Effects of suckling on hypothalamic-pituitary-adrenal axis responses to psychosocial stress in postpartum lactating women

A longitudinal study of breastfeeding relationships at home during the COVID-19 pandemic: A grounded theory method

AIMS

To describe the process of breastfeeding relationships among stay-at-home mother and infant dyads at 1, 3, 5 and 6 months.

DESIGN

A longitudinal qualitative online survey design was used.

METHODS

Data were obtained at 1, 3, 5 and 6 months from 26 breastfeeding mothers who stayed home with their infants and directly breastfed at least once a day for the first 6 months between June 2022 and August 2023. Mothers' written responses to 3 open-ended questions were analysed to assess breastfeeding experiences at home, thoughts/comments while directly breastfeeding and breastfeeding concerns/problems and strategies they used. Based on grounded theory, inductive content analysis was used to analyse the data. Trustworthiness of results was established by coding to consensus, formal peer debriefing and maintaining an audit trail.

RESULTS

'Breastfeeding Relationships at Home,' the core construct, was identified and organized the process of breastfeeding relationships into 5 domains: (1) mothers' emotional well-being while breastfeeding, (2) infant-led feeding, (3) alternatives to breastfeeding, (4) evaluation of breastfeeding and (5) changes in breastfeeding as infants grow older.

CONCLUSION

Breastfeeding is not simply about feeding breast milk but also involves nurturing and developing a relationship between mother and infant. Across the domains, mutual responsiveness, a central element of the breastfeeding relationship was clear. Mothers who were committed to breastfeeding with embedded infant suckling reached emotional well-being in return for their engagement which has potential to reduce maternal stress and prevent postpartum depression.

IMPACT

Findings from the current study add to nurses' knowledge about the relationship building process between stay-at-home mothers and their infants in the first 6 months of breastfeeding during the COVID-19 pandemic. Nurses must remain sensitive to aid the development of breastfeeding relationships in the home environment to maximize mutual responsiveness.

PATIENT OR PUBLIC CONTRIBUTION

No patients or public involved.

Recalibration of the stress response system over adult development: Is there a perinatal recalibration period?

During early life-sensitive periods (i.e., fetal, infancy), the developing stress response system adaptively calibrates to match environmental conditions, whether harsh or supportive. Recent evidence suggests that puberty is another window when the stress system is open to recalibration if environmental conditions have shifted significantly. Whether additional periods of recalibration exist in adulthood remains to be established. The present paper draws parallels between childhood (re)calibration periods and the perinatal period to hypothesize that this phase may be an additional window of stress recalibration in adult life. Specifically, the perinatal period (defined here to include pregnancy, lactation, and early parenthood) is also a developmental switch point characterized by heightened neural plasticity and marked changes in stress system function. After discussing these similarities, lines of empirical evidence needed to substantiate the perinatal stress recalibration hypothesis are proposed, and existing research support is reviewed. Complexities and challenges related to delineating the boundaries of perinatal stress recalibration and empirically testing this hypothesis are discussed, as well as possibilities for future multidisciplinary research. In the theme of this special issue, perinatal stress recalibration may be a mechanism of multilevel, multisystem risk, and resilience, both intra-individually and intergenerationally, with implications for optimizing interventions.

The Mood, Mother and Child Study: Protocol for a Prospective Longitudinal Study and Randomized Controlled Trial

BACKGROUND

Perinatal depression affects >400,000 mother-child dyads in the United States every year and is associated with numerous adverse maternal and child developmental outcomes. Previous research implicates the dysregulation of oxytocin and the hypothalamic-pituitary-adrenal (HPA) axis functioning in mothers and children as potential mechanisms mediating or moderating the transmission of risk associated with maternal depression.

OBJECTIVE

The Mood, Mother and Child study will examine the psychobiological sources of risk and resilience within mother-child dyads affected by maternal depression. This manuscript describes (1) the study rationale and aims, (2) the research design and procedures and how they were altered in response to the COVID-19 pandemic, and (3) the data analysis plan to test the study hypotheses.

METHODS

This is a prospective longitudinal study with an embedded randomized controlled trial that examines (1) correlations among postpartum depression and anxiety symptoms, maternal and child oxytocin and HPA axis functioning, and child developmental outcomes and (2) the causal relationship between exogenous oxytocin and HPA reactivity. This study is funded by the National Institute of Child Health and Human Development with institutional review board approval.

RESULTS

Recruitment and data collection have commenced, and the expected results will be available in 2024. Analyses are presented for testing the proposed hypotheses.

CONCLUSIONS

The unique combination of a prospective longitudinal research design with an embedded randomized controlled trial will allow the Mood, Mother and Child study to apply a developmental lens to the study of maternal depression and anxiety symptoms from birth to middle childhood and the psychobiological mechanisms promoting risk and resiliency for both mother and child outcomes. This will be the first study that simultaneously evaluates (1) the role of oxytocin using multiple methodologies, (2) the causal relationships between exogenous oxytocin and HPA axis functioning among mothers with differing levels of depression and anxiety symptoms, and (3) the multiple mediating and moderating roles of parenting behaviors and maternal and child psychobiological characteristics. The goals of these aims are to provide insights into the psychobiological effects of oxytocin in women and inform future clinical trials to treat perinatal mood disorders.

TRIAL REGISTRATION

ClinicalTrials.gov NCT03593473; https://classic.clinicaltrials.gov/ct2/show/NCT03593473.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/51132.

Does workplace telepressure get under the skin? Protocol for an ambulatory assessment study on wellbeing and health-related physiological, experiential, and behavioral concomitants of workplace telepressure

BACKGROUND

The daily working life of many employees requires the use of modern information and communication technology (ICT) devices such as computers, tablets, and smartphones. The double-edged nature of digital work environments has been increasingly highlighted. Benefits such as increased flexibility come at a personal cost. One of the potential downsides is workplace telepressure, i.e., the experience of urge and preoccupation to quickly reply to work-related messages and demands using ICT. There is initial - mainly survey-based-evidence that workplace telepressure may have negative effects on a variety of wellbeing and health outcomes.

AIMS AND HYPOTHESES

Adopting the Effort-Recovery Model and the concept of allostatic load as theoretical frameworks, the present study aims to investigate the hypothesis that workplace telepressure is significantly associated with increased "wear and tear", in the form of more psychosomatic complaints, worse sleep quality (self-reported and actigraphy-based), worse mood, and biological alterations (lower cardiac vagal tone, lower anabolic balance defined as the ratio of salivary dehydroepiandrosterone to salivary cortisol, and higher salivary alpha-amylase). Additionally, the study aims to investigate the hypothesis that connection to work defined as work-related workload and work-related perseverative cognition plays a significant role in the mediation of these relationships.

METHODS

To test our hypotheses, we will conduct an ambulatory assessment study with a convenience sample of 120 healthy workers regularly using ICTs for job communication. For one week, participants will be asked to complete electronic diaries assessing their level of workplace telepressure, psychosomatic complaints, sleep quality, mood, work-related workload, and work-related perseverative cognition. They will also continuously wear the Bittium Faros 180L ECG monitor, the wrist-worn actigraph MotionWatch 8, and perform saliva sampling five times per day.

DISCUSSION

This study will be the most comprehensive ambulatory investigation of workplace telepressure and its psychophysiological concomitants to date and constitutes an important step towards understanding how high levels of workplace telepressure may lead in the long term to secondary alterations (e.g., hypertension, chronic inflammation) and disease (e.g., heart disease). The findings of this study are also anticipated to contribute to guiding the development and implementation of interventions, programs, and policies relevant to employees' digital wellbeing.

Examining the association between prenatal maternal stress and infant non-nutritive suck

BACKGROUND

This study examined the relationship between prenatal maternal stress (PREMS) and non-nutritive suck (NNS) and tested its robustness across 2 demographically diverse populations.

METHODS

The study involved 2 prospective birth cohorts participating in the national Environmental influences on Child Health Outcomes (ECHO) Program: Illinois Kids Development Study (IKIDS) and ECHO Puerto Rico (ECHO-PROTECT). PREMS was measured during late pregnancy via the 10-item Perceived Stress Scale (PSS-10). NNS was sampled from 1- to 8-week-olds using a custom pacifier for ~5 min.

RESULTS

Overall, 237 mother-infant dyads completed this study. Despite several significant differences, including race/ethnicity, income, education, and PREMS levels, significant PREMS-NNS associations were found in the 2 cohorts. In adjusted linear regression models, higher PREMS, measured through PSS-10 total scores, related to fewer but longer NNS bursts per minute.

CONCLUSIONS

A significant association was observed between PREMS and NNS across two diverse cohorts. This finding is important as it may enable the earlier detection of exposure-related deficits and, as a result, earlier intervention, which potentially can optimize outcomes. More research is needed to understand how NNS affects children's neurofunction and development.

