Programming of the hypothalamo-pituitary-adrenal axis: serotonergic involvement

Prenatal serotonin reuptake inhibitor antidepressant exposure, SLC6A4 genetic variations, and cortisol activity in 6-year-old children of depressed mothers: A cohort study

Prenatal exposure to maternal depression and serotonin reuptake inhibitor (SRI) antidepressants both affect the development of the hypothalamic-pituitary-adrenal (HPA) system, possibly via the neurotransmitter serotonin (5HT). In a community cohort, we investigated the impact of two factors that shape prenatal 5HT signaling (prenatal SRI [pSRI] exposure and child SLC6A4 genotype) on HPA activity at age 6 years. Generalized estimating equation (GEE) models were used to study associations between cortisol reactivity, pSRI exposure, and child SLC6A4 genotype, controlling for maternal depression, child age, and sex (48 pSRI exposed, 74 nonexposed). Salivary cortisol levels were obtained at five time points during a laboratory stress challenge: arrival at the laboratory, following two sequential developmental assessments, and then 20 and 40 min following the onset of a stress-inducing cognitive/social task. Cortisol decreased from arrival across both developmental assessments, and then increased across both time points following the stress challenge in both groups. pSRI-exposed children had lower cortisol levels across all time points. In a separate GEE model, we observed a lower cortisol stress response among children with LG /S alleles compared with children with La/La alleles, and this was particularly evident among children of mothers reporting greater third trimester depressed mood. Our findings suggest that pSRI exposure and a genetic factor associated with modulating 5HT signaling shaped HPA reactivity to a laboratory stress challenge at school age.

Antidepressants as Endocrine Disrupting Compounds in Fish

As antidepressant usage by the global population continues to increase, their persistent detection in aquatic habitats from municipal wastewater effluent release has led to concerns of possible impacts on non-target organisms, including fish. These pharmaceuticals have been marketed as mood-altering drugs, specifically targeting the monoaminergic signaling in the brain of humans. However, the monoaminergic systems are highly conserved and involved in the modulation of a multitude of endocrine functions in vertebrates. While most studies exploring possible impact of antidepressants on fish have focused on behavioural perturbations, a smaller spotlight has been placed on the endocrine functions, especially related to reproduction, growth, and the stress response. The purpose of this review is to highlight the possible role of antidepressants as endocrine disruptors in fish. While studies linking the effects of environmentally relevant levels of antidepressant on the endocrine system in fish are sparse, the emerging evidence suggests that early-life exposure to these compounds have the potential to alter the developmental programming of the endocrine system, which could persist as long-term and multigenerational effects in teleosts.

The role of maternal touch in the association between SLC6A4 methylation and stress response in very preterm infants

Very preterm (VPT) infants requiring hospitalization in the Neonatal Intensive Care Unit (NICU) are exposed to several stressful procedural experiences. One consequence of NICU-related stress is a birth-to-discharge increased serotonin transporter gene (SLC6A4) methylation that has been associated with poorer stress regulation at 3 months of age. Maternal touch is thought to support infants' stress response, but its role in moderating the effects of SLC6A4 methylation changes is unknown. The aim of this study was to assess the role of maternal touch in moderating the association between increased SLC6A4 methylation and stress response in 3-month-old VPT infants. Twenty-nine dyads were enrolled and at 3 months (age corrected for prematurity), participated in the Face-to-Face Still-Face paradigm to measure infants' stress response (i.e., negative emotionality) and the amount of maternal touch (i.e., dynamic and static). Results showed that low level of maternal touch is associated with high level of negative emotionality during social stress. Furthermore, during NICU stay SLC6A4 methylation in VPT exposed to low level of maternal touch at 3 months was associated with increased negative emotionality. Thus, low levels of maternal static touch can intensify the negative effects of SLC6A4 epigenetic changes on stress response in 3-month-old VPT infants.

Structural brain alterations in older adults exposed to early-life adversity

BACKGROUND

Adverse childhood events may have differential effects on the brain that persist into adulthood. Findings on structural brain alterations in older adults exposed to early-life adversity are inconsistent notably due to heterogeneity in imaging studies, population, psychiatric comorbidities, nature of adverse events, and genetic vulnerability. This study examines whether exposure related to physical or sexual maltreatment, emotional maltreatment, and global adverse environment during childhood are associated with specific alterations in grey matter volumes and if this varies according to sex and serotonin transporter-linked promoter region (5-HTTLPR) genotype.

METHOD

Structural MRI was used to acquire anatomical scans from 398 community-dwelling older adults. Quantitative regional estimates of 23 subregional volumes were derived using FreeSurfer software. Retrospective reporting of childhood adversity was collected using structured self-reported questionnaire. Analyses adjusted for age, sex, brain volume, head injury, lifetime depression and anxiety disorder, psychiatric medication, and cardiovascular ischemic pathologies.

RESULTS

Exposure to adverse family environment was associated with smaller volumes of several frontal, cingulate, and parietal subregions and larger amygdala in the 5-HTTLPR SS genotype participants specifically but larger volumes of caudate, putamen, pallidum, and nucleus accumbens in the SL genotype participants. Highly significant differences were found with excessive sharing of parent problems with children, associated with larger grey-matter volumes in the thalamus and several frontal and parietal regions in 5-HTTLPR SL male participants specifically.

CONCLUSIONS

Early-life adversity is associated with grey-matter volume alterations in older adults and this varies according to the type of adversity experienced, sex, and serotonergic genetic vulnerability; 5-HTTLPR SS participants appearing most vulnerable and SL individuals most resilient.

Standardized Bacopa monnieri Extract Ameliorates Learning and Memory Impairments through Synaptic Protein, Neurogranin, Pro-and Mature BDNF Signaling, and HPA Axis in Prenatally Stressed Rat Offspring

Prenatal stress (PNS) influences offspring neurodevelopment, inducing anxiety-like behavior and memory deficits. We investigated whether pretreatment of Bacopa monnieri extract (CDRI-08/BME) ameliorates PNS-induced changes in signaling molecules, and changes in the behavior of Wistar rat offspring. Pregnant rats were randomly assigned into control (CON)/prenatal stress (PNS)/PNS and exposed to BME treatment (PNS + BME). Dams were exposed to stress by placing them in a social defeat cage, where they observed social defeat from gestational day (GD)-16–18. Pregnant rats in the PNS + BME group were given BME treatment from GD-10 to their offspring’s postnatal day (PND)-23, and to their offspring from PND-15 to -30. PNS led to anxiety-like behavior; impaired memory; increased the level of corticosterone (CORT), adrenocorticotropic hormone, glucocorticoid receptor, pro-apoptotic Casepase-3, and 5-HT_2C receptor; decreased anti-apoptotic Bcl-2, synaptic proteins (synaptophysin, synaptotagmin-1), 5-HT_1A, receptor, phosphorylation of calmodulin-dependent protein kinase II/neurogranin, N-methyl-D-aspartate receptors (2A,2B), postsynaptic density protein 95; and conversion of pro and mature brain derived neurotropic factor in their offspring. The antioxidant property of BME possibly inhibiting the PNS-induced changes in observed molecules, anxiety-like behavior, and memory deficits. The observed results suggest that pretreatment of BME could be an effective coping strategy to prevent PNS-induced behavioral impairments in their offspring.

