Impact of Dysphoric Milk Ejection Reflex on Mental Health.

Objective: Postpartum mental health, significantly influences breastfeeding. Dysphoric milk ejection reflex (D-MER) is defined as negative emotional reaction to milk ejection, such as unpleasant feelings, anger-irritability or a strange feeling in the stomach. This study investigates the impacts of D-MER on mothers experiencing negative emotions during breastfeeding. Method: This cross-sectional, descriptive study was conducted between July 1 and September 30, 2023 among surveyed mothers with babies of ages 0-2 experiencing discomfort while breastfeeding. Mothers reached out through Instagram and Facebook and completed a semi-structured 45-question survey using a Google form. Results: Out of 141 mothers, 27.7% (n: 39) had D-MER findings. Common emotions included tension (48%), exhaustion (43%), intolerance (41%), hypersensitivity (35%), and restlessness (33%). Symptoms reported to begin within the first month of breastfeeding in 59% of D-MER cases. Nausea was reported in 30% of mothers. The most common conditions that increased the severity of D-MER symptoms were insomnia, stress and breast fullness. Sleeping or resting, being alone, doing something else, drinking cold water, listening to music and talking to mothers who had similar experiences helped the mothers relax. In cases with D-MER findings, about 17.9% considered stopping breastfeeding, with 7.7% stopping. The postpartum depression score was ≥13 in 59% of D-MER cases. Conclusion: D-MER, which can cause early cessation of breastfeeding, may also be associated with the mother's mental health problems. Raising awareness about D-MER and equipping health professionals on this subject are important in the continuity of breastfeeding.

Dysphoric Milk Ejection Reflex: Characteristics, Risk Factors, and Its Association with Depression Scores and Breastfeeding Self-Efficacy.

Background: Dysphoric milk ejection reflex (D-MER) is a phenomenon that occurs before milk letdown and is described as a wave of negative or devastating emotions, ranging from mild to severe and lasting for seconds to minutes. To date, there has been little research regarding this phenomenon. This study aims to determine the prevalence of D-MER in our population as well as its association with postnatal depression scores and breastfeeding self-efficacy. Methods: Lactating persons between 4 and 12 weeks postpartum at our institution were invited to complete an anonymous 59-question survey via an online platform. Questions asked included patient demographics, presence of symptoms of dysphoria (including timing, duration, and frequency), the Edinburgh Postnatal Depression Scale (EPDS), and the Breastfeeding Self-Efficacy Scale Short Form (BSES-sf). Results: In total, 201 women completed the survey. Twelve women were classified as likely having D-MER (6%). Symptom resolution primarily occurred within a minute to 5 minutes (58%). Mean EPDS scores differed significantly between those with likely D-MER and those without (12.2 vs. 5.4, p = 0.002). BSES-sf scores differed significantly between the two groups (43.1 vs. 52.5, p = 0.009). Preexisting depression or anxiety was not associated with D-MER (p = 0.133), other reported mood disorders differed significantly between those with D-MER and those without (p = 0.004). Demographic characteristics of women with and without D-MER were similar. Conclusion: D-MER prevalence may be lower than previously reported. Patients with likely D-MER appear to have lower breastfeeding self-efficacy and higher depression scores. Those with preexisting mood disorders may be at higher risk of experiencing D-MER.

Acute and chronic sleep restriction differentially modify maternal behavior and milk macronutrient composition in the postpartum rat.