IMPACT

In this double-cohort study, we found that higher maternal perceived stress assessed in late pregnancy was significantly associated with fewer but longer sucking bursts in 1- to 8-week-old infants. This is the first study investigating the association between prenatal maternal stress (PREMS) and infant non-nutritive suck (NNS), an early indicator of central nervous system integrity. Non-nutritive suck is a potential marker of increased prenatal stress in diverse populations. Non-nutritive suck can potentially serve as an early indicator of exposure-related neuropsychological deficits allowing for earlier interventions and thus better prognoses.

The relationship between fatigue, sleep quality, resilience, and the risk of postpartum depression: an emphasis on maternal mental health

BACKGROUND

Several factors can contribute to the development of postpartum depression (PPD) and negatively affect mothers' mental and physical well-being. The objective of this study was to determine the relationship between fatigue, sleep quality, resilience, and the risk of PPD development.

METHODS

A cross-sectional study was conducted using an online questionnaire distributed to mothers during their postpartum period. The risk of PPD was assessed using the Edinburgh Postnatal Depression Scale (EPDS), postpartum fatigue (PPF) was assessed using the Fatigue Severity Scale (FSS), sleep quality was assessed using the Pittsburgh Sleep Quality Index (PSQI), and resilience was assessed using the Brief Resilience Scale (BRS). The Pearson correlation coefficient was calculated to determine the relationship between the study variables. Simple and multiple linear regression analyses were performed to explain the contributions of PPF, sleep quality, and resilience as independent predictors of PPD development.

RESULTS

A total of 1409 postpartum women were included in the analysis, with 75% of the participants reporting a risk of PPD, 61% reporting PPF, 97% reporting having sleep problems, and 36% being in the "low resilience level" category. In terms of correlations, the scores of FSS and the PSQI showed moderate positive relationships with the EPDS scores (r = 0.344 and r = 0.447, respectively, p = .000). The BRS scores were negatively associated with the EPDS scores (r = -0.530, p = 0.000). Fatigue, sleep quality, and resilience were predictors of depressive symptoms (β = 0.127, β = 0.262, and β = -0.393, respectively, R² = 0.37, p = 0.000). The association remained significant in the regression model after adjusting for mother's age, mother's BMI, child's age, smoking status, full-term pregnancy, having a chronic disease, and taking anti-depressant.

CONCLUSIONS

Mothers with higher levels of fatigue, poor sleep quality, and low resilience levels were at high risk of developing PPD. Healthcare providers should identify these factors and thus set better rehabilitation goals to improve overall maternal health.

Advances in human oxytocin measurement: challenges and proposed solutions

Oxytocin, a neuropeptide known for its role in reproduction and socioemotional processes, may hold promise as a therapeutic agent in treating social impairments in patient populations. However, research has yet to uncover precisely how to manipulate this system for clinical benefit. Moreover, inconsistent use of standardized and validated oxytocin measurement methodologies-including the design and study of hormone secretion and biochemical assays-present unresolved challenges. Human studies measuring peripheral (i.e., in plasma, saliva, or urine) or central (i.e., in cerebrospinal fluid) oxytocin concentrations have involved very diverse methods, including the use of different assay techniques, further compounding this problem. In the present review, we describe the scientific value in measuring human endogenous oxytocin concentrations, common issues in biochemical analysis and study design that researchers face when doing so, and our recommendations for improving studies using valid and reliable methodologies.

Efficacy of behavioral interventions to improve maternal mental health and breastfeeding outcomes: a systematic review

BACKGROUND

Despite extensive benefits and high intentions, few mothers breastfeed exclusively for the recommended duration. Maternal mental health is an important underlying factor associated with barriers and reduced rates of breastfeeding intent, initiation, and continuation. Given evidence of a bidirectional association between maternal mental health and breastfeeding, it is important to consider both factors when examining the efficacy of interventions to improve these outcomes. The purpose of this manuscript is to review the literature on the efficacy of behavioral interventions focused on both maternal mental health and breastfeeding outcomes, examining the intersection of the two.

METHODS

This systematic review was completed using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) reporting guidelines. Studies were selected if they were available in English, used primary experimental design, and used a behavioral intervention type to examine maternal mental health and breastfeeding outcomes. Articles were identified from PubMed, CINAHL, Embase, and PsycINFO from database inception to 3 March 2022. Study quality was assessed using the Cochrane Risk of Bias tool. Results were synthesized by intervention success for 1. Mental health and breastfeeding, 2. Breastfeeding only, 3. Mental health only, and 4. No intervention effect. PROSPERO CRD42021224228.

RESULTS

Thirty interventions reported in 33 articles were identified, representing 15 countries. Twelve studies reported statistically significant positive effect of the intervention on both maternal mental health and breastfeeding; most showing a decrease in self-report depressive and/or anxiety symptoms in parallel to an increase in breastfeeding duration and/or exclusivity. Common characteristics of successful interventions were a) occurring across pregnancy and postpartum, b) delivered by hospital staff or multidisciplinary teams, c) offered individually, and d) designed to focus on breastfeeding and maternal mental health or on breastfeeding only. Our results are not representative of all countries, persons, experiences, circumstances, or physiological characteristics.

CONCLUSIONS

Interventions that extend the perinatal period and offer individualized support from both professionals and peers who collaborate through a continuum of settings (e.g., health system, home, and community) are most successful in improving both mental health and breastfeeding outcomes. The benefits of improving these outcomes warrant continued development and implementation of such interventions.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42021224228.

Neonatal breast-suckling skills in the context of lactation and peripartum hormonal changes and additional factors-a pilot study

Background

Childbirth and lactation are intricate processes, involving several hormones, the most important of which are prolactin (a protein hormone) and cortisol (one of the glucocorticoids). The early postpartum period is crucial for both mother and newborn and has an impact on the lactation and breastfeeding process.

Methods

The study included 78 patients who were admitted to the Gynecology-Obstetrics Clinical Hospital in Poznań for labor induction and/or in the active phase of the first labor stage. The levels of cortisol and prolactin in serum were assessed in these women during admission in labor, during the third labor stage, and on the second day postpartum. The levels of cortisol and prolactin in the umbilical cord serum were assessed immediately after cord clamping. The “Protocol for the assessment of breast-suckling skills” was used to assess the neonatal breast-suckling skills on the second day postpartum. Some additional parameters were evaluated in mothers via a telephone interview at three and six months postpartum. The study was conducted from January to August 2020, however the study was suspended during April–July 2020 due to the SARS-CoV-2 pandemic, which led to restrictions in the hospital limiting access to the hospital wards unless necessary.

Results

Early breastfeeding with skin-to-skin contact was associated with low levels of hormones, cortisol levels were lower in serum (p = 0.0108) and umbilical vein (p = 0.0273) in mothers who breastfed immediately after childbirth. At three months postpartum, 88% of the mothers who did not offer a pacifier to the child during the first few days of life breastfed the child naturally (p = 0.037), and at six months, 96% of those who did not offer a pacifier continued to breastfeed (p = 0.0008). Multiple, statistically significant correlations were observed between the variables assessed according to the “Protocol for the assessment of breast-suckling skills” and breastfeeding after three months.

Conclusions

Breastfeeding immediately after childbirth, appropriate assessment of the breast-suckling skills of newborns, avoiding pacifiers and infant formula feeding, and offering support to new mothers in the early days after childbirth seem to be important factors for sustaining breastfeeding after three and six months of childbirth.

Plasma oxytocin is modulated by mental training, but does not mediate its stress-buffering effect

Based on its role in social processing and stress, oxytocin has been suggested to mediate stress reduction of socio-affective, compassion-based mental training. We tested this hypothesis in the ReSource Project, a 9-month longitudinal mental training study. Participants practiced three different types of mental training, targeting either attentional abilities (Presence Module), socio-affective or socio-cognitive abilities (Affect and Perspective Modules). We investigated plasma oxytocin levels, and their link to cortisol and subjective reactivity to acute psychosocial stress as a function of previous mental training (n = 313). In a subsample (n = 113), to better understand oxytocin's involvement in the effects of socio-affective training, we explored oxytocin, cortisol and subjective experiential responses to a single Loving-kindness Meditation (LKM) conducted after three months of Affect training (versus rest without prior training). We found that, independent of mental training, stress triggered acute oxytocin release. Following a single LKM, however, acute oxytocin release was unaffected. Training effects were only found in overall oxytocin release during both, stress and LKM. Compared to no training, 3-month compassion-based Affect training decreased overall oxytocin levels in the context of psychosocial stress, but increased overall oxytocin levels during LKM. Training-induced changes in overall oxytocin were unrelated to cortisol and subjective stress reactivity. Based on Quintana and Guastella's (2020) theory of oxytocin as an allostatic hormone with anticipatory properties, we interpret training-induced changes in overall oxytocin levels as alterations in the anticipated emotional relevance of specific events. After training socio-affective skills for three months, the stressful situation may have lost its emotional saliency, whereas the meditation technique itself gained emotional relevance. We conclude that changes in peripheral oxytocin release do not mediate stress reduction after mental training, and encourage the investigation of an allostatic concept of oxytocin in future research.

