Reduction in ultrasonic vocalizations in pups born to rapid eye movement sleep restricted mothers in rat model

A meta-analysis of sex differences in neonatal rodent ultrasonic vocalizations and the implication for the preclinical maternal immune activation model

As the earliest measure of social communication in rodents, ultrasonic vocalizations (USVs) in response to maternal separation are critical in preclinical research on neurodevelopmental disorders (NDDs). While sex differences in both USV production and behavioral outcomes are reported, many studies overlook sex as a biological variable in preclinical NDD models. We aimed to evaluate sex differences in USV call parameters and determine if USVs are differently impacted based on sex in the preclinical maternal immune activation (MIA) model. Results indicate that sex differences in USVs vary with developmental stage and are more pronounced in MIA offspring. Specifically, developmental stage is a moderator of sex differences in USV call duration, with control females emitting longer calls than males in early development (up to postnatal day [PND] 8), but this pattern reverses after PND8. MIA leads to a reduction in call numbers for females compared to same-sex controls in early development, with a reversal post-PND8. MIA decreased call duration and increased total call duration in males, but unlike females, developmental stage did not influence these differences. In males, MIA effects varied by species, with decreased call numbers in rats but increased call numbers in mice. MIA timing (gestational day ≤ 12.5 vs. > 12.5) did not significantly affect results. Our findings highlight the importance of considering sex, developmental timing, and species in USVs research. We discuss how analyzing USV call types and incorporating sex as a biological variable can enhance our understanding of neonatal ultrasonic communication and its translational value in NDD research.

Acoustic complexity of pup isolation calls in Mongolian hamsters: 3-frequency phenomena and chaos

Studying pup isolation calls of wild rodents provides background for developing new early-life animal models for biomedical research and drug testing. This study discovered a highly complex acoustic phenotype of pup isolation calls in 4-5-day-old Mongolian hamsters Allocricetulus curtatus. We analyzed the acoustic structure of 5,010 isolation calls emitted in the broad range of frequencies (sonic, below 20 kHz, and ultrasonic, from 20 to 128 kHz) by 23 pups during 2-min isolation test trials, 1 trial per pup. In addition, we measured 5 body size parameters and the body weight of each pup. The calls could contain up to 3 independent fundamental frequencies in their spectra, the low (f0), the medium (g0), and the high (h0), or purely consisted of chaos in which the fundamental frequency could not be tracked. By presence/absence of the 3 fundamental frequencies or their combinations and chaos, we classified calls into 6 distinctive categories (low-frequency [LF]-f0, LF-chaos, high-frequency [HF]-g0, HF-h0, HF-g0 + h0, and HF-chaos) and estimated the relative abundance of calls in each category. Between categories, we compared acoustic parameters and estimated their relationship with pup body size index. We discuss the results of this study with data on the acoustics of pup isolation calls reported for other species of rodents. We conclude that such high complexity of Mongolian hamster pup isolation calls is unusual for rodents. Decreased acoustic complexity serves as a good indicator of autism spectrum disorders in knockout mouse models, which makes knockout hamster models prospective new wild animal model of neurodevelopmental disorders.

Sleep and local field potential effect of the D2 receptor agonist bromocriptine during the estrus cycle and postpartum period in female rats

BACKGROUND

Pituitary lactotrophs are under tonic dopaminergic inhibitory control and bromocriptine treatment blocks prolactin secretion.

METHODS

Sleep and local field potential were addressed for 72 h after bromocriptine treatments applied during the different stages of the estrus cycle and for 24 h in the early- and middle postpartum period characterized by spontaneously different dynamics of prolactin release in female rats.

RESULTS

Sleep changes showed strong dependency on the estrus cycle phase of the drug application. Strongest increase of wakefulness and reduction of slow wave sleep- and rapid eye movements sleep appeared during diestrus-proestrus and middle postpartum treatments. Stronger sleep-wake effects appeared in the dark phase in case of the estrus cycle treatments, but in the light phase in postpartum treatments. Slow wave sleep and REM sleep loss in case of estrus cycle treatments was not compensated at all and sleep loss seen in the first day post-injection was gained further later. In opposition, slow wave sleep loss in the light phase after bromocriptine injections showed compensation in the postpartum period treatments. Bromocriptine treatments resulted in a depression of local field potential delta power during slow wave sleep while an enhancement in beta and gamma power during wakefulness regardless of the treatment timing.

