Oxytocin and mutual communication in mother-infant bonding

The Role of Play in the Social Development of Grey Seal (Halichoerus grypus) Pups with Comparative Notes on the Harbour Seal (Phoca vitulina)

Juvenile grey seals are known to be highly social, interacting with contact behaviours interpreted as gentle play. However, minimal sociality of pups with their mothers and among weaned pups has been suggested. The present study aimed to observe the natural social interactions of pups to track the early ontogeny of their sociality. Pup behaviour at a salt marsh colony on the east coast of England was video-recorded. Pups interacted with their mothers around suckling bouts and after weaning as they gathered around pools. The records were transcribed to spreadsheets in 30 s time segments to estimate the frequency and co-occurrence of different behaviours. Mother-pup interaction comprised nosing contacts and sometimes contact play, involving one laying the head and fore-flipper over the other. Initial weaned pup encounters involved tentative nosing and defensive splashing, indicating contact shyness. However, socially orientated locomotor play, supine posturing, and exaggerated raising of fore- and hind-flippers led to reduced shyness and pups following one another towards the sea. Archive data on subadult interactions and on harbour seal behaviours were re-analysed. Gentle play-like contact between mother-pup, juvenile, and adult pairs is interpreted here as a universal mode of social bonding, underscoring the social structure of both grey and harbour seals.

Social Brain Perspectives on the Social and Evolutionary Neuroscience of Human Language

Human language and social cognition are two key disciplines that have traditionally been studied as separate domains. Nonetheless, an emerging view suggests an alternative perspective. Drawing on the theoretical underpinnings of the social brain hypothesis (thesis of the evolution of brain size and intelligence), the social complexity hypothesis (thesis of the evolution of communication), and empirical research from comparative animal behavior, human social behavior, language acquisition in children, social cognitive neuroscience, and the cognitive neuroscience of language, it is argued that social cognition and language are two significantly interconnected capacities of the human species. Here, evidence in support of this view reviews (1) recent developmental studies on language learning in infants and young children, pointing to the important crucial benefits associated with social stimulation for youngsters, including the quality and quantity of incoming linguistic information, dyadic infant/child-to-parent non-verbal and verbal interactions, and other important social cues integral for facilitating language learning and social bonding; (2) studies of the adult human brain, suggesting a high degree of specialization for sociolinguistic information processing, memory retrieval, and comprehension, suggesting that the function of these neural areas may connect social cognition with language and social bonding; (3) developmental deficits in language and social cognition, including autism spectrum disorder (ASD), illustrating a unique developmental profile, further linking language, social cognition, and social bonding; and (4) neural biomarkers that may help to identify early developmental disorders of language and social cognition. In effect, the social brain and social complexity hypotheses may jointly help to describe how neurotypical children and adults acquire language, why autistic children and adults exhibit simultaneous deficits in language and social cognition, and why nonhuman primates and other organisms with significant computational capacities cannot learn language. But perhaps most critically, the following article argues that this and related research will allow scientists to generate a holistic profile and deeper understanding of the healthy adult social brain while developing more innovative and effective diagnoses, prognoses, and treatments for maladies and deficits also associated with the social brain.

Oxytocin Receptor-Expressing Neurons in the Medial Preoptic Area Are Essential for Lactation, whereas Those in the Lateral Septum Are Not Critical for Maternal Behavior

INTRODUCTION

In nurturing systems, the oxytocin (Oxt)-oxytocin receptor (Oxtr) system is important for parturition, and essential for lactation and parental behavior. Among the nerve nuclei that express Oxtr, the lateral septal nucleus (LS) and medial preoptic area (MPOA) are representative regions that control maternal behavior.

METHODS

We investigated the role of Oxtr- and Oxtr-expressing neurons, located in the LS and MPOA, in regulating maternal behavior by regulating Oxtr expression in a region-specific manner using recombinant mice and adeno-associated viruses. We quantified the prolactin (Prl) concentrations in the pituitary gland and plasma when Oxtr expression in the MPOA was reduced.

RESULTS

The endogenous Oxtr gene in the neurons of the LS did not seem to play an essential role in maternal behavior. Conversely, decreased Oxtr expression in the MPOA increased the frequency of pups being left outside the nest and reduced their survival rate. Deletion of Oxtr in MPOA neurons prevented elevation of Prl levels in plasma and pituitary at postpartum day 2.

DISCUSSION/CONCLUSION

Oxtr-expressing neurons in the MPOA are involved in the postpartum production of Prl. We confirmed the essential functions of Oxtr-expressing neurons and the Oxtr gene itself in the MPOA for the sustainability of maternal behavior, which involved Oxtr-dependent induction of Prl.

Revisiting Carl Jung's archetype theory a psychobiological approach

This paper delves into the concept of archetypes, universal patterns of behavior and cognition, and proposes a novel tripartite model distinguishing between structural, regulatory, and representational archetypes. Drawing on insights from code biology, neuroscience, genetics, and epigenetics, the model provides a nuanced framework for understanding archetypes and their role in shaping cognition and behavior. The paper also explores the interplay between these elements to express representational archetypes. Furthermore, it addresses the informational capacity of the genome and its influence on post-natal development and the psyche. The paper concludes by discussing the future trajectory of psychology, emphasizing the need for an integrative approach that combines our understanding of social constructs with insights into our inherent organizational propensities or archetypes. This exploration holds the potential to advance our understanding of the human condition.

Oxytocin and the microbiome

The mammalian host microbiome affects many targets throughout the body, at least in part through an integrated gut-brain-immune axis and neuropeptide hormone oxytocin. It was discovered in animal models that microbial symbionts, such as Lactobacillus reuteri, leverage perinatal niches to promote multigenerational good health and reproductive fitness. While roles for oxytocin were once limited to women, such as giving birth and nurturing offspring, oxytocin is now also proposed to have important roles linking microbial symbionts with overall host fitness and survival throughout the evolutionary journey.