Association between breastfeeding and postpartum depression: A meta-analysis

BACKGROUND

The association of breastfeeding (BF) for postpartum depression (PPD) remains controversial. Currently there are no specific guidelines on the role of BF in the management of PPD.

OBJECTIVES

To determine the association between BF and PPD.

METHODS

We searched PubMed, Cochrane Library, and EMBASE up to December 2021 for relevant articles associated between PPD and BF. Pooled odds ratios (ORs) with 95% confidence intervals (CIs) were calculated with a random-effects model.

RESULTS

A total of 8 studies with 18,570 participants were included. BF was associated with a 14% lower risk of PPD (OR 0.86, 95% CI 0.77-0.94, I² = 51.78%). For a single BF episode, BF duration of >1 month was associated a 37% lower risk (OR 0.63, 95% CI 0.47-0.79, I² = 34.98%, P = 0.19), and BF for <1 month was associated with a 6% lower risk (OR 0.94, 95% CI 0.89-0.99, I² = 0.00%, P = 0.61). Exclusive breastfeeding (EBF) compared with never breastfeeding (NBF) was associated with a 53% lower risk for PPD (OR 0.47, 95% CI 0.27-0.66, I² = 0.00%, P = 0.98). And EBF compared with partial breastfeeding (PBF) was associated with an 8% lower risk for PPD (OR 0.92, 95% CI 0.86-0.98, I² = 13.86%, P = 0.31). The subgroups we studied may be a source of heterogeneity.

CONCLUSIONS

Our results show an association between PPD and risk for BF. To confirm the conclusion, more studies with large sample sizes are required.

Cortisol, Prolactin, and Breastmilk Volume; A Promising Pattern for Reducing Postpartum Depression

BACKGROUND: Research shows postnatal depression and shorter breastfeeding are consistently related, but their causal effect remains debatable. To reduce the impact of mental disorders in the perinatal period, lactation may give a significant neuroendocrine effect. AIM: This study aimed to examine hormonal patterns and estimated breastmilk volume of mothers with depression. MATERIALS AND METHODS: This study was conducted during the three-trimester to 6-week postnatal period. It involved 60 pregnant women from South Sulawesi, Indonesia. Analysis of variance with repeated measures was used to compare and review fluctuations and effect sizes of cortisol, prolactin, and breastmilk volume of mothers with depression symptoms. RESULTS: The mean cortisol levels rose in the 4th week and decreased in the 6th week in both groups. There was no substantial difference in the cortisol levels between these periods (p = 0.534; p = 0.553; and p = 0.660), but the prolactin levels continuously increased by 2 weeks and substantially progressed in the 4th and 6th weeks (p < 0.028, p < 0.009), respectively. There was no positive association between cortisol and prolactin levels (p = 0.384). The breastmilk volume was higher every week only in mothers without depression and it slightly decreased in other categories. This study emphasized the prolactin’s protective effect size on a stressful environment characterized by high cortisol; a significant rise in prolactin levels occurred in the 2nd and 4th weeks of postnatal, marking the higher lactation. CONCLUSIONS: Breastfeeding hormones may provide protection against postpartum depression in moms. It is critical to establish a history of prior trauma in nursing mothers in order to facilitate diagnosis and proper care.

The Effects of Breastfeeding on Maternal Mental Health: A Systematic Review

Background: Breastfeeding has many positive effects on the health of infants and mothers, however, the effect of breastfeeding on maternal mental health is largely unknown. The goal of this systematic review was to (1) synthesize the existing literature on the effects of breastfeeding on maternal mental health, and (2) inform breastfeeding recommendations. Materials and Methods: A literature search was conducted in electronic databases using search terms related to breastfeeding (e.g., breastfeeding, infant feeding practices) and mental health conditions (e.g., mental illness, anxiety, depression), resulting in 1,110 records. After reviewing article titles and abstracts, 339 articles were advanced to full-text review. Fifty-five articles were included in the final analysis. Results: Thirty-six studies reported significant relationships between breastfeeding and maternal mental health outcomes, namely symptoms of postpartum depression and anxiety: 29 found that breastfeeding is associated with fewer mental health symptoms, one found it was associated with more, and six reported a mixed association between breastfeeding and mental health. Five studies found that breastfeeding challenges were associated with a higher risk of negative mental health symptoms. Conclusions: Overall, breastfeeding was associated with improved maternal mental health outcomes. However, with challenges or a discordance between breastfeeding expectations and actual experience, breastfeeding was associated with negative mental health outcomes. Breastfeeding recommendations should be individualized to take this into account. Further research, specifically examining the breastfeeding experiences of women who experienced mental health conditions, is warranted to help clinicians better personalize breastfeeding and mental health counseling.

Multiple Aspects of Inappropriate Action of Renin-Angiotensin, Vasopressin, and Oxytocin Systems in Neuropsychiatric and Neurodegenerative Diseases

The cardiovascular system and the central nervous system (CNS) closely cooperate in the regulation of primary vital functions. The autonomic nervous system and several compounds known as cardiovascular factors, especially those targeting the renin–angiotensin system (RAS), the vasopressin system (VPS), and the oxytocin system (OTS), are also efficient modulators of several other processes in the CNS. The components of the RAS, VPS, and OTS, regulating pain, emotions, learning, memory, and other cognitive processes, are present in the neurons, glial cells, and blood vessels of the CNS. Increasing evidence shows that the combined function of the RAS, VPS, and OTS is altered in neuropsychiatric/neurodegenerative diseases, and in particular in patients with depression, Alzheimer’s disease, Parkinson’s disease, autism, and schizophrenia. The altered function of the RAS may also contribute to CNS disorders in COVID-19. In this review, we present evidence that there are multiple causes for altered combined function of the RAS, VPS, and OTS in psychiatric and neurodegenerative disorders, such as genetic predispositions and the engagement of the RAS, VAS, and OTS in the processes underlying emotions, memory, and cognition. The neuroactive pharmaceuticals interfering with the synthesis or the action of angiotensins, vasopressin, and oxytocin can improve or worsen the effectiveness of treatment for neuropsychiatric/neurodegenerative diseases. Better knowledge of the multiple actions of the RAS, VPS, and OTS may facilitate programming the most efficient treatment for patients suffering from the comorbidity of neuropsychiatric/neurodegenerative and cardiovascular diseases.

Maternal Psychological Distress and Lactation and Breastfeeding Outcomes: a Narrative Review

PURPOSE

Despite recommendations from the World Health Organization and the American Academy of Pediatrics to exclusively breastfeed infants for their first 6 months of life, 75% of women do not meet exclusive breastfeeding guidelines, and 60% do not meet their own breastfeeding goals. Numerous observational studies have linked maternal psychological distress (eg, perceived stress, anxiety, and depression) with nonoptimal breastfeeding outcomes, such as decreased proportion and duration of exclusive breastfeeding. The physiological mechanisms underlying these associations, however, remain unclear.

METHODS

For this narrative review, we evaluated the evidence of relationships between maternal psychological distress and lactation and breastfeeding outcomes in pregnancy and post partum and the possible physiological mechanisms that facilitate these relationships. We searched PubMed using the following terms: stress, anxiety, depression, breastfeeding, and lactation. Additional search by hand was conducted to ensure a thorough review of the literature.

FINDINGS

Among the studies examined, methods used to assess maternal psychological distress were not uniform, with some studies examining perceived distress via a variety of validated tools and others measuring biological measures of distress, such as cortisol. Evidence supports a role for psychological distress in multiple breastfeeding outcomes, including delayed secretory activation and decreased duration of exclusive breastfeeding. One physiological mechanism proposed to explain these relationships is that psychological distress may impair the release of oxytocin, a hormone that plays a critical role in milk ejection during lactation. Continued impairment of milk ejection may lead to decreased milk production because of incomplete emptying of the breast during each feed. Maternal distress may also yield elevated levels of serum cortisol and decreased insulin sensitivity, which are associated with decreased milk production. The relationship between psychological distress and breastfeeding is likely to be bidirectional, however, in that breastfeeding appears to reduce maternal distress, again possibly via effects on the pleasure or reward pathway and calming effects of oxytocin on the mother. This finding suggests that interventions to support lactation and breastfeeding goals in women who score high on measures of psychological distress would be beneficial for both maternal and infant well-being.

IMPLICATIONS

Evidence to date suggests that maternal psychological distress may impair lactation and breastfeeding outcomes, but stronger study designs and rigorous assessment methods are needed. A better understanding of the physiological mechanisms leading to impaired lactation may assist in the development of early interventions for mothers experiencing distress. In addition, stress-reducing programs and policies should be investigated for their potential to improve breastfeeding outcomes.

Breastfeeding Is Inversely Associated with Allostatic Load in Postpartum Women: Cross-Sectional Data from Nationally Representative US Women

BACKGROUND

The postpartum period is a critical transition period when exposures to protective factors such as breastfeeding can have long-lasting health impact. Studies have suggested downregulating effects of breastfeeding on stress biomarkers such as cortisol but have not explored the way breastfeeding interacts with allostatic load, a multisystem indicator of chronic stress.

