More than reproduction: Central gonadotropin-releasing hormone antagonism decreases maternal aggression in lactating rats

Gonadotropin-releasing hormone (GnRH) is a major regulator and activator of the hypothalamic-pituitary-gonadal axis. Many studies have demonstrated the importance of GnRH in reproduction and sexual behaviour. However, to date, only a single study shows an involvement of GnRH in maternal behaviour where a 30% reduction of GnRH neurones abolishes a mother's motivation to retrieve pups. On this basis, we aimed to investigate the effects of acute central GnRH receptor blockade in lactating rats on maternal care under non-stress and stress conditions, maternal motivation in the pup retrieval test, maternal anxiety on the elevated plus maze, and maternal aggression in the maternal defence test. We found that acute central infusion of a GnRH antagonist ([d-Phe^2,6 ,Pro³ ]-luteinising hormone-releasing hormone; 0.5 ng 5 μL^-1 ) impaired a mother's attack behaviour against a female intruder rat during the maternal defence test compared to vehicle controls. However, in contrast to the previous study on reduced GnRH neurones, acute central GnRH antagonism did not affect pup retrieval, nor any other parameter of maternal behaviour or maternal anxiety. Taken together, GnRH receptor activation is mandatory for protection of the offspring. These findings shed new light on GnRH as a neuropeptide acting not exclusively on the reproductive axis but, additionally, on maternal behaviour including pup retrieval and maternal aggression.

Raising overlapping litters: Differential activation of rat maternal neural circuitry after interacting with newborn or juvenile pups

The maternal behaviour of a rat dynamically changes during the postpartum period, adjusting to the characteristics and physiological needs of the pups. This adaptation has been attributed to functional modifications in the maternal circuitry. Maternal behaviour can also flexibly adapt according to different litter compositions. Thus, mothers with two overlapping litters can concurrently take care of neonate and juvenile pups, mostly directing their attention to the newborns. We hypothesised that the maternal circuitry of these mothers would show a differential activation pattern after interacting with pups depending on the developmental stage of their offspring. Thus, we evaluated the activation of several areas of the maternal circuitry in mothers of overlapping litters, using c-Fos immunoreactivity as a marker of neuronal activation, after interacting with newborns or juveniles. The results showed that mothers with overlapping litters display different behavioural responses towards their newborn and their juvenile pups. Interestingly, these behavioural displays co-occurred with specific patterns of activation of the maternal neural circuitry. Thus, a similar expression of c-Fos was observed in some key brain areas of mothers that interacted with newborns or juveniles, such as the medial preoptic area and the nucleus accumbens, whereas a differential activation was quantified in the ventral region of the bed nucleus of the stria terminalis, the infralimbic and prelimbic subregions of the medial prefrontal cortex and the basolateral and medial nuclei of the amygdala. We posit that the specific profile of activation of the neural circuitry controlling maternal behaviour in mothers with overlapping litters enables dams to respond adequately to the newborn and the juvenile pups.

High social motivation induces deficits in maternal behaviour but not plasticity of the subventricular zone in Japanese quail (Coturnix japonica)

Maternal behaviour develops differently depending on the characteristics of an individual, such as age or emotional reactivity. Social motivation, defined as the propensity to establish social contact, has received little attention in relation to maternal behaviour in birds. In addition, the transition to motherhood is a time of plasticity in the brain of the new mother in mammals. However, it remains to be determined how maternal brain plasticity is affected in avian species. The present study investigated how a the social motivation of a mother alters maternal behaviour and brain plasticity of the Japanese quail (Coturnix japonica). Adult females from lines selected for high and low social motivation were exposed to chicks for 11 days. After maternal care testing, and at matched time points in controls, the brains of females were perfused for assessment of doublecortin-immunoreactive staining, a marker of neurogenesis, in the subventricular zone (SVZ), a neurogenic niche. The results obtained showed that high socially motivated female quail spent significantly less time performing maternal behaviour when exposed to chicks compared to low socially motivated females. Moreover, the warming of chicks by high socially motivated females involved less covering postures and mothers were more rejecting of chicks. Interestingly, the plasticity indicators in the SVZ did not differ between low and high socially motivated females and were not associated with differences in maternal caregiving when using doublecortin-immunoreactive staining. Thus, high social motivation in this avian species does not favour maternal behaviour and this level of motivation to the mother is not related to changes in neuroplasticity in the SVZ of the female quail.

