Gastrointestinal hormones in mother and infant

The nine stages of skin-to-skin: practical guidelines and insights from four countries

Incorporating systematic evidence with clinical expertise is a key element in the quest to improve quality of care and patient outcomes. The evidence supporting skin‐to‐skin contact in the first hour after birth is robust and includes significantly improved outcomes for both mother and infant. This paper compares available iterative data about newborn behaviour in the first hour after birth to further describe the observable behaviour pattern and to provide clinical insight for further research. Although the evidence for positive outcomes through skin‐to‐skin contact are robust, there is a dearth of research specifically focused on clinical practice. The methodology considers the four available data sets that used Widström's 9 stages, which consists of studies from Japan, Sweden, Italy and the United States, examining the parameters of each stage across settings from around the world. This research provides an expanded understanding of the timing of the newborn's progression through Widström's 9 observable stages. We found that newborns in all four data sets began with a birth cry and continued through the remaining stages of relaxation, awakening, activity, rest, crawling, familiarization, suckling and sleeping during the first hours after birth and consolidated the data into a Sign of the Stages chart to assist in further research. The evidence supports making a safe space and time for this important newborn behaviour. Clinical practices should encourage and protect this sensitive period.

Early life experience shapes the functional organization of stress-responsive visceral circuits

Emotions are closely tied to changes in autonomic (i.e., visceral motor) function, and interoceptive sensory feedback from body to brain exerts powerful modulatory control over motivation, affect, and stress responsiveness. This manuscript reviews evidence that early life experience can shape the structure and function of central visceral circuits that underlie behavioral and physiological responses to emotive and stressful events. The review begins with a general discussion of descending autonomic and ascending visceral sensory pathways within the brain, and then summarizes what is known about the postnatal development of these central visceral circuits in rats. Evidence is then presented to support the view that early life experience, particularly maternal care, can modify the developmental assembly and structure of these circuits in a way that impacts later stress responsiveness and emotional behavior. The review concludes by presenting a working hypothesis that endogenous cholecystokinin signaling and subsequent recruitment of gastric vagal sensory inputs to the caudal brainstem may be an important mechanism by which maternal care influences visceral circuit development in rat pups. Early life experience may contribute to meaningful individual differences in emotionality and stress responsiveness by shaping the postnatal developmental trajectory of central visceral circuits.

A potential gastrointestinal link between enhanced postnatal maternal care and reduced anxiety-like behavior in adolescent rats

Early life experience impacts emotional development in the infant. In rat pups, repeated, brief (i.e., 15 min) maternal separation (MS15) during the first 1-2 postnatal weeks has been shown to increase active maternal care and to reduce later anxiety-like behavior in the offspring. We hypothesized that the anxiolytic effect of MS15 is partly due to increased intestinal release of cholecystokinin (CCK) in rat pups as a result of increased maternal contact. We predicted that rats with a history of MS15 would display less anxiety in the elevated plus maze (EPMZ) and novelty-suppressed feeding (NSF) tests, as compared with nonseparated (NS) controls, and that the anxiolytic effect of MS15 would be attenuated in rats in which daily MS15 was accompanied by systemic administration of a CCK-1 receptor antagonist (i.e., devazepide). Treatment groups included NS control litters, litters exposed to MS15 from postnatal days (P)1-10, inclusive, and litters exposed to MS15 with concurrent subcutaneous injection of devazepide or vehicle. Litters were undisturbed after P10 and were weaned on P21. Subsets of adolescent males from each litter were tested in the EPMZ on P40-41, while others were tested for NSF on P50-52. As predicted, rats with a developmental history of MS15 displayed reduced anxiety-like behavior in the EPMZ and NSF tests. The anxiolytic effect of MS15 was preserved in vehicle-treated rats, but was reversed in devazepide-treated rats. These results support the view that endogenous CCK-1 receptor signaling in infants is a potential pathway through which maternal-pup interactions regulate the development and functional organization of emotional circuits that control anxiety-like behavior in the offspring.