The 5-HTTLPR long allele predicts two-year longitudinal increases in cortisol and declines in verbal memory in older adults

OBJECTIVES

The short form or s-allele variant of the serotonin transporter polymorphism (5-HTTLPR), as compared with the long-form or l-allele variant, has been associated with the presence of cognitive dysfunction, and particularly memory impairment in older adults. This body of cross-sectional work has culminated in the hypothesis that presence of the s-allele predicts greater memory decline in older adults. Yet, to date, there are no longitudinal studies that have investigated this issue.

METHODS/DESIGN

Here, we examine 109 community-dwelling older adults (mean and SD of age = 70.7 ± 8.7 years) who underwent blood draw for genotyping, cognitive, and psychological testing at baseline, 12-, and 24-monthfollow-ups.

RESULTS

Multilevel modeling found that s-allele carriers (ss or ls) performed worse than ll homozygotes at baseline on delayed verbal recall. Yet, s-allele carriers' memory performance was stable over the two-yearfollow-up period, while l-allele homozygotes experienced significant memory decline. l-allele homozygote status was associated with both increased cortisol and decreased memory over time, resulting in attenuated verbal memory performance differences compared to s-allele carriers with age.

CONCLUSIONS

Overall, our findings do not support the hypothesis that presence of the 5-HTTLPRs-allele is a marker for memory decline in older adults. J Am Geriatr Soc 68:-, 2020.

Fluoxetine Exposure During Sexual Development Disrupts the Stress Axis and Results in Sex- and Time- Dependent Effects on the Exploratory Behavior in Adult Zebrafish Danio rerio

The antidepressant fluoxetine (FLX), generally the first line of pharmacological treatment in adolescents and pregnant women with affective disorders, is an emerging endocrine disruptor that is also released to the environment through sewage. Recently, we demonstrated that FLX exposure during the first 6 days of life in zebrafish (ZF; Danio rerio) induced a male-specific reduction in the exploratory behavior in the adult ZF that was linked to a reduction in cortisol production that persisted across three generations. Here we investigated sex differences in the behavioral and stress responses following FLX (0.54 and 54 μg^⋅L^–1) exposure during two periods of sexual development in ZF; early (0–15 days post-fertilization, dpf) and late (15–42 dpf). Our findings revealed that the stress response in females was reduced compared to that of males independent of the treatment. We also found that FLX reduced total body cortisol levels in the adult ZF regardless of sex and window of exposure. The hypocortisol phenotype of our FLX-treated fish was associated with behavioral alterations in the adult fish, which depended on the window of exposure; males were more sensitive to FLX during early development whereas females were affected during late development. A sexually dimorphic behavioral response induced by the low cortisol phenotype was observed in the FLX-treated ZF; females had higher exploratory activity whereas the males had reduced behavior. In conclusion, FLX results in sex- and window of exposure-specific effects on the behavioral activities in adult ZF. These findings highlight the importance of sex differences and timing on the long-term effects of antidepressant treatments. Knowledge of the sex-specific effects of antidepressants and the importance of early life exposure to chemical stressors may help us understand the impact of highly prescribed drugs such as FLX on the fetus from FLX-treated pregnant women as well as aquatic species in environments receiving sewage effluents.

Cortisol disruption and transgenerational alteration in the expression of stress-related genes in zebrafish larvae following fluoxetine exposure

Fluoxetine (FLX), the active ingredient in well-known therapeutic drugs such as Prozac, is highly prescribed worldwide to treat affective disorders even among pregnant women and adolescents. Given that FLX readily crosses the placenta, a fetus from a treated pregnant woman is potentially at risk from unintended effects of the chemical. Moreover, FLX reaches aquatic ecosystems at biologically active levels through sewage release, so fish may also be inadvertently affected. We previously demonstrated that FLX exposure to environmentally- (Low FLX Lineage; LFL) and human- (High FLX Lineage; HFL) relevant concentrations during the first 6 days of life in zebrafish (ZF; Danio rerio) reduced cortisol levels in the adults (F₀), an effect that persisted across 3 consecutive unexposed generations (F₁ to F₃). Here, we show that the transcriptional profile of selected genes in the steroidogenesis pathway in the F₀ whole-larvae varied in magnitude and direction in both FLX lineages, despite the same attenuated cortisol phenotype induced by both concentrations. We also observed an up-regulation in the transcript levels of some steroidogenic-related genes and a down-regulation of a gene involved in the inactivation of cortisol in the F₃ HFL larvae. These findings on the transcript levels of the selected genes in the larvae from F₀ and F₃ suggest that specific coping mechanism(s) are activated in descendants to attempt to counteract the disruptive effects of FLX. Our data are cause for concern, given the increasing prescription rates of FLX and other antidepressants, and the potential long-term negative impacts on humans and aquatic organisms.

The negative effects of social bond disruption are partially ameliorated by sertraline administration in prairie voles

Negative social experiences influence both depression and cardiovascular dysfunction. Many individuals who experience negative mood states or cardiovascular conditions have limited social support. Therefore, investigation of drug treatments that may protect against the consequences of social stress will aid in designing effective treatment strategies. The current study used an animal model to evaluate the protective effect of sertraline administration on behavioral and cardiovascular consequences of social stress. Specifically, male prairie voles (Microtus ochrogaster), which are socially monogamous rodents that share several behavioral and physiological characteristics with humans, were isolated from a socially-bonded female partner, and treated with sertraline (16 mg/kg/day, ip) or vehicle during isolation. Unexpectedly, sertraline did not protect against depression-relevant behaviors, and it was associated with increased short- and long-term heart rate responses. However, sertraline administration improved heart rate variability recovery following a behavioral stressor, including increased parasympathetic regulation, and altered long-term neuronal activity in brain regions that modulate autonomic control and stress reactivity. These results indicate that sertraline may partially protect against the consequences of social stressors, and suggest a mechanism through which sertraline may beneficially influence neurobiological control of cardiac function.