BACKGROUNDS: Sleep restriction is considered a stressful condition itself, causing a wide variety of physiological alterations, from cognitive and hormonal to immunological status. In addition, it is established that stress in mother rats can modify milk ejection, milk composition, and maternal care of the pups. Also, sleep disturbances during the early stages of motherhood are a common feature of all studied species. In this context, while the impacts of sleep disruption in non-lactating animals were extensively investigated, its repercussions during the initial phases of motherhood have been poorly explored. Therefore, we wonder if maternal behavior, milk ejection and its macronutrient composition would be disrupted when mother rats are subjected to an additional acute or chronic sleep restriction to the already existing sleep disturbances. METHODS: Lactating rats were implanted with unilateral electrodes for polysomnographic recordings and for deep brain electrical stimulation into mesopontine waking-promoting area (for sleep deprivation). During the early postpartum period (postpartum day 5-9), mother rats were randomly assigned into one of three groups: chronic sleep restriction group (CSR; 6 h of sleep deprivation/day for five consecutive days), acute sleep restriction group (ASR; 6 h of sleep deprivation only for one day), or undisturbed group (control group). Active maternal behaviors (retrievals of the pups into the nest, mouthing, lickings [corporal and anogenital] and sniffing the pups) and passive maternal behaviors (kyphotic and supine nursing postures) were evaluated during a 30 min period without sleep restriction immediately after the sleep restriction or control period. The litter weight gain was assessed every day, and on the last experimental session mothers were milked for posterior macronutrients analysis (protein, carbohydrates and fat). RESULTS: When compared to control group, CSR decreased the amount of milk ejected in the middle days of the sleep restriction period, while ASR did not affect this parameter. Moreover, ASR reduced milk protein content compared to control and CSR groups. Finally, compared to the control group, CSR reduced active maternal behaviors towards the end of the treatment days. CONCLUSIONS: We demonstrated that not only acute but also chronic sleep restriction impacts on the postpartum period, each one affecting different aspects of maternal behavior and lactation. Our results suggest the existence of a homeostatic recovery mechanism in breastfeeding during CSR, possibly ensuring the survival of the litter, while the decline in active maternal behaviors appears to be cumulative.

Dysphoric milk ejection reflex among Japanese mothers: a self-administered survey.

BACKGROUND: The dysphoric milk ejection reflex (D-MER) is a reflex that causes temporary discomfort during milk ejection. D-MER develops due to the effects of hormones involved in lactation, and it has been reported that it is a physiological symptom different from postpartum depression, but the actual situation is unknown in Japan. METHODS: This study was conducted using a self-administered, anonymous survey of mothers of children who had undergone health checkups at three years of age at five health centers in Kagoshima city and aimed to clarify the reality and perceptions of mothers regarding D-MER. The survey period was from May to September, 2022. The questionnaires were distributed to 389 mothers, and 216 (55.5% recovery rate) responses were received, of which 202 (valid response rate 93.5%) were included in the analysis. RESULTS: Regarding the experience of D-MER, 202 mothers in the study population had given birth to a total of 403 children and experienced D-MER when breastfeeding 62 children (15.4%). Of the 202 mothers included in the analysis, 47 (23.3%) answered that they had experienced D-MER with at least one child while breastfeeding. Sixty-six mothers (32.7%) knew about D-MER. Compared to those who had not experienced D-MER, those who had experienced D-MER had significantly higher scores on the items related to having had trouble breastfeeding (odds ratio (OR]: 3.78; 95% confidence interval (CI]: 1.57, 9.09) and knowing about D-MER (OR 2.41; 95% CI 1.20, 4.84). Regarding symptoms, irritability (n = 24, 51.1%), anxiety (n = 22, 46.8%), and sadness (n = 18, 38.3%) ranked high. Coping strategies included distraction, focusing on the child, and, in some cases, cessation of breastfeeding. Thirty mothers (63.8%) answered that they did not consult anyone, citing reasons such as a belief that no one would be likely to understand their symptoms, and that they could not sufficiently explain their symptoms. CONCLUSION: The low level of awareness of D-MER suggests that it is necessary to inform and educate mothers and the public about the physiological symptoms of D-MER. Moreover, it is necessary to listen to the feelings of mothers with D-MER and support them in coping with their symptoms.

Dysphoric Milk Ejection Reflex in Human Lactation: An Integrative Literature Review.

BACKGROUND: Dysphoric Milk Ejection Reflex is an understudied condition of lactation involving emotional dysregulation during letdown or milk ejection. Affected individuals may experience transient feelings of helplessness, melancholy, and general unhappiness. RESEARCH AIM: To evaluate the scope of published literature on Dysphoric Milk Ejection Reflex. METHOD: Whittemore and Knafl's methodology guided this integrative review. Five databases were searched for primary research, summaries, and editorials on Dysphoric Milk Ejection Reflex in lactating individuals. Literature searched also included websites, pamphlets, and conference proceedings via Google and Google Scholar. A total of 11 articles, from five different countries, met inclusion criteria for review. RESULTS: Studies on Dysphoric Milk Ejection Reflex and negative emotional sensations during lactation were synthesized under five conceptual umbrellas: (1) Experiences, Sensations, and Symptom Management; (2) Biological Underpinnings; (3) Influence on Maternal Role and Breastfeeding Self-Efficacy; (4) Support, Understanding, and Awareness; and (5) Reduction and Cessation of Breastfeeding. CONCLUSION: Dysphoric Milk Ejection Reflex is a neurobiological condition characterized by low mood and negative feelings during milk ejection throughout lactation. Dysphoric Milk Ejection Reflex is linked to maternal psychological distress and breastfeeding discontinuation. Priority areas for future research include biological origins and interventions aimed at prevention, symptom control, and greater awareness of the condition on a more international scope.

