Early maternal separation: a rodent model of depression and a prevailing human condition

Jmjd3 is involved in the susceptibility to depression induced by maternal separation via enhancing the neuroinflammation in the prefrontal cortex and hippocampus of male rats

Adverse childhood experience is a major risk factor for the onset of depression in adulthood. Neuroinflammation characterized by microglial activation and cytokine secretion is involved in susceptibility to depression induced by early life stress. Jumonji domain-containing protein 3 (Jmjd3), a trimethylated lysine 27 in histone 3 (H3K27me3) demethylase, can be activated by nuclear factor-kappa B (NF-κB), further regulating the expression of pro-inflammatory cytokines and resulting in neuroinflammation. However, its involvement in susceptibility to early life stress-related depression is unknown. In the current study, maternal separation (MS) was utilized as a model of early life stress and systemic lipopolysaccharide (LPS) administration in adulthood was used as a later-life challenge. Depressive- and anxiety-like behaviors and memory impairment were detected by behavioral tests. Microglial activation, pro-inflammatory cytokine expression, and NF-κB, Jmjd3, and H3K27me3 expression were detected in the prefrontal cortex and hippocampus in both infant and adult rats. Meanwhile, the Jmjd3 inhibitor GSK-J4 was used as an intervention in vivo and in vitro. Our results showed that MS induced depression-like behaviors and synchronously caused microglial activation, pro-inflammatory cytokine over-expression, NF-κB and Jmjd3 over-expression, and decreased H3K27me3 expression in infant rats. All these alterations could also be detected in adulthood. Seven-day LPS administration in adult rats induced similar changes of behaviors and biomarkers. Interestingly, compared with rats not exposed to MS, MS-exposed rats receiving LPS administration developed more severe depression-like behaviors and neuroinflammatory status, higher levels of NF-κB and Jmjd3 expression, and lower levels of H3K27me3 expression. In addition, LPS induced microglial activation, pro-inflammatory cytokine expression and increased Jmjd3 expression in vitro. Furthermore, GSK-J4 treatment alleviated these alterations in vivo and in vitro. Thus, our data indicate that Jmjd3 is involved in the susceptibility to depression induced by MS via enhancement of neuroinflammation in the prefrontal cortex and hippocampus of rats.

A simple method for short-term maintenance of neonatal mice without foster mothers

Mice are typically weaned from their mother between 21 and 28 days of age, or at 10 grams of body weight. However, some biochemical experiments need to be done before the weaning days, and the mother might cannibalize or ignore those manipulated pups. Here, we provide a detailed protocol for maintenance of neonatal mice without the presence of their mothers for biomedical research. The basic instinct of neonate mice to hide under covers is harnessed for their survival in a mother-free environment. When covers are soaked with milk and the only targets for hiding, the neonates would acquire their nutrients at least in an involuntary fashion. The protocol is simple and can be used for neonatal rodent studies for short periods of times, and assures the accuracy of the biomedical experiments if survival rate of neonates is critical.

Less NMDA Receptor Binding in Dorsolateral Prefrontal Cortex and Anterior Cingulate Cortex Associated With Reported Early-Life Adversity but Not Suicide

BACKGROUND

Glutamate is an excitatory neurotransmitter binding to 3 classes of receptors, including the N-methyl, D-aspartate (NMDA) receptor. NMDA receptor binding is lower in major depression disorder and suicide. NMDA receptor blocking with ketamine can have antidepressant and anti-suicide effects. Early-life adversity (ELA) may cause glutamate-mediated excitotoxicity and is more common with major depression disorder and in suicide decedents. We sought to determine whether NMDA-receptor binding is altered with suicide and ELA.

METHODS

A total 52 postmortem cases were organized as 13 quadruplets of suicide and non-suicide decedents matched for age, sex, and postmortem interval, with or without reported ELA (≤16 years). Tissue blocks containing dorsal prefrontal (BA8), dorsolateral prefrontal (BA9), or anterior cingulate (BA24) cortex were collected at autopsy. Psychiatrically healthy controls and suicide decedents underwent psychological autopsy to determine psychiatric diagnoses and details of childhood adversity. NMDA receptor binding was determined by quantitative autoradiography of [3H]MK-801 binding (displaced by unlabeled MK-801) in 20-µm-thick sections.

RESULTS

[3H]MK-801 binding was not associated with suicide in BA8, BA9, or BA24. However, [3H]MK-801 binding with ELA was less in BA8, BA9, and BA24 independent of suicide (P < .05). [3H]MK-801 binding was not associated with age or postmortem interval in any brain region or group.

CONCLUSIONS

Less NMDA receptor binding with ELA is consistent with the hypothesis that stress can cause excitotoxicity via excessive glutamate, causing either NMDA receptor downregulation or less receptor binding due to neuron loss consequent to the excitotoxicity.

Progesterone exerts antidepressant-like effect in a mouse model of maternal separation stress through mitigation of neuroinflammatory response and oxidative stress

Context: Experiencing early-life adversity plays a key role in the development of mood disorders in adulthood. Experiencing adversities during early life period negatively affects brain development. Sex steroids such as progesterone affect the brain structure and functions and subsequently affects behaviour.Objective: We assess the antidepressant-like effect of progesterone in a mouse model of maternal separation (MS) stress, focussing on its anti-neuroinflammatory and antioxidative effects.Materials and methods: NMRI mice were treated with progesterone (10, 50, and 100 mg/kg, i.p., respectively) for 14 days. Valid behavioural tests including forced swimming test (FST), splash test and open field test (OFT) were used. Quantitative reverse transcription-PCR (qRT-PCR) was used for evaluation of genetic expression in the hippocampus. Antioxidant capacity was assessed by the FRAP method and the level of malondialdehide by TBA.Results: MS provoked depressive-like behaviour in mice. Treatment of MS mice with progesterone increased the grooming activity time in the splash test and decreased the immobility time in the FST. In addition, progesterone decreased the expression of inflammatory genes related to neuroinflammation (IL-1β, TNF-α, TLR4 and NLRP3) as well as increased the antioxidant capacity and decreased the lipid peroxidation (MDA) in the hippocampus.Discussion and Conclusion: Administration of progesterone significantly mitigated the negative effects of MS on behaviours relevant to depressive-like behaviour as well as attenuated neuro-immune response and oxidative stress in the hippocampus of MS mice. In this context, we conclude that progesterone, at least partially, via attenuation of oxidative stress and neuroinflammation, exerts antidepressant-like effects.