CONCLUSIONS

These results can be explained by the interplay of dopamine D2 receptor agonism, lack of prolactin release and the spontaneous homeostatic sleep drive being altered in the different stages of the estrus cycle and the postpartum period.

Postnatal melatonin administration to stressed dams for ameliorating risk-taking behaviour in rat pups through maternal care improvement

BACKGROUND AND AIM

Anxiety often occurs both concurrently and sequentially in childhood and adolescence in association with prenatal stress, which may reduce the quality of maternal care and then cause mood disorders among children in later life. Against this background, melatonin, as a powerful antioxidant, was used in the present study to ameliorate risk-taking behaviour induced by pure maternal care in rat pups.

MATERIALS AND METHODS

The Wistar rat dams recruited in this study were exposed to restraint stress from gestational day (GD) 11 until delivery. They further received melatonin (10 mg/kg) during the postnatal days (PNDs) 0-7 by intraperitoneal (IP) injections at 4:00 PM. The pregnant rats were then divided into four groups, namely, control, stress, stress + melatonin and melatonin, and their maternal behaviour and corticosterone levels were measured. In the offspring, the outcomes of some behavioural tasks, including the elevated plus-maze (EPM) and open-field (OF) tests were ultimately assessed.

RESULTS

The study results revealed that the quantity and quality of maternal care significantly declined and the plasma corticosterone levels compounded in the stressed dams. Melatonin treatment, however, improved their nursing behaviour and reduced their plasma corticosterone levels. The offspring performance in two tasks also showed an upward trend in risk-taking behaviour in the stress group, and melatonin administration ameliorated the effects of stress and lessened their anxiety-like behaviour.

CONCLUSION

It was concluded that prenatal restraint stress could impair stress responses and quality of maternal care, whereas postnatal melatonin administration potentially contributed to the normalization of stress reaction and anxiolysis.

Altered cognition and anxiety in adolescent offspring whose mothers underwent different-pattern maternal sleep deprivation, and cognition link to hippocampal expressions of Bdnf and Syt-1

Background

Inadequate sleep during pregnancy negatively affects the neural development of offspring. Previous studies have focused on the continuous sleep deprivation (CSD) paradigm, but the sleep pattern during late pregnancy is usually fragmented.

Objective

To compare the effects of CSD and fragmented sleep deprivation (FSD) in late pregnancy on emotion, cognition, and expression of synaptic plasticity-related proteins in offspring mice.

Methods

Pregnant CD-1 mice were either subjected to 3/6 h of CSD/FSD during gestation days 15-21, while those in the control group were left untreated. After delivery, the offspring were divided into five groups, i.e., control (CON), short or long CSD (CSD3h, CSD6h), and short or long FSD (FSD3h, FSD6h). When the offspring were 2 months old, the anxiety-like behavior level was tested using the open field (OF) and elevated plus maze (EPM) test, and spatial learning and memory were evaluated using the Morris water maze (MWM) test. The expression of hippocampal of brain-derived neurotrophic factor (Bdnf) and synaptotagmin-1 (Syt-1) was determined using RT-PCR and western blotting.

Results

The CSD6h, FSD3h, and FSD6h had longer latency, fewer center times in the OF test, less open arms time and fewer numbers of entries in the open arms of the EPM, longer learning distance swam and lower memory percentage of distance swam in the target quadrant in the MWM test, and decreased BDNF and increased Syt-1 mRNA and protein levels in the hippocampus. Compared to the CSD6h, the FSD3h and FSD6h had longer distance swam, a lower percentage of distance swam in the target quadrant, decreased BDNF, and increased Syt-1 mRNA and protein levels in the hippocampus.

Conclusion

The results suggested that maternal sleep deprivation during late pregnancy impairs emotion and cognition in offspring, and FSD worsened the cognitive performance to a higher extent than CSD. The observed cognitive impairment could be associated with the expression of altered hippocampal of Bdnf and Syt-1 genes.