Nurture outpaces nature: fostering with an attentive mother alters social dominance in a mouse model of stress sensitivity

Maternal care is critical for epigenetic programming during postnatal brain development. Stress is recognized as a critical factor that may affect maternal behavior, yet owing to high heterogeneity in stress response, its impact varies among individuals. We aimed here to understand the connection between inborn stress vulnerability, maternal care, and early epigenetic programming using mouse populations that exhibit opposite poles of the behavioral spectrum (social dominance [Dom] and submissiveness [Sub]) and differential response to stress. In contrast to stress-resilient Dom dams, stress-vulnerable Sub dams exhibit significantly lower maternal attachment, serum oxytocin, and colonic Lactobacillus reuteri populations. Sub offspring showed a reduced hippocampal expression of key methylation genes at postnatal day (PND) 7 and a lack of developmentally-dependent increase in 5-methylcytosine (5-mC) at PND 21. In addition, Sub pups exhibit significant hypermethylation of gene promoters connected with glutamatergic synapses and behavioral responses. We were able to reverse the submissive endophenotype through cross-fostering Sub pups with Dom dams (Sub/D). Thus, Sub/D pups exhibited elevated hippocampal expression of DNMT3A at PND 7 and increased 5-mC levels at PND 21. Furthermore, adult Sub/D offspring exhibited increased sociability, social dominance, and hippocampal glutamate and monoamine levels resembling the neurochemical profile of Dom mice. We postulate that maternal inborn stress vulnerability governs epigenetic patterning sculpted by maternal care and intestinal microbiome diversity during early developmental stages and shapes the array of gene expression patterns that may dictate neuronal architecture with a long-lasting impact on stress sensitivity and the social behavior of offspring.

Acute intranasal oxytocin dose enhances social preference for parents over peers in male but not female peri-adolescent California mice (Peromyscus californicus)

Peri-adolescence is a critical developmental stage marked by profound changes in the valence of social interactions with parents and peers. We hypothesized that the oxytocin (OXT) and vasopressin (AVP) systems, known for influencing social behavior, would be involved in the maintenance and breaking of bonding behavior expressed by very early peri-adolescent males and females. In rodents, OXT is associated with mother-pup bonding and may promote social attachment to members of the natal territory. AVP, on the other hand, can act in contrasting ways to OXT and has been associated with aggression and territoriality. Specifically, we predicted that in peri-adolescent male and female juveniles of the biparental and territorial California mouse (Peromyscus californicus), a) OXT would increase the social preferences for the parents over unfamiliar age-matched peers (one male and one female), and b) AVP would break the parent-offspring bond and either increase time in the neutral chamber and/or approach to their unfamiliar and novel peers. We examined anxiety and exploratory behavior using an elevated plus maze and a novel object task as a control. Peri-adolescent mice were administered an acute intranasal (IN) treatment of 0.5 IU/kg IN AVP, 0.5 IU/kg IN OXT, or saline control; five minutes later, the behavioral tests were conducted. As predicted, we found that IN OXT enhanced social preference for parents; however, this was only in male and not female peri-adolescent mice. IN AVP did not influence social preference in either sex. These effects appear specific to social behavior and not anxiety, as neither IN OXT nor AVP influenced behavior during the elevated plus maze or novel object tasks. To our knowledge, this is the first evidence indicating that OXT may play a role in promoting peri-adolescent social preferences for parents and delaying weaning in males.

Infant factors that impact the ecology of human milk secretion and composition-a report from "Breastmilk Ecology: Genesis of Infant Nutrition (BEGIN)" Working Group 3

Infants drive many lactation processes and contribute to the changing composition of human milk through multiple mechanisms. This review addresses the major topics of milk removal; chemosensory ecology for the parent-infant dyad; the infant's inputs into the composition of the human milk microbiome; and the impact of disruptions in gestation on the ecology of fetal and infant phenotypes, milk composition, and lactation. Milk removal, which is essential for adequate infant intake and continued milk synthesis through multiple hormonal and autocrine/paracrine mechanisms, should be effective, efficient, and comfortable for both the lactating parent and the infant. All 3 components should be included in the evaluation of milk removal. Breastmilk "bridges" flavor experiences in utero with postweaning foods, and the flavors become familiar and preferred. Infants can detect flavor changes in human milk resulting from parental lifestyle choices, including recreational drug use, and early experiences with the sensory properties of these recreational drugs impact subsequent behavioral responses. Interactions between the infant's own developing microbiome, that of the milk, and the multiple environmental factors that are drivers-both modifiable and nonmodifiable-in the microbial ecology of human milk are explored. Disruptions in gestation, especially preterm birth and fetal growth restriction or excess, impact the milk composition and lactation processes such as the timing of secretory activation, adequacy of milk volume and milk removal, and duration of lactation. Research gaps are identified in each of these areas. To assure a sustained and robust breastfeeding ecology, these myriad infant inputs must be systematically considered.

[As early as birth, oxytocin plays a key role in both food and social behavior]

Oxytocin (OT) is a neurohormone that regulates the so-called "social brain" and is mainly studied in adulthood. During postnatal development, the mechanisms by which the OT system structures various behaviors are little studied. Here we present the dynamic process of postnatal development of the OT system as well as the OT functions in the perinatal period that are essential for shaping social behaviors. Specifically, we discuss the role of OT, in the newborn, in integrating and adapting responses to early sensory stimuli and in stimulating suckling activity. Sensory dialogue and suckling are involved in mother-infant bonds and structure future social interactions. In rodents and humans, neurodevelopmental diseases with autism spectrum disorders (ASD), such as Prader-Willi and Schaaf-Yang syndromes, are associated with sensory, feeding and behavioral deficits in infancy. We propose that in early postnatal life, OT plays a key role in stimulating the maturation of neural networks controlling feeding behavior and early social interactions from birth. Administration of OT at birth improves sensory integration of environmental factors and the relationship with the mother as well as sucking activity as we have shown in mouse models and in babies with Prader-Willi syndrome. Long-term effects have also been observed on social and cognitive behavior. Therefore, early feeding difficulties might be an early predictive marker of ASD, and OT treatment a promising option to improve feeding behavior and, in the longer term, social behavioral problems.

Mother-Young Bonding: Neurobiological Aspects and Maternal Biochemical Signaling in Altricial Domesticated Mammals

Mother-young bonding is a type of early learning where the female and their newborn recognize each other through a series of neurobiological mechanisms and neurotransmitters that establish a behavioral preference for filial individuals. This process is essential to promote their welfare by providing maternal care, particularly in altricial species, animals that require extended parental care due to their limited neurodevelopment at birth. Olfactory, auditory, tactile, and visual stimuli trigger the neural integration of multimodal sensory and conditioned affective associations in mammals. This review aims to discuss the neurobiological aspects of bonding processes in altricial mammals, with a focus on the brain structures and neurotransmitters involved and how these influence the signaling during the first days of the life of newborns.

Effects of daily full-term infant skin-to-skin contact on behavior and cognition at age three - secondary outcomes of a randomized controlled trial

BACKGROUND

Daily skin-to-skin contact (SSC) during early infancy fosters the long-term development of children born preterm. This is the first randomized controlled trial assessing the potential beneficial effects of daily SSC on executive functioning and socio-emotional behavior of children born full-term. Whether children of mothers who experienced prenatal stress and anxiety benefitted more from SSC was also explored.

