Using animal models to disentangle the role of genetic, epigenetic, and environmental influences on behavioral outcomes associated with maternal anxiety and depression

Dopamine downregulation in novel rodent models useful for the study of postpartum depression

Postpartum depression (PPD) is the most common psychiatric disorder following childbirth and is characterized by maternal mood disturbances, impaired maternal responses, and disrupted caregiving- all of which negatively impact offspring development. Since PPD has detrimental consequences for both mother and child, clinical and preclinical research has focused on identifying brain changes associated with this disorder. In humans, PPD is linked to dysregulated mesolimbic dopamine (DA) system function and altered neural responses (i.e., decreased reward-related activity) to infant-related cues, which are considered hallmark features of PPD. In accordance, rodent models employing translational risk factors useful for the study of PPD have demonstrated alterations in mesolimbic DA system structure and function, and these changes are reviewed here. We also present two novel rodent models based on postpartum adversity exposure (i.e., pup removal, scarcity-adversity) which result in PPD-relevant behavioral changes (e.g., disrupted mother-infant interactions, deficits in maternal behavior, depressive-like phenotypes) and attenuated ventral tegmental area (VTA) DA neuron activity consistent with a hypodopaminergic state. Furthermore, we highlight open questions and future directions for these rodent models. In sum, human and rodent studies converge in showing blunted mesolimbic DA function (i.e., DA downregulation) in PPD. We propose that reduced activity of VTA DA neurons, resulting in downregulation of the mesolimbic DA system, interferes with reward-related processes necessary for maternal motivation and responsiveness. Thus, the mesolimbic DA system may constitute a therapeutic target for ameliorating reward-related deficits in PPD.

The impact of early-life environment on absence epilepsy and neuropsychiatric comorbidities

This review discusses the long-term effects of early-life environment on epileptogenesis, epilepsy, and neuropsychiatric comorbidities with an emphasis on the absence epilepsy. The WAG/Rij rat strain is a well-validated genetic model of absence epilepsy with mild depression-like (dysthymia) comorbidity. Although pathologic phenotype in WAG/Rij rats is genetically determined, convincing evidence presented in this review suggests that the absence epilepsy and depression-like comorbidity in WAG/Rij rats may be governed by early-life events, such as prenatal drug exposure, early-life stress, neonatal maternal separation, neonatal handling, maternal care, environmental enrichment, neonatal sensory impairments, neonatal tactile stimulation, and maternal diet. The data, as presented here, indicate that some early environmental events can promote and accelerate the development of absence seizures and their neuropsychiatric comorbidities, while others may exert anti-epileptogenic and disease-modifying effects. The early environment can lead to phenotypic alterations in offspring due to epigenetic modifications of gene expression, which may have maladaptive consequences or represent a therapeutic value. Targeting DNA methylation with a maternal methyl-enriched diet during the perinatal period appears to be a new preventive epigenetic anti-absence therapy. A number of caveats related to the maternal methyl-enriched diet and prospects for future research are discussed.

PERINATAL MENTAL HEALTH,FREQUENCY, CAUSES AND RESULTS: A REVIEW

ABSTRACT Perinatal mental illnesses occur during pregnancy and up to one year after birth. It is observed that diseases with a wide spectrum such a major depression, anxiety disorders, bipolar disorders and psychosis that are frequently recur in the early postnatal period. Although the underlying psychopatologies are not fully elucidated, multifaceted, multifactorial causes such as hormones during pregnancy, enviromental factors, social support of women and previous disease history, as well as genetic factors and the effects of all these on neurotransmitter levels in the brain are blamed. Clinically, exposure to prenatal depression and anxiety disorders has been associated with cognitive and behavioral problems in children, attention deficit/hyperactivity disorder, autism and emotional problems in early and middle childhood. Interventions for the treatment of mental ilnesses that occur in the perinatal period are in the form of pharmacological, psychotherapeutic and psychosocial interventions these aimed maternal and child health, development and finally healthy families should be planned and applied seriously in the long term by considering the benefit risk balance. Early detection and effective management of perinatal mental ilnesses are critical for the quality of life and welfare of women and their children.