Treadmill running attenuates neonatal hypoxia induced adult depressive symptoms and promoted hippocampal neural stem cell differentiation via modulating AMPK-mediated mitochondrial functions

Neonatal hypoxia can induce the persisting brain dysfunctions and subsequently result in the behavioral abnormalities in adulthood. Improving mitochondrial functions were suggested as the effective strategy for brain functional recovery. In this study, we tested the effects of physical exercise, a well-established way benefits mitochondrion, for its functions to prevent hypoxia induced adult behavioral dysfunctions and the underlying molecular mechanism. Mice was induced with hypoxia and treadmill running were then administrated until the adulthood. The treadmill running resulted in the improved behavioral performance in depressive and anxiety tests together with the enhancement of hippocampal neurogenesis. We then detected treadmill running restored the mitochondrial morphology in adult neural stem cells (NSCs) as well as the ATP production in hippocampal tissue. In addition, activity of AMPK, which playing key roles in regulating mitochondrial functions, was also elevated by treadmill running. Blockage of AMPK with selective inhibitor compound C prohibited effects of treadmill running in attenuating neonatal hypoxia induced neurogenic impairment and antidepressant behavioral deficits in adulthood. In conclusion, treadmill running could prevent neonatal hypoxia induced adult antidepressant dysfunctions and neurogenic dampening via AMPK-mediated mitochondrial regulation.

Animal models of major depression: drawbacks and challenges

Major depression is a leading contributor to the global burden of disease. This situation is mainly related to the chronicity and/or recurrence of the disorder, and to poor response to antidepressant therapy. Progress in this area requires valid animal models. Current models are based either on manipulating the environment to which rodents are exposed (during the developmental period or adulthood) or biological underpinnings (i.e. gene deletion or overexpression of candidate genes, targeted lesions of brain areas, optogenetic control of specific neuronal populations, etc.). These manipulations can alter specific behavioural and biological outcomes that can be related to different symptomatic and pathophysiological dimensions of major depression. However, animal models of major depression display substantial shortcomings that contribute to the lack of innovative pharmacological approaches in recent decades and which hamper our capabilities to investigate treatment-resistant depression. Here, we discuss the validity of these models, review putative models of treatment-resistant depression, major depression subtypes and recurrent depression. Furthermore, we identify future challenges regarding new paradigms such as those proposing dimensional rather than categorical approaches to depression.

Age-dependent differences on neurochemistry and behavior in rats raised with low and high levels of maternal care

In laboratory rats, naturally-occurring variations in maternal care have been used to study the neurobehavioral consequences of maternal nursing and to model the early-life adversity associated with many psychiatric disorders. This study aimed to determine the role of maternal care on behavior and monoamine concentrations at the prepubertal and young adulthood ages. We observed the licking/grooming (LG) behavior of Sprague-Dawley (SD) dams and assigned the litter to either low (LLG) or high (HLG) LG groups. Behavioral testing in the male offspring consisted of the open-field test, the elevated plus-maze, and the forced swimming test. Afterward, neurotransmitters contents were measured in the prefrontal cortex, the nucleus accumbens, the amygdala, and the hippocampus. We found that at the prepubertal stage, the effects of maternal care were only noticeable in the elevated plus-maze and the serotonin concentration in the nucleus accumbens. At adulthood, body weight and monoamines contents increased substantially in LLG rats. Specifically, they showed higher serotonin contents with a reduced turnover in almost all brain regions, followed by higher contents of norepinephrine and dopamine, especially in the nucleus accumbens. Changes in monoamines concentrations seem to be independent of the behavioral phenotype shaped by variations in maternal care, as behavioral effects were somewhat weak in both experiments. If higher monoamines contents in LLG rats represent an adaptive mechanism to deal with further adverse events, the behavioral paradigms used here were insufficiently challenging to bring out noticeable differences, at least in SD rats.

Exposure to early life adversity alters the future behavioral response to a stressful challenge in BALB/C mice

Depression is considered as a maladaptive response to stress in adult life. Exposure to stress in early childhood is recognized as a risk factor for being unable to adapt to environmental changes in adult life. Early life stress (ELS) has been modelled in animals to help understand the behavioral outcome of the adversity. Periodic maternal separation (MS) in rodents for the first two weeks of life is one such model. We used MS as a form of ELS in Balb/c mice to study its effect on a stressful challenge encountered in adult life. According to our results, exposure to MS predisposed mice to an altered behavioral response. However, this response was not worsened by exposure to restraint stress (RS) experienced in early adult life. This controversy may be attributed to methodological and biological variations among animals as well as humans.

Building Resilience Against the Sequelae of Adverse Childhood Experiences: Rise Up, Change Your Life, and Reform Health Care

A reformed approach to health care tackles health at its roots. Adverse childhood experiences (ACEs) in those exposed to them may contribute significantly to the root causes of many diseases of lifestyle. ACEs are traumatic experiences, such as physical and emotional abuse and exposure to risky family environments. In 1998, a ground-breaking study found that nearly 70% of Americans experience at least 1 ACE in their lifetime, and graded exposure is associated with the presence of mental health disorders, heart disease, cancer, and other chronic diseases. Over the past 20 years, evidence has demonstrated further disease risk, outcomes, and epigenetic underpinnings in children and adults with ACEs. Building resilience-the capacity to adapt in healthy ways to traumatic experiences-through lifestyle modification offers potential to combat the negative health effects associated with ACEs. Emerging research demonstrates resilience is cultivated through individual skills (emotional intelligence, coping, and fostering healthy lifestyle choices), and nurturing supportive relationships. Being mindful of the impact and prevalence of ACEs and diversity of individuals' experiences in society will help build resilience and combat the root cause of chronic disease. This review aims to cultivate that awareness and will discuss 3 objectives: to discuss the effects and hypothesized pathophysiological underpinnings of traumatic experiences in childhood on health and wellbeing throughout life, to present ways we can promote resilience in our daily lives and patient encounters, and to demonstrate how advocacy for the reduction of ACEs and promotion of resilient, trauma-informed environments are fundamental to health care reform.

Early life stress by repeated maternal separation induces long-term neuroinflammatory response in glial cells of male rats

Childhood maltreatment and neglect lead to a wide range of mental disorders highlighted by hormone and immune alterations in neglected children. This social-health challenge has led to the creation of early stress models such as maternal separation (MS) in rodents. We performed a MS model (4 h per day, 21 days; n = 16 MS and n = 16 control), and then measured three parameters in adult male rat brains, in order to look for long-term effects of early life stress. We used immunocytochemistry to mark glial fibrillary acidic protein (GFAP)-positive cells, which indicates changes in astroglia, and ionized calcium binding adaptor molecule 1 (Iba-1)-positive cells, which inform about reactive microglia. In order to study mRNA levels of some immune mediators, interleukin determination (interleukin-6, IL-6; tumor necrosis factor, TNFα) mRNAs were evaluated by real-time polymerase chain reaction (rt-PCR) in discrete brain regions. Measurements of numbers of GFAP-positive cells, and expression of Iba-1, IL-6 and TNFα mRNAs were performed in prefrontal cortex (PFC): cingulate cortex (CG), prelimbic cortex (PL) and infralimbic cortex (IL), striatal areas (dorsal striatum, STD; and nucleus accumbens, ACC), and dorsal hippocampus (HC: CA1, CA3 and dentate gyrus (DG)). We found that MS produces a dramatic and sustained decrease in the astroglial population in all the areas measured (from -25% in CA1 to -85.7% in ACC), whereas increased numbers of microglia were found, in more restricted regions: STD (72.6%), ACC (31%) and CA3 (33.3%) areas. Regarding mRNA measurements, we found increased IL-6 mRNA expression in HC (104.2%), and after MS.