Case report: Psychotherapy for enhancing psychological adjustment to dysphoric milk ejection reflex.

Given its endless benefits, breastfeeding is widely acknowledged as the optimal choice for both maternal and infant health. Nevertheless, breastfeeding mothers often encounter various challenges that may hinder their ability to fully embrace this experience. This report delves into a compelling case of Dysphoric Milk Ejection Reflex (D-MER), a largely underexamined mental health issue among lactating mothers. D-MER is characterized by intense aversion right before milk let down, which can significantly impede a mother's willingness to breastfeed. The primary aim of this case report is to provide a comprehensive psychological understanding of D-MER, emphasizing aspects of attachment, the transition into motherhood, and the sociocultural sexualization of the female body. We also offer an overview of the psychotherapeutic journey, highlighting key insights and progress achieved over a span of six months. Therapy adopted an integrative approach combining narrative techniques and skills training such as mindfulness to facilitate a comprehensive therapeutic experience. This case underscores the psychological dimensions of the breastfeeding experience, complementing the well-established biochemical and physiological aspects of D-MER. It also emphasizes the need for further research into the psychological facets of both successful and less successful breastfeeding experiences.

Dysphoric Milk Ejection Reflex: Report of Two Cases and Postulated Mechanisms and Treatment.

Background: The symptoms of Dysphoric Milk Ejection Reflex (D-MER) occur just before milk release, last no more than a few minutes, and then subside spontaneously, which are characterized by a sudden and transient feeling of dysphoria, depression, sadness, or other negative emotions. These emotions may adversely affect the mother's lactation behavior and mental health, negatively influence the mother-child relationship, and even result in self-harm or suicidal tendencies in lactating women. Case Presentation: We reported two cases of breastfeeding mothers with D-MER who experienced unpleasant emotions during lactation. Severely affected by D-MER symptoms, the mother in the first case chose to wean prematurely after struggling for 6 months, and her symptoms disappeared after weaning. With the help of professional guidance, the mother with D-MER in the second case actively adjusted and persisted in breastfeeding until her daughter was 18 months old, after that her symptoms vanished. Discussion: Awareness and knowledge of D-MER are insufficient among the public and health care professionals. D-MER is not a psychological disorder but a physiological issue caused by hormones, which is different from postpartum depression. The severity of D-MER symptoms can be evaluated by the assessment tool of the D-MER spectrum. Lactating women can relieve their symptoms through self-regulation, lifestyle changes, and professional guidance and treatments. Conclusions: The two cases studies about Chinese women with D-MER will enrich the knowledge of D-MER, and it might suggest some directions to health care workers for exploring scientific guidance and treatments for lactating women. Because the literature and published empirical studies about D-MER are scarce, further researches on the theory and interventions of D-MER are necessary.

The Role of Oxytocin in Domestic Animal's Maternal Care: Parturition, Bonding, and Lactation.

Oxytocin (OXT) is one of the essential hormones in the birth process; however, estradiol, prolactin, cortisol, relaxin, connexin, and prostaglandin are also present. In addition to parturition, the functions in which OXT is also involved in mammals include the induction of maternal behavior, including imprinting and maternal care, social cognition, and affiliative behavior, which can affect allo-parental care. The present article aimed to analyze the role of OXT and the neurophysiologic regulation of this hormone during parturition, how it can promote or impair maternal behavior and bonding, and its importance in lactation in domestic animals.

Maternal physiological calming responses to infant suckling at the breast.

