An epigenomic shift in amygdala marks the transition to maternal behaviors in alloparenting virgin female mice
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ABSTRACT: In many species, adults care for young offspring that are not their own, a phenomenon called alloparenting. However, most nonparental adults must be sensitized by repeated or extended exposure to pups before robustly displaying of parental-like behaviors. To capture neurogenomic events underlying the transition to active parental caring behaviors, we analyzed brain gene expression and chromatin profiles of virgin female mice co-housed with mothers during pregnancy and after birth. After an initial display of antagonistic behaviors and a surge of defense-related gene expression, we observed a dramatic shift in the chromatin landscape specifically in amygdala of the pup-exposed virgin females, accompanied by a dampening of defense-related gene expression. This epigenetic shift coincided with hypothalamic expression of the oxytocin gene and the emergence of behaviors and gene expression patterns classically associated with maternal care. The results outline a neurogenomic program associated with dramatic behavioral changes and suggest molecular networks relevant to human postpartum mental health.
Project description:Motherhood is characterized by dramatic changes in brain and behavior, but less is known about fatherhood. Here we report that male sticklebacks – a small fish in which fathers provide care – experience dramatic changes in neurogenomic state as they become fathers. Some genes are unique to different stages of paternal care, some genes are shared across stages, and some genes are added to the previously acquired neurogenomic state. Comparative genomic analysis suggests that some of these neurogenomic dynamics resemble changes associated with pregnancy and reproduction in mammalian mothers. Moreover, gene regulatory analysis identified transcription factors that are regulated in opposite directions in response to a territorial challenge versus during paternal care. Altogether these results show that some of the molecular mechanisms of parental care might be deeply conserved and might not be sex-specific, and suggest that tradeoffs between opposing social behaviors are managed at the gene regulatory level.
Project description:In socially monogamous prairie voles (Microtus ochrogaster), parental behaviors not only occur in mothers and fathers, but also can exist in virgin males. However, some virgin males display aggressive behaviors towards conspecific pups. Although this behavioral dichotomy in response to pup exposure has been well documented in male virgin voles, little is known about the gene expression changes underlie the parental behavioral differences and their regulatory mechanisms. To address this, we profiled the transcriptome and DNA methylome of hippocampal dentate gyrus of four prairie vole groups, attacker virgin males, parental virgin males, fathers, and mothers. We found a concordant pattern of gene transcription in parental virgin males and fathers, when comparing to the attacker group. The methylome analysis also revealed pathways with genes enriched for epigenetic changes involving both receptor-mediated and secondary messenger signaling across both behavioral phenotypes and sexual experiences. Furthermore, we found correlations between gene expression changes and DNA methylation differences between attacker and parental virgin males, which suggests a canonical gene expression regulatory role of DNA methylation in paternal care. Therefore, our study presents an integrated view of transcriptome and epigenome that provides a DNA epigenetic based molecular insight of paternal behavior.
Project description:In socially monogamous prairie voles (Microtus ochrogaster), parental behaviors not only occur in mothers and fathers, but also can exist in virgin males. However, some virgin males display aggressive behaviors towards conspecific pups. Although this behavioral dichotomy in response to pup exposure has been well documented in male virgin voles, little is known about the gene expression changes underlie the parental behavioral differences and their regulatory mechanisms. To address this, we profiled the transcriptome and DNA methylome of hippocampal dentate gyrus of four prairie vole groups, attacker virgin males, parental virgin males, fathers, and mothers. We found a concordant pattern of gene transcription in parental virgin males and fathers, when comparing to the attacker group. The methylome analysis also revealed pathways with genes enriched for epigenetic changes involving both receptor-mediated and secondary messenger signaling across both behavioral phenotypes and sexual experiences. Furthermore, we found correlations between gene expression changes and DNA methylation differences between attacker and parental virgin males, which suggests a canonical gene expression regulatory role of DNA methylation in paternal care. Therefore, our study presents an integrated view of transcriptome and epigenome that provides a DNA epigenetic based molecular insight of paternal behavior.
Project description:The brain plays a critical role in upstream regulation of processes central to mating effort, parental effort, and self-maintenance. For seasonally breeding animals, the brain is likely mediating trade-offs among these processes within a short breeding season, yet research thus far has only explored neurogenomic changes from non-breeding to breeding states or select pathways (e.g., steroids) in male and/or lab-reared animals. Here, we use RNA-seq to explore neural plasticity in three behaviorally relevant neural tissues (ventromedial telencephalon [VmT], hypothalamus [HYPO], and hindbrain), comparing free-living female tree swallows (Tachycineta bicolor) as they shift from territory establishment to incubation. We additionally highlight changes in candidate aggression-related genes to explore the potential for a neurogenomic shift in the mechanisms regulating aggression, a critical behavior both in establishing and maintaining a territory and in defense of offspring. We found hundreds of differentially expressed genes in the VmT and HYPO. Enrichment analyses for the VmT revealed higher expression of genes related to neuroplasticity and processes beneficial for competition during territory establishment, but down-regulated immune processes. The HYPO showed signs of high neuroplasticity during incubation, and a decreased potential for glucocorticoid signaling. Furthermore, expression of aggression-related genes shifted from steroidal to non-steroidal pathways across the breeding season. Altogether, we found genomic signatures suggestive of trade-offs between enhanced activity and immunity in the VmT and between stress responsiveness and parental care in the HYPO, along with a potential shift in the mechanisms regulating aggression. These data highlight important gene regulatory pathways that may underlie behavioral plasticity in females.