Maternal deprivation increases behavioural reactivity to stressful situations in adulthood: suppression by the CCK2 antagonist L365,260

RATIONALE

Maternal deprivation can result in long-term impairment of neuronal functions and in the development of long-lasting behavioural disorders.

OBJECTIVES

This study analysed the effects of a selective cholecystokinin-2 (CCK2) antagonist, 3R-(+)-N-(2,3-dihydro-1methyl-2-oxo-5-phenyl-1H-1,4-benzodiazepin-3yl)-N'-(3-methyl phenyl) urea (L365,260), in anxiety- and stress-related behaviours of adult rats that were deprived (D) from their mother and littermates for 3 h everyday during 14 days after birth.

METHODS

The behaviour was studied in actimeter, in open field and after food and water deprivation. Corticosterone plasma levels were quantified after food and water deprivation. The effects of L365,260 were studied in the behavioural changes observed in D rats.

RESULTS

No differences in circadian motor activity between non-deprived (ND) and D rats were observed. D rats showed a 50% decrease in their number of visits to the central (aversive) part of the open field compared to ND rats. This effect was suppressed by L365,260. After 20 h of food and water deprivation, an increase in plasma corticosterone was observed in D and ND rats. However, the raise of corticosterone secretion in D rats was dramatically increased (300%) compared to ND rats, indicating a hypersensitised state revealed by this stressful situation. Consumption of sucrose solution (1%) was higher for D rats than for ND rats after food and water deprivation. Sucrose consumption returned to control values following L365,260 treatment.

CONCLUSIONS

These results suggest that maternal deprivation led to an increase in anxiety and stress reactivity in adulthood. We propose that these long-lasting changes are partly dependent on CCKergic transmission involving the activation of CCK2 receptors.

[Neurobiological impact of separating mothers from newborns in rodents]

Numerous animal models of early stress are currently being developed because early stress results in long-term disruptions of neuronal functions and the development of long-term behavioral disorders. These models should allow to study the concept of vulnerability applied to psychiatric disorders. The fundamental importance of the bond between the mother and the offsprings, in all mammalian species, for the development of the new-born, point to the great interest of animal models of mother/pups separation. Long periods of deprivation tend to result in anxiety, depressive-like behaviors and drug addiction in adult rats. Neurobiological studies have shown that several neuronal systems, in particular neuropeptidergic systems in the limbic structures of the brain, are disrupted, possibly due to the effects of early stress on neurodevelopment. Models evaluating the impact of early environmental factors should help to improve the prevention and prediction of psychiatric disorders and to develop new therapeutic strategies.

Gastrin, somatostatin and infantile hypertrophic pyloric stenosis

Despite multiple and often contradictory research, no firm conclusions regarding the role of hypergastrinaemia in infantile hypertrophic pyloric stenosis (IHPS) have been established. Evaluation of somatostatin, the main physiological antagonist of gastrin, has not been assessed in previous studies. Long-term evaluation following pyloromyotomy suggests persistent abnormalities in gastrin and somatostatin in IHPS. The objective of this case-controlled study was to compare fasting serum gastrin and somatostatin levels in IHPS. Serum sample were collected from 39 children with IHPS at the time of pyloromyotomy and 20 age-matched controls with no evidence of gastrointestinal disease. Standard radioimmunoassay techniques were used to detect circulating levels of the hormones. A two-tailed t-test was used for statistical analysis. The levels of the two hormones (mean +/- SEM) revealed that there was no evidence of hypergastrinaemia in IHPS compared with controls (75.6 +/- 16.1 and 68.1 +/- 7.8 ng l(-1), respectively), but that the level of somatostatin was significantly elevated (38.9 +/- 6.4 and 30.5 +/- 5.8 ng l(-1), p = 0.016). An inverse trend in the gastrin/somatostatin levels could not be identified in IHPS.

CONCLUSION

Somatostatin but not gastrin is raised in IHPS. Somatostatin is known to inhibit the actions of inhibitory neurotransmitters in the pylorus and may explain the development of pylorospasm, which is believed to be important in the development of pyloric tumours. These results do not agree with a previous long-term follow-up study, but reflect the hormonal imbalance at the time of pyloric hypertrophy.