The mother-infant relation is key to infant physical, cognitive and social development. Mutual regulation and cooperation are required to maintain the dyadic system, but the biological foundation of these responses remains to be clarified. In this study, we report the maternal calming responses to infant suckling during breastfeeding. Using behavioral measures and a Holter electrocardiogram as a readout of the maternal autonomic nervous system, the maternal activities during resting, sitting with her infant on her lap, and breastfeeding were assessed. We found that during breastfeeding, mothers talked less and maternal heart rate was lower than during sitting with the infant without breastfeeding. Congruently, maternal heart rate variability measurements indicated a higher parasympathetic activity during breastfeeding. Time-locked analyses suggested that this maternal calming response was initiated by the tactile stimulation at the breast by the infant face or mouth latch, which preceded the perceived milk ejection. These findings suggest that somatosensory stimuli of breastfeeding activate parasympathetic activity in mothers. Just as how the infant Transport Response facilitates the carrying of infants, the maternal calming responses during breastfeeding may promote efficient milk intake by inhibiting spontaneous maternal activities.

Dysphoric milk ejection reflex (D-MER) and its implications for mental health nursing.

Dysphoric milk ejection reflect (D-MER) is a dysphoria which women may experience within seconds of commencing breastfeeding. It is only recently gaining recognition in the academic literature and may have important implications for breastfeeding continuation, differential diagnosis and perinatal mental health. This perspective piece introduces the topic, sets out the physiological processes underpinning the experience and outlines why increased awareness of D-MER is important for the profession of mental health nursing.

Comparison of 2 types of milk flow meters for detecting bimodality in dairy cows.

The primary objective of this observational study was to investigate whether incremental milk flow rates (in the 0-15 s, 15-30 s, 30-60 s, and 60-120 s intervals) from electronic on-farm milk flow meters can be used to detect bimodal milk flow curves in dairy cows compared with the use of a portable milk flow meter. Our second objective was to study the concordance between an electronic on-farm milk flow meter and a portable milk flow meter for assessing the 2-min milk yield and total milk yield. In this cross-sectional study, data from 92 milking observations from individual cows were analyzed. We collected data on incremental milk flow rates, the 2-min milk yield, and the total milk yield simultaneously with an on-farm milk flow meter and a portable milk flow meter. Bimodality detected by the on-farm milk flow meter was defined as lower milk flow rates during any of the 15-30 s, 30-60 s, and 60-120 s intervals compared with the previous intervals (0-15 s, 15-30 s, and 30-60 s). Bimodality according to the portable milk flow meter (BIMLC) was observed through automatic detection. κ statistics indicated good agreement between bimodality detected by the on-farm milk flow meter and BIMLC [κ (95% confidence interval): 0.69 (0.49-0.90)]. Using BIMLC as the gold standard, diagnostic test statistics for bimodality detected by the on-farm milk flow meter indicated moderate performance for sensitivity [0.73 (0.54-0.86)] as well as high performance for positive predictive value [0.83 (0.63-0.93)], specificity [0.94 (0.85-0.98)], and negative predictive value [0.90 (0.81-0.95)]. Receiver operating characteristic curve analyses revealed that the 30-60 s milk flow rate was the variable that best predicted BIMLC, yielding an area under the curve of 0.89. Pearson correlation coefficients (r) revealed a very strong correlation between the 2 devices for both the 2-min milk yield [0.97 (0.96-0.98)] and total milk yield [r (95% confidence interval), 0.97 (0.96-0.98)]. Additionally, intraclass correlation coefficients (ICC) and concordance correlation coefficients (CCC) indicated excellent agreement between the 2 devices for the 2-min milk yield [ICC, 0.97 (0.96-0.98); CCC, 0.94 (0.92-0.96)] and total milk yield [ICC, 0.97 (0.96-0.98); CCC, 0.97 (0.95-0.98)]. Therefore, we concluded that electronic on-farm milk flow meters that measure incremental milk flow rates can be used to detect bimodality in dairy cows and that on-farm milk flow meters facilitate precise measurements of the 2-min milk yield and total milk yield.

Is sleep critical for lactation in rat?

