The brain atlas of a subsocial bee reflects that of eusocial Hymenoptera
The evolutionary transition from solitary life to group-living in a society with cooperative brood care, reproductive division of labor and morphological castes is associated with increased cognitive demands for task-specialization. Associated with these demands, the brains of eusocial Hymenoptera divide transcriptomic signatures associated with foraging and reproduction to different populations of cells and also show diverse astrocyte and Kenyon cell types compared with solitary non-hymenopteran insects. The neural architecture of subsocial bees, which represent evolutionary antecedent states to eusocial Hymenoptera, could then show how widely this eusocial brain is conserved across aculeate Hymenoptera. Using single-nucleus transcriptomics, we have created an atlas of neuron and glial cell types from the brain of a subsocial insect, the small carpenter bee (Ceratina calcarata). The proportion of C. calcarata neurons related to the metabolism of classes of neurotransmitters is similar to that of other insects, whereas astrocyte and Kenyon cell types show highly similar gene expression patterns to those of eusocial Hymenoptera. In the winter, the transcriptomic signature across the brain reflected diapause. When the bee was active in the summer, however, genes upregulated in neurons reflected foraging, while the gene expression signature of glia associated with reproductive functions. Like eusocial Hymenoptera, we conclude that neural components for foraging and reproduction in C. calcarata are compartmentalized to different parts of its brain. Cellular examination of the brains of other solitary and subsocial insects can show the extent of neurobiological conservation across levels of social complexity.
Stress enhances aggression in male rats with genetic stress hyper-reactivity
The current study investigated stress-induced aggressive behavior in the resident-intruder test in males of the genetically stress hyper-reactive Wistar Kyoto More Immobile (WMI), and the nearly isogenic, control Wistar Kyoto Less Immobile (WLI) strains. Tests were carried out against same-age intruders during adolescence, and same-age and juvenile intruders in adulthood. In adolescence and adulthood, prior acute restraint stress decreased social interactions and decreased aggressive behaviors of adolescents and adult WLIs. However, prior stress precipitated aggression in the adult WMI males toward both same-age, and juvenile intruders compared with control WMIs and WLIs. Trunk blood levels of testosterone and androstenedione increased in stressed WLIs, but not in WMIs, suggesting no direct role of androgens in the increased aggression of WMIs. Expressions of aggression-relevant genes showed patterns commensurate with being causative in aggressive behavior. The methyl-CpG binding protein 2 was lower in the frontal cortex of control WMIs, and in the amygdala of stressed WMIs compared with their respective WLIs. Frontal cortex expression of vasopressin receptor 1a and serotonin transporter increased, solely in WMI males after stress. As behaviors were the same toward same-age and non-threatening juvenile intruders, the stress-induced increase in confrontational behavior of the adult WMI male was not because of enhanced fear or anxiety. These results suggest that genetic stress hyper-reactivity is a risk factor for stress-induced increases in aggression in males. Additionally, as known aggression-related genes showed expression patterns paralleling aggressive behavior, this model system could identify novel molecular pathways leading to stress-enhanced aggression.
Commensal bacteria exacerbate seizure-like phenotypes in Drosophila voltage-gated sodium channel mutants
Mutations in voltage-gated sodium (Na) channels, which are essential for generating and propagating action potentials, can lead to serious neurological disorders, such as epilepsy. However, disease-causing Na channel mutations do not always result in severe symptoms, suggesting that the disease conditions are significantly affected by other genetic factors and various environmental exposures, collectively known as the "exposome". Notably, recent research emphasizes the pivotal role of commensal bacteria in neural development and function. Although these bacteria typically benefit the nervous system under normal conditions, their impact during pathological states remains largely unknown. Here, we investigated the influence of commensal microbes on seizure-like phenotypes exhibited by para-a gain-of-function mutant of the Drosophila Na channel gene, paralytic. Remarkably, the elimination of endogenous bacteria considerably ameliorated neurological impairments in para. Consistently, reintroducing bacteria, specifically from the Lactobacillus or Acetobacter genera, heightened the phenotypic severity in the bacteria-deprived mutants. These findings posit that particular native bacteria contribute to the severity of seizure-like phenotypes in para. We further uncovered that treating para with antibiotics boosted Nrf2 signaling in the gut, and that global Nrf2 activation mirrored the effects of removing bacteria from para. This raises the possibility that the removal of commensal bacteria suppresses the seizure-like manifestations through augmented antioxidant responses. Since bacterial removal during development was critical for suppression of adult para phenotypes, our research sets the stage for subsequent studies, aiming to elucidate the interplay between commensal bacteria and the developing nervous system in conditions predisposed to the hyperexcitable nervous system.