Effects of Environmental Enrichment in Maternally Separated Rats: Age and Sex-Specific Outcomes

Maternal separation (MS) early in life is related to an increase in anxiety and depressive-like behaviors and neurobiological alterations mostly related to alterations in hypothalamic pituitary adrenal (HPA) axis reactivity. Environmental enrichment (EE) has been used to ameliorate the effects of MS. However, the outcomes of this intervention at different developmental periods after MS have not been studied. We subjected male and female Sprague–Dawley pups to MS and subsequently compared the effects of EE started either in the pre-pubertal period [postnatal day (PND) 22] or adulthood (PND 78). Anxiety and depressive-like behaviors as well as in hippocampal synaptic density and basal corticosterone, oxytocin, and vasopressin levels were measured. Our results support the beneficial effects of adulthood EE in decreasing anxiety in males as well as promoting synaptic density in ventral hippocampal CA3. Males displayed higher levels of vasopressin while females displayed higher oxytocin, with no changes in basal corticosterone for any group after EE.

How Early Life Stress Impact Maternal Care: A Systematic Review of Rodent Studies

Background: Maternal care refers to the behavior performed by the dam to nourish and protect her litter during its early development. Frequent and high-quality performance of such maternal behaviors is critical for the neurodevelopment of the pups. Maternal exposure to stress during early development can impair maternal care and amplify the deleterious effects of poor maternal caregiving and neglect. As such, a thorough understanding of the effects caused by several models of early life stress on maternal care may yield more insights into the relationship between stress and maternal behavior.

Methods: A systematic review was performed to identify and address the effects of early life stress on maternal behavior. The search was conducted using three online databases: PUBMED, Embase, and Web of Science. To provide clear evidence of the impact of stress on maternal care, in every study, the stress group was always compared to a control group. Outcomes were categorized into eight different behaviors: (1) licking/grooming; (2) arched-back nursing; (3) blanket-nursing/passive nursing; (4) nest building; (5) contact with pups; (6) harmful/adverse caregiving; (7) no contact; (8) nest exits. Additionally, the methodological quality of the studies was evaluated.

Results: A total of 12 different early life stress protocols were identified from the 56 studies included in this systematic review. Our data demonstrate that different stress models can promote specific maternal patterns of behavior. Regarding the maternal separation protocol, we observed an overall increase in nursing and licking/grooming behaviors, which are essential for pup development. An increase in the number of nest exits, which represents a fragmentation of maternal care, was observed in the limited bedding protocol, but the total amount of maternal care appears to remain similar between groups.

Conclusions: Each stress protocol has unique characteristics that increase the difficulty of rendering comparisons of maternal behavior. The increase in maternal care observed in the maternal separation protocol may be an attempt to overcompensate for the time off-nest. Fragmented maternal care is a key component of the limited bedding protocol. Moreover, the methodological approaches to evaluate maternal behavior, such as time, duration, and behavior type should be more homogeneous across studies.

Effects of maternal separation on serotonergic systems in the dorsal and median raphe nuclei of adult male Tph2-deficient mice

Previous studies have highlighted interactions between serotonergic systems and adverse early life experience as important gene x environment determinants of risk of stress-related psychiatric disorders. Evidence suggests that mice deficient in Tph2, the rate-limiting enzyme for brain serotonin synthesis, display disruptions in behavioral phenotypes relevant to stress-related psychiatric disorders. The aim of this study was to determine how maternal separation in wild-type, heterozygous, and Tph2 knockout mice affects mRNA expression of serotonin-related genes. Serotonergic genes studied included Tph2, the high-affinity, low-capacity, sodium-dependent serotonin transporter (Slc6a4), the serotonin type 1a receptor (Htr1a), and the corticosterone-sensitive, low-affinity, high-capacity sodium-independent serotonin transporter, organic cation transporter 3 (Slc22a3). Furthermore, we studied corticotropin-releasing hormone receptors 1 (Crhr1) and 2 (Crhr2), which play important roles in controlling serotonergic neuronal activity. For this study, offspring of Tph2 heterozygous dams were exposed to daily maternal separation for the first two weeks of life. Adult, male wild-type, heterozygous, and homozygous offspring were subsequently used for molecular analysis. Maternal separation differentially altered serotonergic gene expression in a genotype- and topographically-specific manner. For example, maternal separation increased Slc6a4 mRNA expression in the dorsal part of the dorsal raphe nucleus in Tph2 heterozygous mice, but not in wild-type or knockout mice. Overall, these data are consistent with the hypothesis that gene x environment interactions, including serotonergic genes and adverse early life experience, play an important role in vulnerability to stress-related psychiatric disorders.

Maternal separation in rodents: a journey from gut to brain and nutritional perspectives

The developmental period constitutes a critical window of sensitivity to stress. Indeed, early-life adversity increases the risk to develop psychiatric diseases, but also gastrointestinal disorders such as the irritable bowel syndrome at adulthood. In the past decade, there has been huge interest in the gut-brain axis, especially as regards stress-related emotional behaviours. Animal models of early-life adversity, in particular, maternal separation (MS) in rodents, demonstrate lasting deleterious effects on both the gut and the brain. Here, we review the effects of MS on both systems with a focus on stress-related behaviours. In addition, we discuss more recent findings showing the impact of gut-directed interventions, including nutrition with pre- and probiotics, illustrating the role played by gut microbiota in mediating the long-term effects of MS. Overall, preclinical studies suggest that nutritional approaches with pro- and prebiotics may constitute safe and efficient strategies to attenuate the effects of early-life stress on the gut-brain axis. Further research is required to understand the complex mechanisms underlying gut-brain interaction dysfunctions after early-life stress as well as to determine the beneficial impact of gut-directed strategies in a context of early-life adversity in human subjects.

Childhood adversity and mechanistic links to hypertension risk in adulthood

Adverse childhood experiences (ACEs), defined as traumatic events in childhood that range from various forms of abuse to household challenges and dysfunction, have devastating consequences on adult health. Epidemiological studies in humans and animal models of early life stress (ELS) have revealed a strong association and insight into the mechanistic link between ACEs and increased risk of cardiovascular disease (CVD). This review focuses on the mechanistic links of ACEs in humans and ELS in mice and rats to vasoactive factors and immune mediators associated with CVD and hypertension risk, as well as sex differences in these phenomena. Major topics of discussion in this review are as follows: (a) epidemiological associations between ACEs and CVD risk focusing on hypertension, (b) evidence for association of ACE exposures to immune-mediated and/or vasoactive pathways, (c) rodent models of ELS-induced hypertension risk, (d) proinflammatory mediators and vasoactive factors as mechanisms of ELS-induced hypertension risk. We also provide some overall conclusions and directions of further research. LINKED ARTICLES: This article is part of a themed section on Immune Targets in Hypertension. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v176.12/issuetoc.