It takes two! Exploring sex differences in parenting neurobiology and behaviour

Parents lay the foundation for their children's socio-emotional experiences by sensitively responding to their needs. The hormonal and neurobiological changes that occur during the transition to parenthood importantly contribute to the parents' caregiving behaviour toward their children. Much research has emphasised the relationship between the mother, who is most often the primary caregiver, and her infant, with less focus on the role of fathers in child development. However, recent accounts have suggested that fathers also play an important role in promoting the health, development and psychosocial wellbeing of their children. Evidence from the behavioural literature has indicated that there are significant differences between typical mother-infant versus father-infant interactions. The current review aims to outline differences between maternal and paternal caregiving by discussing the differences in their biological mechanisms. First, we focus on the different hormones that are correlated with sensitive parenting behaviours in mothers and fathers. Next, we discuss the differences between neural bases of motherhood and fatherhood. Lastly, we discuss ways in which parental hormones, parental brain and parental exposure to infant cues interact to shape parental caregiving behaviour. In summary, this review highlights the distinct but complementary nature of maternal and paternal caregiving.

Maternal care activates the ventral tegmental area but not dopaminergic cells in the rat

The ventral tegmental area (VTA), together with the preoptic area, is part of a neural circuit necessary for the expression of maternal behaviour (MB); destruction of either area disrupts MB in postpartum rats. Central to the proposal of VTA activation are dopaminergic cells, for which the cell bodies lie in the VTA and project to forebrain structures. This mesolimbic system is a motivational circuit involved in rewarding behaviours such as sex and MB. Despite their recognised importance, surprisingly, unlike the preoptic area, there are no anatomical descriptions of the pattern of VTA activation or of the dopaminergic cell activation, specifically in relation to MB in the rat. In the present study, we explore the possible activation (as indicated by Fos protein via immunohistochemistry) of the anterior and medial portions of the VTA and in the dopaminergic cells in these regions, as well as in the medial preoptic area, in lactating rats, at postpartum day 7 (after a 12-hour mother/pups separation), and in dioestrous females. After 12 hours, mothers were perfused at that moment or after a 90 minutes of interaction, or not, with their pups. We found a strong significant Fos induction in both the preoptic area and in the anterior portion of VTA in dams that interacted with their pups. The number of dopaminergic cells that coexpressed Fos did not differ across groups. Additionally, we determined Fos and GABA colocalisation in the anterior part of the VTA and found dense GABAergic processes, possibly varicosities, in the area of increased Fos expression. The results of the present study support a proposed GABAergic pathway from medial preoptic area to VTA cells, critical for the expression of MB. Future experiments are warranted to explore the neurochemical identity of the Fos and no-Fos expressing cells that are recipients of GABAergic processes in the VTA, aiming to better understand the neural circuitry of the VTA in relation to MB.

Maternal brain resting-state connectivity in the postpartum period

In the postpartum period, the maternal brain experiences both structural and functional plasticity. Although we have a growing understanding of the responses of the human maternal brain to infant stimuli, little is known about the intrinsic connectivity among those regions during the postpartum months. Resting-state functional connectivity (rsFC) provides a measure of the functional architecture of the brain based upon intrinsic functional connectivity (ie, the temporal correlation in blood oxygenation level dependent signal when the brain is not engaged in a specific task). In the present study, we used resting-state functional magnetic resonance imaging to examine how later postpartum months are associated with rsFC and maternal behaviours. We recruited a sample of 47 socioeconomically diverse first-time mothers with singleton pregnancies. Because the amygdala has been shown to play a critical role in maternal behaviours in the postpartum period, this was chosen as the seed for a seed-based correlation analysis. For the left amygdala, later postpartum months were associated with greater connectivity with the anterior cingulate gyrus, left nucleus accumbens, right caudate and left cerebellum (P < 0.05, false discovery rate corrected). Furthermore, in an exploratory analysis, we observed indications that rsFC between the left amygdala and left nucleus accumbens was positively associated with maternal structuring during a mother child-interaction. In addition, later postpartum months were associated with greater connectivity between the right amygdala and the bilateral caudate and right putamen. Overall, we provide evidence of relationships between postpartum months and rsFC in the regions involved in salience detection and regions involved in maternal motivation. Greater connectivity between the amygdala and nucleus accumbens may play a role in positive maternal behaviours.