Project description:For many species, parental care critically affects offspring survival. But what drives animals to display parental behaviours towards young? In mammals, pregnancy‐induced physiological transformations seem key in preparing the neural circuits that lead towards attraction (and reduced‐aggression) to young. Beyond mammalian maternal behaviour, knowledge of the neural mechanisms that underlie young‐directed parental care is severely lacking. We took advantage of a domesticated bird species, the Japanese quail, for which parental behaviour towards chicks can be induced in virgin non‐ reproductive adults through a sensitization procedure, a process that is not effective in all animals. We used the variation in parental responses to study neural transcriptomic changes associated with the sensitization procedure itself and with the outcome of the procedure (i.e., presence of parental behaviours). We found differences in gene expression in the hypothalamus and bed nucleus of the stria terminalis, but not the nucleus taeniae. Two genes identified are of particular interest. One is neurotensin, previously only demonstrated to be causally associated with maternal care in mammals. The other one is urocortin 3, causally demonstrated to affect young‐directed neglect and aggression in mammals. Because our studies were conducted in animals that were reproductively quiescent, our results reflect core neural changes that may be associated with avian young‐directed care independently of extensive hormonal stimulation. Our work opens new avenues of research into understanding the neural basis of parental care in non‐placental species.
Project description:The importance of fathers' engagement in care and its critical role in the offspring’s cognitive and emotional development is now well established. Yet, little is known on the underlying neurobiology due to the lack of appropriate animal models. In the socially monogamous and bi-parental prairie vole (Microtus ochrogaster), while most virgin males show spontaneous paternal behaviors (Paternal), others display pup-directed aggression (Attackers). Here we took advantage of this phenotypic dichotomy and used RNA-sequencing in three important brain areas to characterize gene expression associated with paternal behaviors of Paternal males and compare it to experienced fathers and mothers. This strategy allowed the identification of spontaneous paternal behaviors independently from fatherhood and pair-bonding. While Paternal males displayed the same range and extent of paternal behaviors than experienced Fathers, the nucleus accumbens (NAc) and medial preoptic area (MPOA) transcriptomes mainly reflected pair-bonded status or sex differences, respectively. The lateral septum (LS) transcriptome, however, primarily reflected phenotypic differences between Paternal and Attackers and suggested the involvement of the mitochondria, RNA translation, and protein degradation processes. Altogether, these observations highlight a marked structure- and phenotype-specific pattern of gene expression underlying paternal behaviors in prairie voles and highlight similarities and differences from those underlying fatherhood.
Project description:In humans, mutations in the transcription factor encoding gene, FOXP2, are associated with language and Autism Spectrum (ASD) Disorders, the latter characterized by deficits in social interactions. However, little is known regarding the function of Foxp2 in male or female social behavior. Our previous studies in mice revealed high expression of Foxp2 within the medial subnucleus of the amygdala (MeA), a limbic brain region highly implicated in innate social behaviors such as mating, aggression, and parental care. Here, using a comprehensive panel of behavioral tests in male and female Foxp2+/- heterozygous mice, we investigated the role Foxp2 plays in MeA-linked innate social behaviors. We reveal significant deficits in olfactory processing, social interaction, mating, aggressive and parental behaviors. Interestingly, some of these deficits displayed in a sex-specific manner. To examine the consequences of Foxp2 loss of function specifically in the MeA, we conducted a proteomic analysis of microdissected MeA tissue and found sex differences in a host of proteins implicated in neuronal communication, connectivity and dopamine signaling. Consistent with this, we discovered that MeA Foxp2-lineage cells were responsive to dopamine with differences between males and females. Thus, our findings reveal a central and sex-specific role for Foxp2 in social behavior and MeA function.
Project description:CHD8, encoding a chromatin remodeling protein, is one of the most frequently mutated genes in autism spectrum disorders. However, how such mutations cause autistic behaviors remain unclear. In mice carrying a heterozygous frame-shift mutation in the Chd8 gene (Asn2373LysfsX2) identified in autistic human individuals, we observed autistic-like behaviors that are much stronger in males than in females, similar to human cases. These behaviors included enhanced mother-seeking ultrasonic vocalizations in pups, mother-attachment behaviors in juveniles, and isolation-induced self-grooming in adults. These behaviors were associated with opposite changes in synaptic excitation/inhibition and neuronal firing in male and female mice, but with strong changes in gene expression in female mice. Therefore, this CHD8 mutation may cause male-preponderant autistic-like behaviors in mice through differential synaptic/neuronal changes and gene expression
Project description:CHD8, encoding a chromatin remodeling protein, is one of the most frequently mutated genes in autism spectrum disorders. However, how such mutations cause autistic behaviors remain unclear. In mice carrying a heterozygous frame-shift mutation in the Chd8 gene (Asn2373LysfsX2) identified in autistic human individuals, we observed autistic-like behaviors that are much stronger in males than in females, similar to human cases. These behaviors included enhanced mother-seeking ultrasonic vocalizations in pups, mother-attachment behaviors in juveniles, and isolation-induced self-grooming in adults. These behaviors were associated with opposite changes in synaptic excitation/inhibition and neuronal firing in male and female mice, but with strong changes in gene expression in female mice. Therefore, this CHD8 mutation may cause male-preponderant autistic-like behaviors in mice through differential synaptic/neuronal changes and gene expression