METHODS

Pregnant women (N = 116) were randomly assigned to a SSC or care-as-usual (CAU) condition. Women in the SSC condition were instructed to perform one hour of SSC daily from birth until postnatal week five. Prenatal stress was measured with questionnaires on general and pregnancy-specific stress and anxiety completed by the mothers in gestational week 37. At child age three, mothers filled in questionnaires on children's executive functioning, and externalizing and internalizing behavior. Analyses were performed in an intention-to-treat (ITT), per-protocol, and dose-response approach. Netherlands Trial Register: NL5591.

RESULTS

In the ITT approach, fewer internalizing (95% CI = 0.11-1.00, U = 2148.50, r = .24, p = .001) and externalizing (95% CI = 0.04-2.62, t = 2.04, d = 0.38, p = .04) problems were reported in the SSC condition compared to the CAU condition. Multivariate analyses of variance did not show group differences on executive functioning. Additional analyses of covariance showed no moderations by maternal prenatal stress.

CONCLUSIONS

Current findings indicate that early daily SSC in full-term infants may foster children's behavioral development. Future replications, including behavioral observations of child behavior to complement maternal reports, are warranted.

Neonatal oxytocin gives the tempo of social and feeding behaviors

The nonapeptide oxytocin (OT) is a master regulator of the social brain in early infancy, adolescence, and adult life. Here, we review the postnatal dynamic development of OT-system as well as early-life OT functions that are essential for shaping social behaviors. We specifically address the role of OT in neonates, focusing on its role in modulating/adapting sensory input and feeding behavior; both processes are involved in the establishing mother-infant bond, a crucial event for structuring all future social interactions. In patients and rodent models of Prader-Willi and Schaaf-Yang syndromes, two neurodevelopmental diseases characterized by autism-related features, sensory impairments, and feeding difficulties in early infancy are linked to an alteration of OT-system. Successful preclinical studies in mice and a phase I/II clinical trial in Prader-Willi babies constitute a proof of concept that OT-treatment in early life not only improves suckling deficit but has also a positive long-term effect on learning and social behavior. We propose that in early postnatal life, OT plays a pivotal role in stimulating and coordinating the maturation of neuronal networks controlling feeding behavior and the first social interactions. Consequently, OT therapy might be considered to improve feeding behavior and, all over the life, social cognition, and learning capabilities.

Mother-young bond in non-human mammals: Neonatal communication pathways and neurobiological basis

Mother-young bonding is a process by which the young establish social preferences for their mother. It fosters reproductive success and the survival of offspring by providing food, heat, and maternal care. This process promotes the establishment of the mother-young bond through the interaction of olfactory, auditory, tactile, visual, and thermal stimuli. The neural integration of multimodal sensory stimuli and attachment is coordinated into motor responses. The sensory and neurobiological mechanisms involved in filial recognition in precocial and altricial mammals are summarized and analyzed in this review.

Missing pieces in decoding the brain oxytocin puzzle: Functional insights from mouse brain wiring diagrams

The hypothalamic neuropeptide, oxytocin (Oxt), has been the focus of research for decades due to its effects on body physiology, neural circuits, and various behaviors. Oxt elicits a multitude of actions mainly through its receptor, the Oxt receptor (OxtR). Despite past research to understand the central projections of Oxt neurons and OxtR- coupled signaling pathways in different brain areas, it remains unclear how this nonapeptide exhibits such pleiotropic effects while integrating external and internal information. Most reviews in the field either focus on neuroanatomy of the Oxt-OxtR system, or on the functional effects of Oxt in specific brain areas. Here, we provide a review by integrating brain wide connectivity of Oxt neurons and their downstream circuits with OxtR expression in mice. We categorize Oxt connected brain regions into three functional modules that regulate the internal state, somatic visceral, and cognitive response. Each module contains three neural circuits that process distinct behavioral effects. Broad innervations on functional circuits (e.g., basal ganglia for motor behavior) enable Oxt signaling to exert coordinated modulation in functionally inter-connected circuits. Moreover, Oxt acts as a neuromodulator of neuromodulations to broadly control the overall state of the brain. Lastly, we discuss the mismatch between Oxt projections and OxtR expression across various regions of the mouse brain. In summary, this review brings forth functional circuit-based analysis of Oxt connectivity across the whole brain in light of Oxt release and OxtR expression and provides a perspective guide to future studies.

Dairy Buffalo Behavior: Calving, Imprinting and Allosuckling

Maternal behavior, in water buffalo and other ruminants, is a set of patterns of a determined species, including calving, imprinting, and suckling. This behavior is mainly triggered by hormone concentration changes and their interactions with their respective receptors in the brain, particularly oxytocin. These chemical signals also influence mother-young bonding, a critical process for neonatal survival that develops during the first postpartum hours. Currently, dairy buffalo behavior during parturition has rarely been studied. For this reason, this review aims to analyze the existing scientific evidence regarding maternal behavior in water buffalo during calving. It will address the mechanisms of imprinting, maternal care, and allosuckling strategies that may influence the survival and health of calves.

Triggers for mother love

Harry Harlow found that infant monkeys form strong and lasting attachments to inanimate surrogates, but only if the surrogate is soft; here I report that postpartum monkey mothers can also form strong and lasting attachments to soft inanimate objects. Thus, mother/infant and infant/mother bonds may both be triggered by soft touch.

Previous studies showed that baby monkeys separated from their mothers develop strong and lasting attachments to inanimate surrogate mothers, but only if the surrogate has a soft texture; soft texture is more important for the infant’s attachment than is the provision of milk. Here I report that postpartum female monkeys also form strong and persistent attachments to inanimate surrogate infants, that the template for triggering maternal attachment is also tactile, and that even a brief period of attachment formation can dominate visual and auditory cues indicating a more appropriate target.

Oxytocin: An Old Hormone, A Novel Psychotropic Drug And Possible Use In Treating Psychiatric Disorders

BACKGROUND

Oxytocin is a nonapeptide synthesized in the paraventricular and supraoptic nuclei of the hypothalamus. Historically, this molecule has been involved as a key factor in the formation of infant attachment, maternal behavior and pair bonding and, more generally, in linking social signals with cognition, behaviors and reward. In the last decades, the whole oxytocin system has gained a growing interest as it was proposed to be implicated in etiopathogenesis of several neurodevelopmental and neuropsychiatric disorders.