Female pups receive more maltreatment from stressed dams

The effects of exposure to developmental stress often diverge for males and females. Using the scarcity-adversity model of low nesting resources outside the home cage, our lab has discovered sex differences in both behavioral and epigenetic consequences of repeated exposure to caregiver maltreatment. For the measures we have performed to date, we have found more consequences for females. The reasons underlying this sex disparity are unknown. In the current experiment, we aimed to discern the quality of maternal care received by male and female pups in our model. As we have previously found more behavioral and epigenetic consequences in females, we hypothesized that females receive more adverse care compared to their male littermates. Our hypothesis was supported; in our maltreatment condition, we found that female pups received more adverse care than males. This sex difference in adverse care was not present in our two control conditions (cross-foster and normal maternal care). These data lend support to the notion that one reason females in our model incur more behavioral and epigenetic consequences is a result of greater mistreatment by the dam.

Maternal responsiveness to suckling is modulated by time post-nursing: A behavioural and c-Fos/oxytocin immunocytochemistry study in rabbits

Doe rabbits nurse once/day for approximately 3 minutes, with circadian periodicity, inside the nest box. The amount of suckling received at each bout regulates this behaviour because reducing the litter size to four kits or less disrupts nursing circadian periodicity and increases suckling bout duration. Additionally, the likelihood that does will nurse kits at a given time of day depends on the time elapsed since the last suckling episode and the litter size nursed then. We hypothesised that the time elapsed since the last nursing would impact the number of c-Fos immunoreactive (IR) cells observed after suckling five kits and also that observed before the next nursing ("no kits"). Suckling significantly increased, relative to "no kits", the number of c-Fos-IR cells in the medial preoptic area and lateral septum but not in the bed nucleus of the stria terminalis (BNST), suprachiasmatic nucleus or ventromedial hypothalamus in does nursing at 18 or 24 hours after the previous bout. No effects of suckling were observed in mothers nursing at 6 hours. Does given kits at 3 hours post last suckling refused to nurse but, in the remaining three groups, all does nursed normally. At "no kits", more c-Fos-IR cells were seen (in all regions except the BNST) in does given kits at 24 hours after the last nursing and killed 1 hour later (ie, 4 hours after lights on) than in those killed earlier. The percentage of oxytocinergic (OT) cells co-expressing c-Fos was not modified by nursing in the paraventricular or supraoptic nuclei but, in the latter, the largest number of total OT-IR cells occurred at 18 and 24 hours post-last nursing. In conclusion, the responsiveness of particular forebrain regions involved in regulating circadian rhythms, lactation, and maternal behaviour is modulated by suckling and time of day.

A tumultuous transition to motherhood: Altered brain and hormonal responses in mothers with postpartum depression

Postpartum depression (PPD) is a common but complex condition that is poorly understood and multifactorial in aetiology. It is a condition that can compromise the mother's care for her infant, which may pose challenges to the formation of the mother-infant bond and the infant's overall development. Past research has looked at abnormalities in the brain circuitry and hormonal profiles of mothers with PPD compared to non-depressed mothers. However, abnormalities in PPD that may specifically affect the mother's care of her infant have not been clearly assessed. Thus, the present review aims to synthesise studies of altered brain and hormonal responses in mothers with PPD in relation to their care of their infant. First, we review maternal brain responses and their relation to PPD symptomatology, focusing on the salience/fear network, reward/attachment network and default mode network. Next, we discuss oxytocin and hypothalamic-pituitary-adrenal axis hormones in the context of maternal behaviour and PPD. Finally, we synthesise these findings and propose how future studies may benefit from the combined study of both neural and hormonal activity to better understand the underlying neurobiology of maternal care in PPD.