Influence of early social isolation on general activity and spatial learning in adult WAG/Rij rats

The study identifies the critical period of early ontogeny, during which social factors have the greatest influence on the operant behavior with positive reinforcement in adult WAG/Rij rats. Individual social isolation of rats from dam and siblings was performed daily for 3 h during postnatal day (PND) 2-8, 9-15, and 16-22. General activity and water consumption were examined using the IntelliCage (IC) in adulthood. The operant behavior training was performed in four consecutive sessions: free exploration of the IC environment (adaptation), learning to retrieve water by nosepoking (nosepoke adaptation), spatial learning to retrieve water in the specific corner (place learning), and retraining with a change of a place preference (reversal learning). Social isolation during PND16-22 led to the greatest behavioral changes in all sessions of the experiment. These rats were more active, consumed more water, demonstrated a higher ratio of visits with drinking to the total number, and relearned faster after changing the location of the rewarded corner. Thus, the postnatal period between days 16 and 22 in WAG/Rij rat pups is more sensitive to social isolation for change of adaptive behavior in the IC in adulthood.

Ultrasonic Vocalizations Emission across Development in Rats: Coordination with Respiration and Impact on Brain Neural Dynamics

Rats communicate using ultrasonic vocalizations (USV) throughout their life when confronted with emotionally stimulating situations, either negative or positive. The context of USV emission and the psychoacoustic characteristics of the vocalizations change greatly between infancy and adulthood. Importantly, the production of USV is tightly coordinated with respiration, and respiratory rhythm is known to influence brain activity and cognitive functions. This review goes through the acoustic characteristics and mechanisms of production of USV both in infant and adult rats and emphasizes the tight relationships that exist between USV emission and respiration throughout the rat's development. It further describes how USV emission and respiration collectively affect brain oscillatory activities. We discuss the possible association of USV emission with emotional memory processes and point out several avenues of research on USV that are currently overlooked and could fill gaps in our knowledge.

Effects of sleep deprivation on maternal behaviour in animal models: A systematic review and meta-analysis

Pregnancy is a period of numerous physical and emotional changes in women's lives, including alterations in sleep patterns and worsening of pre-existing sleep disturbances, which possibly lead to impaired postpartum maternal behaviour and mother-infant relationship. The effects of sleep deprivation during pregnancy in maternal behaviour have been evaluated in preclinical studies, but have provided inconsistent results. Thus, in the present study, we aimed to evaluate the effects of sleep deprivation during pregnancy on maternal behaviour of animals through a systematic review and meta-analyses. After a two-step selection process, six articles were included, all of them describing rat studies. The most frequently used method of sleep deprivation was rapid eye movement sleep restriction, using the multiple-platform method. Four meta-analyses were performed, none of them presenting significant impact of sleep deprivation on maternal behaviour, failing to reproduce the results observed in previous clinical studies. In conclusion, our results show a lack of translational applicability of animal models to evaluate the effects of sleep deprivation during pregnancy on maternal behaviour.

Effects of sleep restriction during pregnancy on postpartum maternal behavior in female rats

Preclinical studies evaluating the effects of gestational sleep restriction on maternal behavior are needed in order to provide information on the background mechanisms underlying this relationship. In this study, 32 female 90 days-old Wistar-Hannover rats were distributed in two groups: Control group (CTRL - n = 13), not subjected to any manipulation during pregnancy; and sleep restriction group (SR - n = 19) - subjected to sleep restriction during the whole pregnancy (21 days). Maternal behavioral analysis was conducted from postpartum day 1 (PPD1) to PPD7, based on observational ethograms. On PPD11 the animals were subjected to the grooming analysis algorithm, followed by the elevated plus maze. Results from an ethogram-based analysis indicated a decrease in self-grooming among sleep-deprived rats (denoting reduced anxiety-like behavior), but no significant differences were found in maternal behavior (except for a slight increase in high arched-back nursing). Controlled analysis detected an impairment in high-arched back nursing in sleep-deprived animals. The grooming microstructure analysis showed an increased frequency of incorrect transitions among sleep restricted animals, indicating increased anxiety-like behavior. No significant differences were observed in the elevated-plus maze. In conclusion, sleep-restricted pregnant rats display an equivalent or slightly increased maternal behavior during the postpartum period, when compared to control animals.