Beta-Carotene derivatives as novel therapy for the prevention and treatment of autistic symptoms

Autistic Spectrum Disorders (ASD) are neurodevelopmental disorders characterized by impaired social interaction & communication as well as restricted and repetitive behavior. The currently reported incidence of ASD is 1-2%, and it increases dramatically to 10-20% in families predisposed to ASD. To date, there is no effective way to treat or prevent ASD, and only symptomatic treatment with limited efficacy is available. Oxytocin (Oxt) enhances affiliative behavior and improves social cognition. Social deficits characteristic of autism may be related to dysfunctional Oxt neurotransmission. Thus, administration of Oxt may relieve ASD, however it has a short plasma half-life and poor Blood Brain Barrier (BBB) permeability. CD38, a multifunctional ecto-enzyme expressed in brain and immune cells, was found to be critical for social behavior via regulation of Oxt secretion. All-trans retinoic acid (ATRA) is a potent inducer of CD38 and improves social behavior, but it is toxic and teratogenic. We have shown that beta-carotene has a similar therapeutic effect. The present study aimed to investigate the activity of novel beta-carotene derivatives in rescuing low sociability found in BTBR mice, providing an in vivo "proof of principle" that beta-carotene derivatives are potential agents to prevent/ameliorate the reappearance of ASD in high-risk populations for ASD. Beta-carotene and its synthetic analogs were administered orally to newborn BTBR mice with ASD associated like behavior. After 2 months, they were tested (at dosages of 0.1 and 1.0 mg/kg) by cognitive (T-maze spontaneous alteration and neurological score) and behavioral tests (reciprocal social interaction, repetitive grooming / bedding behavior), previously shown as indicators for autistic behavior. The following biochemical and molecular biology parameters were also examined: serum Oxt; gene expression in hippocampus and hypothalamus of CD 38, Oxt, Oxt receptor, BDNF, and retinoic acid receptor. The new compounds were significantly more effective than control. The most effective compounds, both in the behavioral tests and in their biochemical effects, were (3R,3'R)-astaxanthin bis(N-Cbz-l-alanine ester) (3B(and (3S,3'S)-astaxanthin bis(N,N-dimethylglycine ester (5). They did not exert any neurological symptoms. Thus, beta-carotene derivatives may have the potential to prevent and/or ameliorate autistic symptoms when administered orally after birth to newborns of families predisposed to autism.

The Importance of Epigenetics in Diagnostics and Treatment of Major Depressive Disorder

Recent studies imply that there is a tight association between epigenetics and a molecular mechanism of major depressive disorder (MDD). Epigenetic modifications, i.e., DNA methylation, post-translational histone modification and interference of microRNA (miRNA) or long non-coding RNA (lncRNA), are able to influence the severity of the disease and the outcome of the therapy. This article summarizes the most recent literature data on this topic, i.e., usage of histone deacetylases as therapeutic agents with an antidepressant effect and miRNAs or lncRNAs as markers of depression. Due to the noteworthy potential of the role of epigenetics in MDD diagnostics and therapy, we have gathered the most relevant data in this area.

Role of midwife-supported psychotherapy on antenatal depression, anxiety and maternal health: A meta-analysis and literature review

The onset of depression and anxiety during the antenatal stage of pregnancy is common. Despite the conception of numerous interventions in the past decades, studies show no signs of decline in the prevalence of antenatal depression and anxiety. Recently, the use of midwife-supported psychotherapy to treat these psychosomatic disorders has garnered a lot of attention. However, no attempt to date has been made to synthesize the evidence evaluating the influence of midwife-supported psychotherapy on antenatal depression, anxiety, and overall maternal health-status. The aim of the present meta-analysis was to demonstrate the effectiveness of midwife-supported psychotherapy on depression, anxiety, and maternal health-status outcome during the antenatal stage of pregnancy. A systematic identification of literature was performed according to PRISMA guidelines on four academic databases: MEDLINE, Scopus, EMBASE and CENTRAL. A meta-analysis evaluated the influence of midwife-supported psychotherapy on depression, anxiety, and maternal health-status outcome as compared to conventional obstetric care. Of the 1,011 records, 17 articles, including 6,193 pregnant women (mean age: 28.9±2.2 years) were included in this meta-analysis. Eleven studies compared the effects of midwife-supported therapy on depression, 14 compared its effects on anxiety and 2 compared its effects on maternal health-status outcome. The meta-analysis reveals the beneficial effects of midwife-supported psychotherapy for reducing depression (Hedge's g: -0.9), anxiety (-0.8) and enhancing maternal health-status outcome (0.1), as compared to conventional obstetric care. The current systematic review and meta-analysis recommend the use of midwife-supported psychotherapy for the reduction of depression, anxiety and enhancing maternal health-status during the antenatal stage of pregnancy.