Maternal social environment affects offspring cognition through behavioural and immune pathways in rats

The social environment of lactation is a key etiological factor for the occurrence of postpartum disorders affecting women and their children. Postpartum depression and anxiety disorders are highly prevalent in new mothers and negatively affect offspring's cognitive development through mechanisms which are still unclear. Here, using a rat model, we manipulated the maternal social environment during lactation and explored the pathways through which social isolation (vs. the opportunity for limited social interaction with another lactating female, from 1 day before parturition to postpartum day 16) and chronic social conflict (daily exposure to a male intruder from postpartum day 2 to day 16) affect offspring learning and memory, measured at 40 to 60 days of age. We specifically explored the consequences of these social treatments on two main hypothesized mediators likely to affect offspring neurophysiological development: the quality of maternal care and maternal inflammation factors (brain-derived neurotrophic factor, granulocyte-macrophage colony-stimulating factor, intercellular adhesion molecule 1, tissue inhibitor of metalloproteinases 1 and vascular endothelial growth factor) likely to influence offspring development through lactation. Maternal rats which had the opportunity to interact with another lactating female spent more time with their pups which, in turn, displayed improved working and reference memory. Social stress affected maternal plasma levels of cytokines that were associated with cognitive deficits in their offspring. However, females subjected to social stress were protected from these stress-induced immune changes and associated offspring cognitive impairment by increased social affiliation. These results underscore the effects of social interaction for new mothers and their offspring and can be used to inform the development of clinical preventative measures and interventions.

Glyphosate and glyphosate-based herbicide exposure during the peripartum period affects maternal brain plasticity, maternal behaviour and microbiome

Glyphosate is found in a large array of non-selective herbicides such as Roundup® (Monsanto, Creve Coeur, MO, USA) and is by far the most widely used herbicide. Recent work in rodent models suggests that glyphosate-based herbicides during development can affect neuronal communication and result in altered behaviours, albeit through undefined mechanisms of action. To our knowledge, no study has investigated the effects glyphosate or its formulation in herbicide on maternal behaviour and physiology. In the present study, relatively low doses of glyphosate (5 mg kg-1  d-1 ), Roundup® (5 mg kg-1  d-1 glyphosate equivalent), or vehicle were administered by ingestion to Sprague-Dawley rats from gestational day (GD) 10 to postpartum day (PD)22. The treatments significantly altered licking behaviour toward pups between PD2 and PD6. We also show in the dams at PD22 that Roundup exposure affected the maturation of doublecortin-immunoreactive new neurones in the dorsal dentate gyrus of the hippocampus of the mother. In addition, the expression of synaptophysin was up-regulated by glyphosate in the dorsal and ventral dentate gyrus and CA3 regions of the hippocampus, and down-regulated in the cingulate gyrus. Although a direct effect of glyphosate alone or its formulation on the central nervous system is currently not clear, we show that gut microbiota is significantly altered by the exposure to the pesticides, with significant alteration of the phyla Bacteroidetes and Firmicutes. This is the first study to provide evidence that glyphosate alone or in formulation (Roundup) differentially affects maternal behaviour and modulates neuroplasticity and gut microbiota in the mother.

The association between maternal interaction and infant cortisol stress reactivity among preterm and full term infants at 4 months adjusted age

The purpose of this study was to assess the association between maternal interactive behavior and infant cortisol stress reactivity in response to the Still Face paradigm (SF) in a cohort of four-month old infants (adjusted age) born preterm (<32 weeks gestation, N = 22) compared with infants born full term (>37 weeks gestation, N = 28). Infant cortisol reactivity was calculated as area under the curve (AUC) from baseline to the third cortisol sample (30 min post-SF) using the trapezoidal rule, while the percent of time mothers spent using a contingent interaction style was measured (0-100%) during episodes 1 (Play; baseline), 3 (Reunion#1), and 5 (Reunion#2) while mother-infant dyads participated in the SF paradigm. We hypothesized that because infants born preterm are at increased risk for dysregulation, they would show, compared to full-term infants, a blunted stress response, involving under-responsiveness. We found blunted cortisol stress reactivity among the preterm infants. We also found that mothers of preterm infants demonstrated less contingent maternal interaction during Renion#1 of the SF; and that contingent maternal interaction at Reunion#2 of the SF was protective against cortisol stress reactivity in response to the SF. However, we did not find that the influence of maternal interaction on cortisol reactivity was moderated by gestational age group (full term vs preterm): the association between contingent maternal interaction and stress reactivity was similar for both gestational groups across episodes. In order to improve self-regulation and longer term social and cognitive developmental outcomes in medically at-risk infants, future research is warranted to determine how these findings relate to infants' stress reactions in naturalistic settings, and the directionality and temporal relationship between cortisol stress responses and maternal interactive behavior.