Transcriptome Analysis on Maternal Separation Rats With Depression-Related Manifestations Ameliorated by Electroacupuncture

Maternal separation (MS), a stressful event in early life, has been linked to neuropsychiatric disorders later in life, especially depression. In this study we investigated whether treatment with electroacupuncture (EA) could ameliorate depression-related manifestations in adult animals that had adverse early life experiences. We demonstrated depression-like behavior deficiencies in a sucrose preference test and a forced swimming test in a rat model with neonatal MS. Repeated EA treatment at the acupoints Baihui (GV20) and Yintang (GV29) during adulthood was shown to be remarkably attenuated above behavioral deficits. Using unbiased genome-wide RNA sequencing to investigate alterations in the transcriptome of the prefrontal cortex (PFC), we explored the altered gene sets involved in circadian rhythm and neurotransmitter transporter activity in MS rats, and their expression tended to be reversed after EA treatment. In addition, we analyzed the interaction network of differentiated lncRNA- or circRNA-miRNA-mRNA by using the principle of competitive endogenous RNA (ceRNA). These results suggest that EA at GV20 and GV29 ameliorates depression-related manifestations by regulating the expression of multiple genes.

Lactobacillus paracasei PS23 reduced early-life stress abnormalities in maternal separation mouse model

Maternal separation (MS) has been developed as a model for inducing stress and depression in studies using rodents. The concept of the gut-brain axis suggests that gut health is essential for brain health. Here, we present the effects of administration of a probiotic, Lactobacillus paracasei PS23 (PS23), to MS mice against psychological traits including anxiety and depression. The administration of live and heat-killed PS23 cells showed positive behavioural effects on MS animals, where exploratory tendencies and mobility were increased in behavioural tests, indicating reduced anxiety and depression compared to the negative control mice (P<0.05). Mice administered with both live and heat-killed PS23 cells also showed lower serum corticosterone levels accompanied by higher serum anti-inflammatory interleukin 10 (IL-10) levels, compared to MS separated mice (P<0.05), indicating a stress-elicited response affiliated with increased immunomodulatory properties. Assessment of neurotransmitters in the brain hippocampal region revealed that PS23 affected the concentrations of dopaminergic metabolites differently than the control, suggesting that PS23 may have improved MS-induced stress levels via neurotransmitter pathways, such as dopamine or other mechanisms not addressed in the current study. Our study illustrates the potential of a probiotic in reversing abnormalities induced by early life stress and could be an alternative for brain health along the gut-brain axis.

Physiology of Stress and Use of Skin-to-Skin Care as a Stress-Reducing Intervention in the NICU

Advances in neonatal care have allowed for the increasing survival of critically ill infants. These infants experience significant stress related to painful procedures and physical separation from their parents. The purpose of this article is to describe the physiologic stress mechanisms that contribute to mortality and morbidity in infants in the NICU and the physiologic mechanisms by which skin-to-skin care (SSC) acts on the stress response system. Findings from current literature supporting the use of SSC and barriers and facilitators to implementation are reviewed. SSC is a safe and effective intervention to reduce stress for infants and their parents. Nurses play a key role in facilitating SSC to optimize outcomes of care in the NICU.

Early Attachment Disruption, Inflammation, and Vulnerability for Depression in Rodent and Primate Models

Early experiments in nonhuman primates established the relation between disruption of filial attachment and depressive-like outcomes. Subsequent studies in rats and mice have been instrumental in linking depressive-like outcomes to disturbances in maternal behavior. Another aspect of attachment disruption, absence of the attachment object per se, may be studied more effectively in a different laboratory rodent-the guinea pig. Here, we discuss the rationale for using guinea pigs for this work. We then review guinea pig studies providing evidence for inflammatory mechanisms mediating both depressive-like behavior during separation as well as sensitization of stress responsiveness such as is thought to lead to increased vulnerability to depression at later ages. Finally, we discuss recent complementary work in adult monkeys that suggests cross-species generalizability of broad principles derived from the guinea pig experiments. Overall, the findings provide experimental support for human research implicating inflammatory mechanisms in the development of increased stress responsiveness and vulnerability to depression following attachment disruption and other forms of early-life stress. Specifically, the findings suggest inflammatory mechanisms may set in motion a cascade of underlying processes that mediate later increased stress responsiveness and, therefore, depression susceptibility.

Postnatal calpeptin treatment causes hippocampal neurodevelopmental defects in neonatal rats

Our previous studies showed that the early use of calpain inhibitors reduces calpain activity in multiple brain regions, and that postnatal treatment with calpeptin may lead to cerebellar motor dysfunction. However, it remains unclear whether postnatal calpeptin application affects hippocampus-related behaviors. In this study, Sprague-Dawley rats were purchased from the Animal Center of Anhui Medical University of China. For the experiments in the adult stage, rats were intraperitoneally injected with calpeptin, 2 mg/kg, once a day, on postnatal days 7-14. Then on postnatal day 60, the Morris water maze test was used to evaluate spatial learning and memory abilities. The open field test was carried out to assess anxiety-like activities. Phalloidin staining was performed to observe synaptic morphology in the hippocampus. Immunohistochemistry was used to count the number of NeuN-positive cells in the hippocampal CA1 region. DiI was applied to label dendritic spines. Calpeptin administration impaired spatial memory, caused anxiety-like behavior in adulthood, reduced the number and area of apical dendritic spines, and decreased actin polymerization in the hippocampus, but did not affect the number of NeuN-positive cells in the hippocampal CA1 region. For the neonatal experiments, neonatal rats were intraperitoneally injected with calpeptin, 2 mg/kg, on postnatal days 7 and 8. Western blot assay was performed to analyze the protein levels of Akt, Erk, p-Akt, p-Erk1/2, Erk1/2, SCOP, PTEN, mTOR, p-mTOR, CREB and p-CREB in the hippocampus. SCOP expression was increased, and the phosphorylation levels of Akt, mTOR and CREB were reduced in the hippocampus. These findings show that calpeptin administration after birth affects synaptic development in neonatal rats by inhibiting the Akt/mTOR signaling pathway, thereby perturbing hippocampal function. Therefore, calpeptin administration after birth is a risk factor for neurodevelopmental defects.

Antidepressant-Like Activity of Typical Antidepressant Drugs in the Forced Swim Test and Tail Suspension Test in Mice Is Augmented by DMPX, an Adenosine A2A Receptor Antagonist

Unsatisfactory therapeutic effects of currently used antidepressants force to search for new pharmacological treatment strategies. Recent research points to the relationship between depressive disorders and the adenosinergic system. Therefore, the main goal of our studies was to evaluate the effects of DMPX (3 mg/kg, i.p.), which possesses selectivity for adenosine A_2A receptors versus A₁ receptors, on the activity of imipramine (15 mg/kg, i.p.), escitalopram (2.5 mg/kg, i.p.), and reboxetine (2 mg/kg, i.p.) given in subtherapeutic doses. The studies carried out using the forced swim and tail suspension tests in mice showed that DMPX at a dose of 6 and 12 mg/kg exerts antidepressant-like effect and does not affect the locomotor activity. Co-administration of DMPX at a dose of 3 mg/kg with the studied antidepressant drugs caused the reduction of immobility time in both behavioral tests. The observed effect was not associated with an increase in the locomotor activity. To evaluate whether the observed effects were due to a pharmacokinetic/pharmacodynamic interaction, the levels of the antidepressants in blood and brain were measured using high-performance liquid chromatography. It can be assumed that the interaction between DMPX and imipramine was exclusively pharmacodynamic in nature, whereas an increased antidepressant activity of escitalopram and reboxetine was at least partly related to its pharmacokinetic interaction with DMPX.