Role of psychotherapy on antenatal depression, anxiety, and maternal quality of life: A meta-analysis

BACKGROUND

Depression and anxiety are common psychological manifestations encountered during the antenatal stage of pregnancy. Treatments by pharmacological interventions have been reported to impart negative implications on maternal and fetal health outcomes. Therefore, the use of psychotherapeutic interventions to bypass these side-effects and manage depression, anxiety has received a lot of attention. A meta-statistical consensus regarding the intervention is available, but with several limitations. In this study, we attempt to address these limitations and provide the current state of evidence evaluating the influence of psychotherapy on antenatal depression, anxiety, and maternal quality of life.

OBJECTIVE

To demonstrate the effects of psychotherapy on depression, anxiety, and maternal quality of life during the antenatal stage of pregnancy.

METHODS

A systematic identification of literature was performed according to PRISMA guidelines on four academic databases: MEDLINE, Scopus, EMBASE, and CENTRAL. A meta-analysis evaluated the influence of psychotherapy on depression, anxiety, and maternal quality of life as compared to conventional obstetric care.

RESULTS

Out of 1146 records, 22 articles including 2146 pregnant women (mean age: 28.6 ± 2.8 years) were included in this review. This systematic review presents a 1b level of evidence supporting the use of psychotherapy for reducing depression, anxiety and enhancing maternal quality of life. The meta-analysis reveals the beneficial effects of psychotherapy for reducing depression (Hedge g: -0.48), anxiety (-0.47) and enhancing maternal quality of life (0.19) as compared to conventional obstetric care.

CONCLUSIONS

The current systematic review and meta-analysis recommend the use of psychotherapy as for reducing depression, anxiety and enhancing maternal quality of life during the antenatal stage of pregnancy.

DNA methylation studies of depression with onset in the peripartum: A critical systematic review

OBJECTIVE

Major depression with peripartum onset (MDP) has been associated with multiple adverse offspring health outcomes. The biological mechanisms underlying this relationship remain unclear, but DNA methylation (DNAm) represents a plausible mechanism for mediating MDP exposures and changes in offspring development, behavior, and health. Advances in DNAm research necessitate reevaluating the MDP-DNAm literature to determine how well past studies conform with current best practices.

METHOD

Five databases were searched to identify studies of prenatal-onset MDP and DNAm. Quality scores were assigned to each article independently by two raters using a novel scale specific for MDP-DNAm research.

RESULTS

Nineteen studies met inclusion criteria. Quality scores ranged from 10 to 17 out of 24 points (M = 12.8; SD = 1.9), with higher scores indicating increased study rigor. Poor covariate reporting was the most significant contributor to lower scores.

CONCLUSION

No longitudinal MDP-DNAm studies exist. Earlier MDP-DNAm studies should be interpreted with caution, and future research must commit to sharing methodology and data to facilitate cross-study comparisons and maximize dataset utility.

Animal models of maternal depression for monitoring neurodevelopmental changes occurring in dams and offspring

Depression is one of the most prevalent and life-threatening forms of mental illness affecting about 20% of the population. Depressive disorder as a biochemical phenomenon, was first recognized in the mid-20^th century of research, however the etiology of this disease is still not well understood. Although the need to investigate depressive disorders has emerged from the needs of clinical practice, there are many preclinical studies, which brought new insights into this field of research. During experimental work it was crucial to develop appropriate animal models, where the neurohumoral mechanism was similar to humans. In the past decades, several animal models of maternal depression have been developed. We describe the three most popular rodent models of maternal depression which are based on 1. stress prior to gestation, 2. prenatal stress and 3. early life stress. The above-mentioned animal models appear to fulfill many criteria for a relevant animal model of depression; they alter the regulation of the HPA, induce signs of depression-like behavior and several antidepressant treatments can reverse the state induced by maternal stress. Although, they are not able to model all aspects of maternal depression, they are useful models for monitoring neurodevelopmental changes occurring in dams and offspring.