METHODS

With the main goal of an in-depth understanding of the oxytocin role in the regulation of different functions and complex behaviors as well as its intriguing implications in different neuropsychiatric disorders, we performed a critical review of the current state of art. We carried out this work through PubMed database up to June 2021 with the search terms: 1) "oxytocin and neuropsychiatric disorders"; 2) "oxytocin and neurodevelopmental disorders"; 3) "oxytocin and anorexia"; 4) "oxytocin and eating disorders"; 5) "oxytocin and obsessive-compulsive disorder"; 6) "oxytocin and schizophrenia"; 7) "oxytocin and depression"; 8) "oxytocin and bipolar disorder"; 9) "oxytocin and psychosis"; 10) "oxytocin and anxiety"; 11) "oxytocin and personality disorder"; 12) "oxytocin and PTSD".

RESULTS

Biological, genetic, and epigenetic studies highlighted quality and quantity modifications in the expression of oxytocin peptide or in oxytocin receptor isoforms. These alterations would seem to be correlated with a higher risk of presenting several neuropsychiatric disorders belonging to different psychopathological spectra. Collaterally, the exogenous oxytocin administration has shown to ameliorate many neuropsychiatric clinical conditions.

CONCLUSION

Finally, we briefly analyzed the potential pharmacological use of oxytocin in patient with severe symptomatic SARS-CoV-2 infection due to its anti-inflammatory, anti-oxidative and immunoregulatory properties.

Oxytocin promotes species-relevant outgroup attention in bonobos and chimpanzees

Previous research has found that oxytocin (OT) is associated with intergroup behaviour in humans as well as wild chimpanzees, and that exogenous OT affects Pan social attention. The two Pan species, bonobos and chimpanzees, differ drastically from one another in their intensity of intergroup competition, with lethal intergroup aggression often led by males in chimpanzees and more tolerant associations often centered around females in bonobos. However, it remains unclear how exogenous OT changes the two species' responses to ingroup and outgroup individuals. In this study, after intranasal administration of nebulized OT or placebo control, chimpanzees and bonobos viewed image pairs of ingroup and outgroup conspecifics while their eye movements were tracked with an eye-tracker. Although the overall effect of OT was small, we found that OT shifted bonobos' and chimpanzees' attention to outgroup images of the sex primarily involved in intergroup encounters in each species. Specifically, OT selectively shifted attention towards outgroup photos of female conspecifics in bonobos, and those of outgroup male conspecifics in chimpanzees. This suggests that OT generally promotes outgroup attention in both bonobos and chimpanzees but this effect is restricted to the sex most relevant in intergroup relations. These results suggest that, although OT may have a generally conserved role in hominid intergroup behaviour, it may act in species-relevant ways under the influence of their socio-ecological backgrounds.

Identification of genes associated with human-canine communication in canine evolution

The dog (Canis familiaris) was the first domesticated animal and hundreds of breeds exist today. During domestication, dogs experienced strong selection for temperament, behaviour, and cognitive ability. However, the genetic basis of these abilities is not well-understood. We focused on ancient dog breeds to investigate breed-related differences in social cognitive abilities. In a problem-solving task, ancient breeds showed a lower tendency to look back at humans than other European breeds. In a two-way object choice task, they showed no differences in correct response rate or ability to read human communicative gestures. We examined gene polymorphisms in oxytocin, oxytocin receptor, melanocortin 2 receptor, and a Williams-Beuren syndrome-related gene (WBSCR17), as candidate genes of dog domestication. The single-nucleotide polymorphisms on melanocortin 2 receptor were related to both tasks, while other polymorphisms were associated with the unsolvable task. This indicates that glucocorticoid functions are involved in the cognitive skills acquired during dog domestication.

Receptor for advanced glycation end-products and child neglect in mice: A possible link to postpartum depression

The receptor for advanced glycation end-products (RAGE), a pattern recognition molecule, has a role in the remodeling of vascular endothelial cells mainly in lungs, kidney and brain under pathological conditions. We recently discovered that RAGE binds oxytocin (OT) and transports it to the brain from circulation on neurovascular endothelial cells. We produced knockout mice of the mouse homologue of the human RAGE gene, Ager, designated RAGE KO mice. In RAGE KO mice, while hyperactivity has been reported in male mice, maternal behavior was impaired in female mice. After an additional stress, deficits in pup care were observed in RAGE KO mother mice. This resulted in pup death within 1–2 days, suggesting that RAGE plays a critical role during the postpartum period. Thus, RAGE seems to be important in the manifestation of normal maternal behavior in dams. In this review, we summarize the significance of brain OT transport by RAGE and propose that RAGE-dependent OT can dampen stress signals during pregnancy, delivery and early postpartum periods. To the best of our knowledge, there have been no previous articles on these RAGE-dependent results. Based on these results in mice, we discuss a potential critical role of RAGE in emotion swings at the puerperium (peripartum) and postpartum periods in women.

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RAGE play a role in oxytocin transport via the blood-brain barrier into the brain.

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RAGE KO dams had maternal behavior impairment after stress exposure that is in line with the two-hit theory. The first hit is RAGE signaling absence, the second hit is a stress event occurred in the postpartum period.

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We can hypothesize that RAGE signaling can affect maternal depression development through oxytocin transportation into the brain.

The early-life stress induced by oxytocin inhibition in p53 knockout mouse dams increases adulthood tumorigenesis in first and second generations

BACKGROUND

Early-life stress due to poor parental care has been suggested to increase cancer risk, though, so far, no experimental evidence established a link between defective parental behavior and spontaneous tumorigenesis in progeny. Essential maternal behavior is regulated, in particular, by the oxytocin (OT) hormonal circuit, which in turn responds to stimuli from the offspring and impinges on the central nervous systems.

METHODS

By providing L-368,899 OT receptor (OTR) inhibitor to lactating mothers, we set up a model of defective maternal care in p53 knockout mice.

RESULTS

The progeny of these dams showed, later in life, higher cortisol levels, shortened life span and increased tumorigenic potential of bone marrow cells (BMC). Notably, these phenotypes were transmitted to the following generation.

CONCLUSIONS

Therefore, the inhibition of OT function in mothers is a novel paradigm of early-life stress that is inherited across generations and increases cancer risk in tumor-prone mice.

