA A receptor agonist, gaboxadol (5 mg/kg s.c.). In the PF region, mRNA and protein levels for the alpha4 and delta subunits were significantly higher and beta3 and gamma2 subunit mRNAs were also increased in the AE group. In the VLPO region, only the delta subunit mRNA was increased. Spontaneous motor activity was lower and suppressed more by gaboxadol in the AE than S group, and the latency to a transient total loss of activity after gaboxadol was shorter in the AE group. Thus, perinatal AE leads to GABA A receptor overexpression in the vigilance- and motor activity-promoting hypothalamic PF region, with the neurochemical and functional outcomes lasting long beyond the period of the insult.

Neonatal alcohol exposure differentially alters clock gene oscillations within the suprachiasmatic nucleus, cerebellum, and liver of adult rats

BACKGROUND

In rats, alcohol exposure during the period of rapid brain growth produces long-term changes in the free-running period, photoentrainment and phase-shifting responses of the circadian rhythm in wheel-running behavior. To determine whether these alterations in circadian behavior are associated with permanent damage to the circadian timekeeping mechanism or reconfiguration of its molecular components, we examined the long-term effects of neonatal alcohol exposure on clock gene rhythms in the pacemaker located in the suprachiasmatic nucleus (SCN) and in other brain or peripheral tissues of adult rats.

METHODS

Artificially reared male rat pups were exposed to alcohol (4.5 g/kg/d) or isocaloric milk formula (gastrostomy control; GC) on postnatal days 4 to 9. At 3 months of age, animals were exposed to constant darkness and then SCN, cerebellum, and liver tissue were harvested at 6-hour intervals for subsequent analysis of Period1 (Per1), Per2, Cryptochrome1 (Cry1), Bmal1, and Rev-erbalpha mRNA levels by quantitative PCR.

RESULTS

In the SCN, cerebellum and liver, Per1, Per2, Cry1, Bmal1, and Rev-erbalpha expression oscillated with a similar amplitude (peak-to-trough differences of 2- to 9-fold) and phase in the suckle control (SC) and GC groups. These clock gene rhythms in control animals were marked by peak expression of Per1, Per2, Cry1, and Rev-erbalpha during the subjective day and of Bmal1 during the subjective night. The EtOH group was distinguished by altered rhythms in the expression of specific clock genes within the SCN, cerebellum and liver. In EtOH-treated rats, the SCN rhythm in Cry1 expression was strongly damped and the Per2 rhythms in the cerebellum and liver were phase-advanced such that peak expression occurred during the mid-subjective day.

CONCLUSIONS

These results demonstrate alcohol exposure during the brain growth spurt alters the circadian regulation of some molecular components of the clock mechanism in the rat SCN, cerebellum, and liver. The observed alterations in the temporal configuration of essential "gears" of the molecular clockworks may play a role in the long-term effects of neonatal alcohol exposure on the regulation of circadian behavior.

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.

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.

Fetal Ethanol Exposure Disrupts the Daily Rhythms of Splenic Granzyme B, IFN-gamma, and NK Cell Cytotoxicity in Adulthood

BACKGROUND

Circadian (and daily) rhythms are physiological events that oscillate with a 24-hour period. Circadian disruptions may hamper the immune response against infection and cancer. Several immune mechanisms, such as natural killer (NK) cell function, follow a daily rhythm. Although ethanol is known to be a potent toxin for many systems in the developing fetus, including the immune system, the long-term effects of fetal ethanol exposure on circadian immune function have not been explored.

METHODS

Daily rhythms of cytotoxic factors (granzyme B and perforin), interferon-gamma (IFN-gamma), and NK cell cytotoxic activity were determined in the spleens of adult male rats obtained from mothers who were fed during pregnancy with chow food or an ethanol-containing liquid diet or pair-fed an isocaloric liquid diet.

RESULTS

We found that adult rats exposed to ethanol during their fetal life showed a significant alteration in the physiological rhythms of granzyme B and IFN-gamma that was associated with decreased NK cell cytotoxic activity.

CONCLUSION

These data suggest that fetal ethanol exposure causes a permanent alteration of specific immune rhythms that may in part underlie the immune impairment observed in children prenatally exposed to alcohol.