OBJECTIVE

We aimed to examine the association between breastfeeding and maternal allostatic load among women within 2 y postpartum using nationally representative data.

METHODS

A cross-sectional analysis of 10 waves of data from the NHANES (1999-2018) was conducted in a sample of 1302 women aged ≥18 y who provided information on breastfeeding through the reproductive health questionnaire. Clinical and empirical allostatic load scores (range: 0-10; higher numbers associated with increased risk) were derived for each participant based on 10 biomarkers reflecting metabolic, cardiovascular, and immune health. Multiple linear regression tested associations between breastfeeding and allostatic load, adjusting for maternal age, race and ethnicity, education, poverty level, and survey wave.

RESULTS

Breastfeeding had a significant inverse association with allostatic load in unadjusted and adjusted models. Controlling for age, race and ethnicity, education, poverty level, and survey wave, breastfeeding women had a 0.36-point lower clinical allostatic load score than nonbreastfeeding women (β = -0.36, SE = 0.11; 95% CI: -0.59, -0.14; P = 0.002) and a 0.44-point lower empirical allostatic load score (β = -0.44, SE = 0.15; 95% CI: -0.74, -0.14; P = 0.005).

CONCLUSIONS

Our study suggests that breastfeeding is protective of maternal stress and provides a more comprehensive picture of breastfeeding's influence on multiple body systems, exemplifying physiological benefits beyond effects on single biomarkers. However, limitations of cross-sectional data and non-classification of breastfeeding duration, mode, and intensity should be considered when interpreting these findings, and further research to address the role of breastfeeding and allostatic load is needed.

Lactation is not required for maintaining maternal care and active coping responses in chronically stressed postpartum rats: Interactions between nursing demand and chronic variable stress

Women who do not breastfeed or discontinue breastfeeding early are more likely to develop postpartum depression (PPD) and stress is a significant risk factor for depression, including PPD. Using a rat model, we investigated whether the absence of nursing would increase the susceptibility to chronic stress-related behavioral and neural changes during the postpartum period. Adult female rats underwent thelectomy (thel; removal of teats), sham surgery, or no surgery (control) and were paired with males for breeding. All litters were rotated twice daily until postpartum day (PD) 26. Sham rats served as surrogates for thel litters, yielding a higher nursing demand for sham rats. Concurrently, rats received either no stress or chronic variable stress until PD 25. Rats were observed for maternal behaviors and tested in a series of tasks including open field, sucrose preference, and forced swim. We used immunohistochemistry (IHC) for doublecortin (DCX; to label immature neurons) or for mineralocorticoid receptor (MR). Contrary to our expectations, non-nursing thel rats were resistant to the effects of stress in all dependent measures. Our data indicate that even in chronic adverse conditions, nursing is not required for maintaining stable care to offspring or active coping responses in an acutely stressful task. We discuss the possible role of offspring contact and consider future directions for biomedical and clinical research. In rats with high nursing demand, however, chronic stress increased immobility, hippocampal neurogenesis, and MR expression (largely in opposition to the effects of stress in rats with typical nursing demand). We discuss these patterns in the context of energetics and allostatic load. This research highlights the complexity in relationships between stress, nursing, and neurobehavioral outcomes in the postpartum period and underscores the need for additional biomedical and clinical research geared toward optimizing treatments and interventions for women with PPD, regardless of breastfeeding status. SIGNIFICANCE STATEMENT: The goal of this research was to determine how the absence of nursing and higher nursing demand impact stress-coping behaviors and neural changes associated with chronic stress in order to disentangle the complex interplay of factors that contribute to psychological illness during the postpartum period.

Alterations in corticotropin-releasing factor receptor type 1 in the preoptic area and hypothalamus in mice during the postpartum period

Corticotropin-releasing factor (CRF) signaling through CRF receptor 1 (CRFR1) regulates autonomic, endocrine, and behavioral responses to stress, as well as behavioral changes during the maternal period. Previous work in our lab reported higher levels of CRFR1 in female, compared to male, mice within the rostral anteroventral periventricular nucleus (AVPV/PeN), a brain region involved in maternal behaviors. In this study, we used CRFR1-GFP reporter mice to investigate whether the reproductive status (postpartum vs. nulliparous) of acutely stressed females affects levels of CRFR1 in the AVPV/PeN and other regions involved in maternal functions. Compared to nulliparous, postpartum day 14 females showed increased AVPV/PeN CRFR1-GFP immunoreactivity and an elevated number of restraint stress-activated AVPV/PeN CRFR1 cells as assessed by immunohistochemical co-localization of CRFR1-GFP and phosphorylated CREB (pCREB). The medial preoptic area (MPOA) and paraventricular hypothalamus (PVN) of postpartum mice showed modest decreases in CRFR1-GFP immunoreactivity, while increased CRFR1-GFP/pCREB co-expressing cells were found in the PVN following restraint stress relative to nulliparous mice. Tyrosine hydroxylase (TH) and CRFR1-GFP co-localization was also assessed in the AVPV/PeN and other regions and revealed a decrease in co-localized neurons in the AVPV/PeN and ventral tegmental area of postpartum mice. Corticosterone analysis of restrained mice revealed blunted peak, but elevated recovery, levels in postpartum compared to nulliparous mice. Finally, we investigated projection patterns of AVPV/PeN CRFR1 neurons using female CRFR1-Cre mice and revealed dense efferent projections to several preoptic, hypothalamic, and hindbrain regions known to control stress-associated and maternal functions. Together, these findings contribute to our understanding of the neurobiology that might underlie changes in stress-related functions during the postpartum period.

Problems with Social Cognition and Decision-Making in Huntington's Disease: Why Is it Important?

Huntington’s disease starts slowly and progresses over a 15–20 year period. Motor changes begin subtly, often going unnoticed by patients although they are typically visible to those close to them. At this point, it is the early non-motor problems of HD that arguably cause the most functional impairment. Approximately 65% of gene carriers will experience a reduction in their occupational level, and just under half will feel unable to manage their finances independently before a clinical diagnosis is made. Understanding what drives this impairment in activities of daily living is the key to helping people with HD to live more independently for longer, especially in early disease. Early cognitive decline is likely to play a contributory factor although few studies have looked directly at this relationship. Recently, it has been shown that along with the well documented dysexecutive syndrome seen in HD, changes in social cognition and decision-making are more common than previously thought. Furthermore, some of the early neuropathological and neurochemical changes seen in HD disrupt networks known to be involved in social functioning. In this review, we explore how HD changes the way individuals interact in a social world. Specifically, we summarise the literature on both classical and social decision-making (value-based decision-making in a social context) along with studies of theory of mind, empathy, alexithymia, and emotion recognition in HD. The literature specific to HD is discussed and supported by evidence from similar neurodegenerative disorders and healthy individuals to propose future directions and potential therapeutic avenues to be explored.

GABA in the medial prefrontal cortex regulates anxiety-like behavior during the postpartum period

The postpartum period is commonly accompanied by emotional changes, which for many new mothers includes a reduction in anxiety. Previous research in rodents has shown that the postpartum attenuation in anxiety is dependent on offspring contact and has further implicated enhanced GABAergic neurotransmission as an underlying mechanism. However, the specific brain regions where GABA acts to regulate the offspring-induced reduction in postpartum anxiety requires further investigation. Here, we test the hypothesis that offspring interactions suppress anxiety-like behavior in postpartum female rats via GABA signaling in the medial prefrontal cortex (mPFC). Our results show a postpartum reduction in anxiety-like behavior, an effect which was abolished by localized infusion of the GABAA receptor antagonist bicuculline in the mPFC. We also show that activation of GABAA receptors in the mPFC by the agonist muscimol was effective in restoring anxiolyisis in mothers separated from their pups. Lastly, we show that heightened anxiety-like behavior in pup-separated mothers was accompanied by a lower number and percentage of activated GABAergic neurons within the mPFC. Together, these results suggest that mother-offspring interactions reduce anxiety-like behavior in postpartum females via GABAA neurotransmission in the mPFC and in doing so provide insight into mechanisms that may become dysfunctional in mothers who experience high postpartum anxiety.

Perinatal psychological interventions to promote breastfeeding: a narrative review

Background

Emotional distress in mothers inhibits the let-down reflex, thus affecting breastfeeding self-efficacy. A breastfeeding mother may have to cope with both physical discomfort and psychological distress. However, literature on initiatives to improve breastfeeding rates has focused mainly on providing community-based peer support, or social policies. The aim of this review is to assess evidence on the effectiveness of a broad range of psychological interventions to facilitate breastfeeding for mothers facing difficulties around the time of delivery.

Methods

The review of the literature is derived from a search on Cochrane Library, PubMed, EBSCOhost, and PsycINFO for papers published since 1980. The approach was to explore quantitative and qualitative parameters. Quantitative parameters included breastfeeding initiation, duration, and composition. Qualitative parameters recorded the evaluation of maternal perceptions on breastfeeding success. The high heterogeneity of the studies led to a narrative review; 20 selected papers that report on breastfeeding outcomes and psychological programs met the inclusion criteria.