Orf Virus Detection in the Saliva and Milk of Dairy Goats

Orf is a zoonotic and highly contagious disease caused by Orf virus (ORFV) infection. Orf outbreaks in sheep and goats usually lead to high culling rate and mortality in newborn kids and lambs, posing a great threat to the development of goat and sheep industry. Human Orf occurs via direct contact with infected animals or fomites. While this disease is traditionally thought to spread through direct contact, whether other transmission routes exist remains unclear. Herein, we report the detection of ORFV in the saliva and milk of dairy goats without clinical Orf symptoms. Further analyses showed that these ORFV are infectious, as they can induce characteristic cytopathic changes in primary mammary and lip cells. Importantly, these ORFV can induce typical Orf lesions after inoculation in ORFV-free dairy goats. This is the first study showing that live, infectious ORFV can be isolated from the saliva and milk of asymptomatic goats, highlighting novel potential transmission routes of ORFV. These findings provide a novel idea for the prevention and control of Orf spread.

From Mating to Milk Access: A Review of Reproductive Vocal Communication in Mice

Vocalisations play a central role in rodent communication, especially in reproduction related behaviours. In adult mice (Mus musculus) the emission of ultrasonic vocalisations (USVs) has been observed in courtship and mating behaviour, especially by males. These have been found to have distinctive individual signatures that influence female choice of mating partner. The most recent findings show that vocal communication also has a role in parental cooperation, in that female mice communicate with male partners in ultrasonic frequencies to induce paternal behaviour. Infant vocalisations form the other important part of reproductive vocal communication. Although born deaf, neonatal mice are capable of producing vocalisations since birth. As an altricial species, successful mother-infant communication is essential for survival, and these vocalisations are important modulators of maternal behaviour. Three main types of infant vocalisations have been identified and characterised. Most research has addressed pure USVs, related to stressful situations (e.g., cold, isolation, handling, presence of unfamiliar males or predators), which usually elicit maternal search and retrieval. In addition, broad-band spectrum signals, emitted post-partum during cleaning of foetal membranes, inhibit biting and injury by adults and “wriggling calls,” emitted during suckling, release maternal behaviour (such as licking). Several variables have been identified to modulate vocalisations in mice, including individual characteristics such as strain/genotype, age, sex, and experimental factors such as pharmacological compounds and social context. In recent years, there has been a big increase in the knowledge about the characteristics of vocal communication in rodents due to recent technological advances as well as a growing interest from the neuroscience community. Vocalisation analysis has become an essential tool for phenotyping and evaluating emotional states. In this review, we will (i) provide a comprehensive summary of the current knowledge on mouse reproductive vocal communication and (ii) discuss the most recent findings in order to provide a broad overview on this topic.

Early life adversity affecting the attachment bond alters ventral tegmental area transcriptomic patterning and behavior almost exclusively in female mice

Early life experiences that affect the attachment bond formation can alter developmental trajectories and result in pathological outcomes in a sex-related manner. However, the molecular basis of sex differences is quite unknown. The dopaminergic system originating from the ventral tegmental area has been proposed to be a key mediator of this process. Here we exploited a murine model of early adversity (Repeated Cross Fostering, RCF) to test how interfering with the attachment bond formation affects the VTA-related functions in a sex-specific manner. Through a comprehensive behavioral screening, within the NiH RDoC framework, and by next-generation RNA-Seq experiments, we analyzed the long-lasting effect of RCF on behavioral and transcriptional profiles related to the VTA, across two different inbred strains of mouse in both sexes. We found that RCF impacted to an extremely greater extent VTA-related behaviors in females than in males and this result mirrored the transcriptional alterations in the VTA that were almost exclusively observed in females. The sexual dimorphism was conserved across two different inbred strains in spite of their divergent long lasting consequences of RCF exposure. Our data suggest that to be female primes a sub-set of genes to respond to early environmental perturbations. This is, to the best of our knowledge, the first evidence of an almost exclusive effect of early life experiences on females, thus mirroring the extremely stronger impact of precocious aversive events reported in clinical studies in women.

Early-life oxytocin attenuates the social deficits induced by caesarean-section delivery in the mouse

The oxytocin (OXT) system has been strongly implicated in the regulation of social behaviour and anxiety, potentially contributing to the aetiology of a wide range of neuropathologies. Birth by Caesarean-section (C-section) results in alterations in microbiota diversity in early-life, alterations in brain development and has recently been associated with long-term social and anxiety-like behaviour deficits. In this study, we assessed whether OXT intervention in the early postnatal period could reverse C-section-mediated effects on behaviour, and physiology in early life and adulthood. Following C-section or per vaginum birth, pups were administered with OXT (0.2 or 2 μg/20 μl; s.c.) or saline daily from postnatal days 1-5. We demonstrate that early postnatal OXT treatment has long-lasting effects reversing many of the effects of C-section on mouse behaviour and physiology. In early-life, high-dose OXT administration attenuated C-section-mediated maternal attachment impairments. In adulthood, low-dose OXT restored social memory deficits, some aspects of anxiety-like behaviour, and improved gastrointestinal transit. Furthermore, as a consequence of OXT intervention in early life, OXT plasma levels were increased in adulthood, and dysregulation of the immune response in C-section animals was attenuated by both doses of OXT treatment. These findings indicate that there is an early developmental window sensitive to manipulations of the OXT system that can prevent lifelong behavioural and physiological impairments associated with mode of birth.

Biological Functions of Rat Ultrasonic Vocalizations, Arousal Mechanisms, and Call Initiation

This review summarizes all reported and suspected functions of ultrasonic vocalizations in infant and adult rats. The review leads to the conclusion that all types of ultrasonic vocalizations subserving all functions are vocal expressions of emotional arousal initiated by the activity of the reticular core of the brainstem. The emotional arousal is dichotomic in nature and is initiated by two opposite-in-function ascending reticular systems that are separate from the cognitive reticular activating system. The mesolimbic cholinergic system initiates the aversive state of anxiety with concomitant emission of 22 kHz calls, while the mesolimbic dopaminergic system initiates the appetitive state of hedonia with concomitant emission of 50 kHz vocalizations. These two mutually exclusive arousal systems prepare the animal for two different behavioral outcomes. The transition from broadband infant isolation calls to the well-structured adult types of vocalizations is explained, and the social importance of adult rat vocal communication is emphasized. The association of 22 kHz and 50 kHz vocalizations with aversive and appetitive states, respectively, was utilized in numerous quantitatively measured preclinical models of physiological, psychological, neurological, neuropsychiatric, and neurodevelopmental investigations. The present review should help in understanding and the interpretation of these models in biomedical research.