Effects of sleep modulation during pregnancy in the mother and offspring: Evidences from preclinical research

Disturbed sleep during gestation may lead to adverse outcomes for both mother and child. Animal research plays an important role in providing insights into this research field by enabling ethical and methodological requirements that are not possible in humans. Here, we present an overview and discuss the main research findings related to the effects of prenatal sleep deprivation in animal models. Using systematic review approaches, we retrieved 42 articles dealing with some type of sleep alteration. The most frequent research topics in this context were maternal sleep deprivation, maternal behaviour, offspring behaviour, development of sleep-wake cycles in the offspring, hippocampal neurodevelopment, pregnancy viability, renal physiology, hypertension and metabolism. This overview indicates that the number of basic studies in this field is growing, and provides biological plausibility to suggest that sleep disturbances might be detrimental to both mother and offspring by promoting increased risk at the behavioural, hormonal, electrophysiological, metabolic and epigenetic levels. More studies on the effects of maternal sleep deprivation are needed, in light of their major translational perspective.

Pioglitazone alleviates maternal sleep deprivation-induced cognitive deficits in male rat offspring by enhancing microglia-mediated neurogenesis

Maternal sleep disturbance in pregnancy causes cognitive impairments and emotional disorders in offspring. Microglia-mediated inflammatory processes contribute to prenatal stress-induced neurodevelopmental deficits. Peroxisome proliferator-activated receptor gamma (PPARγ) activation underlies the switching of microglial activation phenotypes, which has emerged as a pharmacological target for regulating neuroinflammatory responses in the treatment of neuropsychiatric disorders. Here we investigated the effects of PPARγ-dependent microglial activation on neurogenesis and cognitive behavioral outcomes in male rat offspring exposed to maternal sleep deprivation (MSD) for 72 h from days 18-21 of pregnancy. In the Morris water maze test, male MSD rat offspring needed more time than control offspring to escape to the hidden platform and spent less time in the target quadrant when the hidden platform was removed. In MSD rat offspring, microglial density as determined by immunofluorescence was higher, microglia showed fewer and shorter processes, and neurogenesis in the hippocampus was significantly reduced. Levels of mRNA encoding pro-inflammatory markers IL-6, TNFα, and IL-1β were higher in male MSD offspring, whereas levels of anti-inflammatory markers Arg1, IL-4, and IL-10 were lower, as was PPARγ expression in the hippocampus. PPARγ activation by pioglitazone (30 mg/kg/day, i.p., 7 d) mitigated these negative effects of MSD, rescuing hippocampal neurogenesis and improving cognitive function. The PPARγ inhibitor GW9662 (1 mg/kg/day, i.p., 7 d) eliminated the effects of pioglitazone. Conditioned medium from pioglitazone-treated microglia promoted proliferation and differentiation of neural progenitor cells. These results suggest that MSD-induced deficits in spatial learning and memory can be ameliorated through PPARγ-dependent modulation of microglial phenotypes.

Complete sleep and local field potential analysis regarding estrus cycle, pregnancy, postpartum and post-weaning periods and homeostatic sleep regulation in female rats

Sleep and local field potential (LFP) characteristics were addressed during the reproductive cycle in female rats using long-term (60-70 days) recordings. Changes in homeostatic sleep regulation was tested by sleep deprivation (SDep). The effect of mother-pup separation on sleep was also investigated during the postpartum (PP) period. First half of the pregnancy and early PP period showed increased wakefulness (W) and higher arousal indicated by elevated beta and gamma activity. Slow wave sleep (SWS) recovery was suppressed while REM sleep replacement was complete after SDep in the PP period. Pup separation decreased maternal W during early-, but increased during middle PP while did not affect during late PP. More W, less SWS, higher light phase beta activity but lower gamma activity was seen during the post-weaning estrus cycle compared to the virgin one. Maternal sleep can be governed by the fetuses/pups needs and their presence, which elevate W of mothers. Complete REM sleep- and incomplete SWS replacement after SDep in the PP period may reflect the necessity of maternal REM sleep for the offspring while SWS increase may compete with W essential for maternal care. Maternal experience may cause sleep and LFP changes in the post-weaning estrus cycle.