Sleep deprivation is a feature shared by most studied mammals at some point during the postpartum period. Unlike the rabbit, the pig, or the human mother, sleep has been claimed as an essential state for milk ejection in mother rats, where sleep deprivation using gentle handling (GH) prevents milk ejection and pup weight gain. Though sleep deprivation is a stressful situation itself, most common methodologies used in laboratory animals, including GH, usually involve aversive stimulus to prevent sleep, adding further stress to the animal. Deep brain electrical stimulation (DBES) of the brainstem reticular formation is a less common technique used to prevent sleep, and while this methodology may also carry unwanted effects, it avoids stressful conditions. In the present study, we examined the relationship between sleep and nursing, and how different sleep deprivation methodologies impact nursing and lactation. For this purpose, we carried out two sets of experiments. First, we correlated sleep and waking states with different nursing parameters of lactating rats under undisturbed conditions. Second, we slept deprived another group of mother rats using two different techniques: GH and DBES. Our main findings show that sleeping time was positively correlated with the time devote to nurse the pups, but not either with milk ejection or pup weight gain. When mother rats were sleep deprived, maternal behavior was fragmented using both methods, but was substantially more disrupted when using GH. Additionally, lactating dams were capable of ejecting milk and their pups gained weight despite of being sleep deprived using both techniques, but these parameters were significantly reduced using GH compared to control values, while DBES did not differ from control group. Overall, these results suggest that sleep and nursing are behaviorally compatible, but in disagreement with previous findings, we concluded that sleep is not necessary for milk ejection. These observations have critical implications for using the rat as a model to explore sleep loss during the postpartum period.

The Integration of the Maternal Care with Sleep During the Postpartum Period.

Our entire life occurs in a constant alternation between wakefulness and sleep. The impossibility of living without sleep implies that any behavior must adapt to the need for sleep, and maternal behavior does not escape from this determination. Additionally, maternal behavior in mammals is a highly motivated behavior, essential for the survival of the offspring. Thus, the mother has to adapt her physiology of sleep to the constant demands of the pups, where each species will have different strategies to merge these two physiological needs. However, all studied female mammals will experience sleep disturbances at some point of the postpartum period.

Recording and manipulation of the maternal oxytocin neural activities in mice.

Pulsatile release of the hormone oxytocin (OT) mediates uterine contraction during parturition and milk ejection during lactation.1-3 These pulses are generated by the unique activity patterns of the central neuroendocrine OT neurons located in the paraventricular and supraoptic hypothalamus. Classical studies have characterized putative OT neurons by in vivo extracellular recording techniques in rats and rabbits.1,4-10 Due to technical limitations, however, the identity of OT neurons in these previous studies was speculative based on their electrophysiological characteristics and axonal projection to the posterior pituitary, not on OT gene expression. To pinpoint OT neural activities among other hypothalamic neurons that project to the pituitary11,12 and make better use of cell-type-specific neuroscience toolkits,13 a mouse model needs to be developed for the studies of parturition and lactation. We herein introduce viral genetic approaches in mice to characterize the maternal activities of OT neurons by fiber photometry. A sharp photometric peak of OT neurons appeared at approximately 520 s following simultaneous suckling stimuli from three pups. The amplitude of the peaks increased as the mother mice experienced lactation, irrespective of the age of the pups, suggesting the intrinsic plasticity of maternal OT neurons. Based on a mono-synaptic input map to OT neurons, we pharmacogenetically activated the inhibitory neurons in the bed nucleus of the stria terminalis and found the suppression of the activities of OT neurons. Collectively, our study illuminates temporal dynamics in the maternal neural activities of OT neurons and identifies one of its modulatory inputs.

Suitability of milk lactate dehydrogenase and serum albumin for pathogen-specific mastitis detection in automatic milking systems.

In response to intramammary infection (IMI), blood-derived leukocytes are transferred into milk, which can be measured as an increase of somatic cell count (SCC). Additionally, pathogen-dependent IgG increases in milk following infection. The IgG transfer into milk is associated with the opening of the blood-milk barrier, which is much more pronounced during gram-negative than gram-positive IMI. Thus, milk IgG concentration may help to predict the pathogen type causing IMI. Likewise, lactate dehydrogenase (LDH) and serum albumin (SA) cross the blood-milk barrier with IgG if its integrity is reduced. Because exact IgG analysis is complicated and difficult to automate, LDH activity and SA concentration aid as markers to predict the IgG transfer into milk in automatic milking systems (AMS). This study was conducted to test the hypothesis that LDH and SA in milk correlate with the IgG transfer, and in combination with SCC these factors allow the differentiation between gram-positive and gram-negative IMI or even more precisely the infection-causing pathogen. Further, the expression of these parameters in foremilk before (BME) and after (AME) milk ejection was tested. In the AMS, quarter milk samples (n = 686) from 48 Holstein-Friesian cows were collected manually BME and AME, followed by an aseptic sample for bacteriological culture. Mixed models were used to (1) predict the concentration of IgG transmitted from blood into milk based on LDH and SA; (2) use principal component analysis to evaluate joint patterns of SCC (cells/mL), IgG (mg/mL), LDH (U/L), and SA (mg/mL) and use the principal component scores to compare gram-positive, gram-negative, and control IMI types and BME versus AME samples; and (3) predict gram-positive and gram-negative IMI by inclusion of combined SCC-LDH and SCC-SA as predictors in the model. Overall, the SA and LDH had similar ability to predict IgG transmission from blood into milk. Comparing the areas under the curve (AUC) of the receiver operator characteristic curves, the SCC-LDH versus SCC-SA had lower gram-positive (AUC = 0.984 vs. 0.986) but similar gram-negative (AUC = 0.995 vs. 0.998) IMI prediction ability. The SCC, IgG, LDH, and SA were greater in gram-negative than in gram-positive IMI (BME and AME) in early lactation. All measured factors had higher values in milk samples taken BME than AME. In conclusion, LDH and SA could be used as replacement markers to indicate the presence of IgG transfer from blood into milk; in combination with SCC, both SA and LDH are suitable for differentiating IMI type, and BME is better for mastitis detection in AMS.