Changes in salivary oxytocin after stroking in dogs: Validation of two assays for its assessment

Oxytocin is currently of high interest as a biomarker of welfare and stress in humans and animals. The purpose of this study was to validate two new assays (one using a monoclonal antibody and the other using a polyclonal antibody) for the oxytocin measurement in the saliva of dogs. For this purpose, an analytical validation was performed, and these assays were applied in an experimental trial in which dogs were stroked by their owners. In the experimental trial, saliva samples of 17 dogs were collected by the owners at three different times: a basal sample, at the end of 10 min of an affiliative interaction with their owners consisting of stroking and 15 min after the end of the affiliative interaction. The dogs were separated into two groups (group 1, n = 8 and group 2, n = 9) according to the acceptance of the sponge and the response to the stroking. Significant differences in the response of salivary oxytocin after stroking in the two groups were found when the assay with the monoclonal antibody was used. This assay showed a significant increase just after the end of affiliative interaction (P < 0.01) and 15 min after (P < 0.01) in those dogs that had a good acceptance of the sponge and the stroking induced a positive response on them (based in a Likert-type scale from 1 to 10). These data reflect that the assays used in this study can lead to different results when quantifying oxytocin in the saliva of dogs after stroking.

Receptor for advanced glycation end-products (RAGE) plays a critical role in retrieval behavior of mother mice at early postpartum

Receptor for advanced glycation end-products (RAGE) is a pattern recognition molecule belonging to the immunoglobulin superfamily, and it plays a role in the remodeling of endothelial cells under pathological conditions. Recently, it was shown that RAGE is a binding protein for oxytocin (OT) and a transporter of OT to the brain on neurovascular endothelial cells via blood circulation. Deletion of the mouse RAGE gene, Ager (RAGE KO), induces hyperactivity in male mice. Impairment of pup care by mother RAGE KO mice after stress exposure results in the death of neonates 1-2 days after pup birth. Therefore, to understand the role of RAGE during the postpartum period, this study aims to examine parental behavior in female RAGE KO mice and ultrasonic vocalizations in pups. RAGE KO mothers without stress before delivery raised their pups and displayed hyperactivity at postpartum day (PPD) 3. KO dams showed impaired retrieval or interaction behavior after additional stress, such as body restraint stress or exposure to a novel environment, but such impaired behavior disappeared at PPD 7. Postnatal day 3 pups emitted ultrasonic vocalizations at >60 kHz as a part of the mother-pup relationship, but the number and category of calls by RAGE KO pups were significantly lower than wild-type pups. The results indicate that RAGE is important in the manifestation of normal parental behavior in dams and for receiving maternal care by mouse pups; moreover, brain OT recruited by RAGE plays a role in damping of signals of additional external stress and endogenous stress during the early postpartum period. Thus, RAGE-dependent OT may be critical for initiating and maintaining the normal mother-child relationship.

The Recorded Interaction Task: A Validation Study of a New Observational Tool to Assess Mother-Infant Bonding

INTRODUCTION

Mother-infant bonding describes the early emotional connectedness between a mother and her infant. The quality of the mother-infant bond early in life is related to the subsequent quality of the child's attachment, the quality of further mother-infant interactions, and various other social outcomes across the child's life span. The Recorded Interaction Task (RIT) was developed to assess mother-infant bonding using observational methods in a naturalistic but standardized setting, thus addressing shortcomings of previous self-report tools. The RIT focusses on the common interaction between mother and infant (aged 2 to 5 months old), during a diaper (nappy) change. The interaction is video recorded and later assessed. The RIT must be validated before it can be used to assess mother-infant bonding in future research or in clinical practice.

METHODS

Face and content validity of the RIT were assessed by a panel of 6 experts in bonding and assessment of maternal and infant behavior. The RIT and self-reported Postpartum Bonding Questionnaire (PBQ) were administered to 15 mother-infant dyads with the correlation between their scores used to assess convergent validity.

RESULTS

Acceptable face and content validity of the RIT was demonstrated. A weak correlation between the RIT and PBQ (r = -0.13) and their subscales (r = -0.22) were observed. A strong correlation between the RIT maternal behavior and infant behavior subscales was recorded (r = 0.69).

DISCUSSION

The RIT appears to be a viable tool for the observational assessment of mother-infant bonding. Reliability testing and piloting will be required before the RIT can be used in future research or clinical practice.

Dual Profile of Environmental Enrichment and Autistic-Like Behaviors in the Maternal Separated Model in Rats

BACKGROUND

Environmental Enrichment (EE) has been suggested as a possible therapeutic intervention for neurodevelopmental disorders such as autism. Although the benefits of this therapeutic method have been reported in some animal models and human studies, the unknown pathophysiology of autism as well as number of conflicting results, urge for further examination of the therapeutic potential of EE in autism. Therefore, the aim of this study was to examine the effects of environmental enrichment on autism-related behaviors which were induced in the maternal separation (MS) animal model.

MATERIAL AND METHODS

Maternally separated (post-natal day (PND) 1-14, 3h/day) and control male rats were at weaning (PND21) age equally divided into rats housed in enriched environment and normal environment. At adolescence (PND42-50), the four groups were behaviorally tested for direct social interaction, sociability, repetitive behaviors, anxiety behavior, and locomotion. Following completion of the behavioral tests, the blood and brain tissue samples were harvested in order to assess plasma level of brain derived neurotrophic factor (BDNF) and structural plasticity of brain using ELISA and stereological methods respectively.

RESULTS

We found that environmental enrichment reduced repetitive behaviors but failed to improve the impaired sociability and anxiety behaviors which were induced by maternal separation. Indeed, EE exacerbated anxiety and social behaviors deficits in association with increased plasma BDNF level, larger volume of the hippocampus and infra-limbic region and higher number of neurons in the infra-limbic area (p < 0.05). Conclusion: We conclude that environmental enrichment has a significant improvement effect on the repetitive behavior as one of the core autistic-like behaviors induced by maternal separation but has negative effect on the anxiety and social behaviors which might have been modulated by BDNF.

Searching where the treasure is: on the emergence of human companion animal partnership (HCAP)

In our view, the discipline, often referred to as human-animal interaction (HAI), lacks a well-defined conceptual framework. It is too narrow both with respect to the animal species investigated and the nature of human-animal interactions studied. So instead, we introduce the term human-companion animal partnership (HCAP) that is not only a better descriptor for most research efforts within HAI but also helps to direct research efforts on an ethological basis. In our approach, 'companion' is a function and not a feature of some species. This means that many species had and could have a potential to form mixed social groups with humans if they evolve some capacity of social competence. This view may initiate new comparative research involving a range of species to find out how complex social engagement could be maintained in such hetero-specific social groups based on evolutionary heritage, recent selection and individual experience (socialisation). Our approach emphasises the role of human caring behaviour and social competence in the emergence of a partnership with several species, and thus could also help in setting expectations for welfare and aid in designing artificial companions for specific purposes.