Oxytocin ameliorates maternal separation-induced ultrasonic vocalisation calls in mouse pups prenatally exposed to valproic acid

Autism spectrum disorder (ASD) is a neurodevelopmental disorder estimated by the World Health Organization to occur in one of 160 children worldwide. No pharmaceutical treatments are available to improve the deficits in social communication that are common symptoms of ASD. Recent clinical trials have focused on the nasal application of oxytocin, a neuronal peptide known to regulate a variety of social behaviours. However, the effect of oxytocin on this deficit is inconclusive. By contrast, evidence from ASD animal model studies indicates that when animals are treated with oxytocin during early development, improvements in social deficits are observed in adulthood. Thus, it is necessary to examine the effect of therapeutic target medication prescribed in early development. Mice prenatally exposed to valproic acid (VPA) are widely used as an animal model of ASD. However, many behavioural studies have been conducted during adulthood rather than early development. To establish a screening system to identify therapeutic drugs that are effective when delivered during the early postnatal period, it is important to examine the early developmental changes in their communicative behaviours. In the present study, we examined the ultrasonic vocalisation (USV) of VPA-exposed mice pups during their early postnatal developmental days. USV rates were comparable to those of the controls until the first week of their life but declined more on postnatal day 11. We checked the expression of oxytocin system in the hypothalamus and found the down-regulation of oxytocin and CD38, and up-regulation of oxytocin receptor in the VPA pups. Acute administration of oxytocin on postnatal day 11 increased the call rate of VPA pups. Taken together, we have demonstrated there was a deficiency in the oxytocinergic signalling in the VPA pups and also shown the existence of time periods that are effective with respect to screening the therapeutic drugs.

Rapid development of mature vocal patterns of ultrasonic calls in a fast-growing rodent, the yellow steppe lemming (Eolagurus luteus)

Ultrasonic vocalizations (USV) of laboratory rodents may serve as age-dependent indicators of emotional arousal and anxiety. Fast-growing Arvicolinae rodent species might be advantageous wild-type animal models for behavioural and medical research related to USV ontogeny. For the yellow steppe lemming Eolagurus luteus, only audible calls of adults were previously described. This study provides categorization and spectrographic analyses of 1176 USV calls emitted by 120 individual yellow steppe lemmings at 12 age classes, from birth to breeding adults over 90 days (d) of age, 10 individuals per age class, up to 10 USV calls per individual. The USV calls emerged since 1st day of pup life and occurred at all 12 age classes and in both sexes. The unified 2-min isolation procedure on an unfamiliar territory was equally applicable for inducing USV calls at all age classes. Rapid physical growth (1 g body weight gain per day from birth to 40 d of age) and the early (9-12 d) eyes opening correlated with the early (9-12 d) emergence of mature vocal patterns of USV calls. The mature vocal patterns included a prominent shift in percentages of chevron and upward contours of fundamental frequency (f0) and the changes in the acoustic variables of USV calls. Call duration was the longest at 1-4 d, significantly shorter at 9-12 d and did not between 9-12-d and older age classes. The maximum fundamental frequency (f0max) decreased with increase of age class, from about 50 kHz in neonates to about 40 kHz in adults. These ontogenetic pathways of USV duration and f0max (towards shorter and lower-frequency USV calls) were reminiscent of those in laboratory mice Mus musculus.

Understanding the role of sleep and its disturbances in Autism spectrum disorder

BACKGROUND

Several studies have established a positive relationship between sleep difficulties and symptomatology in ASD children. The rationale for this review is to describe and discuss the sleep difficulties, which are one of the significant complications associated with autism spectrum disorder (ASD).

PURPOSE

Many types of sleep disorders have been reported in ASD individuals, but still lack a comprehensive study and in-depth analysis. Despite the contribution of sleep problems to the overall symptoms of ASD, the symptoms of disturbed sleep experienced by many affected patients have only recently started to receive attention from clinicians and family members.

MATERIALS AND METHODS

This narrative overview has been prepared based on searching standard research databases with specific keywords; b. Additional search was made using the bibliographies of the retrieved articles; and c. author's collection of relevant peer-reviewed articles. Once selected, manuscripts are then compared and summarized based on the author's perspective. Results are based on a qualitative rather than a quantitative level.