The polyvagal theory: phylogenetic substrates of a social nervous system

The evolution of the autonomic nervous system provides an organizing principle to interpret the adaptive significance of physiological responses in promoting social behavior. According to the polyvagal theory, the well-documented phylogenetic shift in neural regulation of the autonomic nervous system passes through three global stages, each with an associated behavioral strategy. The first stage is characterized by a primitive unmyelinated visceral vagus that fosters digestion and responds to threat by depressing metabolic activity. Behaviorally, the first stage is associated with immobilization behaviors. The second stage is characterized by the sympathetic nervous system that is capable of increasing metabolic output and inhibiting the visceral vagus to foster mobilization behaviors necessary for 'fight or flight'. The third stage, unique to mammals, is characterized by a myelinated vagus that can rapidly regulate cardiac output to foster engagement and disengagement with the environment. The mammalian vagus is neuroanatomically linked to the cranial nerves that regulate social engagement via facial expression and vocalization. As the autonomic nervous system changed through the process of evolution, so did the interplay between the autonomic nervous system and the other physiological systems that respond to stress, including the cortex, the hypothalamic-pituitary-adrenal axis, the neuropeptides of oxytocin and vasopressin, and the immune system. From this phylogenetic orientation, the polyvagal theory proposes a biological basis for social behavior and an intervention strategy to enhance positive social behavior.

Kangaroo mother care in the nursery

Kangaroo mother care is becoming an integral part of the care of low birth weight infants worldwide. It provides economic savings to families and health care facilities and many physiologic and psychobehavioral benefits to mothers and infants, the most important of which is the promotion of successful breastfeeding. The benefits of breastfeeding, of human milk over formula, and of feeding from the breast per se, are beyond dispute, and so KMC should be actively promoted. The full impact of KMC on breastfeeding low birth weight infants is yet to be realized.

Love: an emergent property of the mammalian autonomic nervous system

The evolution of the autonomic nervous system provides an organizing principle to interpret the adaptive significance of mammalian affective processes including courting, sexual arousal, copulation, and the establishment of enduring social bonds. According to the Polyvagal Theory (Porges, 1995, 1996, 1997), the well-documented phylogenetic shift in the neural regulation of the autonomic nervous system passes through three stages, each with an associated behavioral strategy. The first stage is characterized by a primitive unmyelinated visceral vagus that fosters digestion and responds to threat by depressing metabolic activity. Behaviorally, the first stage is associated with immobilization behaviors. The second stage is characterized by the sympathetic nervous system that is capable of increasing metabolic output and inhibiting the visceral vagus to foster mobilization behaviors necessary for 'fight or flight'. The third stage, unique to mammals, is characterized by a myelinated vagus that can rapidly regulate cardiac output to foster engagement and disengagement with the environment. The mammalian vagus is neuroanatomically linked to the cranial nerves that regulate social engagement via facial expression and vocalization. The Polyvagal Theory provides neurobiological explanations for two dimensions of intimacy: courting and the establishment of enduring pair-bonds. Courting is dependent upon the social engagement strategies associated with the mammalian vagus. The establishment of enduring pair-bonds is dependent upon a co-opting of the visceral vagus from an immobilization system associated with fear and avoidance to an immobilization system associated with safety and trust. The theory proposes that the phylogenetic development of the mammalian vagus is paralleled by a specialized communication, via oxytocin and vasopressin, between the hypothalamus and the medullary source nuclei of the viscera vagus, which facilitates sexual arousal, copulation, and the development of enduring pair-bonds.