Exploring associations between perinatal depression, anxiety, and urinary oxytocin levels in Latinas

Perinatal depression has been associated with lower oxytocin (OT) levels. However, few studies have explored this topic in relation to Latinas who are at high risk of perinatal depression. The objective of this study was to explore these associations in Latinas. A total of 108 Latinas in the third trimester of pregnancy participated in the study. Depression and urinary OT levels were assessed in pregnancy and 6 weeks postpartum. Nonparametric tests were implemented to test the proposed associations. Results revealed that 28% of the participants had probable depression in pregnancy, and 23% at 6 weeks postpartum. OT levels significantly decreased from prenatal to postpartum in the whole sample; however, participants with probable prenatal depression did not exhibit a significant change in OT levels. Participants who were depressed or anxious at 6 weeks postpartum exhibited persistently higher mean OT levels over time. A distinct pattern of higher levels of OT in depressed Latinas suggests that OT levels may be an important neuroendocrine factor contributing to depressive and anxious symptoms.

Does touch matter? The impact of stroking versus non-stroking maternal touch on cardio-respiratory processes in mothers and infants

The beneficial effects of touch in development were already observed in different types of skin-to-skin care. In the current study, we aimed at studying potential underlying mechanisms of these effects in terms of parasympatho-inhibitory regulation. We examined the specific impact of affective maternal stroking versus non-stroking touch on the cardio-respiration of both mothers and infants in terms of respiratory sinus arrhythmia (RSA). We compared a 3-min TOUCH PERIOD (stroking or non-stroking touch) with a baseline before (PRE-TOUCH) and after (POST-TOUCH) in 45 dyads (24 stroking/21 non-stroking touch) with infants aged 4-16 weeks. We registered mother-infant ECG, respiration and made video-recordings. We calculated RR-interval (RRI), respiration rate (fR) and (respiratory corrected) RSA and analyzed stroking mean velocity rate (MVR) of the mothers. ANOVA-tests showed a significant different impact on infants' respiratory corrected RSA of stroking touch (increase) versus non-stroking touch (decrease). Further, during and after stroking touch, RRI significantly increased whereas fR significantly decreased. Non-stroking touch had no significant impact on infants' RRI and fR. In the mothers, RRI significantly decreased and fR significantly increased during the TOUCH PERIOD. The mothers' MVR occurred within the range of 1-10 cm/s matching with the optimal afferent stimulation range of a particular class of cutaneous unmyelinated, low-threshold mechano-sensitive nerves, named c-tactile (CT) afferents. We suggest CT afferents to be the a potential missing link between the processing of affective touch and the development of physiological and emotional self-regulation. The results are discussed with regard to the potential role of CT afferents within the building of early self-regulation as part of a multisensory intuitive parenting system and the importance to respect this ecological context of an infant in research and clinical applications.

Effects of single parenthood on mothers' behavior, morphology, and endocrine function in the biparental California mouse

Motherhood is energetically costly for mammals and is associated with pronounced changes in mothers' physiology, morphology and behavior. In ~5% of mammals, fathers assist their mates with rearing offspring and can enhance offspring survival and development. Although these beneficial consequences of paternal care can be mediated by direct effects on offspring, they might also be mediated indirectly, through beneficial effects on mothers. We tested the hypothesis that fathers in the monogamous, biparental California mouse (Peromyscus californicus) reduce the burden of parental care on their mates, and therefore, that females rearing offspring with and without assistance from their mates will show differences in endocrinology, morphology and behavior, as well as in the survival and development of their pups. We found that pups' survival and development in the lab did not differ between those raised by a single mother and those reared by both mother and father. Single mothers spent more time in feeding behaviors than paired mothers. Both single and paired mothers had higher lean mass and/or lower fat mass and showed more anxiety-like behavior in open-field tests and tail-suspension tests, compared to non-breeding females. Single mothers had higher body-mass-corrected liver and heart masses, but lower ovarian and uterine masses, than paired mothers and/or non-breeding females. Mass of the gastrointestinal tract did not differ between single and paired mothers, but single mothers had heavier gastrointestinal tract compared to non-breeding females. Single motherhood also induced a flattened diel corticosterone rhythm and a blunted corticosterone response to stress, compared to non-breeding conditions. These findings suggest that the absence of a mate induces morphological and endocrine changes in mothers, which might result from increased energetic demands of pup care and could potentially help maintain normal survival and development of pups.