Postpartum Lactation-Mediated Behavioral Outcomes and Drug Responses in a Spontaneous Mouse Model of Obsessive-Compulsive Disorder

Using a spontaneous mouse model of obsessive-compulsive disorder (OCD), the current study evaluated the influence of postpartum lactation on the expression of compulsive-like behaviors, SSRI effectiveness, and the putative role of oxytocin and dopamine in mediating these lactation specific behavioral outcomes. Compulsive-like lactating mice were less compulsive-like in nest building and marble burying and showed enhanced responsiveness to fluoxetine (50 mg/kg) in comparison to compulsive-like nonlactating and nulliparous females. Lactating mice exhibited more anxiety-like behavior in the open field test compared to the nulliparous females, while chronic fluoxetine reduced anxiety-like behaviors. Blocking the oxytocin receptor with L368-899 (5 mg/kg) in the lactating mice exacerbated the compulsive-like and depression-like behaviors. The dopamine D2 receptor (D2R) agonist bromocriptine (10 mg/kg) suppressed marble burying, nest building, and central entries in the open field, but because it also suppressed overall locomotion in the open field, activation of the D2R receptor may have inhibited overall activity nonspecifically. Lactation- and fluoxetine-mediated behavioral outcomes in compulsive-like mice, therefore, appear to be partly regulated by oxytocinergic mechanisms. Serotonin immunoreactivity and serum levels were higher in lactating compulsive-like mice compared to nonlactating and nulliparous compulsive-like females. Together, these results suggest behavioral modulation, serotonergic alterations, and changes in SSRI effectiveness during lactation in compulsive-like mice. This warrants further investigation of postpartum events in OCD patients.

Gene-environment interaction influences attachment-like style in mice

Attachment styles are established soon after birth and form the basis for a healthy psychological life during adulthood. Here, we investigated whether genetic background (i.e. isogenic strains: C57BL/6N and BALB/c) and parent-of-origin (i.e. reciprocal hybrids) epigenetic effects influence attachment-like styles in mice. We discovered that a specific genetic and epigenetic assortment exerts a role on the development of a secure or insecure attachment-like style. In particular, when biological mothers raise their pups, the attachment-like style is mainly secure, independently of the genetic background. However, when foster mothers raise pups, the attachment-like style can be either secure or insecure, depending on the particular genetic background, and this effect is paternally transmitted. Finally, we observed that secure attachment-like in mice leads to greater sociability during adulthood, while insecure attachment-like leads to reduced sociability. Our study sheds light on gene-environment interactions that shape the attachment-like style early in development and pave the way for a healthy psychological life.

Epigenetic regulation of G protein coupled receptor signaling and its implications in psychiatric disorders

G protein-coupled receptors (GPCRs) act as a relay center through which extracellular signals, in the form of neurotransmitters or therapeutics, are converted into an intracellular response, which ultimately shapes the overall response at the tissue and behavioral level. Remarkably in similar ways, epigenetic mechanisms also modulate the expression pattern of a large number of genes in response to the dynamic environment inside and outside of the body, and consequently overall response. Emerging evidences from the pharmacogenomics and preclinical studies clearly suggest that these two distinct mechanisms criss-cross each other in several neurological disorders. At one hand such cross-talks between two distinct mechanisms make disease etiology more challenging to understand, while on the other hand if dealt appropriately, such situations might provide an opportunity to find novel druggable target and strategy for the treatment of complex diseases. In this review article, we have summarized and highlighted the main findings that tie epigenetic mechanisms to GPCR mediated signaling in the pathophysiology of central nervous system (CNS) disorders, including depression, addiction and pain.

Pervasive and opposing effects of Unpredictable Chronic Mild Stress (UCMS) on hippocampal gene expression in BALB/cJ and C57BL/6J mouse strains

Background

BALB/cJ is a strain susceptible to stress and extremely susceptible to a defective hedonic impact in response to chronic stressors. The strain offers much promise as an animal model for the study of stress related disorders. We present a comparative hippocampal gene expression study on the effects of unpredictable chronic mild stress on BALB/cJ and C57BL/6J mice. Affymetrix MOE 430 was used to measure hippocampal gene expression from 16 animals of two different strains (BALB/cJ and C57BL/6J) of both sexes and subjected to either unpredictable chronic mild stress (UCMS) or no stress. Differences were statistically evaluated through supervised and unsupervised linear modelling and using Weighted Gene Coexpression Network Analysis (WGCNA). In order to gain further understanding into mechanisms related to stress response, we cross-validated our results with a parallel study from the GENDEP project using WGCNA in a meta-analysis design.