RESULTS

This article highlights the role of sleep in the brain and neural development of children and emphasizes that the intensity of sleep problems is associated with an increased occurrence of ASD symptoms. It also suggests the significance of treating sleep problems in ASD individuals.

CONCLUSIONS

The review provides broader perspectives and a better understanding of sleep problems in pathophysiology, mechanism, and management with respect to ASD individuals. Finally, the implications for clinical practice and future agendas have also been discussed.

Ultrasonic vocalization of pup and adult fat-tailed gerbils (Pachyuromys duprasi)

Ultrasonic vocalizations (USVs) of laboratory rodents indicate animal emotional arousal and may serve as models of human disorders. We analysed spectrographically USV calls of pup and adult fat-tailed gerbils Pachyuromys duprasi during 420-s tests, including isolation, touch and handling. Based on combination of six different USV syllable contour shapes and six different note compositions, we classified 782 USV syllables of 24 pups aged 5-10 days to 18 types and 232 syllables of 7 adults to 24 types. Pups and adults shared 16 of these 26 USV types. Percentages of USV syllables with certain contour shapes differed between pups and adults. The contour shape and note composition significantly affected most acoustic variables of USV syllables in either pups or adults. The 1-note USV syllables were most common in either pups or adults. Pup USV syllables were overall longer and higher-frequency than adult ones, reminiscent of the USV ontogenetic pathway of bats and distinctive to rats and mice. We discuss that the USV syllable types of fat-tailed gerbils were generally similar in contour shapes and note compositions with USV syllable types of mice and rats, what means that software developed for automated classifying of mice ultrasound might be easily adapted or re-tuned to gerbil USV calls. However, using fat-tailed gerbils as model for biomedical research including control of USV vocalization is only possible since 6th day of pup life, because of the delayed emergence of USV calls in ontogeny of this species.

Prenatal Developmental Origins of Future Psychopathology: Mechanisms and Pathways

The developmental origins of health and disease hypothesis applied to neurodevelopmental outcomes asserts that the fetal origins of future development are relevant to mental health. There is a third pathway for the familial inheritance of risk for psychiatric illness beyond shared genes and the quality of parental care: the impact of pregnant women's distress-defined broadly to include perceived stress, life events, depression, and anxiety-on fetal and infant brain-behavior development. We discuss epidemiological and observational clinical data demonstrating that maternal distress is associated with children's increased risk for psychopathology: For example, high maternal anxiety is associated with a twofold increase in the risk of probable mental disorder in children. We review several biological systems hypothesized to be mechanisms by which maternal distress affects fetal and child brain and behavior development, as well as the clinical implications of studies of the developmental origins of health and disease that focus on maternal distress. Development and parenting begin before birth.

Facilitated AMPAR endocytosis causally contributes to the maternal sleep deprivation-induced impairments of synaptic plasticity and cognition in the offspring rats

Maternal sleep deprivation (MSD) has been suggested to be associated with increased frequency of neurodevelopmental disorders in offspring in both humans and animal models. However, the underlying cellular and molecular mechanism is still unclear. We have recently reported that MSD at different stages of pregnancy impairs the emotional and cognitive functions, and suppresses hippocampal CA1 long-term potentiation (LTP) in the offspring rats. Here, we report that the MSD induced LTP impairment at the CA1 hippocampus of the offspring rats is associated with increased long-term depression (LTD) and reduced expression of postsynaptic GluA2-containing α-amino-3-hydroxy-5-methyl-isoxazole-4-propionic acid receptors (AMPARs). Importantly, we found that inhibition of AMPAR endocytosis by a synthetic peptide Tat-GluA2_3Y (3 μmol/kg, i.p.) not only increased level of AMPARs and reduced LTD, but also restored LTP. Moreover, treatment with Tat-GluA2_3Y peptide markedly alleviated the MSD-induced impairments of spatial learning and memory; and decreased depressive- and anxiety-like behaviors in the offspring. Together, our findings suggest that the MSD-induced postsynaptic AMPAR endocytosis causally contributes to the impairments of hippocampal synaptic plasticity, thereby disrupting the emotional and cognitive functions in the offspring.