Assessing knowledge and behavioural changes on maternal and newborn health among mothers following post-earthquake health promotion in Nepal

Introduction

Disasters can disrupt the existing health system affecting the whole population, but especially vulnerable people such as pregnant women, new mothers and their babies. Despite the global progress in maternal, newborn and child health (MNCH) programmes over the years, emergency responses after a disaster are often poor. Post-disaster health promotion could play an important role in improving MNCH outcomes. However, evidence remains limited on the effect of post disaster health promotion activities in low-income countries such as Nepal.

Methods

This is an uncontrolled before and after study conducted in Dhading district which was severely affected by the 2015 earthquake in Nepal. The study participants were mothers who had a child in the previous 12 months. The intervention was implemented between 2016 and 2018 and included community-engagement health promotion activities where the local stakeholders and resources were mobilized. The outcome variables included: knowledge of danger signs of pregnancy, childbirth and in newborns; and behaviours including ever attending antenatal care (ANC), a minimum of four ANC sessions and having an institutional delivery. Data were analysed using chi-squared tests, independent sample t-tests and multiple logistic regression models.

Results

In total 364 mothers were recruited in the pre-intervention group and 377 in the post-intervention group. The post-intervention group was more likely to have knowledge of at least three danger signs in pregnancy (AOR [Adjusted Odds Ratio] = 2.96, P<0.001), at least three danger signs in childbirth (AOR = 3.8, P<0.001), and at least five danger signs in newborns (AOR = 1.56, P<0.001) compared to the pre-intervention group. The mothers in the post-intervention group were also more likely to ever attend ANC (AOR = 7.18, P<0.001), attend a minimum of four ANC sessions (AOR = 5.09, P<0.001), and have institutional deliveries (AOR = 2.56, P<0.001). Religious minority groups were less likely to have knowledge of all danger signs compared to the majority Hindu group. Mothers from poorer households were also less likely to attend four ANC sessions. Mothers with higher education were more likely to have knowledge of all the danger signs. Mothers whose husbands had achieved higher education were also more likely to have knowledge of danger signs and have institutional deliveries.

Conclusion

Health promotion intervention helped the disaster-affected mothers in improving the knowledge and behaviours related to MNCH. However, the vulnerable population would need more support to gain benefit from such intervention.

Pharmacological manipulation of DNA methylation normalizes maternal behavior, DNA methylation, and gene expression in dams with a history of maltreatment

The quality of parental care received during development profoundly influences an individual's phenotype, including that of maternal behavior. We previously found that female rats with a history of maltreatment during infancy mistreat their own offspring. One proposed mechanism through which early-life experiences influence behavior is via epigenetic modifications. Indeed, our lab has identified a number of brain epigenetic alterations in female rats with a history of maltreatment. Here we sought to investigate the role of DNA methylation in aberrant maternal behavior. We administered zebularine, a drug known to alter DNA methylation, to dams exposed during infancy to the scarcity-adversity model of low nesting resources, and then characterized the quality of their care towards their offspring. First, we replicate that dams with a history of maltreatment mistreat their own offspring. Second, we show that maltreated-dams treated with zebularine exhibit lower levels of adverse care toward their offspring. Third, we show that administration of zebularine in control dams (history of nurturing care) enhances levels of adverse care. Lastly, we show altered methylation and gene expression in maltreated dams normalized by zebularine. These findings lend support to the hypothesis that epigenetic alterations resulting from maltreatment causally relate to behavioral outcomes.