The Gaze Communications Between Dogs/Cats and Humans: Recent Research Review and Future Directions

Dogs (Canis familiaris) and cats (Felis silvestris catus) have been domesticated through different processes. Dogs were the first domesticated animals, cooperating with humans by hunting and guarding. In contrast, cats were domesticated as predators of rodents and lived near human habitations when humans began to settle and farm. Although the domestication of dogs followed a different path from that of cats, and they have ancestors of a different nature, both have been broadly integrated into-and profoundly impacted-human society. The coexistence between dogs/cats and humans is based on non-verbal communication. This review focuses on "gaze," which is an important signal for humans and describes the communicative function of dogs' and cats' eye-gaze behavior with humans. We discuss how the function of the gaze goes beyond communication to mutual emotional connection, namely "bond" formation. Finally, we present a research approach to multimodal interactions between dogs/cats and humans that participate in communication and bond formation.

Aggression: Perspectives from social and systems neuroscience

Exhibiting behavioral plasticity in order to mount appropriate responses to dynamic and novel social environments is crucial to the survival of all animals. Thus, how animals regulate flexibility in the timing, duration, and intensity of specific behaviors is of great interest to biologists. In this review, we discuss how animals rapidly respond to social challenges, with a particular focus on aggression. We utilize a conceptual framework to understand the neural mechanisms of aggression that is grounded in Wingfield and colleagues' Challenge Hypothesis, which has profoundly influenced how scientists think about aggression and the mechanisms that allow animals to exhibit flexible responses to social instability. Because aggressive behavior is rooted in social interactions, we propose that mechanisms modulating prosocial behavior may be intricately tied to mechanisms of aggression. Therefore, in order to better understand how aggressive behavior is mediated, we draw on perspectives from social neuroscience and discuss how social context, species-typical behavioral phenotype, and neural systems commonly studied in relation to prosocial behavior (i.e., neuropeptides) contribute to organizing rapid responses to social challenges. Because complex behaviors are not the result of one mechanism or a single neural system, we consider how multiple neural systems important for prosocial and aggressive behavior (i.e., neuropeptides and neurosteroids) interact in the brain to produce behavior in a rapid, context-appropriate manner. Applying a systems neuroscience perspective and seeking to understand how multiple systems functionally integrate to rapidly modulate behavior holds great promise for expanding our knowledge of the mechanisms underlying social behavioral plasticity.

Post-weaning infant-to-mother bonding in nutritionally independent female mice

Infant-parent attachment is highly selective and continues beyond essential care in primates, most prominently in humans, and the quality of this attachment crucially determines cognitive and emotional development of the infant. Altricial rodent species such as mice (Mus musculus) display mutual recognition and communal nursing in wild and laboratory environments, but parental bonding beyond the nursing period has not been reported. We presently demonstrated that socially and nutritionally independent mice still prefer to interact selectively with their mother dam. Furthermore, we observed gender differences in the mother-infant relationship, and showed disruption of this relationship in haploinsufficient Nbea+/- mice, a putative autism model with neuroendocrine dysregulation. To our knowledge, this is the first observation of murine infant-to-mother bonding beyond the nursing period.

The Role of the Oxytocin System in Anxiety Disorders

Oxytocin, a neuropeptide synthesized by the hypothalamus, plays a central role in human social behavior, social cognition, anxiety, mood, stress modulation, and fear learning and extinction. The relationships between oxytocin and psychiatric disorders including depression, anxiety, schizophrenia, and autism spectrum disorder have been extensively studied. In this chapter, we focus on the current knowledge about oxytocin and anxiety disorder. We discuss the anxiolytic effects of oxytocin in preclinical and clinical findings, possible related neurobehavioral mechanisms (social cognition, fear learning, and extinction), related neurotransmitter and neuroendocrine systems (hypothalamus-pituitary-adrenal axis, serotoninergic, and GABAergic systems), and studies regarding plasma levels of oxytocin, genetic and epigenetic findings, and effects of intranasal oxytocin in DSM-5 anxiety disorder (primarily social anxiety disorder and separation anxiety disorder) patients.

Early Life Maternal Separation and Maternal Behaviour Modulate Acoustic Characteristics of Rat Pup Ultrasonic Vocalizations

Early separation of preterm infants from their mothers has adverse, long-term neurodevelopmental consequences. We investigated the effects of daily maternal separation (MS) of rat pups from postnatal days 2-10 (PND2-10) on neurobehavioural responses to brief isolation at PND12 compared with pups receiving controlled handling without MS. Ultrasonic vocalizations (USV) were measured at PND12 during two, 3-minute isolations occurring immediately before and after a 3-minute maternal reunion. There were no significant differences in acoustic characteristics between MS and control animals in the first isolation. However, in the second isolation, MS pups produced a greater proportion of high (~60 kHz) vs low (~40 kHz) frequency calls. During this isolation, control pups made longer and louder low frequency calls compared to the first isolation, whereas MS pups did the opposite. Maternal behaviour of control and MS mothers modulated pup acoustic characteristics in opposite directions; higher maternal care was associated with more low frequency calls in control pups but more high frequency calls in MS pups. We hypothesize that MS results in USV emission patterns reflective of a greater stress response to isolation. This translational model can be used to identify mechanisms and interventions that may be exploited to overcome the negative, long-term effects of MS.

A review of maternal behaviour in dogs and potential areas for further research

Here we review information on maternal behaviour in dogs, defined as a combination of all the acts of the mother towards her offspring, which begins before parturition and continues until weaning. In dogs, maternal care is measured using the most commonly observed behaviours, such as the time spent in contact, licking/grooming and nursing of the puppies. Since newborn puppies have a very limited capacity for movement, maternal interaction is essential to their survival, nourishment and protection. It is also an important element of the bonding process between puppies and the bitch and is thought to play a role in the social development of the puppies. Nevertheless, some questions still need to be clarified, such as the best way to quantify factors that may interfere with maternal behaviour. In recent studies, maternal care, or maternal style, was measured using a scoring system and found to be influenced by factors such as litter size, breed and parity, or even human interaction. However, the impact of the emotional state of the bitch and the quality of maternal behaviour on puppy survival and development remain unclear. The long-lasting effects of mother-puppy interactions on puppy behaviour during their adult life are still poorly understood, despite their importance for breeders who wish to prevent future problem behaviours.