Targeting anandamide metabolism rescues core and associated autistic-like symptoms in rats prenatally exposed to valproic acid

Autism spectrum disorders (ASD) are characterized by altered sociability, compromised communication and stereotyped/repetitive behaviors, for which no specific treatments are currently available. Prenatal exposure to valproic acid (VPA) is a known, although still underestimated, environmental risk factor for ASD. Altered endocannabinoid activity has been observed in autistic patients, and endocannabinoids are known to modulate behavioral traits that are typically affected in ASD. On this basis, we tested the hypothesis that changes in the endocannabinoid tone contribute to the altered phenotype induced by prenatal VPA exposure in rats, with focus on behavioral features that resemble the core and associated symptoms of ASD. In the course of development, VPA-exposed rats showed early deficits in social communication and discrimination, compromised sociability and social play behavior, stereotypies and increased anxiety, thus providing preclinical proof of the long-lasting deleterious effects induced by prenatal VPA exposure. At the neurochemical level, VPA-exposed rats displayed altered phosphorylation of CB1 cannabinoid receptors in different brain areas, associated with changes in anandamide metabolism from infancy to adulthood. Interestingly, enhancing anandamide signaling through inhibition of its degradation rescued the behavioral deficits displayed by VPA-exposed rats at infancy, adolescence and adulthood. This study therefore shows that abnormalities in anandamide activity may underlie the deleterious impact of environmental risk factors on ASD-relevant behaviors and that the endocannabinoid system may represent a therapeutic target for the core and associated symptoms displayed by autistic patients.

Maternal sleep deprivation at different stages of pregnancy impairs the emotional and cognitive functions, and suppresses hippocampal long-term potentiation in the offspring rats

Background

Sleep deprivation during pregnancy is a serious public health problem as it can affect the health of pregnant women and newborns. However, it is not well studied whether sleep deprivation at different stages of pregnancy has similar effects on emotional and cognitive functions of the offspring, and if so, the potential cellular mechanisms also remain poorly understood.

Methods

In the present study, the pregnant rats were subjected to sleep deprivation for 6 h per day by gentle handling during the first (gestational days 1–7), second (gestational days 8–14) and third trimester (gestational days 15–21) of pregnancy, respectively. The emotional and cognitive functions as well as hippocampal long-term potentiation (LTP) were tested in the offspring rats (postnatal days 42-56).

Results

The offspring displayed impaired hippocampal-dependent spatial learning and memory, and increased depressive- and anxiety-like behaviors. Quantification of BrdU-positive cells revealed that adult hippocampal neurogenesis was significantly reduced compared to control. Electrophysiological recording showed that maternal sleep deprivation impaired hippocampal CA1 LTP and reduced basal synaptic transmission, as reflected by a decrease in the frequency and amplitude of miniature excitatory postsynaptic current in the hippocampal CA1 pyramidal neurons.

Conclusions

Taken together, these results suggest that maternal sleep deprivation at different stages of pregnancy disrupts the emotional and cognitive functions of the offspring that might be attributable to the suppression of hippocampal LTP and basal synaptic transmission.

Sleep deprivation during late pregnancy produces hyperactivity and increased risk-taking behavior in offspring

Sleep deprivation in women resulting from their modern lifestyle, especially during pregnancy, is a serious concern as it can affect the health of the newborn. Anxiety disorders and cognitive deficits in the offspring are also on the rise. However, experimental studies on the effects of sleep loss during pregnancy, on emotional development and cognitive function of the newborn, are scanty in literature. In the current study, female rats were sleep-deprived for 5h by gentle handling, during the 6 days of the third trimester (days 14-19 of pregnancy). The effects of this sleep deprivation on anxiety-related behaviors of pups during their peri-adolescence age were studied using elevated plus maze (EPM). In addition to body weights of dams and offspring, the maternal behavior was also monitored. The weanlings of sleep-deprived dams showed heightened risk-taking behavior as they made increased explorations into the open arms of EPM. They also showed higher mobility in comparison to the control group. Though the body weights of sleep-deprived dams were comparable to those of the control group, their newborns had lower birth weight. Nevertheless, these pups gained weight and reached the control group values during the initial post-natal week. But after weaning, their rate of growth was lower than that of the control group. This is the first report providing evidences for the role of sleep during late pregnancy in shaping the neuropsychological development in offspring.