The role of the orexin system in stress response

Orexins are neuropeptides that are exclusively produced by hypothalamic neurons, which project throughout the entire brain. Orexin, also known as hypocretins, were initially identified to play a fundamental role in food intake, arousal and the regulation of sleep and wakefulness. Recent studies identified orexins to be critical for diverse physiological processes including motivation, reward, attention, emotional regulation, stress and anxiety. Here, I review recent findings that indicate orexin has an important role in acute and chronic stress. I also summarize the recent optogenetic and chemogenetic studies that have advanced our understanding of the orexin system. I will conclude by discussing clinical studies that implicate orexins in mental health disorders. This article is part of the Special Issue entitled 'Hypothalamic Control of Homeostasis'.

Evidence for intact 5-HT1A receptor-mediated feedback inhibition following sustained antidepressant treatment in a rat model of depression

Serotonin (5-HT) neurons are strongly implicated in mood disorders such as depression and are importantly regulated by feedback inhibition mediated by 5-HT_1A receptors. These receptors may play a role, albeit a poorly understood one, in the generation of mood disorders, treatment response to antidepressants and delayed therapeutic efficacy. Here we sought to gain insight into the role of 5-HT_1A receptor-mediated feedback inhibition in these processes by studying Fos protein expression within serotonin neurons in a rat model of stress-related mood disorder, early life maternal separation (MS), combined with two-week treatment with the antidepressant fluoxetine (FLX) in adulthood. We gauged 5-HT_1A receptor-mediated feedback inhibition by the ability of the antagonist, WAY-100635 (WAY), to disinhibit Fos expression in 5-HT neurons. We found that two-week FLX treatment dramatically inhibited Fos expression in serotonin neurons and that this effect was reversed by blocking 5-HT_1A receptors with WAY. Together these observations reveal that after prolonged exposure to SSRIs, endogenous 5-HT_1A receptors continue to exert feedback inhibition of serotonin neurons. Furthermore we found unique effects of pharmacological treatments after MS in that the WAY effect was greatest in MS rats treated with FLX, a phenomenon selective to the rostral 2/3 of the dorsal raphe nucleus (B7). These results indicate that the balance between activation and feedback inhibition of serotonin neurons in B7 is altered and uniquely sensitive to FLX after early-life stress.

Maternal Regulation of Pups' Cortical Activity: Role of Serotonergic Signaling

A developing brain shows intense reorganization and heightened neuronal plasticity allowing for environmental modulation of its development. During early life, maternal care is a key factor of this environment and defects in this care can derail adaptive brain development and may result in susceptibility to neuropsychiatric disorders. Nevertheless, the mechanisms by which those maternal interactions immediately impact the offspring's brain activity to initiate the pathway to pathology are not well understood. We do know that multiple neurotransmitter systems are involved, including the serotonergic system, a key neuromodulator involved in brain development and emotional regulation. We tested the importance of the serotonergic system and pups' immediate neural response to maternal presence using wireless electrophysiological recordings, a novel approach allowing us to record neural activity during pups' interactions with their mother. We found that maternal contact modulates the P10-P12 rat pups' anterior cingulate cortex (ACC) activity by notably increasing local-field potential (LFP) power in low-frequency bands. We demonstrated, by blocking serotonergic receptors, that this increase is mediated through 5-HT2 receptors (5-HT2Rs). Finally, we showed in isolated pups that enhancing serotonergic transmission, using a selective-serotonin-reuptake-inhibitor, is sufficient to enhance LFP power in low-frequency bands in a pattern similar to that observed when the mother is in the nest. Our results highlight a significant contribution of the serotonergic system in mediating changes of cortical activity in pups related to maternal presence.

Relevance of Rodent Models of Depression in Clinical Practice: Can We Overcome the Obstacles in Translational Neuropsychiatry?

The diagnosis of a mental disorder generally depends on clinical observations and phenomenological symptoms reported by the patient. The definition of a given diagnosis is criteria based and relies on the ability to accurately interpret subjective symptoms and complex behavior. This type of diagnosis comprises a challenge to translate to reliable animal models, and these translational uncertainties hamper the development of new treatments. In this review, we will discuss how depressive-like behavior can be induced in rodents, and the relationship between these models and depression in humans. Specifically, we suggest similarities between triggers of depressive-like behavior in animal models and human conditions known to increase the risk of depression, for example exhaustion and bullying. Although we acknowledge the potential problems in comparing animal findings to human conditions, such comparisons are useful for understanding the complexity of depression, and we highlight the need to develop clinical diagnoses and animal models in parallel to overcome translational uncertainties.

Abnormal Serotonin Levels During Perinatal Development Lead to Behavioral Deficits in Adulthood

Serotonin (5-HT) is one of the best-studied modulatory neurotransmitters with ubiquitous presynaptic release and postsynaptic reception. 5-HT has been implicated in a wide variety of brain functions, ranging from autonomic regulation, sensory perception, feeding and motor function to emotional regulation and cognition. The role of this neuromodulator in neuropsychiatric diseases is unquestionable with important neuropsychiatric medications, e.g., most antidepressants, targeting this system. Importantly, 5-HT modulates neurodevelopment and changes in its levels during development can have life-long consequences. In this mini-review, we highlight that exposure to both low and high serotonin levels during the perinatal period can lead to behavioral deficits in adulthood. We focus on three exogenous factors that can change 5-HT levels during the critical perinatal period: dietary tryptophan depletion, exposure to serotonin-selective-reuptake-inhibitors (SSRIs) and poor early life care. We discuss the effects of each of these on behavioral deficits in adulthood.

Neonatal whisker trimming in WAG/Rij rat pups causes developmental delay, encourages maternal care and affects exploratory activity in adulthood

WAG/Rij rats are genetically predisposed to absence epilepsy. Maternal behavior in WAG/Rij female rats is known to differ from that in non-epileptic females. We hypothesize that (1) mother's behavior may be changed as response to changes in pup's conditions; (2) sensory deprivation at the neonatal age affect learning and behavior in adulthood. All whiskers in WAG/Rij rat pups were trimmed daily during PN1-PN8. Maternal behavior was examined during the same period. It was found that in the control group, WAG/Rij females often demonstrated abnormally long (>1 min) repetitive purposeless stereotypical actions that were roughly classified as compulsive-like behavior. Mothers of the trimmed pups showed less compulsive-like behavior and more intensively interacted with pups and built better nests. Rat pups in the trimmed group had lower body weight on PN7-PN19 as compared to the control. In the trimmed group, maturation of motor skills and early behavioral patterns (i.e. walking, grooming, vertical activity, motor functions of forelimbs) showed 1-2 days delay in comparison to the control. At the age of 2-2.5 months, the locomotor activity in the trimmed rats differed from the control, but the level of anxiety was the same (the open field and the elevated plus maze). At the age of 6 months, the trimmed and control rats showed no differences in conditioned avoidance learning test, therefore, neonatal whisker trimming did not influence fear-based learning abilities in adulthood. It is hypothesized that an enhanced maternal care is capable to modulate development of brain functions in sensory deprived progeny.