High oxytocin infants gain more mass with no additional maternal energetic costs in wild grey seals (Halichoerus grypus)

Maximising infant survival requires secure attachments and appropriate behaviours between parents and offspring. Oxytocin is vital for parent-offspring bonding and behaviour. It also modulates energetic balance and neural pathways regulating feeding. However, to date the connections between these two areas of the hormone's functionality are poorly defined. We demonstrate that grey seal (Halichoerus grypus) mothers with high oxytocin levels produce pups with high oxytocin levels throughout lactation, and show for the first time a link between endogenous infant oxytocin levels and rates of mass gain prior to weaning. High oxytocin infants gained mass at a greater rate without additional energetic cost to their mothers. Increased mass gain in infants was not due to increased nursing, and there was no link between maternal mass loss rates and plasma oxytocin concentrations. Increased mass gain rates within high oxytocin infants may be due to changes in individual behaviour and energy expenditure or oxytocin impacting on tissue formation. Infancy is a crucial time for growth and development, and our findings connect the oxytocin driven mechanisms for parent-infant bonding with the energetics underlying parental care. Our study demonstrates that oxytocin release may connect optimal parental or social environments with direct physiological advantages for individual development.

Endocrine Regulations in Human-Dog Coexistence through Domestication

Endocrine system regulation is important for the maintenance of homeostasis; it controls hormonal functions in complex physiology and behavior and adaptations to social environments. Evidence indicates that for more than 35 000 years, dogs (Canis familiaris) have been domesticated through living with humans. For example, they have acquired human-like social skills, such as eye gazing and pointing gestures. These unique behaviors are, at least partially, regulated by hormones and are thought to have been genetically altered throughout domestication. Glucocorticoids affect social tolerance, while oxytocin facilitates social coordination and familiarity between individuals. We review historical and recent literature to facilitate an understanding of the roles of glucocorticoid and oxytocin functions in the human-canine coexistence dynamic established during domestication.

On the origin of puppies: breeding and selling procedures relevant for canine behavioural development

The success of the dog as a companion animal has undeniably led to a shift in dog breeding practices. While effects of inbreeding or large-scale breeding have given rise to numerous studies about potentially related health issues, it remains unclear to what extent behavioural development of dogs is influenced. By investigating the environment of puppies while at the breeder, the authors aimed to make an inventory of current practices regarding management, socialisation and environmental learning and subsequently to identify potential differences between breeder types. The cross-sectional study, conducted during 2016, revealed considerable variability in environment among dog breeders. Small-scale breeders, and especially occasional breeders (less than 10 adult dogs on-site) provided most enrichment, both social and non-social, by, for instance, providing more outdoor access for pregnant dams and puppies or by providing access to visitors more freely. Environmental stimuli were less controlled in occasional breeders, raising the debate about quantity versus quality of stimuli at a young age. Large-scale breeders declared to screen potential owners less intensely and time to advise them was limited. To the authors' knowledge, this is the first study that compares a large number of environmental factors between the different dog breeding categories.

Pain, Parental Involvement, and Oxytocin in the Neonatal Intensive Care Unit

Preterm infants (PTI) typically experience many painful and stressful procedures or events during their first weeks of life in a neonatal intensive care unit, and these can profoundly impact subsequent brain development and function. Several protective interventions during this sensitive period stimulate the oxytocin system, reduce pain and stress, and improve brain development. This review provides an overview of the environmental risk factors experienced by PTI during hospitalization, with a focus on the effects of pain, and early maternal separation. We also describe the long-term adverse effects of the simultaneous experiences of pain and maternal separation, and the potential beneficial effects of maternal vocalizations, parental contact, and several related processes, which appear to be mediated by the oxytocin system.

Expanding Regulation Theory With Oxytocin: A Psychoneurobiological Model for Infant Development

BACKGROUND

Oxytocin (OT), an affiliation hormone released during supportive social interactions, provides an exemplar of how social environments are reflected in our neurobiology from the beginning of life. A growing body of OT research has uncovered previously unknown functions of OT, including modulation of parenting behaviors, neuroprotection, affiliation, and bonding. Regulation theory provides a strong framework for describing how the maternal care environment affects infant neurodevelopment through a symphony of molecules that form the neurobiological milieu of the developing infant brain.

OBJECTIVES

The purpose of this article was to expand on regulation theory by discussing how OT-based processes contribute to infant neurobiology and by proposing a new model for maternal-infant nursing practice and research.

APPROACH

We structure our discussion of the socially based, neurobiological processes of OT through its effects in the nested hierarchies of genetic, epigenetic, molecular, cellular, neural circuit, multiorgan, and behavioral levels. Our discussion is also presented chronologically, as OT works through a positive feedback loop during infant neurodevelopment, beginning prenatally and continuing after birth.

IMPLICATIONS

Nurses are in a unique position to use innovative discoveries made by the biologic sciences to generate new nursing theories that inform clinical practice and inspire the development of innovative interventions that maximize the infant's exposure to supportive maternal care.

Associations Between Nurse-Guided Variables and Plasma Oxytocin Trajectories in Premature Infants During Initial Hospitalization

BACKGROUND

Oxytocin (OT) is a social hormone that may help researchers understand how nurse-guided interventions during initial infant hospitalization, such as supporting human milk expression, promoting comforting touch, and reducing exposure to stressors, affect preterm brain development.

PURPOSE

To determine whether factors related to human milk, touch, or stressor exposure are related to plasma OT trajectories in premature infants.

METHODS

Plasma from 33 premature infants, born gestational ages 25 to (Equation is included in full-text article.)weeks, was collected at 14 days of life and then weekly until 34 weeks' corrected gestational age (CGA). Variables related to feeding volumes of human milk and formula; touch, as indexed by skin-to-skin contact (SSC) and swaddled holding; and clinical stressors were extracted from the electronic medical record. Linear mixed-models tested associations between nurse-guided variables and plasma OT trajectories.

RESULTS

In the final model, same-day SSC was positively related not only to plasma OT levels at 27 weeks' CGA (β= .938, P = .002) but also to a decline in plasma OT levels over time (β=-.177, P = .001). Volume of enteral feeds (mL/kg/d), its interaction with CGA, and number of stressful procedures were not statistically significant (β= .011, P = .077; β=-.002, P = .066; and β= .007, P = .062, respectively).

IMPLICATIONS FOR PRACTICE

Nurse-guided interventions are associated with infant plasma OT levels, suggesting nurses may impact the neurobiology of the developing premature infant.

IMPLICATIONS FOR RESEARCH

Replication with larger sample sizes and randomized controlled trial designs is needed to test effects of specific nursing interventions on infant OT.