Low maternal care enhances the skin barrier resistance of offspring in mice

Deprivation of maternal care via lack of somatosensory input causes offspring to experience adverse consequences, especially in the central nervous system. However, little is known about the developmental effect of maternal care on peripheral tissues such as the skin, which includes cutaneous sensory neurons. In the present study, we examined the involvement of maternal care in the development of the skin. We investigated offspring reared by early-weaned mother mice who spontaneously showed lower frequency of licking/grooming on nursing. Offspring of early-weaned mothers showed higher resistance against skin barrier disruption than did offspring of normally-weaned mothers, and had normal skin barrier function in the intact trunk skin. In the dorsal root ganglion of early-weaned mother offspring, we also found up-regulation of mRNA levels of the Mas-related G-protein coupled receptor B4 (MrgprB4), which is a marker of sensory neurons that detect gentle stroking. We further found that levels of MrgprB4 mRNA were correlated with the enhancement of skin resistance. The present findings suggest that maternal somatosensory inputs have a developmental impact on the cutaneous sensory neurons of the skin in offspring. Interestingly, the present results suggest that lower maternal care has a benefit on the skin resistance. This provides important information for understanding the development of peripheral tissues in offspring reared under severe conditions such as lower maternal care in the wild.

Associations between oxytocin receptor gene (OXTR) polymorphisms, childhood trauma, and parenting behavior

Maternal oxytocin is connected to aspects of parenting including sensitivity, warmth, positive affect, and affectionate touch. Oxytocin receptor gene (OXTR) polymorphisms are associated with circulating oxytocin levels, altered brain activity, and parenting behaviors. This study aimed to replicate prior work on OXTR single-nucleotide polymorphisms (SNPs) rs1042778 and rs53576 in relation to maternal sensitivity, explore associations with other aspects of parenting (i.e., negative parenting), evaluate observational and self-report measures of parenting in relation to OXTR SNPs, and examine whether childhood trauma exposure moderates the relation between OXTR SNPs and parenting. Mothers (N = 100) were observed during 2 teaching interaction tasks with their 7-month-old infant, completed questionnaire and interview measures related to parenting and trauma history, and provided saliva specimens to derive OXTR genotypes. Mothers with OXTR rs1042778 TT genotypes demonstrated lower behavioral sensitivity, lower engagement, higher intrusiveness, and more frequent frightened/frightening behavior than mothers with TG or GG genotypes. Genotype interacted with childhood trauma history such that mothers who had experienced childhood trauma were more likely to demonstrate frightened/frightening behavior if they had the TT genotype on rs1042778 relative to the TG or GG genotype; however, small cell sizes for this interaction suggest replication is warranted. Contrary to expectations, mothers with the TT genotype on rs1042778 self-reported that they had less impaired bonding than mothers with TG or GG genotypes. Results are discussed with respect to prior work with oxytocin in lower versus higher risk samples, and the potential role of mothers' self-awareness in explaining discrepancies between results from observational versus self-report measures of parenting. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Experience-dependent mechanisms in the regulation of parental care

Maternal behavior is a defining characteristic of mammals, which is regulated by a core, conserved neural circuit. However, mothering behavior is not always a default response to infant conspecifics. For example, initial fearful, fragmented or aggressive responses toward infants in laboratory rats and mice can give way to highly motivated and organized caregiving behaviors following appropriate hormone exposure or repeated experience with infants. Therefore hormonal and/or experiential factors must be involved in determining the extent to which infants access central approach and avoidance neural systems. In this review we describe evidence supporting the idea that infant conspecifics are capable of activating distinct neural pathways to elicit avoidant, aggressive and parental responses from adult rodents. Additionally, we discuss the hypothesis that alterations in transcriptional regulation within the medial preoptic area of the hypothalamus may be a key mechanism of neural plasticity involved in programming the differential sensitivity of these neural pathways.

Investigation of a developmental pathway from infant anger reactivity to childhood inhibitory control and ADHD symptoms: interactive effects of early maternal caregiving

BACKGROUND

ADHD is a neurodevelopmental disorder with a complex pathogenesis. Individual differences in temperamental reactivity - in particular, anger reactivity - are predictive of ADHD. The goal of this study was to examine the moderating (maternal caregiving behaviors; MCB) and mediating (inhibitory control) variables of reactivity using a 9-year multimethod prospective longitudinal design.

METHODS

Participants included 291 children (135 male; 156 female) who participated in a larger study of temperament and social-emotional development. Anger reactivity was assessed by observation of facial anger during an arm restraint task, and MCB were observed during a series of semi-structured mother-infant tasks, both at 9 months of age. Inhibitory control was assessed by performance on a go/no-go task at 5 years of age. ADHD symptoms were assessed by parent and teacher report questionnaires at 7 and 9 years, respectively.