[How oxytocin became overtime the attachment-mediating hormone]. / Comment, au fil du temps, l'ocytocine est devenue l'hormone de l'attachement.

Oxytocin is a pleiotropic molecule which, in addition to its facilitating action during parturition and milk ejection, is involved in social and prosocial behaviors such as attachment. This article presents, after a brief historical review, the action of oxytocin during the milk ejection reflex. Oxytocin is indeed essential for this vital function in mammals. It is both a neurohormone released into the bloodstream by the axon terminals of the posterior pituitary and a neuromodulator released in the hypothalamus by the soma and dendrites of oxytocinergic magnocellular neurons. In addition, oxytocin is also released by the axon terminals of parvocellular neurons and axon collaterals of magnocellular neurons in the brain. Both maternal attachment in rats and ewes and attachment between sexual partners in the prairie vole, one of the few monogamous rodent species, are mediated by central oxytocin. However, neither administering oxytocin into the brain nor increasing expression of the oxytocin receptor in the nucleus accumbens using a gene transfer technique converts polygamous voles to monogamous ones. Unfortunately, translation of animal data to human remains problematic due to still unsolved difficulties in modifying the level of oxytocin in the brain.

Title: Comment, au fil du temps, l'ocytocine est devenue l'hormone de l'attachement. Abstract: L'ocytocine est une molécule pléiotrope qui, en plus de son action facilitatrice au cours de l'accouchement et de l'allaitement, est impliquée dans des comportements sociaux et prosociaux comme l'attachement. Cet article présente, après un bref rappel historique, l'action de l'ocytocine pendant le réflexe d'éjection de lait. L'ocytocine est en effet indispensable à cette fonction vitale chez les mammifères. Elle est à la fois une neurohormone, libérée dans la circulation sanguine par les terminaisons axonales de la post-hypophyse, et un neuromodulateur, libéré dans l'hypothalamus par le soma et les dendrites des neurones magnocellulaires ocytocinergiques. D'autre part, l'ocytocine est également libérée dans le cerveau par les terminaisons axonales des neurones parvocellulaires et des collatérales d'axones des neurones magnocellulaires. La libération centrale de l'ocytocine est à l'origine de ses effets dans l'attachement, qu'il s'agisse de l'attachement maternel comme chez la ratte et la brebis ou de l'attachement entre les partenaires sexuels chez le campagnol des prairies, une des rares espèces de rongeurs monogames. Toutefois, ni l'injection d'ocytocine dans le cerveau, ni l'augmentation de l'expression du récepteur de l'ocytocine dans le noyau accumbens grâce à une technique de transfert de gène, ne rendent monogames des campagnols polygames. La transposition à l'espèce humaine des données obtenues chez l'animal reste problématique en raison principalement de la difficulté à modifier le taux d'ocytocine dans le cerveau.

Dysphoric Milk Ejection Reflex: The Psychoneurobiology of the Breastfeeding Experience.