Differences Between the Prenatal Effects of Fluoxetine or Buspirone Alone or in Combination on Pain and Affective Behaviors in Prenatally Stressed Male and Female Rats

The selective serotonin reuptake inhibitor fluoxetine and the 5-HT1A receptor agonist buspirone are used to treat depression and anxiety. Previously we demonstrated that chronic stress during pregnancy (prenatal stress) in rats, used as a model of maternal depression risk, increased inflammatory pain and depressive-like behavior in the offspring; buspirone injected to pregnant dams was protective. Clinically, the addition of buspirone to fluoxetine increases the latter’s efficacy in treating depression in patients. Here, we investigated the influence of repeated prenatal injections of fluoxetine, buspirone or their combination on pain- and depressive-like behaviors in prenatally stressed young male and female rats. Prenatal stress augmented depressive-like behavior and both thermal and inflammatory pain (formalin test), replicating our prior findings, and increased basal levels of corticosterone in the blood plasma. Both drugs and their combination reduced the effects of prenatal stress on thermal pain and depressive-like behavior independently of sex. The combination of fluoxetine and buspirone, compared with fluoxetine, was more antinociceptive in the hot plate test in both sexes, and when compared with buspirone, was more antinociceptive only in males. A detailed study of the time-course of formalin-induced pain showed a nuanced effect of these drugs that was sex-dependent. The combination of the two drugs was less effective in females than males during the initial acute phase of nociceptive behavior in flexing + shaking behaviors, whereas that combination was more effective than fluoxetine alone in the first acute phase of licking behavior in females. The antinociceptive effect of buspirone dominated that of the drug combination and of fluoxetine alone, especially during the interphase of the formalin test in both sexes for both flexing + shaking and licking, suggesting a more effective prenatal action of buspirone on the development of a descending serotonergic inhibitory system modulating pain in the spinal cord dorsal horn neurons. Our results indicate that inflammatory pain-like responses integrated at the spinal level in males were more vulnerable to prenatal stress than females. In licking, the antinociceptive effect of fluoxetine and drug combination in the interphase was more in males than females. The data underscore the importance of considering sexual dimorphism when using drug therapy.

Chronic fluoxetine treatment of juvenile zebrafish (Danio rerio) does not elicit changes in basal cortisol levels and anxiety-like behavior in adulthood

Exposure to selective serotonin reuptake inhibitors (SSRIs) during development may elicit long-term neuroadaptive changes that could alter the basal regulation of stress-associated physiological and behavioral processes later in life. Currently, the effects of juvenile fluoxetine exposure in rodent models appear to be dependent on the developmental window targeted as well as the duration of drug exposure. The zebrafish (Danio rerio) model is rapidly becoming a useful tool in pharmacological research and can be used to help elucidate some of the long-term effects of fluoxetine exposure prior to sexual maturation on neuroendocrine and behavioral stress markers. In the current study, juvenile zebrafish were chronically exposed to fluoxetine hydrochloride (0 or 100 μg/L) for 14 days (31–44 days post-fertilization (dpf)), then were left untreated until young adulthood. Starting at 90 dpf, basal neuroendocrine stress and behavioral responses of zebrafish were assessed. Cortisol was extracted from the young adult zebrafish body (trunk) and quantified via enzyme-linked immunosorbent assay (ELISA). Anxiety-like behaviors were assessed in response to introduction to the novel tank test. It was expected that juvenile exposure to fluoxetine would (1) reduce basal cortisol levels and (2) elicit anxiolytic effects in the novel tank test in adulthood. However, fluoxetine exposure during the juvenile period was not associated with alterations in basal levels of cortisol nor were there any significant changes in anxiety-like behavior in the young adult zebrafish. Thus, in zebrafish, it does not appear that SSRI exposure during the juvenile period has a long-term adverse or maladaptive impact on the basal expression of cortisol and anxiety-like behavior in adulthood. Further studies are needed to determine if SSRI exposure during this developmental window influences neuroendocrine and behavioral responses to acute stress.

Maternal exposure to fluoxetine during gestation and lactation does not alter plasma concentrations of testosterone, oestrogen or corticosterone in peripubertal offspring

Antidepressants are widely used around the world, primarily for the treatment of mood disorders, anxiety and pain syndromes. Women who use antidepressants often continue to use them during pregnancy. Selective serotonin reuptake inhibitors, including fluoxetine, are the main class of antidepressants prescribed to pregnant women. It is known that fluoxetine crosses the placental-blood barrier and is excreted in breast milk. Consequently, indirect exposure of the infant occurs. Knowing that fluoxetine alters the balance of neurotransmitters in the central nervous system, several studies have shown that maternal exposure to this drug leads to various adverse effects on the nervous, reproductive and cardiovascular systems of the offspring. The aim of the present study was to evaluate the effects of exposure to fluoxetine during gestation and lactation on parameters related to steroid hormones in prepubertal and pubertal male and female rats. The endpoints evaluated were date of puberty onset, plasma testosterone and oestrogen concentrations before and after puberty onset and corticosterone concentration before and after adrenocorticotrophin stimulus. None of the parameters was affected by fluoxetine exposure.

Transgenerational hypocortisolism and behavioral disruption are induced by the antidepressant fluoxetine in male zebrafish Danio rerio

The global prevalence of depression is high during childbearing. Due to the associated risks to the mother and baby, the selective serotonin reuptake inhibitor fluoxetine (FLX) is often the first line of treatment. Given that FLX readily crosses the placenta, a fetus may be susceptible to the disruptive effects of FLX during this highly plastic stage of development. Here, we demonstrate that a 6-day FLX exposure to a fetus-relevant concentration at a critical developmental stage suppresses cortisol levels in the adult zebrafish (F₀). This effect persists for three consecutive generations in the unexposed descendants (F₁ to F₃) without diminution and is more pronounced in males. We also show that the in vivo cortisol response of the interrenal (fish "adrenal") to an i.p. injection of adrenocorticotropic hormone was also reduced in the males from the F₀ and F₃ FLX lineages. Transcriptomic profiling of the whole kidney containing the interrenal cells revealed that early FLX exposure significantly modified numerous pathways closely associated with cortisol synthesis in the male adults from the F₀ and F₃ generations. We also show that the low cortisol levels are linked to significantly reduced exploratory behaviors in adult males from the F₀ to F₂ FLX lineages. This may be a cause for concern given the high prescription rates of FLX to pregnant women and the potential long-term negative impacts on humans exposed to these therapeutic drugs.

The effect of an adverse psychological environment on salivary cortisol levels in the elderly differs by 5-HTTLPR genotype

BACKGROUND

An adverse psychological environment (e.g. stressful events or depression) has been shown to influence basal cortisol levels and cortisol response to stress. This differs depending on the adverse stimuli, but also varies across individuals and may be influenced by genetic predisposition. An insertion/deletion polymorphism in the serotonin transporter gene (5-HTTLPR) is a strong candidate in this regard.

OBJECTIVE

To investigate how stressful life events and depression are associated with diurnal cortisol levels in community-dwelling elderly and determine whether this varies according to genetic variability in the 5-HTTLPR.