Results

The effects of UCMS are visible through Principal Component Analysis which highlights the stress sensitivity of the BALB/cJ strain. A number of genes and gene networks related to stress response were uncovered including the Creb1 gene. WGCNA and pathway analysis revealed a gene network centered on Nfkb1. Results from the meta-analysis revealed a highly significant gene pathway centred on the Ubiquitin C (Ubc) gene. All pathways uncovered are associated with inflammation and immune response.

Conclusions

The study investigated the molecular mechanisms underlying the response to adverse environment in an animal model using a GxE design. Stress-related differences were visible at the genomic level through PCA analysis highlighting the high sensitivity of BALB/cJ animals to environmental stressors. Several candidate genes and gene networks reported are associated with inflammation and neurogenesis and could serve to inform candidate gene selection in human studies and provide additional insight into the pathology of Major Depressive Disorder.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-015-1431-6) contains supplementary material, which is available to authorized users.

The role of reproductive hormones in postpartum depression

Despite decades of research aimed at identifying the causes of postpartum depression (PPD), PPD remains common, and the causes are poorly understood. Many have attributed the onset of PPD to the rapid perinatal change in reproductive hormones. Although a number of human and nonhuman animal studies support the role of reproductive hormones in PPD, several studies have failed to detect an association between hormone concentrations and PPD. The purpose of this review is to examine the hypothesis that fluctuations in reproductive hormone levels during pregnancy and the postpartum period trigger PPD in susceptible women. We discuss and integrate the literature on animal models of PPD and human studies of reproductive hormones and PPD. We also discuss alternative biological models of PPD to demonstrate the potential for multiple PPD phenotypes and to describe the complex interplay of changing reproductive hormones and alterations in thyroid function, immune function, hypothalamic-pituitary-adrenal (HPA) axis function, lactogenic hormones, and genetic expression that may contribute to affective dysfunction. There are 3 primary lines of inquiry that have addressed the role of reproductive hormones in PPD: nonhuman animal studies, correlational studies of postpartum hormone levels and mood symptoms, and hormone manipulation studies. Reproductive hormones influence virtually every biological system implicated in PPD, and a subgroup of women seem to be particularly sensitive to the effects of perinatal changes in hormone levels. We propose that these women constitute a "hormone-sensitive" PPD phenotype, which should be studied independent of other PPD phenotypes to identify underlying pathophysiology and develop novel treatment targets.

A lack of functional NK1 receptors explains most, but not all, abnormal behaviours of NK1R-/- mice(1)

Mice lacking functional neurokinin-1 receptors (NK1R-/-) display abnormal behaviours seen in Attention Deficit Hyperactivity Disorder (hyperactivity, impulsivity and inattentiveness). These abnormalities were evident when comparing the behaviour of separate (inbred: 'Hom') wildtype and NK1R-/- mouse strains. Here, we investigated whether the inbreeding protocol could influence their phenotype by comparing the behaviour of these mice with that of wildtype (NK1R+/+) and NK1R-/- progeny of heterozygous parents ('Het', derived from the same inbred strains). First, we recorded the spontaneous motor activity of the two colonies/genotypes, over 7 days. This continuous monitoring also enabled us to investigate whether the diurnal rhythm in motor activity differs in the two colonies/genotypes. NK1R-/- mice from both colonies were hyperactive compared with their wildtypes and their diurnal rhythm was also disrupted. Next, we evaluated the performance of the four groups of mice in the 5-Choice Serial Reaction-Time Task (5-CSRTT). During training, NK1R-/- mice from both colonies expressed more impulsive and perseverative behaviour than their wildtypes. During testing, only NK1R-/- mice from the Hom colony were more impulsive than their wildtypes, but NK1R-/- mice from both colonies were more perseverative. There were no colony differences in inattentiveness. Moreover, a genotype difference in this measure depended on time of day. We conclude that the hyperactivity, perseveration and, possibly, inattentiveness of NK1R-/- mice is a direct consequence of a lack of functional NK1R. However, the greater impulsivity of NK1R-/- mice depended on an interaction between a functional deficit of NK1R and other (possibly environmental and/or epigenetic) factors.

Behavioural changes in mothers and maternally sensitised female mice

The maternal motivation and depression-like behaviour of primiparous mother and maternally sensitised virgin female mice were investigated. During a 1-h test period, dams and sensitised female mice spent significantly more time in pup-associated than in control cages when they could freely choose between them, while virgin control and ovariectomised females had no such preference. In the forced swim test, the time spent in active (swimming and struggling) and passive (floating) behaviours was measured for 6 min. Mother mice spent more time engaged in active behaviours than virgin and sensitised female mice, while the latter two groups did not differ from each other in the forced swim test. The results suggest that maternal motivation is increased in postpartum mothers and maternally sensitised female mice. We also provide the first demonstration that postpartum mother mice display anti-depression-like behaviours in the forced swim test, while maternally sensitised females do not show such emotional changes.