Breastfeeding, given its biochemical and physiological basis, is known for its many benefits for both the lactating mother and the infant. Among the many challenges new breastfeeding mothers experience is the feeling of aversion in response to their newborn's suckling which has been termed dysphoric milk-ejection reflex (D-MER). Characterized by intense feelings of dysphoria which may eventually interfere with the mother's ability to breastfeed regularly, evidence suggests both the neurobiological and psychological basis of D-MER in an attempt to explain its complexity. Biologically, breastfeeding is expressed by the intracerebral release of oxytocin, an increased expression of oxytocin receptors in specific brain regions, increased mesocorticolimbic reward region activation, the secretion of prolactin and possibly the inhibition of dopamine. Hence, different theories explain D-MER in terms of disrupted neurotransmitter and hormonal activity. Breastfeeding has also proven to influence mood and stress reactivity in nursing mothers with a potential link with postpartum depression. Psychological theories attempt to explain D-MER from a sociopsychosexual lense shedding light on the significance of mother-infant attachment, the sexualization of the female body and the motherhood experience as a developmental stage in a woman's lifespan. The aim of this review is to provide a literature update of D-MER incorporating both neurobiological and psychological theories calling for raising awareness about the complexity of breastfeeding and for the need for mother-centered interventions for the management of D-MER and other postpartum-specific conditions.

Visualising oxytocin neurone activity in vivo: The key to unlocking central regulation of parturition and lactation.

During parturition and lactation, oxytocin neurones in the supraoptic and paraventricular nuclei fire high-frequency bursts of action potentials that are coordinated across the entire population. Each burst generates a large pulse of oxytocin release into the circulation to induce uterine contraction for parturition and mammary duct contraction for milk ejection. Bursts are stimulated by cervical stretch during parturition and by suckling during lactation. However, the mechanisms by which these stimuli are translated into episodic bursts are poorly understood, as are the mechanisms that coordinate bursts across the oxytocin neurone population. An elegant series of experiments conducted in the 1980s and 1990s used serial paired recordings to show that oxytocin neurones do not act as a syncytium during bursts; rather, they start each burst within a few hundred milliseconds of each other but with no distinct "leaders" or "followers". In addition to afferent noradrenergic inputs that relay the systemic stimuli to oxytocin neurones, bursts depend on somato-dendritic oxytocin release within the hypothalamus. Hence, bursts are considered to be an emergent property of oxytocin neurones that is bootstrapped by appropriate afferent stimulation. Although much progress was made using traditional electrophysiological recordings in head-fixed anaesthetised animals, research has effectively stalled in the last few decades. However, the emergence of new technologies to monitor neuronal activity in freely-behaving animals has reinvigorated efforts to understand the biology underpinning burst firing in oxytocin neurones. Here, we report the use of fibre photometry to monitor the dynamics of milk ejection bursts in the oxytocin neurone population of freely-behaving mice. This approach will shed light on the neural mechanisms that control the oxytocin bursts underpinning parturition and lactation.

Impact of expression mode and timing of sample collection, relative to milk ejection, on human milk bacterial DNA profiles.

AIM: To investigate the impact of expression mode: electric breast pump or hand expression, and timing of sample collection: pre- and post-milk ejection on human milk (HM) bacterial DNA profiles. METHODS AND RESULTS: Three HM samples from the same breast were collected from 30 breastfeeding mothers: a pre-milk ejection pump-expressed sample (pre-pump), a post-milk ejection pump-expressed sample (post-pump) and a post-milk ejection hand-expressed sample (post-hand). Full-length 16S rRNA gene sequencing was used to assess milk bacterial DNA profiles. Bacterial profiles did not differ significantly based on mode of expression nor timing of sample collection. No significant differences were detected in the relative abundance of any OTUs based on expression condition (pre-pump/ post-pump and post-pump/post-hand) with univariate linear mixed-effects regression analyses (all P-values > 0·01; α = 0·01). Similarly, no difference in richness was observed between sample types (number of observed OTUs: post-pump/post-hand P = 0·13; pre-pump/post-pump P = 0. 45). CONCLUSION: Bacterial DNA profiles of HM did not differ according to either expression method or timing of sample collection. SIGNIFICANCE AND IMPACT OF THE STUDY: Hand or pump expression can be utilized to collect samples for microbiome studies. This has implications for the design of future HM microbiome studies.

Maternal lactation initiation behavior / 中华围产医学杂志

The initiation of lactation is the critical initial event contributing to breastfeeding. It is of great significance for maternal lactation and neonatal access to breast milk. However, various factors limit the successful initiation of lactation and increase the risk of poor neonatal prognosis. We provide an overview of the mechanism, significance, method, time, and factors that influence lactation initiation behavior, and summarize related guidelines aiming to gain more insight into the lactation initiation behavior to promote maternal lactation and improve neonatal prognosis.