METHODS

This population-based study included 334 subjects aged 65 and older (mean (SD) = 76.5 (6.3)). Diurnal cortisol was measured on two separate days, under quiet (basal) and stressful conditions. The number of recent major stressful events experienced during the past year was assessed from a 12-item validated questionnaire as an index of cumulative recent stressful events. Lifetime trauma was evaluated using the validated Watson's PTSD inventory, which evaluates the most severe traumatic or frightening experience according to DSM criteria. Depression was defined as having a Mini-International Neuropsychiatric Interview (MINI) diagnosis of current major depressive disorder or high levels of depressive symptoms (Center for Epidemiologic Studies-Depression Scale ≥16). 5-HTTLPR genotyping was performed on blood samples.

RESULTS

Exposure to stressful life events was associated with lower basal evening cortisol levels overall, and in the participants with the 5-HTTLPR L allele but not the SS genotype. The greatest effects (over 50% decrease, p < 0.001) were observed for the LL participants having experienced multiple recent stressful events or severe lifetime traumas. Participants with the L allele also had higher evening cortisol stress response. Conversely, depression tended to be associated with a 42% higher basal morning cortisol in the SS participants specifically, but did not modify the association between stressful events and cortisol levels.

CONCLUSION

An adverse psychological environment is associated with basal cortisol levels and cortisol stress response, but this differs according to 5-HTTLPR genotype.

Social stress regulation in 4-month-old infants: contribution of maternal social engagement and infants' 5-HTTLPR genotype

BACKGROUND

Maternal behavior and infant 5-HTTLPR polymorphism have been linked to infants' social stress reactivity and recovery at different ages. Nonetheless, Gene×Environment (G×E) studies focusing on early infancy are rare and have led to mixed results.

AIM

To investigate the contribution of maternal social engagement and infants' 5-HTTLPR polymorphism in predicting infants' negative emotionality in response to a social stressor, namely maternal unresponsiveness.

STUDY DESIGN

Cross-sectional, G×E study.

SUBJECTS

73 4-month-old infants and their mothers took part to the Face-to-Face Still-Face (FFSF) procedure.

OUTCOME MEASURES

A micro-analytical coding of negative emotionality was adopted to measure infants' reactivity to social stress (Still-Face episode) and infants' recovery after social stress (Reunion episode). Maternal contribution was measured as maternal social engagement during the Play episode. Infants were genotyped as S-carriers or L-homozygotes.

RESULTS

The interplay between maternal social engagement and infants' genotype was found to be predictive of infants' negative emotionality during both Still-Face and Reunion episodes of the FFSF paradigm. The interaction highlighted that maternal social engagement predicted minor negative emotionality during Still-Face and Reunion episodes for S-carrier infants, but not for L-homozygotes.

CONCLUSIONS

Findings extend previous results on adults and children, highlighting that maternal behavior might be a protective factor for stress reactivity and regulation, especially for S-carrier infants who are at risk for heightened stress susceptibility.

Diurnal cortisol rhythms in youth from risky families: effects of cumulative risk exposure and variation in the serotonin transporter gene-linked polymorphic region (5-HTTLPR) [corrected]

Building on research on cumulative risk and psychopathology, this study examines how cumulative risk exposure is associated with altered diurnal cortisol rhythms in an ethnically diverse, low-income sample of youth. In addition, consistent with a diathesis-stress perspective, this study explores whether the effect of environmental risk is moderated by allelic variation in the promoter region of the serotonin transporter gene-linked polymorphic region (5-HTTLPR). Results show that youth with greater cumulative risk exposure had flatter diurnal cortisol slopes, regardless of 5-HTTLPR genotype. However, the association of cumulative risk with average cortisol output (area under the curve [AUC]) was moderated by the 5-HTTLPR genotype. Among youth homozygous for the long allele, greater cumulative risk exposure was associated with lower cortisol AUC, driven by significant reductions in cortisol levels at waking. In contrast, there was a trend-level association between greater cumulative risk and higher cortisol AUC among youth carrying the short allele, driven by a trend-level increase in bedtime cortisol levels. Findings are discussed with regard to the relevance of dysregulated diurnal cortisol rhythms for the development of psychopathology and the implications of genetically mediated differences in psychophysiological adaptations to stress.

Early life trauma and attachment: immediate and enduring effects on neurobehavioral and stress axis development

Over half a century of converging clinical and animal research indicates that early life experiences induce enduring neuroplasticity of the HPA-axis and the developing brain. This experience-induced neuroplasticity is due to alterations in the frequency and intensity of stimulation of pups' sensory systems (i.e., olfactory, somatosensory, gustatory) embedded in mother-infant interactions. This stimulation provides "hidden regulators" of pups' behavioral, physiological, and neural responses that have both immediate and enduring consequences, including those involving the stress response. While variation in stimulation can produce individual differences and adaptive behaviors, pathological early life experiences can induce maladaptive behaviors, initiate a pathway to pathology, and increase risk for later-life psychopathologies, such as mood and affective disorders, suggesting that infant-attachment relationships program later-life neurobehavioral function. Recent evidence suggests that the effects of maternal presence or absence during this sensory stimulation provide a major modulatory role in neural and endocrine system responses, which have minimal impact on pups' immediate neurobehavior but a robust impact on neurobehavioral development. This concept is reviewed here using two complementary rodent models of infant trauma within attachment: infant paired-odor-shock conditioning (mimicking maternal odor attachment learning) and rearing with an abusive mother that converge in producing a similar behavioral phenotype in later-life including depressive-like behavior as well as disrupted HPA-axis and amygdala function. The importance of maternal social presence on pups' immediate and enduring brain and behavior suggests unique processing of sensory stimuli in early life that could provide insight into the development of novel strategies for prevention and therapeutic interventions for trauma experienced with the abusive caregiver.

Central nervous system effects of prenatal selective serotonin reuptake inhibitors: sensing the signal through the noise

RATIONALE

Women are increasingly prescribed selective serotonin reuptake inhibitors (SSRIs) during pregnancy, with potential implications for neurodevelopment. Whether prenatal SSRI exposure has an effect on neurodevelopment and behavior in the offspring is an important area of investigation.

OBJECTIVES

The aim of this paper was to review the existing preclinical and clinical literature of prenatal SSRI exposure on serotonin-related behaviors and markers in the offspring. The goal is to determine if there is a signal in the literature that could guide clinical care and/or inform research.

RESULTS

Preclinical studies (n = 4) showed SSRI exposure during development enhanced depression-like behavior. Half of rodent studies examining anxiety-like behavior (n = 13) noted adverse effects with SSRI exposure. A majority of studies of social behavior (n = 4) noted a decrease in sociability in SSRI exposed offspring. Human studies (n = 4) examining anxiety in the offspring showed no adverse effects of prenatal SSRI exposure. The outcome of one study suggested that children with autism were more likely to have a mother who was prescribed an SSRI during pregnancy.