Artificial Lighting in the Industrialized World: Circadian Disruption and Breast Cancer

Breast cancer risk is high in industrialized societies, and increases as developing countries become more Westernized. The reasons are poorly understood. One possibility is circadian disruption from aspects of modern life, in particular the increasing use of electric power to light the night, and provide a sun-free environment during the day inside buildings. Circadian disruption could lead to alterations in melatonin production and in changing the molecular time of the circadian clock in the suprachiasmatic nuclei (SCN). There is evidence in humans that the endogenous melatonin rhythm is stronger for persons in a bright-day environment than in a dim-day environment; and the light intensity necessary to suppress melatonin at night continues to decline as new experiments are done. Melatonin suppression can increase breast tumorigenesis in experimental animals, and altering the endogenous clock mechanism may have downstream effects on cell cycle regulatory genes pertinent to breast tissue development and susceptibility. Therefore, maintenance of a solar day-aligned circadian rhythm in endogenous melatonin and in clock gene expression by exposure to a bright day and a dark night, may be a worthy goal. However, exogenous administration of melatonin in an attempt to achieve this goal may have an untoward effect given that pharmacologic dosing with melatonin has been shown to phase shift humans depending on the time of day it's given. Exogenous melatonin may therefore contribute to circadian disruption rather than alleviate it.

Alcohol consumption and the body's biological clock

This review summarizes new findings on the bidirectional interactions between alcohol and the clock genes, underlying the generation of circadian rhythmicity. At the behavioral level, both adult and perinatal ethanol treatments after the free-running period and light response of the circadian clock in rodents; genetic ethanol preference in alcohol-preferring rat lines is also associated with alterations in circadian pacemaker function. At the neuronal level, it has been shown that ethanol consumption alters the circadian expression patterns of period (per) genes in various brain regions, including the suprachiasmatic nucleus. Notably, circadian functions of beta-endorphin-containing neurons that participate in the control of alcohol reinforcement become disturbed after chronic alcohol intake. In turn, per2 gene activity regulates alcohol intake through its effects on the glutamatergic system through glutamate reuptake mechanisms and thereby may affect a variety of physiological processes that are governed by our internal clock. In summary, a new pathologic chain has been identified that contributes to the negative health consequences of chronic alcohol intake. Thus, chronic alcohol intake alters the expression of per genes, and as a consequence, a variety of neurochemical and neuroendocrine functions become disturbed. Further steps in this pathologic chain are alterations in physiological and immune functions that are under circadian control, and, as a final consequence, addictive behavior might be triggered or sustained by this cascade.

Neonatal alcohol exposure permanently disrupts the circadian properties and photic entrainment of the activity rhythm in adult rats

BACKGROUND

Alcohol exposure during the period of rapid brain development produces structural damage in different brain regions, including the suprachiasmatic nucleus (SCN), that may have permanent neurobehavioral consequences. Thus, this study examined the long-term effects of neonatal alcohol exposure on circadian behavioral activity in adult rats.

METHODS

Artificially reared Sprague-Dawley rat pups were exposed to alcohol (EtOH; 4.5 g/kg/day) or isocaloric milk formula (gastrostomy control; GC) on postnatal days 4-9. At 2 months of age, rats from the EtOH, GC, and suckle control (SC) groups were housed individually, and properties of the circadian rhythm in wheel-running behavior were continuously analyzed during exposure to a 12-hr light:12-hr dark photoperiod (LD 12:12) or constant darkness (DD).

RESULTS

Neonatal alcohol exposure had distinctive effects on the rhythmic properties and quantitative parameters of adult wheel-running behavior. EtOH-treated animals were distinguished by unstable and altered entrainment to LD 12:12 such that their daily onsets of activity were highly variable and occurred at earlier times relative to control animals. In DD, circadian regulation of wheel-running behavior was altered by neonatal alcohol exposure such that the free-running period of the activity rhythm was shorter in EtOH-exposed rats than in control animals. Total amount of daily wheel-running activity in EtOH-treated rats was greater than that observed in the SC group. In addition, the circadian activity patterns of EtOH-exposed rats were fragmented such that the duration of the active phase and the number of activity bouts per day were increased.

CONCLUSIONS

These data indicate that neonatal alcohol exposure produces permanent changes in the circadian regulation of the rat activity rhythm and its entrainment to LD cycles. These long-term alterations in circadian behavior, along with the developmental alcohol-induced changes in SCN endogenous rhythmicity, may have important implications in clinical sleep-wake disturbances observed in neonates, children, and adults exposed to alcohol in utero.