Results

The evidence on breastfeeding support through psychotherapy is heterogeneous and scant. Out of the included studies, 11 were randomized controlled trials, two were non-randomised trials, and two used a quasi-experimental design. None of the studies reported an increase in adverse breastfeeding outcomes. Three studies failed to report an association between psychological procedures and improved breastfeeding outcomes. A literature review showed that 17 (85%) analyses support stress-releasing techniques to facilitate breastfeeding.

Conclusions

This review suggests that relaxation interventions carefully tailored to address perinatal emotional distress may lead to important health benefits, including improvement in breastfeeding outcomes. There is also some indication that psychotherapy support while breastfeeding may have more impact than routine counselling. Conversely, this review did not find an association between self-hypnosis and breastfeeding outcomes. Data from this study can be used in designing prevention programs and future research with appropriate theoretical underpinning.

How stress can influence brain adaptations to motherhood

Research shows that a woman's brain and body undergo drastic changes to support her transition to parenthood during the perinatal period. The presence of this plasticity suggests that mothers' brains may be changed by their experiences. Exposure to severe stress may disrupt adaptive changes in the maternal brain and further impact the neural circuits of stress regulation and maternal motivation. Emerging literature of human mothers provides evidence that stressful experience, whether from the past or present environment, is associated with altered responses to infant cues in brain circuits that support maternal motivation, emotion regulation, and empathy. Interventions that reduce stress levels in mothers may reverse the negative impact of stress exposure on the maternal brain. Finally, outstanding questions regarding the timing, chronicity, types, and severity of stress exposure, as well as study design to identify the causal impact of stress, and the role of race/ethnicity are discussed.

Effects of Breastfeeding on Stress Measured by Saliva Cortisol Level and Perceived Stress

Purpose: The effects of breastfeeding on postpartum depression symptoms and stress using physiological measures require investigation.

Background: Breastfeeding suppresses the secretion of cortisol. Oxytocin levels correlate negatively with symptoms of postpartum depression.

Aim: To investigate the effects of breastfeeding on stress and postpartum depression.

Methods: We examined 79 breastfeeding women using the Edinburgh Postnatal Depression Scale, the Perceived Stress Scale-10, and the Breastfeeding Self-Efficacy Scale, and measured the salivary cortisol levels before and after breastfeeding.

Findings: There was a negative correlation between the duration of suckling and changes in salivary cortisol levels following breastfeeding (r_s = −0.333, p < 0.05). Salivary cortisol levels immediately following breastfeeding were significantly lower compared to mothers who used mixed feeding methods (p < 0.001). Breastfeeding mothers had lower perceived stress than mothers using mixed feeding methods (β = −0.260, p < 0.05). There was no association between breastfeeding and postpartum depression; however, there was an association between postpartum depression and perceived stress (β = 0.526, p < 0.001).

Conclusion: Salivary cortisol levels significantly decreased following breastfeeding, with longer suckling times correlating with lower cortisol levels. Breastfeeding reduced stress and increased breastfeeding self-efficacy.

Status does not predict stress: Women in an egalitarian hunter-gatherer society

It is widely believed that there is strong association between physiological stress and an individual's social status in their social hierarchy. This has been claimed for all humans cross-culturally, as well as in non-human animals living in social groups. However, the relationship between stress and social status has not been explored in any egalitarian hunter-gatherer society; it is also under investigated in exclusively female social groups. Most of human evolutionary history was spent in small, mobile foraging bands of hunter-gatherers with little economic differentiation - egalitarian societies. We analysed women's hair cortisol concentration along with two domains of women's social status (foraging reputation and popularity) in an egalitarian hunter-gatherer society, the Hadza. We hypothesized that higher social status would be associated with lower physiological indicators of stress in these women. Surprisingly, we did not find any association between either foraging reputation or popularity and hair cortisol concentration. The results of our study suggest that social status is not a consistent or powerful predictor of physiological stress levels in women in an egalitarian social structure. This challenges the notion that social status has the same basic physiological implications across all demographics and in all human societies.

Breastfeeding dynamically changes endogenous oxytocin levels and emotion recognition in mothers

Breastfeeding behaviours can significantly change mothers' physiological and psychological states. The hormone oxytocin may mediate breastfeeding and mothers' emotion recognition. This study examined the effects of endogenous oxytocin fluctuation via breastfeeding on emotion recognition in 51 primiparous mothers. Saliva oxytocin was assessed before and after the manipulation (breastfeeding or holding an infant), and emotion recognition tasks were conducted. Among mothers who breastfed daily, mothers with more increased levels of oxytocin after breastfeeding showed more reduced negative recognition and enhanced positive recognition of adult facial expressions. These oxytocin functions accompanying breastfeeding may support continued nurturing behaviours and also affect the general social cognition of other adults beyond any specific effect on infants.

The oxytocinergic system in PTSD following traumatic childbirth: endogenous and exogenous oxytocin in the peripartum period

Birth experiences can be traumatic and may give rise to PTSD following childbirth (PTSD-FC). Peripartum neurobiological alterations in the oxytocinergic system are highly relevant for postpartum maternal behavioral and affective adaptions like bonding and lactation but are also implicated in the response to traumatic events. Animal models demonstrated that peripartum stress impairs beneficial maternal postpartum behavior. Early postpartum activation of the oxytocinergic system may, however, reverse these effects and thereby prevent adverse long-term consequences for both mother and infant. In this narrative review, we discuss the impact of trauma and PTSD-FC on normal endogenous oxytocinergic system fluctuations in the peripartum period. We also specifically focus on the potential of exogenous oxytocin (OT) to prevent and treat PTSD-FC. No trials of exogenous OT after traumatic childbirth and PTSD-FC were available. Evidence from non-obstetric PTSD samples and from postpartum healthy or depressed samples implies restorative functional neuroanatomic and psychological effects of exogenous OT such as improved PTSD symptoms and better mother-to-infant bonding, decreased limbic activation, and restored responsiveness in dopaminergic reward regions. Adverse effects of intranasal OT on mood and the increased fear processing and reduced top-down control over amygdala activation in women with acute trauma exposure or postpartum depression, however, warrant cautionary use of intranasal OT. Observational and experimental studies into the role of the endogenous and exogenous oxytocinergic system in PTSD-FC are needed and should explore individual and situational circumstances, including level of acute distress, intrapartum exogenous OT exposure, or history of childhood trauma.

Mothering revisited: A role for cortisol?

This selective review first describes the involvement of the maternal hypothalamic-pituitary-adrenal (HPA) axis during pregnancy and the postpartum period, and the relation between peripartum HPA axis function and maternal behavior, stress reactivity and emotional dysregulation in human mothers. To provide experimental background to this correlational work, where helpful, animal studies are also described. It then explores the association between HPA axis function in mothers and their infants, under ongoing non-stressful conditions and during stressful challenges, the moderating role of mothers' sensitivity and behavior in the mother-child co-regulation and the effects of more traumatic risk factors on these relations. The overarching theme being explored is that the HPA axis - albeit a system designed to function during periods of high stress and challenge - also functions to promote adaptation to more normative processes, shown in the new mother who experiences both high cortisol and enhanced attraction and attention to and recognition of, their infants and their cues. Hence the same HPA system shows positive relations with behavior at some time points and inverse ones at others. However, the literature is not uniform and results vary widely depending on the number, timing, place, and type of samplings and assessments, and, of course, the population being studied and, in the present context, the state, the stage, and the stress levels of mother and infant.

Parasympathetic nervous activity is associated with oxytocin in multiparous, but not primiparous, women during the perinatal period

Oxytocin (OXT) is thought to have antidepressant/anxiolytic effects in postpartum women. Primiparous women tend toward an attenuated lactation compared with multiparous women. However, so far, little is known about the relationship between OXT and autonomic nervous activity (ANA) in perinatal women and whether it may be different in primiparous and multiparous women. Therefore, the objective of this study was to answer this question by determining both ANA and salivary OXT levels in primiparous and multiparous perinatal women. In 18 primiparous and 18 multiparous women, who underwent a physical and physiological examination, ANA measurement by heart rate variability and saliva sampling were performed during the perinatal period. Saliva OXT concentration was determined by a highly sensitive ELISA. OXT release into saliva was obtained from multiplying saliva OXT concentration by saliva flow rate. In the postpartum period, multiparous women had higher parasympathetic nervous activity (PNA) and lower physical stress index (PSI) compared with primiparous women. Furthermore, multiparous postpartal women had higher OXT compared with primiparous or multiparous prepartal women. In addition, in multiparous perinatal women, OXT correlated positively with PNA, but negatively with PSI. These results suggest that after parturition, multiparous mothers may switch over to the "feed and breed" system more quickly due to increased OXT compared with primiparous mothers. Our findings support antidepressant/anxiolytic and anti-stress effects of OXT. In postpartal women exposed to synthetic OXT, ANA measurement may provide a clue to clarify the effects of exogenous OXT on postpartum psychiatric disorders.