A CCK(A)-receptor antagonist administered to the neonate alters mother-infant interactions in the rat

The importance of the infant's cholecystokinin (CCK) system for eliciting optimal maternal care was examined in 6-9-day-old Sprague-Dawley rats. After administration of either vehicle, CCK-8 (1 or 8 microg/kg) or devazepide (1 mg/kg; a selective CCK(A) receptor antagonist), pups were either individually isolated (Experiment 1) or individually reunited with their dam (Experiment 2) and the rats' behavior was observed. When isolated, pups that received devazepide displayed significantly more head-lifting and wall-climbing attempts than vehicle-treated controls, suggesting that endogenous CCK dampens activity. Devazepide-treated rats were found more frequently in proximity with their mothers when reunited with them, and they emitted more ultrasonic vocalizations compared to vehicle controls. Pups treated with 1 microg/kg CCK received less body licking than vehicle controls. In addition, dams hovered and crouched over devazepide-treated pups more than over pups treated with 1 microg/kg CCK. The results suggest that endogenous CCK has a calming, quieting effect in the neonatal pup and that this, in turn, results in less infant-mother attractivity and reduced levels of maternal care.

Development of the Preterm Infant Breastfeeding Behavior Scale (PIBBS): a study of nurse-mother agreement

Research on the development of preterm infant feeding behavior has focused mainly on bottlefeeding, using invasive methods or observations by professionals. In this study, a clinical method for observing breastfeeding was developed in collaboration between observers and mothers for the purpose of enabling neonatal personnel and mothers to describe developmental stages in preterm infant breastfeeding behavior. Tests of interobserver reliability resulted in acceptable agreement between observers, but a somewhat lower level of agreement between observers and mothers. The scale showed a good capacity to discriminate between infant gestational ages and can be used for helping mothers to identify their infants' emerging competence.

Orienting in a defensive world: mammalian modifications of our evolutionary heritage. A Polyvagal Theory

The vagus, the 10th cranial nerve, contains pathways that contribute to the regulation of the internal viscera, including the heart. Vagal efferent fibers do not originate in a common brainstem structure. The Polyvagal Theory is introduced to explain the different functions of the two primary medullary source nuclei of the vagus: the nucleus ambiguus (NA) and the dorsal motor nucleus (DMNX). Although vagal pathways from both nuclei terminate on the sinoatrial node, it is argued that the fibers originating in NA are uniquely responsible for respiratory sinus arrhythmia (RSA). Divergent shifts in RSA and heart rate are explained by independent actions of DMNX and NA. The theory emphasizes a phylogenetic perspective and speculates that mammalian, but not reptilian, brainstem organization is characterized by a ventral vagal complex (including NA) related to processes associated with attention, motion, emotion, and communication. Various clinical disorders, such as sudden infant death syndrome and asthma, may be related to the competition between DMNX and NA.

Cardiac vagal tone: a physiological index of stress

Cardiac vagal tone is proposed as a novel index of stress and stress vulnerability in mammals. A model is described that emphasizes the role of the parasympathetic nervous system and particularly the vagus nerve in defining stress. The model details the importance of a branch of the vagus originating in the nucleus ambiguus. In mammals the nucleus ambiguus not only coordinates sucking, swallowing, and breathing, but it also regulates heart rate and vocalizations in response to stressors. In mammals it is possible, by quantifying the amplitude of respiratory sinus arrhythmia, to assess the tonic and phasic regulation of the vagal pathways originating in the nucleus ambiguus. Measurement of this component of vagal tone is proposed as a method to assess, on an individual basis, both stress and the vulnerability to stress.

Behavioral effects of gut hormones in neonatal rats: II. Cholecystokinin administration during the first postnatal week

This exploratory study attempted to uncover physical and behavioral consequences of changes in the peripheral cholecystokinin (CCK) system in the first postnatal week. Sprague-Dawley rat pups received s.c. injections of CCK (8 micrograms/kg) or saline, on postnatal days 1-7 (2 times/day). Physical growth and neurobehavioral development of the pups were assessed on days 3, 6, 9 & 12, their social play was assessed on day 35, and the maternal behavior of their dams was assessed on days 9-12. CCK administration was associated with slower maturation of physical characteristics, more rapid reflexive performance on day 9, and increased maternal licking of pups. These findings stress the importance of further examining the impact of CCK and other gut-hormones on physical and behavioral development and on the quality of the mother-infant interaction.