RESULTS

Anger reactivity and poor inhibitory control were predictive of later ADHD symptoms. Results supported a moderated mediation model, in which the indirect effects of anger reactivity on ADHD symptoms through inhibitory control were conditional on quality of early MCB. Inhibitory control mediated the effect of anger reactivity on ADHD symptoms, but only among children exposed to lower-quality MCB.

CONCLUSIONS

Infant anger reactivity exerts a direct effect on later ADHD from infancy, suggesting anger reactivity as a very early indicator of ADHD risk. Higher-quality caregiving did not buffer against the direct risk of anger reactivity on ADHD but did buffer against the indirect risk by reducing the negative effect of anger reactivity on inhibitory control. Thus, in the developmental pathway from anger reactivity to ADHD, more sensitive, less intrusive parenting supports the development of protective mechanisms (i.e. inhibitory control) to remediate ADHD risk.

Effects of opioids on the parental brain in health and disease

The epidemic of opioid use disorder (OUD) directly affects millions of women of child-bearing age. Unfortunately, parenting behaviors - among the most important processes for human survival - are vulnerable to the effects of OUD. The standard of care for pregnant women with OUD is opioid maintenance therapy (OMT), of which the primary objective is to mitigate addiction-related stress. The aim of this review is to synthesize current information specific to pregnancy and parenting that may be affected by OUD. We first summarize a model of the parental brain supported by animal research and human neuroimaging. We then review animal models of exogenous opioid effects on parental brain and behavior. We also present preliminary data for a unifying hypothesis that may link different effects of exogenous opioids on parenting across species and in the context of OMT. Finally, we discuss future directions that may inform research and clinical decision making for peripartum women with OUD.

Impact of Nonmedical Factors on Neurobehavior and Language Outcomes of Preterm Infants

Preterm infants are at increased risk for adverse neurodevelopmental outcomes. The impact of maternal, NICU, and social environmental factors on early neurobehavior and language outcomes of preterm infants is recognized. There is a need for health care professionals to have a clear understanding of the importance of facilitating positive mother-infant relationships, and to address not only the infant's sensory and language environment, but also focus on adverse maternal mental health and social adversities to optimize infant outcomes.

Functional Ontogeny of Hypothalamic Agrp Neurons in Neonatal Mouse Behaviors

Hypothalamic Agrp neurons regulate food ingestion in adult mice. Whether these neurons are functional before animals start to ingest food is unknown. Here, we studied the functional ontogeny of Agrp neurons during breastfeeding using postnatal day 10 mice. In contrast to adult mice, we show that isolation from the nursing nest, not milk deprivation or ingestion, activated Agrp neurons. Non-nutritive suckling and warm temperatures blunted this effect. Using in vivo fiber photometry, neonatal Agrp neurons showed a rapid increase in activity upon isolation from the nest, an effect rapidly diminished following reunion with littermates. Neonates unable to release GABA from Agrp neurons expressed blunted emission of isolation-induced ultrasonic vocalizations. Chemogenetic overactivation of these neurons further increased emission of these ultrasonic vocalizations, but not milk ingestion. We uncovered important functional properties of hypothalamic Agrp neurons during mouse development, suggesting these neurons facilitate offspring-to-caregiver bonding.

The maternal reward system in postpartum depression

The experience of motherhood is most often emotionally positive and rewarding, but for many new mothers suffering from postpartum depression (PPD), this is not the case. Preclinical and clinical research has sought to uncover brain changes underlying PPD in order to gain a better understanding of how this disorder develops. This review focuses on the mesolimbic dopamine system, particularly the ventral tegmental area-nucleus accumbens pathway which has been implicated in the regulation of critical functions disrupted in PPD including mood, motivation, and mothering. Specifically, we discuss normative changes in the mesolimbic system during motherhood in both rodents and humans and how these are impacted in PPD. We also consider modulation of mesolimbic dopamine by the hypothalamic neuropeptide oxytocin and how oxytocin-dopamine interactions regulate mood and mothering during the postpartum period. In addition to providing an overview of reward mechanisms in PPD, our goal is to highlight open questions which warrant further research.