CONCLUSIONS

Preclinical findings in rodents exposed to SSRIs during development point to an increase in depression- and anxiety-like behavior and alteration in social behaviors in the offspring, though both the methods used and the findings were not uniform. These data are not robust enough to discourage use of SSRIs during human pregnancy, particularly given the known adverse effects of maternal mental illness on pregnancy outcomes and infant neurodevelopment. Future research should focus on consistent animal models and prospective human studies with larger samples.

The effects of maternal depression and maternal selective serotonin reuptake inhibitor exposure on offspring

It has been estimated that 20% of pregnant women suffer from depression and it is well-documented that maternal depression can have long-lasting effects on the child. Currently, common treatment for maternal depression has been the selective serotonin reuptake inhibitor medications (SSRIs) which are used by 2–3% of pregnant women in the Nordic countries and by up to 10% of pregnant women in the United States. Antidepressants cross the placenta and are transferred to the fetus, thus, the question arises as to whether children of women taking antidepressants are at risk for altered neurodevelopmental outcomes and, if so, whether the risks are due to SSRI medication exposure or to the underlying maternal depression. This review considers the effects of maternal depression and SSRI exposure on offspring development in both clinical and preclinical populations. As it is impossible in humans to study the effects of SSRIs without taking into account the possible underlying effects of maternal depression (healthy pregnant women do not take SSRIs), animal models are of great value. For example, rodents can be used to determine the effects of maternal depression and/or perinatal SSRI exposure on offspring outcomes. Unraveling the joint (or separate) effects of maternal depression and SSRI exposure will provide more insights into the risks or benefits of SSRI exposure during gestation and will help women make informed decisions about using SSRIs during pregnancy.

Developmental fluoxetine exposure normalizes the long-term effects of maternal stress on post-operative pain in Sprague-Dawley rat offspring

Early life events can significantly alter the development of the nociceptive circuit. In fact, clinical work has shown that maternal adversity, in the form of depression, and concomitant selective serotonin reuptake inhibitor (SSRI) treatment influence nociception in infants. The combined effects of maternal adversity and SSRI exposure on offspring nociception may be due to their effects on the developing hypothalamic-pituitary-adrenal (HPA) system. Therefore, the present study investigated long-term effects of maternal adversity and/or SSRI medication use on nociception of adult Sprague-Dawley rat offspring, taking into account involvement of the HPA system. Dams were subject to stress during gestation and were treated with fluoxetine (2×/5 mg/kg/day) prior to parturition and throughout lactation. Four groups of adult male offspring were used: 1. Control+Vehicle, 2. Control+Fluoxetine, 3. Prenatal Stress+Vehicle, 4. Prenatal Stress+Fluoxetine. Results show that post-operative pain, measured as hypersensitivity to mechanical stimuli after hind paw incision, was decreased in adult offspring subject to prenatal stress alone and increased in offspring developmentally exposed to fluoxetine alone. Moreover, post-operative pain was normalized in prenatally stressed offspring exposed to fluoxetine. This was paralleled by a decrease in corticosteroid binding globulin (CBG) levels in prenatally stressed offspring and a normalization of serum CBG levels in prenatally stressed offspring developmentally exposed to fluoxetine. Thus, developmental fluoxetine exposure normalizes the long-term effects of maternal adversity on post-operative pain in offspring and these effects may be due, in part, to the involvement of the HPA system.

Maternal prenatal stress in rats influences c-fos expression in the spinal cord of the offspring

Previous studies in humans have reported a link between maternal stress and disturbed infant physiological behavior. The objective of our study was to examine in experimental rats how maternal prenatal stress induced by a forced swim test affects offspring afferent spinal responses mediated by stimulation of vaginocervical receptors. The activation of spinal cord neurons showing c-fos expression was examined following vaginocervical mechanical stimulation in adult rats, which were the offspring of dams exposed to gestational stress from E10 until delivery. Vaginocervical stimulation of both prenatal-stressed and non-prenatal-stressed rats induced an increase in immunoreactive protein in the spinal cord ranging from T12 to S1 segmental levels. However, a significantly higher (40%) increase in the expression of Fos-immunoreactive neurons was observed in vaginocervical stimulated prenatally stressed rats than in non-stimulated prenatally stressed ones. This increase was higher in L5-S1 levels than in T12-L4. When the regional distribution was examined, results showed that up to 80% of activated neurons were located in the dorsal horn in both non-stimulated prenatally stressed and stimulated prenatally stressed groups, with a significantly higher density in the latter. Our results demonstrate that maternal prenatal stress can have consequences on vaginocervical responses conveyed to the spinal cord. The increase in Fos labeled neurons in T12-S1 in prenatally stressed rats induced by vaginocervical stimulation suggests the hypersensitivity of the genital tract associated with activation of spinal circuits spanning multiple segments.

Raphe-Hippocampal Serotonin Neurotransmission In The Sex Related Differences of Adaptation to Stress: Focus on Serotonin-1A Receptor

Stress is the major predisposing and precipitating factor in the onset of depression which is the most significant mental health risk for women. Behavioral studies in animal models show that female sex though less affected by an acute stressor; exposure to repeated stressors induces coping deficits to impair adaptation in them. A decrease in the function of 5-hydroxytryptamine (5-HT; serotonin) in the hippocampus and an increased function of the 5-HT-1A receptor in the raphe nucleus coexist in depression. Pharmacological and neurochemical data are relevant that facilitation of serotonin neurotransmission via hippocampus due to desensitization of somatodendritic 5-HT1A receptors may lead to adaptation to stress. The present article reviews research on sex related differences of raphe-hippocampal serotonin neurotransmission to find a possible answer that may account for the sex differences of adaptation to stress reported in preclinical research and greater incidence of depression in women than men.

Prenatal SSRI exposure alters neonatal corticosteroid binding globulin, infant cortisol levels, and emerging HPA function

BACKGROUND

Serotonin influences the development of the hypothalamic-pituitary-adrenal (HPA) system; therefore prenatal exposure to selective serotonin reuptake inhibitor antidepressants (SSRIs) may alter HPA axis development and function. To address this, prenatal exposure to SSRIs and maternal mood were examined in relation to neonatal and infant levels of cortisol and its binding protein, corticosteroid-binding globulin (CBG).

METHODS

Serum cortisol and CBG levels were assayed from SSRI-exposed and non-exposed mothers and their neonates at delivery. Maternal mood symptoms were documented at 36 weeks gestation. To determine the long-term implications of changes in CBG, levels of salivary cortisol were assessed in infants at 3 months of age.