Voluntary Exercise During Adolescence Mitigated Negative the Effects of Maternal Separation Stress on the Depressive-Like Behaviors of Adult Male Rats: Role of NMDA Receptors

Evidence indicates that experiencing early-life stress (ELS) is a risk factor for the development of mental disorders such as depression. Maternal separation stress (MS) is a valid animal model of ELS that caused to induce long-lasting effects on the brain and behaviors of animals. It hypothesized that adolescence is a critical stage in which the brain is still developing, and applying (non)pharmacological therapies in this period may attenuate the effects of ELS on the brain and behavior. Male rats were subjected to MS from postnatal day (PND) 2-14, and the stressed animals were then treated with (1) chronic fluoxetine (FLX) (5 mg/kg) and (2) voluntary running wheel exercise (RW) from PND 30, for 30 days. Then, we subjected the animals to behavioral and molecular assessments at PND 60. Our data showed that MS provoked depressive-like behaviors in rats, tested by the forced swimming test, splash test, and sucrose preference test. Additionally, we found that MS increased the gene expression of the NR2A (and not NR2B) subunit of N-methyl-D-aspartate (NMDA) receptors in the hippocampus of adult rats. Both FLX and RW treatments during adolescence were able to mitigate the negative effects of ELS on stressed animals. These results highlighted the importance of adolescence in treating stressed animals with FLX/voluntary RW exercise to alleviate the depressive effects of ELS. In addition, we found that ELS altered the transcriptional level of Grin2a (and not Grin2b) in the hippocampus. Finally, our results showed that FLX/voluntary RW exercise during adolescence could normalize altered expression of Grin2a in the hippocampus of adult rats.

Early life stress induces immune priming in kidneys of adult male rats

Early life stress (ELS) in humans is associated with elevated proinflammatory markers. We hypothesized that ELS induces activation of the immune response in a rat model of ELS, maternal separation (MatSep), in adulthood. MatSep involves separating pups from the dam from postnatal day 2 to postnatal day 14 for 3 h/day. Control rats are nonseparated littermates. We determined circulating and renal immune cell numbers, renal immune cell activation markers, renal cytokine levels, and the renal inflammatory gene expression response to low-dose lipopolysaccharide (LPS) in male MatSep and control rats. We observed that MatSep did not change the percentage of gated events for circulating CD3+, CD4+, CD8+, and CD4+/Foxp3+ cells or absolute numbers of mononuclear and T cells in the circulation and kidneys; however, MatSep led to an increase in activation of renal neutrophils as well as CD44+ cells. Renal toll-like receptor 4 (TLR4) and interleukin 1 beta (IL-1β) was significantly increased in MatSep rats, specifically in the outer and inner medulla and distal nephron, respectively. Evaluation of renal inflammatory genes showed that in response to a low-dose LPS challenge (2 mg/kg iv) a total of 20 genes were significantly altered in kidneys from MatSep rats (17 genes were upregulated and 3 were downregulated), as opposed to no significant differences in gene expression in control vs. control + LPS groups. Taken together, these findings indicate that MatSep induces priming of the immune response in the kidney.

Epigenetic mechanisms in alcohol- and adversity-induced developmental origins of neurobehavioral functioning

The long-term effects of developmental alcohol and stress exposure are well documented in both humans and non-human animal models. Damage to the brain and attendant life-long impairments in cognition and increased risk for psychiatric disorders are debilitating consequences of developmental exposure to alcohol and/or psychological stress. Here we discuss evidence for a role of epigenetic mechanisms in mediating these consequences. While we highlight some of the common ways in which stress or alcohol impact the epigenome, we point out that little is understood of the epigenome's response to experiencing both stress and alcohol exposure, though stress is a contributing factor as to why women drink during pregnancy. Advancing our understanding of this relationship is of critical concern not just for the health and well-being of individuals directly exposed to these teratogens, but for generations to come.

How does early maternal separation and chronic stress in adult rats affect the immunoreactivity of serotonergic neurons within the dorsal raphe nucleus?

Vulnerability to emotional disorders like depression derives from interactions between early and late environments, including stressful conditions. The serotonin (5HT) system is strongly affected by stress and chronic unpredictable stress can alter the 5HT system. We evaluated the distribution of active serotonergic neurons in the dorsal raphe nucleus (DR) through immunohistochemistry in maternally separated and chronically stressed rats treated with an antidepressant, tianeptine, whose mechanism of action is still under review. Male Wistar rats were subjected to daily maternal separation (MS) for 4.5 h between postnatal days (PND) 1-21, or to animal facility rearing (AFR). Between (PND) days 50-74, rats were exposed to chronic unpredictable stress and were treated daily with tianeptine (10 mg/kg) or vehicle. We found an interaction between the effects of MS and chronic unpredictable stress on Fos-5HT immunoreactive cells at mid-caudal level of the DR. MS-chronically stressed rats showed an increase of Fos-5HT immunoreactive cells compared with AFR-chronically stressed rats. The ventrolateral (DRL/VLPAG) and dorsal (DRD) subdivisions of the DR were significantly more active than the ventral part (DRV). At the rostral level of the DR, tianeptine decreased the number of Fos-5HT cells in DR in the AFR groups, both unstressed and stressed. Overall, our results support the idea of a match in phenotype exhibited when the early and the adult environment correspond.

Microglia in health and pain: impact of noxious early life events

NEW FINDINGS

What is the topic of this review? This review discusses the origins and development of microglia, and how stress, pain or inflammation in early life disturbs microglial function during critical developmental periods, leading to altered pain sensitivity and/or increased risk of chronic pain in later life. What advances does it highlight? We highlight recent advances in understanding how disrupted microglial function impacts the developing nervous system and the consequences for pain processing and susceptibility for development of chronic pain in later life. The discovery of microglia is accredited to Pío del Río-Hortega, who recognized this 'third element' of CNS cells as being morphologically distinct from neurons and astrocytes. For decades after this finding, microglia were altogether ignored or relegated as simply being support cells. Emerging from virtual obscurity, microglia have now gained notoriety as immune cells that assume a leading role in the development, maintenance and protection of a healthy CNS. Pioneering studies have recently shed light on the origins of microglia, their role in the developing nervous system and the complex roles they play beyond the immune response. These studies reveal that altered microglial function can have a profoundly negative impact on the developing brain and may be a determinant in a range of neurodevelopmental disorders and neurodegenerative diseases. The realization that aberrant microglial function also critically underlies chronic pain, a debilitating disorder that afflicts over 1.5 billion people worldwide, was a major conceptual leap forward in the pain field. Adding to this advance is emerging evidence that early life noxious experiences can have a long-lasting impact on central pain processing and adult pain sensitivity. With microglia now coming of age, in this review we examine the association between adverse early life events, such as stress, injury or inflammation, and the influence of sex differences, on the role of microglia in pain physiology in adulthood.