Phenotypic instability between the near isogenic substrains BALB/cJ and BALB/cByJ

Closely related substrains of inbred mice often show phenotypic differences that are presumed to be caused by recent mutations. The substrains BALB/cJ and BALB/cByJ, which were separated in 1935, have been reported to show numerous highly significant behavioral and morphological differences. In an effort to identify some of the causal mutations, we phenotyped BALB/cJ and BALB/cByJ mice as well as their F1, F2, and N2 progeny for behavioral and morphological phenotypes. We also generated whole-genome sequence data for both inbred strains (~3.5× coverage) with the intention of identifying polymorphic markers to be used for linkage analysis. We observed significant differences in body weight, the weight of the heart, liver, spleen and brain, and corpus callosum length between the two substrains. We also observed that BALB/cJ animals showed greater anxiety-like behavior in the open field test, less depression-like behavior in the tail suspension test, and reduced aggression compared to BALB/cByJ mice. Some but not all of these physiological and behavioral results were inconsistent with prior publications. These inconsistencies led us to suspect that the differences were due to, or modified by, non-genetic factors. Thus, we did not perform linkage analysis. We provide a comprehensive summary of the prior literature about phenotypic differences between these substrains as well as our current findings. We conclude that many differences between these strains are unstable and therefore ill-suited to linkage analysis; the source of this instability is unclear. We discuss the broader implications of these observations for the design of future studies.

Using animal models to study post-partum psychiatric disorders

The post-partum period represents a time during which all maternal organisms undergo substantial plasticity in a wide variety of systems in order to ensure the well-being of the offspring. Although this time is generally associated with increased calmness and decreased stress responses, for a substantial subset of mothers, this period represents a time of particular risk for the onset of psychiatric disorders. Thus, post-partum anxiety, depression and, to a lesser extent, psychosis may develop, and not only affect the well-being of the mother but also place at risk the long-term health of the infant. Although the risk factors for these disorders, as well as normal peripartum-associated adaptations, are well known, the underlying aetiology of post-partum psychiatric disorders remains poorly understood. However, there have been a number of attempts to model these disorders in basic research, which aim to reveal their underlying mechanisms. In the following review, we first discuss known peripartum adaptations and then describe post-partum mood and anxiety disorders, including their risk factors, prevalence and symptoms. Thereafter, we discuss the animal models that have been designed in order to study them and what they have revealed about their aetiology to date. Overall, these studies show that it is feasible to study such complex disorders in animal models, but that more needs to be done in order to increase our knowledge of these severe and debilitating mood and anxiety disorders.

The role of brain-derived neurotrophic factor in comorbid depression: possible linkage with steroid hormones, cytokines, and nutrition

Increasing evidence demonstrates a connection between growth factor function (including brain-derived neurotrophic factor, BDNF), glucocorticoid levels (one of the steroid hormones), and the pathophysiology of depressive disorders. Because both BDNF and glucocorticoids regulate synaptic function in the central nervous system, their functional interaction is of major concern. Interestingly, alterations in levels of estrogen, another steroid hormone, may play a role in depressive-like behavior in postpartum females with fluctuations of BDNF-related molecules in the brain. BDNF and cytokines, which are protein regulators of inflammation, stimulate multiple intracellular signaling cascades involved in neuropsychiatric illness. Pro-inflammatory cytokines may increase vulnerability to depressive symptoms, such as the increased risk observed in patients with cancer and/or autoimmune diseases. In this review, we discuss the possible relationship between inflammation and depression, in addition to the cross-talk among cytokines, BDNF, and steroids. Further, since nutritional status has been shown to affect critical pathways involved in depression through both BDNF function and the monoamine system, we also review current evidence surrounding diet and supplementation (e.g., flavonoids) on BDNF-mediated brain functions.