RESULTS

Prenatal SSRI exposure significantly increased serum CBG levels in neonates after vaginal delivery (p ≤ 0.038), even when controlling for maternal depression. Neonatal serum cortisol levels did not vary with SSRI exposure or antenatal maternal mood, but were significantly higher following vaginal delivery (p ≤ 0.003). Neonatal serum CBG levels were associated with infant salivary levels of evening cortisol (p ≤ 0.051). In SSRI-exposed infants, increased levels of neonatal CBG predicted a smaller diurnal change in infant salivary cortisol (p ≤ 0.028), regardless of maternal depression.

CONCLUSIONS

Prenatal SSRI exposure affects the developing HPA system by altering serum CBG levels in neonates and infant salivary cortisol levels. Further research is warranted on the long-term functional implications of the effect of prenatal SSRI exposure on fetal hepatic CBG gene expression and the developing HPA system.

Long term impact of prenatal exposure to SSRIs on growth and body weight in childhood: evidence from animal and human studies

Prenatal exposure to SSRIs has the potential to alter fetal 5-HT signalling during critical periods of development: the long-term consequences of which have not been well studied. Of particular interest are the potential long-term effects of prenatal SSRI exposure on growth and body weight in later life, given the role of the serotonergic system in regulating food intake and body weight. Animal studies demonstrate that changes in 5-HT homeostasis during critical periods of fetal development can lead to sex-specific molecular and functional alterations in the serotonergic and HPA systems, leading to an increased risk of overweight in male, but not female, offspring in later life. This review highlights the evidence and the need for studies in humans to determine whether prenatal SSRI exposure is associated with alterations in child growth and body weight and the importance of delineating these effects from those of the underlying maternal illness.

Advances in tryptophan hydroxylase-2 gene expression regulation: new insights into serotonin-stress interaction and clinical implications

Serotonin (5-HT) modulates the stress response by interacting with the hormonal hypothalamic-pituitary-adrenal (HPA) axis and neuronal sympathetic nervous system (SNS). Tryptophan hydroxylase (TPH) is the rate-limiting enzyme in 5-HT biosynthesis, and the recent identification of a second, neuron-specific TPH isoform (TPH2) opened up a new area of research. While TPH2 genetic variance has been linked to numerous behavioral traits and disorders, findings on TPH2 gene expression have not only reinforced, but also provided new insights into, the long-recognized but not yet fully understood 5-HT-stress interaction. In this review, we summarize advances in TPH2 expression regulation and its relevance to the stress response and clinical implications. Particularly, based on findings on rhesus monkey TPH2 genetics and other relevant literature, we propose that: (i) upon activation of adrenal cortisol secretion, the cortisol surge induces TPH2 expression and de novo 5-HT synthesis; (ii) the induced 5-HT in turn inhibits cortisol secretion by modulating the adrenal sensitivity to ACTH via the suprachiasmatic nuclei (SCN)-SNS-adrenal system, such that it contributes to the feedback inhibition of cortisol production; (iii) basal TPH2 expression or 5-HT synthesis, as well as early-life experience, influence basal cortisol primarily via the hormonal HPA axis; and (iv) 5'- and 3'-regulatory polymorphisms of TPH2 may differentially influence the stress response, presumably due to their differential roles in gene expression regulation. Our increasing knowledge of TPH2 expression regulation not only helps us better understand the 5-HT-stress interaction and the pathophysiology of neuropsychiatric disorders, but also provides new strategies for the treatment of stress-associated diseases.

Pre-gestational stress reduces the ratio of 5-HIAA to 5-HT and the expression of 5-HT1A receptor and serotonin transporter in the brain of foetal rat

Background

Many studies have found that stress before or during pregnancy is linked to an increased incidence of behavioural disorders in offspring. However, few studies have investigated hypothalamic-pituitary-adrenal (HPA) axis activity and the serotonergic system as a consequence of pregestational stress. In the present study, we investigated the effect of pre-gestational stress on HPA axis activity in maternal rats and their foetuses and examined whether changes in HPA axis activity of maternal rats produced functional changes in the serotonergic system in the brain of foetuses.

Results

We used the behavioural tests to assess the model of chronic unpredictable stress (CUS) in maternal rats. We found the activity in the open field and sucrose consumption was lower for rats with CUS than for the controls. Body weight but not brain weight was higher for control foetuses than those from the CUS group. Serum corticosterone and corticotrophin-releasing hormone levels were significantly higher for mothers with CUS before pregnancy and their foetuses than for the controls. Levels of 5-hydroxytryptamine (5-HT) were higher in the hippocampus and hypothalamus of foetuses in the CUS group than in the controls, and 5-hydroxyindoleacetic acid (5-HIAA) levels were lower in the hippocampus in foetuses in the CUS group than in the control group. Levels of 5-HIAA in the hypothalamus did not differ between foetuses in the CUS group and in the control group. The ratio of 5-HIAA to 5-HT was significantly lower for foetuses in the CUS group than in the control group. Levels of 5-HT1A receptor were significantly lower in the foetal hippocampus in the CUS group than in the control group, with no significant difference in the hypothalamus. The levels of serotonin transporter (SERT) were lower in both the foetal hippocampus and foetal hypothalamus in the CUS group than in the control group.

Conclusions

Our data demonstrate that pre-gestational stress alters HPA axis activity in maternal rats and their foetuses, which is associated with functional changes in 5-HT activity (5-HT, 5-HIAA and ratio of 5-HIAA to 5-HT), as well as the levels of the 5-HT1A receptor and SERT in the hippocampus and hypothalamus of foetuses.

Perinatal selective serotonin reuptake inhibitor exposure: impact on brain development and neural plasticity

Selective serotonin reuptake inhibitor (SSRI) medications are the most common antidepressant treatment used during pregnancy and the postpartum period. Up to 10% of pregnant women are prescribed SSRIs. Serotonin plays an integral part in neurodevelopment, and questions have been raised about the placental transfer of SSRIs and the effects of preventing reuptake of presynaptic serotonin on fetal neurodevelopment. Preclinical data is beginning to document a role of early exposure to SSRIs in long-term developmental outcomes related to a number of brain regions, such as the hippocampus, cortex and cerebellum. To date, the majority of preclinical work has investigated the developmental effects of SSRIs in the offspring of healthy mothers; however, more research is needed on the effects of these medications in the face of maternal adversity. This minireview will highlight emerging evidence from clinical and preclinical studies investigating the impact of perinatal SSRI exposure on brain development and neural plasticity.