Long-term effects of neonatal alcohol exposure on photic reentrainment and phase-shifting responses of the activity rhythm in adult rats

In rats, neonatal alcohol (EtOH) exposure coinciding with the period of rapid brain growth produces structural damage in some brain regions that often persists into adulthood and thus may have long-term consequences in the neural regulation of behavior. Because recent findings indicate that the circadian clock located in the rat suprachiasmatic nucleus is vulnerable to alcohol-induced insults during development, the present study examined the long-term effects of neonatal alcohol exposure on the photic regulation of circadian behavior in adult rats. Rat pups were exposed to alcohol (3.0, 4.5, or 6.0 g x kg(-1) x day(-1)) or isocaloric milk formula on postnatal days 4-9 using artificial-rearing methods. At 2 months of age, animals were housed individually and circadian wheel-running behavior was continuously analyzed to determine the effects of neonatal alcohol treatment on the rate of reentrainment to a 6-h advance in the 12-h light:12-h dark photoperiod and the phase-shifting properties of free-running rhythms in response to discrete light pulses on a background of constant darkness. For all doses, neonatal alcohol exposure had a significant effect in reducing the time for reentrainment such that EtOH-treated rats required four to five fewer days than control animals for stable realignment of the activity rhythm to the shifted light-dark cycle. Coupled with the accelerated rate of reentrainment, the amplitude of light-evoked phase delays at circadian time 14 and advances at circadian time 22 in the 4.5 and 6.0 g x kg(-1) x day(-1) EtOH groups was almost twofold greater than that observed in control animals. The present observations indicate that the mechanisms by which photic signals regulate circadian behavior are permanently altered following alcohol exposure during the period of rapid brain development. These long-term alterations in the photic regulation of circadian rhythms may account, at least partially, for some neurobehavioral consequences of prenatal alcohol exposure in humans such as depression.

Chronic ethanol intake alters circadian period-responses to brief light pulses in rats

Although chronic alcohol intake is associated with widespread disruptions of sleep-wake cycles and other daily biological rhythms in both human alcoholics and experimental animals, the extent to which the chronobiological effects of alcohol are mediated by effects on the underlying circadian pacemaker remains unknown. Nevertheless, recent studies indicate that both adult and perinatal ethanol treatments may alter the free-running period and photic responsiveness of the circadian pacemaker. The present experiment was designed to further characterize the effects of chronic ethanol intake on the response of the rat circadian pacemaker to brief light pulses. Ethanol-treated and control animals were exposed to 15-min light pulses during either early or late subjective night on the first day of constant darkness following entrainment to a 12:12 light-dark cycle. Relative to pulses delivered during early subjective night and to "no-pulse" conditions, light pulses delivered during late subjective night resulted in period-shortening after-effects under constant darkness, but only in control animals, not in ethanol-treated animals. These results indicate that chronic ethanol intake reduces the responsiveness of the circadian pacemaker to acute photic stimulation, and suggest that the chronobiological disruptions seen in human alcoholics are due in part to alterations in circadian pacemaker function.

Circadian activity rhythms in selectively bred ethanol-preferring and nonpreferring rats

Chronic alcohol intake is associated with dramatic disruptions in sleep and other circadian biological rhythms in both humans and experimental animals. In human alcoholics, these disruptions persist during extended abstinence and appear to promote relapse to drinking. Whereas chronic ethanol intake alters fundamental properties of the circadian pacemaker in unselected rats, nothing is known concerning circadian pacemaker function in selectively bred ethanol-preferring and nonpreferring rats, which are the most widely accepted animal models of genetic predisposition to alcoholism. The present experiments were designed to characterize free-running circadian activity (wheel-running) rhythms under both constant darkness and constant light in selectively bred ethanol-preferring (P, HAD2) and nonpreferring (NP, LAD2) rats. Differences in circadian organization between ethanol-preferring and nonpreferring animals were seen for both pairs of selected lines (P vs. NP; HAD2 vs. LAD2), but these differences were not identical in the two line pairs. For example, although P rats showed shorter free-running periods than NP rats only in constant light, HAD2 rats showed shorter free-running periods than LAD2 rats only in constant darkness. In addition, ethanol-preferring HAD2 rats showed a high rate of rhythm "splitting" that was not seen in any of the other three lines. Taken together, these results suggest that the circadian pacemakers of P and NP rats differ mainly in light sensitivity, whereas those of HAD2 and LAD2 rats differ in their intrinsic period.