Neuroendocrine Effects of Lactation and Hormone-Gene-Environment Interactions

While correlational studies suggest that lactation may confer a certain level of protection from mental illness, this benefit is not uniformly expressed in all women who choose to breastfeed. We propose here that the neuroendocrine "resetting" induced by lactation may predispose toward positive affect states in a subset of hormone-sensitive mothers, with hormone-gene and hormone-environment interactions determining the ultimate psychological outcome. We find evidence to suggest that higher secretion of prolactin/oxytocin as well as lower secretion of vasopression/androgens in lactating mothers may protect against postpartum depression and anxiety, decrease levels of irritability, and optimize stress responses. On the other hand, while the abrupt withdrawal of estradiol/progesterone in the immediate postpartum period tends to be associated with adverse psychological outcomes, the chronic suppression of estrogens/progestogens induced by lactation may have antidepressant and anxiolytic effects over time. Finally, the hypo-cortisolemic state seen in lactating mothers appears to be associated with improved stress reactivity and circadian rhythms. We also discuss hormone-gene and hormone-environment interactions likely to modulate any potential psychological benefits related to lactation and focus on those factors that are either easy to screen for or known to be modifiable. In sum, neuroendocrine alterations induced by lactation may play a key role in determining reproductive psychiatric risk in a subset of hormone-sensitive women. Using these neuroendocrine factors as an individualized index of risk can help in devising targeted programs to support these women in pursuing lactation or, for those not able or willing, accessing psychological interventions in a timely manner.

The association between breastfeeding and attachment: A systematic review

OBJECTIVE

In the popular and scientific literature an association between breastfeeding and attachment is often supposed although this has not been systematically investigated. This is the first review that provides a systematic overview of the current state of research on the association between breastfeeding and attachment. The objective is to determine whether breastfeeding is associated with child attachment as well as if maternal attachment is associated with breastfeeding behaviour.

DESIGN

A systematic electronic literature search for English language articles published from 1963 to 2019 using the databases Web of Science, PubMed, PsycInfo, and PsycArticles was conducted. Studies were included if (1) the association between breastfeeding and attachment of the child or maternal attachment style and breastfeeding was investigated, (2) participants were mothers or mother-child dyads, and (3) quantitative measures of breastfeeding and attachment were used. Study quality was rated using the NIH Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies.

PARTICIPANTS

Studies examining mothers or mother-child dyads were reviewed. Sample sizes varied between N = 60 and N = 8900 participants. On average, mothers were between 27.56 and 32.50 years old.

FINDINGS

Eleven studies were eligible for inclusion. Of seven studies examining breastfeeding and child attachment, four found that a longer duration of breastfeeding was significantly associated with higher levels of attachment security after controlling for various covariates. No significant differences in attachment security between breastfeeding and bottle-feeding were reported, but one study found higher levels of attachment disorganization for bottle-feeding, although mean levels were below a clinically relevant level. The initiation of breastfeeding directly after childbirth was not related to child attachment. Of four studies examining maternal attachment and breastfeeding, three found a significant association between secure attachment of the mother and breastfeeding behaviour. Secure attached mothers initiated breastfeeding more often and preferred breast- over bottle-feeding than insecure attached mothers. Mixed results were found for breastfeeding duration. Most studies had limitations regarding adequate sample size, and valid and reliable measurement of breastfeeding.

KEY CONCLUSIONS

The findings provide some evidence that breastfeeding might contribute to child attachment security. Furthermore, maternal attachment style might play a role in breastfeeding behaviour. However, more prospective studies are needed to draw a solid conclusion.

IMPLICATIONS FOR PRACTICE

With regard to breastfeeding recommendations, health professionals should be aware of and communicate towards clients that the effect of breastfeeding on child attachment might be rather small. Screening of maternal attachment style as a part of maternity practice could be useful to support insecure attached mothers experiencing breastfeeding difficulties.

Oxytocin is a principal hormone that exerts part of its effects by active fragments

Oxytocin is a nonapeptide consisting of a cyclic six amino-acid structure and a tail of three amino acids. It was originally known for its ability to induce milk ejection and to stimulate uterine contractions. More recently, oxytocin has been shown to stimulate social behaviors, and exert pain-relieving, anti-stress/anti-inflammatory and restorative effects. We hypothesize that oxytocin is a principal hormone that, in part, exerts its effects after degradation to active fragments with more specific effect profiles. Experimental findings on rats show that administered oxytocin exerts biphasic effects. For example, after an initial increase in pain threshold, a second more long-lasting increase follows. Blood pressure and cortisol levels initially increase and then reverse into a long-lasting decrease in blood pressure and cortisol. Whereas the initial effects are, the second-phase effects are not blocked by an oxytocin antagonist, but by an opioid mu-antagonist and by an alpha 2-adrenoreceptor antagonist, respectively, suggesting that other receptors are involved. Repeated administration of oxytocin induces multiple anti-stress effects, which are mediated by alpha 2-adrenoreceptors. Repeated administration of linear oxytocin and linear oxytocin fragments with a retained C-terminal reduce spontaneous motor activity, a sedative or anti-stress effect, suggesting that alpha 2-adrenoreceptors have been activated. In contrast, linear mid-fragments stimulate motor activity. Low-intensity stimulation of cutaneous nerves in rats, as well as breastfeeding and skin-to-skin contact between mothers and babies, trigger immediate anti-stress effects. Some of these effects are likely caused by open ring/linear C-terminal fragments activating alpha 2-adrenoreceptors. Oxytocin fragments may be pre-formed and released in the brain or created by metabolic conversion of the principal hormone oxytocin in the central nervous system. Oxytocin and its fragments may also be released from peripheral sites, such as peripheral nerves, the gastrointestinal tract, and blood vessels in response to decreased sympathetic or increased parasympathetic nervous tone. Smaller fragments of oxytocin produced in the periphery may easily pass the blood-brain barrier to induce effects in the brain. In conclusion, oxytocin is linked to many different, sometimes opposite effects. The intact cyclic molecule may act to initiate social interaction and associated psychophysiological effects, whereas linear oxytocin and C-terminal fragments may induce relaxation and anti-stress effects following social interaction. In this way, the principal hormone oxytocin and its fragments may take part in a behavioral sequence, ranging from approach and interaction to calm and relaxation. Linear fragments, with an exposed cysteine-residue, may exert anti-inflammatory and antioxidant effects and thereby contribute to the health-promoting effects of oxytocin.

Invited review: A systematic review of the effects of prolonged cow-calf contact on behavior, welfare, and productivity

Separation of calves from cows within hours or days of birth is common on dairy farms. Stakeholders have conflicting perspectives on whether this practice is harmful or beneficial for the animals' welfare and production. Our objective was to critically evaluate the scientific evidence for both acute and long-term effects of early separation versus an extended period of cow-calf contact. The outcomes investigated were the behavior, welfare (excluding physical health), and performance (milk yield and growth, respectively) of dairy cows and calves. Primary research papers were found through targeted Web of Science searches, the reference lists of recent reviews for each topic, and the reference lists of papers identified from these sources. Studies were included if they were published in English, the full text was accessible, and they compared treatments with and without contact between dairy cows and calves for a specified period. Early separation (within 24 h postpartum) was found to reduce acute distress responses of cows and calves. However, longer cow-calf contact typically had positive longer-term effects on calves, promoting more normal social behavior, reducing abnormal behavior, and sometimes reducing responses to stressors. In terms of productivity, allowing cows to nurse calves generally decreased the volume of milk available for sale during the nursing period, but we found no consistent evidence of reduced milk production over a longer period. Allowing a prolonged period of nursing increased calf weight gains during the milk-feeding period. In summary, extended cow-calf contact aggravates the acute distress responses and reduces the amount of saleable milk while the calves are suckling, but it can have positive effects on behaviors relevant to welfare in the longer term and benefit calf growth. The strength of these conclusions is limited, however, given that relatively few studies address most of these effects and that experimental design including timing of contact and observations are often inconsistent across studies. Few studies presented indicators of long-term welfare effects other than abnormal and social behavior of the calves.

HPA axis responses to psychological challenge linking stress and disease: What do we know on sources of intra- and interindividual variability?

Stress is an ubiquitous phenomenon with significant impact on human physiology when it lasts too long, when it is too intense, or when it hits vulnerable individuals. Examining the mechanisms linking stress exposure with health and disease is an important endeavor in psychoneuroendocrine research. Empirical evidence so far revealed large intra- as well as inter-individual variability in hypothalamic-pituitary-adrenal (HPA) axis responses to acute psychosocial stress, showing that the HPA axis is a highly adaptive system. Thus, the characterization of intra- und inter-individual patterns of HPA axis reactivity is of high scientific interest and forms the basis on which mechanistic links between stress response (dys)regulation and health impairments can be examined. To date, basic knowledge has been, and still is, accumulated on demographic, biological (including genetic and epigenetic) factors, lifestyle behavioral variables, consumption of substances and medication, psychological and personality factors, as well as on methodological aspects. Besides this, there is also very recent progress in respect to the development of laboratory stress paradigms that can be applied in virtual reality or inside an MRI-scanner. In sum, the present review updates our current knowledge on moderating and intervening factors as sources of intra- und inter-individual variability in human cortisol stress responses and offers recommendations for future research designs.