Interpersonal stress regulation and the development of anxiety disorders: an attachment-based developmental framework

Anxiety disorders represent a common but often debilitating form of psychopathology in both children and adults. While there is a growing understanding of the etiology and maintenance of these disorders across various research domains, only recently have integrative accounts been proposed. While classical attachment history has been a traditional core construct in psychological models of anxiety, contemporary attachment theory has the potential to integrate neurobiological and behavioral findings within a multidisciplinary developmental framework. The current paper proposes a modern attachment theory-based developmental model grounded in relevant literature from multiple disciplines including social neuroscience, genetics, neuroendocrinology, and the study of family factors involved in the development of anxiety disorders. Recent accounts of stress regulation have highlighted the interplay between stress, anxiety, and activation of the attachment system. This interplay directly affects the development of social-cognitive and mentalizing capacities that are acquired in the interpersonal context of early attachment relationships. Early attachment experiences are conceptualized as the key organizer of a complex interplay between genetic, environmental, and epigenetic contributions to the development of anxiety disorders - a multifactorial etiology resulting from dysfunctional co-regulation of fear and stress states. These risk-conferring processes are characterized by hyperactivation strategies in the face of anxiety. The cumulative allostatic load and subsequent "wear and tear" effects associated with hyperactivation strategies converge on the neural pathways of anxiety and stress. Attachment experiences further influence the development of anxiety as potential moderators of risk factors, differentially impacting on genetic vulnerability and relevant neurobiological pathways. Implications for further research and potential treatments are outlined.

The use of the zebrafish model in stress research

The study of the causes and mechanisms underlying psychiatric disorders requires the use of non-human models for the test of scientific hypotheses as well as for use in pre-clinical drug screening and discovery. This review argues in favor of the use of zebrafish as a novel animal model to study the impact of early (stressful) experiences on the development of differential stress phenotypes in later life. This phenomenon is evolutionary conserved among several vertebrate species and has relevance to the etiology of psychiatric disorders. Why do we need novel animal models? Although significant progress has been achieved with the use of traditional mammalian models, there are major pitfalls associated with their use that impedes progress on two major fronts: 1) uncovering of the molecular mechanisms underlying aspects of compromised (stress-exposed) brain development relevant to the etiology of psychiatric disorders, and 2) ability to develop high-throughput technology for drug discovery in the field of psychiatry. The zebrafish model helps resolve these issues. Here we present a conceptual framework for the use of zebrafish in stress research and psychiatry by addressing three specific domains of application: 1) stress research, 2) human disease mechanisms, and 3) drug discovery. We also present novel methodologies associated with the development of the zebrafish stress model and discuss how such methodologies can contribute to remove the main bottleneck in the field of drug discovery.

Evolutionary functions of early social modulation of hypothalamic-pituitary-adrenal axis development in humans

The hypothalamic-pituitary-adrenal axis (HPAA) is highly responsive to social challenges. Because stress hormones can have negative developmental and health consequences, this presents an evolutionary paradox: Why would natural selection have favored mechanisms that elevate stress hormone levels in response to psychosocial stimuli? Here we review the hypothesis that large brains, an extended childhood and intensive family care in humans are adaptations resulting from selective forces exerted by the increasingly complex and dynamic social and cultural environment that co-evolved with these traits. Variations in the modulation of stress responses mediated by specific HPAA characteristics (e.g., baseline cortisol levels, and changes in cortisol levels in response to challenges) are viewed as phenotypically plastic, ontogenetic responses to specific environmental signals. From this perspective, we discuss relations between physiological stress responses and life history trajectories, particularly the development of social competencies. We present brief summaries of data on hormones, indicators of morbidity and social environments from our long-term, naturalistic studies in both Guatemala and Dominica. Results indicate that difficult family environments and traumatic social events are associated with temporal elevations of cortisol, suppressed reproductive functioning and elevated morbidity. The long-term effects of traumatic early experiences on cortisol profiles are complex and indicate domain-specific effects, with normal recovery from physical stressors, but some heightened response to negative-affect social challenges. We consider these results to be consistent with the hypothesis that developmental programming of the HPAA and other neuroendocrine systems associated with stress responses may facilitate cognitive targeting of salient social challenges in specific environments.

Development of individual differences in stress responsiveness: an overview of factors mediating the outcome of early life experiences

RATIONALE

Human epidemiology and animal studies have convincingly shown the long-lasting impact of early life experiences on the development of individual differences in stress responsiveness in later life. The interplay between genes and environment underlies this phenomenon.

OBJECTIVES

We provide an overview of studies investigating the impact of early life experiences on the development of individual differences in neuroendocrine stress responsiveness in adulthood and address (1) impact of environment on later stress phenotypes, (2) role of genetic factors in modulating the outcome of environment, and (3) role of nonshared environmental experience in the outcome of gene × environment interplays. We present original findings where we investigated the influence of nonshared experiences in terms of individual differences in maternal care received, on the development of stress phenotype in later life in rats.

RESULTS

Environmental influences in early life exert powerful effects on later stress phenotypes, but they do not always lead to expression of diseases. Heterogeneity in response is explained by the role of particular genetic factors in modulating the influence of environment. Nonshared experiences are important in the outcome of gene × environment interplays in humans. We show that nonshared experiences acquired through within-litter variation in maternal care in rats predict the stress phenotype of the offspring.

CONCLUSION

The outcome of early experience is not deterministic and depends on several environmental and genetic factors interacting in an intricate manner to support stress adaptation. The degree of "match" and "mismatch" between early and later life environments predicts resilience and vulnerability to stress-related diseases, respectively.

Effects of developmental stress and lead (Pb) on corticosterone after chronic and acute stress, brain monoamines, and blood Pb levels in rats

Despite restrictions, exposure to lead (Pb) continues. Moreover, exposure varies and is often higher in lower socioeconomic status (SES) families and remains a significant risk to cognitive development. Stress is another risk factor. Lower SES may be a proxy for stress in humans. When stress and Pb co-occur, risk may be increased. A few previous experiments have combined Pb with intermittent or acute stress but not with chronic stress. To determine if chronic developmental stress affects outcome in combination with Pb, we tested such effects on growth, organ weight, brain monoamines, and response to an acute stressor. Sprague Dawley rats were gavaged with Pb acetate (1 or 10 mg/kg) or vehicle every other day from postnatal day (P)4-29 and reared in standard or barren cages. Subsets were analyzed at different ages (P11, 19, 29). Chronic stress did not alter blood Pb levels but altered HPA axis response during early development whereas Pb did not. Pb treatment and rearing each altered organ-to-body weight ratios, most notably of thymus weights. Both Pb and rearing resulted in age- and region-dependent changes in serotonin and norepinephrine levels and in dopamine and serotonin turnover. The model introduced here may be useful for investigating the interaction of Pb and chronic developmental stress.

Neuroendocrine effects of citalopram, a selective serotonin re-uptake inhibitor, during lifespan in humans

OBJECTIVE

Serotonergic system contributes to the regulation of hypothalamus-pituitary-adrenal axis. In humans, serotonergic agonists increase PRL, ACTH, and cortisol, while serotonin (5HT) influence on GH is controversial. Central 5HT activity and neuroendocrine function change during lifespan.