Etiopathogenesis and Pharmacological Prevention of a Type-2 Diabetes Model in Male Mice

We describe a stress-derived type-2 diabetes model in male mice, and formulate new hypotheses on how the model was induced, how diabetes-like alterations were prevented through specific pharmacological treatments, and how its possible neuroendocrine pathogenesis could be hypothesized. Pregnant females arrived in our laboratory on their 14th day of conceptional age. After birth, control mice never showed any apparent behavioral-metabolic-endocrine alterations. However, application of postnatal stress (brief mother deprivation, plus sham injection, daily from birth to weaning), was followed in adult male mice by two series of diabetes-like alterations. Some alterations (e.g., body overweight, immune, neurophysiologic, neurobehavioral alterations) were selectively prevented by opioid antagonist naloxone daily administered during nursing period. The aforementioned alterations plus several others (e.g., hyperglycemia, neuroendocrine alterations) were prevented by administration of specific antisense oligodeoxinucleotide, which modulated synthesis-hyperfunction of proopiomelanocortin-derived corticotropin (ACTH)-corticosterone and endorphins in the pituitary. Surprisingly, together with metabolic alterations, enduring increment of neurophysiologic/neurobehavioral brain performances were observed, accompanied by energy compensative reactions, and brain mitochondria hyperfunction. Thus, increased glycemia/lipidemia appeared to furnish fuel necessary to cope with increased request of energy. Diabetes-like alterations were accompanied by enduring hyperfunction of opioid- and ACTH-corticosterone-endogenous structures in the brain, which were apparently due to failure of negative feedback hormone mechanisms in the pituitary, for the control of the hypothalamus-pituitary-adrenal axis. In conclusion, for the first time we can hypothesize that a diabetes-like syndrome is produced by enduring hyperfunction of two proopiomelanocortin-dependent endogenous systems (brain opioid- and ACTH-corticosterone systems), following failure of pituitary feedback hormonal control, after complex stress procedures.

Animal models for bipolar disorder: from bedside to the cage

Bipolar disorder is characterized by recurrent manic and depressive episodes. Patients suffering from this disorder experience dramatic mood swings with a wide variety of typical behavioral facets, affecting overall activity, energy, sexual behavior, sense of self, self-esteem, circadian rhythm, cognition, and increased risk for suicide. Effective treatment options are limited and diagnosis can be complicated. To overcome these obstacles, a better understanding of the neurobiology underlying bipolar disorder is needed. Animal models can be useful tools in understanding brain mechanisms associated with certain behavior. The following review discusses several pathological aspects of humans suffering from bipolar disorder and compares these findings with insights obtained from several animal models mimicking diverse facets of its symptomatology. Various sections of the review concentrate on specific topics that are relevant in human patients, namely circadian rhythms, neurotransmitters, focusing on the dopaminergic system, stressful environment, and the immune system. We then explain how these areas have been manipulated to create animal models for the disorder. Even though several approaches have been conducted, there is still a lack of adequate animal models for bipolar disorder. Specifically, most animal models mimic only mania or depression and only a few include the cyclical nature of the human condition. Future studies could therefore focus on modeling both episodes in the same animal model to also have the possibility to investigate the switch from mania-like behavior to depressive-like behavior and vice versa. The use of viral tools and a focus on circadian rhythms and the immune system might make the creation of such animal models possible.

Common Marmosets: A Potential Translational Animal Model of Juvenile Depression

Major depression is a psychiatric disorder with high prevalence in the general population, with increasing expression in adolescence, about 14% in young people. Frequently, it presents as a chronic condition, showing no remission even after several pharmacological treatments and persisting in adult life. Therefore, distinct protocols and animal models have been developed to increase the understanding of this disease or search for new therapies. To this end, this study investigated the effects of chronic social isolation and the potential antidepressant action of nortriptyline in juvenile Callithrix jacchus males and females by monitoring fecal cortisol, body weight, and behavioral parameters and searching for biomarkers and a protocol for inducing depression. The purpose was to validate this species and protocol as a translational model of juvenile depression, addressing all domain criteria of validation: etiologic, face, functional, predictive, inter-relational, evolutionary, and population. In both sexes and both protocols (IDS and DPT), we observed a significant reduction in cortisol levels in the last phase of social isolation, concomitant with increases in autogrooming, stereotyped and anxiety behaviors, and the presence of anhedonia. The alterations induced by chronic social isolation are characteristic of the depressive state in non-human primates and/or in humans, and were reversed in large part by treatment with an antidepressant drug (nortriptyline). Therefore, these results indicate C. jacchus as a potential translational model of juvenile depression by addressing all criteria of validation.

Behavioral and cognitive impact of early life stress: Insights from an animal model

BACKGROUND

Children subjected to traumatic events during childhood are reported to exhibit behavioral and cognitive deficits later in life, often leading to post-traumatic stress disorder (PTSD) and major depression. Interestingly, some children continue to remain normal despite being exposed to the same risk factors. These trauma-related behavioral and cognitive profiles across different stages of life are not well understood. Animal studies can offer useful insights.

OBJECTIVE

The goal of this study was to determine the impact of early life exposure to traumatic events on behavioral and cognitive profile in rats by tracking the behavior of each rat at different ages.

METHODS

We utilized the single prolonged stress (SPS), a rodent model of PTSD, to study the effects of early life stress. Male Sprague-Dawley rats were exposed to SPS on post-natal day (PND) 25. Tests to assess anxiety- and depression-like behavior, as well as learning and memory function were performed at PND32, 60 and 90.

RESULTS

Rats exposed to SPS exhibited both anxiety- and depression-like behavior at PND32. And, short-term (STM) but not long-term memory (LTM) was impaired. Rats exposed to SPS at PND60 exhibited anxiety- but not depression-like behavior. STM but not LTM was impaired. Rats exposed to SPS at PND90 exhibited fearful (as indicated by elevated plus maze test) but not an overall anxiety-like behavior (in light and dark test). These rats also displayed significant depression-like behavior with no changes in STM or LTM. Interestingly, when data was further analyzed, two subsets of PND90 rats exposed to SPS were identified, "susceptible": with depression-like behavior and "resilient": without depression-like behavior. Importantly, while resilient group expressed early signs of anxiety- (at PND32 and PND60) and depression-like behavior (at PND32), these behavioral deficits were absent at PND90. On the other hand, susceptible PND90 rats exposed to SPS expressed later onset of anxiety-like behavior (at PND60), while depression-like phenotype was evident only later on at PND90.

CONCLUSIONS

Our findings suggest that early life stress caused co-occurrence of anxiety and depression-like behavior at PND32 (mimics human early-adolescent period). This co-occurrence was lost at PND60 with demonstration of anxiety- but not depression-like behavior. Later, depression but not anxiety-like behavior was observed at PND90. It seems that behavioral adaptations occur at the critical PND60 stage (mimics human late-adolescent period), where behavioral and cognitive switching occurs, thereby, expressing susceptible and resilient phenotypes.