Breastfeeding reduces risk of depression later in life in the postmenopausal period: A Korean population-based study

OBJECTIVE

The relationship between breastfeeding and maternal depression in later life has not yet been investigated. We examined whether the number of breastfed infants or the period of breastfeeding influenced maternal depression in postmenopausal women.

METHODS

We analyzed 1,372 parous postmenopausal women aged ≥ 50 years who had participated in the Korea National Health and Nutrition Examination Survey 2014. Depression was diagnosed using the Patient Health Questionnaire 9, with scores of 10 or higher indicating depression. Logistic regression analyses were performed to examine the relationships between breastfeeding and postmenopausal depression.

RESULTS

Women with a moderate (2-3) or high (4-12) number of breastfed infants had 65% [odds ratio (OR) = 0.35, 95% confidence interval (CI) = 0.19-0.65] and 77% (OR = 0.23, 95% CI = 0.10-0.55) decreased risks of depression, respectively, compared to those with low numbers of infants (0-1). Women who breastfed their infants for long periods (47-432 months) had 67% (OR = 0.33, 95% CI = 0.16-0.68) decreased risk of depression, compared to those who breastfed for short periods (0-23 months). The risk of depression decreased by 29% (OR = 0.71, 95% CI = 0.58-0.87) for each additional infant breastfed and by 9% (OR = 0.91, 95% CI = 0.82- < 1.00) for each additional year of breastfeeding. The population-attributable fraction of depression associated with < 2 infants breastfed was 17.3% (95% CI = 14.2-20.3%), while the fraction associated with a period of breastfeeding < 24 months was not significant.

CONCLUSIONS

Women with more breastfed infants or longer period of breastfeeding are at decreased risk of depression in the postmenopausal period.

The long and short term effects of motherhood on the brain

Becoming a mother is associated with dramatic changes in physiology, endocrinology, immune function, and behaviour that begins during pregnancy and persists into the postpartum. Evidence also suggests that motherhood is accompanied by long-term changes in brain function. In this review, we summarize the short (pregnancy and postpartum) and long-term (beyond the postpartum and into middle age) effects of pregnancy and motherhood on cognition, neuroplasticity, and neuroimmune signalling. We also discuss the effects of previous history of pregnancy and motherhood (parity) on brain health and disease (neurodegenerative diseases and stroke outcomes) and on efficacy of hormone and antidepressant treatments. Finally, we argue that pregnancy and motherhood are unique female experiences that need to be taken into account to better understand female brain function and aging.

Chronic and acute stress monitoring by electrophysiological signals from adrenal gland

We present electrophysiological (EP) signals correlated with cellular cell activities in the adrenal cortex and medulla using an adrenal gland implantable flexible EP probe. With such a probe, we could observe the EP signals from the adrenal cortex and medulla in response to various stress stimuli, such as enhanced hormone activity with adrenocorticotropic hormone, a biomarker for chronic stress response, and an actual stress environment, like a forced swimming test. This technique could be useful to continuously monitor the elevation of cortisol level, a useful indicator of chronic stress that potentially causes various diseases.

Influence of the number of calves and lactating adult females in a herd on the adrenocortical activity of free-ranging Asian elephants

Abstract ContextPhysiological stress has the potential to influence animal population persistence. The endangered Asian elephant (Elephas maximus) is involved in intense conflict with humans in many parts of its range, which likely leads to stress for individuals and groups, with consequences for population survival. Thus, it is important to understand how the elephants’ stress levels are influenced by socio-ecological factors when not directly exposed to human-induced threats, and to use this understanding to improve conservation and management strategies. AimsThe present study was designed to provide baseline information on the link between socio-ecological factors and stress levels of undisturbed populations of elephants. The main aim was to determine the influence of a number of factors – herd size, season, number of calves and adult females present in a herd and their lactational status and body condition – on the adrenocortical activity of free-ranging adult female Asian elephants living in protected forests (without any direct exposure to human-induced threats), by measuring their faecal glucocorticoid metabolite (fGCM) levels. MethodsA total of 145 fresh faecal samples were collected from 123 identified adult female elephants inhabiting Bandipur and Nagarahole National Parks of southern India, between the years 2013 and 2015. fGCM levels were measured by employing a group-specific standardised 11-oxoetiocholanolone enzyme immunoassay (EIA). A generalised linear mixed-effects model (GLMM) was used to assess the influence of socio-ecological factors on fGCM levels of adult female elephants. Key resultsWhen fGCM levels were analysed with a GLMM, the following patterns were observed: fGCM levels were negatively correlated with the number of adult females (herd size) and positively correlated with the number of calves in a herd and active lactational status of an adult female. fGCM levels of adult female elephants were higher during the dry season (February to May) than wet season (August to December) and negatively correlated with body condition scores. ConclusionsAdrenocortical activity of female elephants is significantly influenced by the number of calves and adult females present in the herd, seasonality and lactational status. ImplicationsIt is important to consider the influence of multiple ecological and social correlates when assessing and interpreting the adrenocortical activity of Asian elephants. Our findings highlight the importance of maintaining the social structure of elephants in the wild to avoid detrimental effects on their physiological health. Insights from such assessments could be used to evaluate the stress in elephants that are involved in direct conflicts with humans to take appropriate management decisions for mitigating conflicts.

The impact of oxytocin on stress: the role of sex

Accumulating research indicates oxytocin plays a significant role in regulating the behavioral and neurobiological responses to stress. Evidence from preclinical models suggests the effect of oxytocin on stress-responsivity appears to be dependent on individual characteristics, including sex. Although the interaction between oxytocinergic and stress systems has been widely studied in rodents, recent efforts have been made to examine the interface between these two systems in humans. This brief review examines how administration of oxytocin can influence the neuroendocrine, behavioral, and neural responses to stress, explores how sex may impact these effects, and provides considerations for future work.

The Oxytocin Receptor: From Intracellular Signaling to Behavior

The many facets of the oxytocin (OXT) system of the brain and periphery elicited nearly 25,000 publications since 1930 (see FIGURE 1 , as listed in PubMed), which revealed central roles for OXT and its receptor (OXTR) in reproduction, and social and emotional behaviors in animal and human studies focusing on mental and physical health and disease. In this review, we discuss the mechanisms of OXT expression and release, expression and binding of the OXTR in brain and periphery, OXTR-coupled signaling cascades, and their involvement in behavioral outcomes to assemble a comprehensive picture of the central and peripheral OXT system. Traditionally known for its role in milk let-down and uterine contraction during labor, OXT also has implications in physiological, and also behavioral, aspects of reproduction, such as sexual and maternal behaviors and pair bonding, but also anxiety, trust, sociability, food intake, or even drug abuse. The many facets of OXT are, on a molecular basis, brought about by a single receptor. The OXTR, a 7-transmembrane G protein-coupled receptor capable of binding to either Gαior Gαqproteins, activates a set of signaling cascades, such as the MAPK, PKC, PLC, or CaMK pathways, which converge on transcription factors like CREB or MEF-2. The cellular response to OXT includes regulation of neurite outgrowth, cellular viability, and increased survival. OXTergic projections in the brain represent anxiety and stress-regulating circuits connecting the paraventricular nucleus of the hypothalamus, amygdala, bed nucleus of the stria terminalis, or the medial prefrontal cortex. Which OXT-induced patterns finally alter the behavior of an animal or a human being is still poorly understood, and studying those OXTR-coupled signaling cascades is one initial step toward a better understanding of the molecular background of those behavioral effects.

Role of oxytocin in parental behaviour

Both animal and human studies have provided conclusive evidence that oxytocin (OXT) acts in the brain (eg, medial preoptic area, ventral tegmental area, nucleus accumbens) to promote parental behaviour under different reproductive and physiological conditions. OXT appears to accelerate and strengthen the neural process that makes newborns attractive or rewarding. Furthermore, OXT reduces stress/anxiety and might improve mood and well being, resulting in indirect benefits for parents. However, OXT also plays a role in the development of species reproductive and social strategies, making some species or individuals more prone to display caring activities in nonreproductive contexts. There are important differences in the development of the OXT system and its regulation by gonadal hormones that can make individuals or species very different. Those intra- and interspecific differences in the OXT system have been associated with differences in parental behaviour. For example, differences in OXT levels in body fluids and genetic variants for the OXT and OXT receptor genes have been associated with variability in parental mood and behaviour in humans. Thus, OXT has received much attention as a potential therapeutic agent for affective, emotional and behavioural problems. Despite many preliminary studies indicating promising findings, several unknown aspects of the OXT system remain to be addressed before we can achieve a complete understanding of its function in the brain. The enormous interest that this area of study has attracted in the last decade will likely continually contribute to advancing our understanding of the role of OXT in parental behaviour and other behavioural and physiological functions.