DESIGN

To clarify the neuroendocrine response to 5HT across lifespan, we assessed ACTH, cortisol, DHEA, PRL, and GH responses to citalopram (CT) in young adults (YA) (no.=12, 29.2±1.7 yr mean±SEM), middle aged (MA) (no.=12, 54.3±0.9 yr), and elderly (ES) (no.=12, 69.3±0.9 yr) males. All the subjects received placebo (saline iv over 120 min) or CT (20 mg iv over 120 min). Blood samples were taken every 15 min up to 240 min.

RESULTS

During placebo, ACTH, cortisol, GH, and PRL were similar in all groups while DHEA showed an age-dependent reduction from middle age (p<0.001). During CT, ACTH, and cortisol were higher than during placebo in YA (p<0.05) and even more in MA (p<0.01 vs placebo, p<0.05 vs YA); in ES, the increase of both ACTH and cortisol (p<0.05 vs placebo) was lower than in MA (p<0.05) and higher than in YA (p<0.05 for cortisol only). No changes were observed for DHEA, GH, and PRL in any group.

CONCLUSIONS

Corticotrope response to CT is age-dependent in normal men, being amplified starting from middle age, suggesting precocious changes in the serotonergic neuroendocrine control during lifespan. CT is a useful tool to evaluate the age-dependent serotonergic function in humans.

Maternal social stress during late pregnancy affects hypothalamic-pituitary-adrenal function and brain neurotransmitter systems in pig offspring

Maternal stress in pregnant sows may induce long-lasting alterations in the behavior, physiology, and immunity of their offspring. The aim of the present study was to investigate the consequences of repeated social stress during late gestation on determinants of the hypothalamic-pituitary-adrenal axis and on hippocampal neurotransmitter profiles in pig offspring. All pregnant gilts were housed in pairs. Each Stress gilt was mixed with an unfamiliar gilt twice a week between days 77 and 105 of gestation (n=18). Control gilts were housed in stable pairs over the same period (n=18). Plasma cortisol and corticosteroid binding globulin (CBG) were measured in 1 male and 1 female per litter in a basal situation on postnatal days (PND) 4, 26, and 60 and in a stressful situation at PND 28 (2 d after weaning) and 62 (2 d after relocation to a new building). Prenatal stress had no effect on plasma cortisol, but it decreased CBG at PND 26. Brain and adrenals were collected from 1 female per litter after weaning or relocation at PND 28 and PND 62. Adrenals were additionally collected at PND 4. Glucocorticoid receptor binding in the hippocampus and hypothalamus was not affected by prenatal treatment. However, prenatal stress increased the expression of 11beta-hydroxysteroid dehydrogenase type 1 mRNA in the hippocampus after weaning (P<0.05) and after relocation (P=0.08). In addition, prenatally stressed piglets showed an increased 5-hydroxyindole-3-acetic acid to 5-hydroxytryptamine ratio in the hippocampus after weaning and increased hippocampal c-fos mRNA expression and noradrenaline concentration after relocation (P<0.05). Prenatal stress also increased the relative adrenal weight at PND 4 and the cell density in the cortex and the medulla at PND 28, whereas no difference was found for activities of catecholamine-synthesising enzymes in the medulla. Overall, our data indicate that repeated social stress during pregnancy has long-lasting consequences on hypothalamic-pituitary-adrenal axis and hippocampal neurotransmitter activity in the offspring of pigs.

Sex-specific association between the 5-HTT gene-linked polymorphic region and basal cortisol secretion

OBJECTIVE

A key regulator of serotonergic neurotransmission is the serotonin transporter (5-HTT) and a common 5HTT gene promoter polymorphism, termed 5HTTLPR, is associated with phenotypes related to anxiety and depression. Furthermore, the serotonergic system influences hypothalamus-pituitary-adrenal (HPA) axis activity, which, in turn, is related to psychiatric diseases.

METHODS

To explore the association between the 5-HTTLPR and HPA axis regulation we performed a detailed endophenotyping in 216 healthy subjects (all 126 females used oral contraceptives).

RESULTS

While ACTH and cortisol responses to an established psychosocial stress paradigm (Trier Social Stress Test) were not found to be related to the 5-HTTLPR, we observed a significant and sex-specific association with the cortisol awakening response, which is a reliable marker of basal cortisol secretion, and with ACTH levels after dexamethasone administration. The supplementary inclusion of a 5-HTT A/G polymorphism (rs25531) in the analyses did not substantially modify our results.

CONCLUSION

These findings support the view that the 5-HTTLPR is associated with a major neuroendocrine stress system. It could be speculated that the sex-specific nature of this association contributes to the distinct gender differences in the vulnerability for depression.

Serotonin transporter genotype, morning cortisol and subsequent depression in adolescents

BACKGROUND

The short (s) allele of the serotonin transporter gene promoter (5-HTTLPR) may be associated with exposure to social adversities and the subsequent onset of depressive illness in adulthood.

AIMS

To test in adolescents at high risk for depression whether the short 's' allele is associated with levels of morning cortisol and the subsequent onset of a depressive episode.

METHOD

High-risk adolescents (n = 403) were genotyped for 5-HTTLPR. Salivary samples were obtained on four consecutive school days within 1 h of waking from 393 (97.5%) individuals and 367 (91%) underwent a mental state reassessment at 12 months.

RESULTS

Multilevel analysis revealed higher levels of salivary cortisol in short allele carriers (s/s>s/l>l/l). A subsequent episode of depression was increased in those with higher cortisol and the 's' allele, and independently by depressive symptoms at entry, in both genders.

CONCLUSIONS

The short allele of 5-HTTLPR may moderate the association between morning cortisol and the subsequent onset of a depressive episode.

Heterogeneity of the infant stage of rat development: inflammatory pain response, depression-related behavior, and effects of prenatal stress

The infant stage of rat development is a very important period for potential correction of adverse consequences produced by negative prenatal events. However the age limit for this correction needs to be investigated. The last prenatal and first two weeks after birth are "critical" for maturation of the nociceptive and emotional systems. Clinical observations suggest a correlation between persistent pain response and emotional behavior. In infant male rats of different ages, we studied indices of the inflammatory pain response (the number of flexes+shakes in the formalin test), depression-related behavior (immobility in the forced swim test) and the relations between them, as well as the effects of prenatal stress on these indices. Furthermore, we assessed the trend of body weight and the relations between body weight and the depression- and pain-related behaviors. We demonstrate heterogeneity of the infant stage: control prenatally non-stressed rat pups showed significantly lower immobility at 7 days of age than at 10 days; prenatal stress caused an increase of immobility and the number of flexes+shakes in 7-8-day-old pups but not in 10-11-day-olds. These findings should be taken into account in the treatment of abnormalities of emotional and inflammatory pain-related behaviors produced by prenatal stressful events. The present data and our previous findings indicate that the deficiency of body weight in prenatally stressed newborns may predict the development of abnormalities in inflammatory pain-related responses during postnatal ontogeny.