Gestational environment programs adult depression-like behavior through methylation of the calcitonin gene-related peptide gene

Early life exposure to specific environmental factors can increase risk for developing psychopathology including major depression in adulthood. However, the molecular pathways and epigenetic mechanisms that mediate the effects of early environments on adult mood remain poorly understood. We examined the effects of different gestational and rearing conditions on adult anxiety- and depression-like behavior using a combined reciprocal outcrossing and cross-fostering design in Balb/cJ (cJ) and C57BL/6J (B6) mouse strains. First filial (F1) hybrid offspring, which were gestated by B6 or cJ dams and then reared by either strain, were evaluated for behavior and whole-genome hippocampal gene expression during adulthood. Adult hybrid mice gestated by B6 dams showed increased depression-like behavior in the forced swim and sucrose preference tests, increased hippocampal expression of alpha calcitonin gene-related peptide (αCGRP) transcripts, and decreased methylation of the αCGRP promoter compared with those gestated by cJ dams. Differential expression of αCGRP in adulthood did not result from genomic imprinting, and differences between B6 and cJ mitochondrial DNA were not responsible for behavioral phenotypes observed. Finally, central administration of αCGRP to adult hybrid mice increased depression-like behavior, whereas the CGRP1 receptor antagonist CGRP8-37 reduced depression-like behavior in the forced swim test. Our findings suggest that gestational factors influence adult depression-like behavior through methylation of the αCGRP gene.

The long-term psychiatric and medical prognosis of perinatal mental illness

The perinatal period provides an important window into a woman's long-term health. Perinatal mental illness is a common condition conferring potential serious long-term psychiatric and medical consequences for the mother and family. It is known that childbirth acts as a powerful trigger for depressive episodes in some women, and that women with histories of a mood disorder are particularly vulnerable. Some evidence links perinatal mental illness with obstetrical complications and reduced lactation initiation and duration. Therefore, perinatal mental illness may be a marker for long-term risk, and may contribute directly to subsequent cardiometabolic disease through both neuroendocrine mechanisms and the effects of mental illness on health behaviours. In clinical practice, these associations underscore the importance of screening and treating women with perinatal mental illness to ensure best possible long-term outcomes. Early screening and treatment may both mitigate the primary disease process and reduce the risk of comorbid medical conditions.

Late preterm birth, maternal depression, and risk of preschool psychiatric disorders

OBJECTIVE

Preterm children are at greater risk for psychiatric disorders, including anxiety disorders and attention-deficit/hyperactivity disorder (ADHD), than their term-born peers. Prior research has focused primarily on children born at early gestational ages. Less is known about the rate of psychiatric disorders among late preterm or early term children. In addition, whether a history of maternal depression also associated with prematurity has an impact on the risk for psychiatric disorders remains underexplored.

METHOD

Preschoolers between ages 3 and 6 years (N = 306) were recruited for a study examining preschool depression that included healthy and disruptive preschoolers. Preschoolers were placed in the following groups: late preterm (34-36 weeks, n = 39), early term (37-39 weeks, n = 78), and full term (40-41 weeks, n = 154). DSM-IV psychiatric disorders were assessed via the Preschool Age Psychiatric Assessment. Maternal history of psychiatric disorders was assessed using the Family Interview for Genetic Studies.

RESULTS

Late preterm children had higher rates of any Axis I psychiatric diagnosis (odds ratio = 3.18, 95% confidence interval = 1.09-4.76) and of any anxiety disorder (odds ratio = 3.74, 95% confidence interval = 1.59-8.78) than full term children after adjusting for gender, ethnicity, family income, and IQ. There were no differences in rates of psychiatric diagnoses between early term and full term children. A history of maternal depression mediated the relationship between late preterm birth and anxiety disorders in preschoolers.

CONCLUSIONS

Late preterm children were at increased risk for anxiety disorders at preschool age. A history of maternal depression mediated this association. Findings confirm the extension of the risk of psychiatric disorders associated with prematurity to the late preterm group, and suggest that maternal depression may play a key role in this risk trajectory.

Epigenetics and eating disorders

PURPOSE OF REVIEW

Eating disorders are complex psychiatric disorders in which genes, environment, and gene-environment interactions (G×E) have a role. Such G×E may occur in adulthood or during development. They may also be modified by factors such as (mal)nutrition or stress and this may result in acute or long-term epigenetic modifications. This review discusses the potential for recent developments in epigenetics to address ongoing aetiological issues in eating disorders.