7-Fluoro-1,3-diphenylisoquinoline-1-amine reverses the reduction in self-care behavior induced by maternal separation stress in rats by modulating glutamatergic/GABAergic systems

7-Fluoro-1,3-diphenylisoquinoline-1-amine (FDPI) is a promising isoquinoline that elicits an antidepressant-like action in rodents. In this study, an animal model of stress induced by maternal separation was used to investigate the effects of FDPI in Wistar rats of 30 and 90 days of age. It was investigated the effects of maternal separation in the self-care behavior and the contribution of glutamatergic and gamma-aminobutyric acid (GABA)ergic systems in the FDPI action. Male Wistar rats were separated from their mothers for 3 h/day from postnatal day (PND) 1-10. The rats were treated at different ages (PND-30 and PND-90) with FDPI (5 mg/kg, intragastrically/7 days) and performed the splash test. Maternal separation reduced total grooming time in the splash test, an index of motivational and self-care behavior, and FDPI treatment was effective in reversing this behavior in rats at both ages. The neurochemical parameters were differently affected, dependent on the age of rats, by maternal separation and FDPI. Maternal separation increased the GABA uptake and the excitatory amino acid transporter 1 levels in the prefrontal cortices of rats at PND-30 and FDPI was effective against these alterations. At PND-90, maternal separation decreased the glutamate uptake and increased the GABA uptake and the N-methyl-D-aspartate (NMDA) receptor 2B levels in the prefrontal cortices of rats. FDPI reversed the neurochemical alterations caused by maternal separation in the prefrontal cortices of rats at PND-90. The results of this study demonstrated that FDPI reversed the reduction in self-care behavior induced by maternal separation stress in rats by modulating the glutamatergic/GABAergic systems in rats.

Parent-Infant Skin-to-Skin Contact Following Birth: History, Benefits, and Challenges

It is a practice with strong roots in nature and has a significant influence on health outcomes, particularly for at-risk newborns in low-resource settings. In this comprehensive review, benefits of SSC for newborns, mothers, and fathers after vaginal and cesarean births are discussed as well as the benefits of SSC observed for infants in the NICU. Barriers to SSC practice implementation are discussed, and proposed solutions and recommendations are offered. By understanding the many benefits of SSC and strategies for implementation, health care providers can best support and promote this high-quality, evidence-based practice with mothers, newborns, and their families.

Intestinal epithelial injury induced by maternal separation is protected by hydrogen sulfide

PURPOSE

Oxidative stress has been implicated in the pathogenesis of various neonatal diseases involving the intestine. Hydrogen sulfide (H₂S) has been shown to protect against oxidative stress. We hypothesized that administration of sodium hydrosulfide (NaHS), an H₂S donor, to neonatal mice can decrease the intestinal epithelial injury associated with maternal separation (MS).

METHODS

C57BL/6 mice received either intraperitoneal phosphate buffered saline (PBS; n=10) or NaHS (1mg/kg/day; n=10), followed by MS for 3h daily between postnatal day P5 and P9. Control neonatal mice were untreated and were not exposed to MS (n=10). Proximal colon was harvested and analyzed for crypt length, goblet cell number per crypt, oxidative stress and inflammation. Groups were compared using one-way ANOVA with Bonferroni post-test.

RESULTS

Compared to controls, MS+PBS mice had shorter crypt lengths, fewer goblet cells per crypt, reduced glutathione peroxidase activity, increased expression of thiobarbituric acid reactive substances and inducible nitric oxide synthase mRNA, as well as increased IL-6, TNFα and myeloperoxidase. Administration of NaHS significantly counteracted these negative effects of MS.

CONCLUSIONS

H₂S protects the colon from the epithelial damage, oxidative stress and inflammation caused by maternal separation. This study provides insights on the pathogenesis of neonatal bowel diseases and indicates the potential for a pharmacological intervention to rescue the colonic epithelium.

LEVEL OF EVIDENCE

n/a - animal and laboratory study.

Impairment of decision making and disruption of synchrony between basolateral amygdala and anterior cingulate cortex in the maternally separated rat

There is considerable evidence to suggest early life experiences, such as maternal separation (MS), play a role in the prevalence of emotional dysregulation and cognitive impairment. At the same time, optimal decision making requires functional integrity between the amygdala and anterior cingulate cortex (ACC), and any dysfunction of this system is believed to induce decision-making deficits. However, the impact of MS on decision-making behavior and the underlying neurophysiological mechanisms have not been thoroughly studied. As such, we consider the impact of MS on the emotional and cognitive functions of rats by employing the open-field test, elevated plus-maze test, and rat gambling task (RGT). Using multi-channel recordings from freely behaving rats, we assessed the effects of MS on the large scale synchrony between the basolateral amygdala (BLA) and the ACC; while also characterizing the relationship between neural spiking activity and the ongoing oscillations in theta frequency band across the BLA and ACC. The results indicated that the MS rats demonstrated anxiety-like behavior. While the RGT showed a decrease in the percentage of good decision-makers, and an increase in the percentage of poor decision-makers. Electrophysiological data revealed an increase in the total power in the theta band of the LFP in the BLA and a decrease in theta power in the ACC in MS rats. MS was also found to disrupt the spike-field coherence of the ACC single unit spiking activity to the ongoing theta oscillations in the BLA and interrupt the synchrony in the BLA-ACC pathway. We provide specific evidence that MS leads to decision-making deficits that are accompanied by alteration of the theta band LFP in the BLA-ACC circuitries and disruption of the neural network integrity. These observations may help revise fundamental notions regarding neurophysiological biomarkers to treat cognitive impairment induced by early life stress.

Safe Sleep and Skin-to-Skin Care in the Neonatal Period for Healthy Term Newborns

Skin-to-skin care (SSC) and rooming-in have become common practice in the newborn period for healthy newborns with the implementation of maternity care practices that support breastfeeding as delineated in the World Health Organization's "Ten Steps to Successful Breastfeeding." SSC and rooming-in are supported by evidence that indicates that the implementation of these practices increases overall and exclusive breastfeeding, safer and healthier transitions, and improved maternal-infant bonding. In some cases, however, the practice of SSC and rooming-in may pose safety concerns, particularly with regard to sleep. There have been several recent case reports and case series of severe and sudden unexpected postnatal collapse in the neonatal period among otherwise healthy newborns and near fatal or fatal events related to sleep, suffocation, and falls from adult hospital beds. Although these are largely case reports, there are potential dangers of unobserved SSC immediately after birth and throughout the postpartum hospital period as well as with unobserved rooming-in for at-risk situations. Moreover, behaviors that are modeled in the hospital after birth, such as sleep position, are likely to influence sleeping practices after discharge. Hospitals and birthing centers have found it difficult to develop policies that will allow SSC and rooming-in to continue in a safe manner. This clinical report is intended for birthing centers and delivery hospitals caring for healthy newborns to assist in the establishment of appropriate SSC and safe sleep policies.