The role of oxytocin receptor gene (OXTR) DNA methylation (DNAm) in human social and emotional functioning: a systematic narrative review

BACKGROUND

The neuropeptide Oxytocin (OXT) plays a central role in birthing, mother-infant bonding and a broad range of related social behaviours in mammals. More recently, interest has extended to epigenetic programming of genes involved in oxytocinergic neurotransmission. This review brings together early findings in a rapidly developing field of research, examining relationships between DNA methylation (DNAm) of the Oxytocin Receptor Gene (OXTR) and social and emotional behaviour in human populations.

METHOD

A systematic search across Web of Knowledge/Science, Scopus, Medline and EMBASE captured all published studies prior to June 2017 examining the association between OXTR DNAm and human social and emotional outcomes. Search terms included 'oxytocin gene' or 'oxytocin receptor gene' and 'epigenetics' or 'DNA methylation'. Any article with a focus on social and emotional functioning was then identified from this set by manual review.

RESULTS

Nineteen studies met eligibility criteria. There was considerable heterogeneity of study populations, tissue samples, instrumentation, measurement, and OXTR site foci. Only three studies examined functional consequences of OXTR DNAm on gene expression and protein synthesis. Increases in OXTR DNAm were associated with callous-unemotional traits in youth, social cognitive deficits in Autistic Spectrum Disorder (ASD), rigid thinking in anorexia nervosa, affect regulation problems, and problems with facial and emotional recognition. In contrast, reductions in DNAm were associated with perinatal stress, postnatal depression, social anxiety and autism in children.

CONCLUSIONS

Consistent with an emerging field of inquiry, there is not yet sufficient evidence to draw conclusions about the role of OXTR DNAm in human social and emotional behaviour. However, taken together, findings point to increased OXTR DNAm in general impairments in social, cognitive and emotional functioning, and decreased OXTR DNAm in specific patterns of impairment related to mood and anxiety disorders (but not in all). Future progress in this field would be enhanced by adequately powered designs, greater phenotypic precision, and methodological improvements including longitudinal studies with multiple time-points to facilitate causal inference.

Inability to suppress the stress-induced activation of the HPA axis during the peripartum period engenders deficits in postpartum behaviors in mice

The stress-induced activation of the hypothalamic-pituitary-adrenal (HPA) axis is normally suppressed during pregnancy. Dysregulation of the HPA axis has been proposed to play a role in postpartum depression. However, direct investigation into the relationship between the HPA axis and postpartum depression has been hindered by the lack of useful animal models. Building on our discovery of a role for the K+/Cl-co-transporter, KCC2, in the GABAergic regulation of CRH neurons in the paraventricular nucleus of the hypothalamus (PVN), critical for mounting the body's physiological response to stress, we assessed the role of KCC2 in the regulation of the HPA axis during pregnancy and the postpartum period. Here we demonstrate that the normal suppression of the stress-induced activation of the HPA axis during the peripartum period involves maintenance of KCC2 in the PVN. Mice lacking KCC2 specifically in corticosterone-releasing hormone (CRH) neurons, which govern the activity of the HPA axis (KCC2/Crh mice), exhibit dysregulation of the HPA axis and abnormal postpartum behaviors. Loss of KCC2 specifically in CRH neurons in the PVN is sufficient to reproduce the depression-like phenotype and deficits in maternal behaviors during the postpartum period. Similarly, chemogenetic activation of CRH neurons in the PVN is sufficient to induce abnormal postpartum behaviors and chemogenetic silencing of CRH neurons in the PVN can ameliorate abnormal postpartum behaviors observed in KCC2/Crh mice. This study demonstrates that dysregulation of the HPA axis is sufficient to induce abnormal postpartum behaviors and deficits in maternal behaviors in mice, providing empirical support for a role of HPA axis dysfunction in the pathophysiology of postpartum depression.

Adaptive Modifications of Maternal Hypothalamic-Pituitary-Adrenal Axis Activity during Lactation and Salsolinol as a New Player in this Phenomenon

Both basal and stress-induced secretory activities of the hypothalamic-pituitary-adrenal (HPA) axis are distinctly modified in lactating females. On the one hand, it aims to meet the physiological demands of the mother, and on the other hand, the appropriate and stable plasma cortisol level is one of the essential factors for the proper offspring development. Specific adaptations of HPA axis activity to lactation have been extensively studied in several animal species and humans, providing interesting data on the HPA axis plasticity mechanism. However, most of the data related to this phenomenon are derived from studies in rats. The purpose of this review is to highlight these adaptations, with a particular emphasis on stress reaction and differences that occur between species. Existing data on breastfeeding women are also included in several aspects. Finally, data from the experiments in sheep are presented, indicating a new regulatory factor of the HPA axis-salsolinol-which typical role was revealed in lactation. It is suggested that this dopamine derivative is involved in both maintaining basal and suppressing stress-induced HPA axis activities in lactating dams.

Oxytocin and Human Sensitive and Protective Parenting

In this chapter we review the evidence for the role of oxytocin in parenting, and discuss some crucial but outstanding questions. This is not meant to be a comprehensive review of all studies on oxytocin and parenting in general. Instead, special attention will be paid to a dimension of parenting that has been largely neglected in behavioral and neurobiological research on parental caregiving, namely protection. Parental protection has received considerable attention in animal research but, despite its evolutionary importance, not in studies on humans. It is argued that oxytocin may have specific significance for the protective dimension of parenting. The effects of exogenous oxytocin may be dependent not only on contextual factors, but also on personal characteristics, most notably gender, on endogenous levels of oxytocin, and on early childhood experiences. Examining the contextual, personal, hormonal, neural, genetic, and behavioral mechanisms of protective parenting in tandem is essential for the development of a comprehensive theory of protective parenting, and for the identification of "biomarkers" for insensitive and unprotective parenting that should be taken into account in preventive parenting interventions.

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.

Oxytocin inhibited stress induced visceral hypersensitivity, enteric glial cells activation, and release of proinflammatory cytokines in maternal separated rats

Visceral hypersensitivity (VH) is a significant contributor to irritable bowel syndrome (IBS). Oxytocin (OT) possesses analgesic effects on the central nervous system (CNS) and attenuates microglial activation, however, little is known about its peripheral effects and involvement in VH of IBS. Reactive enteric glial cells (EGCs) contributes to abnormal motility in gastrointestinal (GI) diseases. The aim of this study was to evaluate the peripheral use of OT to maintain VH and activation of EGCs through involvement of the Toll-like receptor (TLR) 4/MyD88/NF-κB signaling. After assessing a baseline visceromotor response (VMR) to colorectal distension (CRD), rats were exposed to a 1h water avoidance stress (WAS) session. Before each WAS session, intraperitoneal injection of OT (1mg/kg body weight, in phosphate-buffered saline (PBS)) atosiban (0.5mg/kg body weight, in PBS) or PBS (as a vehicle control, 1ml/kg body weight) was administered. Animas are killed 24h after the last WAS session. EGCs activity, relative OT receptor expression, glial fibrillary acidic protein (GFAP) expression and TLR4/MyD88/NF-κB signaling were evaluated. Neonatal maternal separation (MS) significantly increased the OT receptor expression and enhanced VMR to CRD. WAS improved VMR to CRD only during neonatal MS. OT treatment prevented WAS-induced higher VMRs to CRD, which was reversed by an OT receptor antagonist administration. Compared to the vehicle, OT pre-treated rats reduced EGCs activation, GFAP expression and TLR4/MyD88/NF-κB signaling. We conclude that neonatal MS induces VH and visceral pain in rats. Furthermore, exogenous OT attenuated stress-induced VH and EGCs activation, which was mediated by TLR4/MyD88/NF-κB signaling.

Breastfeeding Challenges and the Preterm Mother-Infant Dyad: A Conceptual Model

Breastfeeding is an experience that only a mother and her infant(s) can share. Infants who can feed from the breast receive not only the best nutrition but also, due to the close physical contact between mother and child, it is the optimal nurturance they can receive from their mother. When breastfeeding is trouble free, maternal well-being is uniquely heightened. However, breastfeeding remains a challenge for many mother-infant dyads and more so for those whose infants are born prematurely. This article introduces a conceptual model of the breastfeeding challenges facing preterm mother-infant dyads. It distinguishes between a maternal caregiving and an infant growth/development components. Within the maternal component, two primary elements are considered, that is, maternal behavioral and nutritional care. The two primary elements within the infant component include infant non-nutritional and nutritional growth/development. It is proposed that an improved understanding of the factors associated with these four elements and how they interplay with each other within individual dyads will facilitate the identification of the breastfeeding challenges facing these mother-infant entities. Due to the intimate relationships existing between a mother and her infant(s), it is further advanced that breastfeeding studies would be optimized if mother-infant pairs are studied as one entity rather than mother and infant separately. It is proposed that this conceptual model will assist health professionals develop personalized breastfeeding management plans for individual preterm mother-infant dyads, while furthering the development of evidence-based interventions to optimize their breastfeeding experiences.