RECENT FINDINGS

Epigenetic studies in eating disorders have focussed on the DNA methylation status of promoter regions of candidate genes: differences have been reported between people with eating disorders and healthy controls, and between subtypes of eating disorders. Animal studies related to eating disorders have focussed on understanding the acute and long-term effects of environmental manipulation on epigenetic changes and on the resultant phenotypes: these studies are promising, but they have also identified some of the complexity of epigenetic processing.

SUMMARY

Because of the difficulties in obtaining brain samples, epigenetic studies in eating disorders (like in other psychiatric illnesses) have used peripheral tissues, usually blood: this raises various problems. It is likely, therefore, that in the immediate future, animal, rather than human studies will guide the progress in epigenetics studies of eating disorders and other psychiatric disorders.

A three-phase model of the social emotional functioning in eating disorders

BACKGROUND

Problems with social emotional functioning are an important part of eating disorder psychopathology.

AIM

This study aimed to propose a model of social emotional functioning before and during the illness and to explain the consequences for those involved.

METHOD

We propose a three-phase model of social and emotional processes as both causal and maintaining factors in anorexia nervosa. The predictions from this model are examined, and we consider the relevance for treatment.

RESULTS

The evidence base for the theoretical model is presented: Phase 1 describes causal predispositions and environments, Phase 2 notes the way in which the symptoms themselves impact on brain function and social cognition and Phase 3 explains the reactions of close others.

CONCLUSIONS

A three-phase model including interpersonal and socio-emotional elements can be used to shape and plan treatment interventions. Understanding causal chains and consequences can give a rationale for change and frame therapeutic interventions.

Animal models of depression vulnerability

The rapid increase in the number of proposed animal models of depression reflects the dissatisfaction with our current state of knowledge on neurobiology of depression and unsuccessful drug development. Results obtained with even the best validated models can be difficult to compare. Because evidence from epidemiological studies suggests that depression occurs in biologically predisposed subjects under the impact of adverse life events, increasing attempts have been made to use the diathesis-stress concept in animal models. In this way, factors underpinning vulnerability to depression have been identified by measuring behavioural traits analogous to facets of human personality, or created by inducing neurochemical lesions. Stressful interventions administered prenatally, in early life or in adulthood have been combined with other vulnerability factors including genetic changes. As a result, several putative animal models of endophenotypes of depression or depression vulnerability have been proposed. Diathesis-stress models may aid in separating adaptive and maladaptive strategies in coping with stress, and understanding the relevant neurobiology. Studies comparing effects of stress on males and females should reveal to which extent the pathogenetic processes leading to depression can be specific to sex/gender.

Plant-derived extracts in the neuroscience of anxiety on animal models: biases and comments

Generalized anxiety disorders probably represent one of the world's biggest mental health problems. A large number of studies have also shown that anxiety disorders and depression are often associated with quality of life impairments. As anxiety represents a big concern in public health, a substantial literature supports clinically important associations between psychiatric illness and chronic medical conditions. Actually, most research focuses on depression, finding that depression can adversely affect self-care and increase the risk of incident medical illness, complications, and mortality. Anxiety disorders are less well studied, but robust epidemiological and clinical evidences show that they play an equally important role. Recent reported articles have raised a debate about the effectiveness of some plant-derived extracts in anxiety-like models in mice. Biases about several aspects related with experimental setting, animal selection, environments, operators and investigators, selection and performance of behavioral tests, controls, results managing, and statistics are here discussed.

Molecular mechanisms of maternal cannabis and cigarette use on human neurodevelopment

Prenatal development is highly sensitive to maternal drug use due to the vulnerability for disruption of the fetal brain with its ongoing neurodevelopment, resulting in lifelong consequences that can enhance risk for psychiatric disorders. Cannabis and cigarettes are the most commonly used illicit and licit substances, respectively, among pregnant women. Although the behavioral consequences of prenatal cannabis and cigarette exposure have been well-documented in epidemiological and clinical studies, only recently have investigations into the molecular mechanisms associated with the developmental impact of early drug exposure been addressed. This article reviews the literature relevant to long-term gene expression disturbances in the human fetal brain in relation to maternal cannabis and cigarette use. To provide translational insights, we discuss animal models in which protracted molecular consequences of prenatal cannabis and cigarette exposure can be better explored and which enable future evaluation of epigenetic pathways, such as DNA methylation and histone modification, that could potentially maintain abnormal gene regulation and related behavioral disturbances. Altogether, this information may help to address the current gaps of knowledge regarding the impact of early drug exposure that set in motion lifelong molecular disturbances that underlie vulnerability to psychiatric disorders.