Divergent neural nodes are species- and hormone-dependent in the brood parasitic brain
Avian brood parasitism is an evolutionarily derived behavior for which the neurobiological mechanisms are mostly unexplored. We aimed to identify brain regions that have diverged in the brood-parasitic brain using relative transcript abundance of social neuropeptides and receptors. We compared behavioral responses and transcript abundance in three brain regions in the brown-headed cowbird (BHCO), a brood parasite, and a closely related parental species, the red-winged blackbird (RWBL). Females of both species were treated with mesotocin (MT; avian homolog of oxytocin) or saline prior to exposure to nest stimuli. Results reveal that MT promotes approach toward nests with eggs rather than nests with begging nestlings in both species. We also examined relative transcript abundance of the five social neuropeptides and receptors in the brain regions examined: preoptic area (POA), paraventricular nucleus (PVN) and bed nucleus of the stria terminalis (BST). We found that MT-treated cowbirds but not blackbirds exhibited lower transcript abundance for two receptors, corticotropin-releasing factor 2 (CRFR2) and prolactin receptor (PRLR) in BST. Additionally, MT-treated cowbirds had higher PRLR in POA, comparable to those found in blackbirds, regardless of treatment. No other transcripts of interest exhibited significant differences as a result of MT treatment, but we found a significant effect of species in the three regions. Together, these results indicate that POA, PVN, and BST represent neural nodes that have diverged in avian brood parasites and may serve as neural substrates of brood-parasitic behavior.
Cognitive behavioral phenotyping of DSCAM heterozygosity as a model for autism spectrum disorder
It is estimated that 1 in 36 children are affected by autism spectrum disorder (ASD) in the United States, which is nearly a twofold increase from a decade ago. Recent genetic studies have identified de novo loss-of-function (dnLoF) mutations in the Down Syndrome Cell Adhesion Molecule (DSCAM) as a strong risk factor for ASD. Previous research has shown that DSCAM ablation confers social interaction deficits and perseverative behaviors in mouse models. However, it remains unknown to what extent DSCAM underexpression captures the full range of behaviors, specifically cognitive phenotypes, presented in ASD. Here, we conducted a comprehensive cognitive behavioral phenotyping which revealed that loss of one copy of DSCAM, as in the DSCAM+/-, that is, DSCAM heterozygous mice, displayed hyperactivity, increased anxiety-like behavior, and motor coordination deficits. Additionally, hippocampal-dependent learning and memory was affected, including impairments in working memory, long-term memory, and contextual fear learning. Interestingly, implicit learning processes remained intact. Therefore, DSCAM LoF produces autistic-like behaviors that are similar to those observed in human cases of ASD. These findings further support a role for DSCAM dnLoF mutations in ASD and suggest DSCAM+/- as a suitable model for ASD research.
Mical1 deletion in tyrosinase expressing cells affects mouse running gaits
Neuronal development is a highly regulated process that is dependent on the correct coordination of cellular responses to extracellular cues. In response to semaphorin axon guidance proteins, the MICAL1 protein is stimulated to produce reactive oxygen species that oxidize actin on specific methionine residues, leading to filamentous actin depolymerization and consequent changes in neuronal growth cone dynamics. Crossing genetically modified mice homozygous for floxed Mical1 (Mical1) alleles with transgenic mice expressing Cre recombinase under the control of a tyrosinase gene enhancer/promoter (Tyr::Cre) enabled conditional Mical1 deletion. Immunohistochemical analysis showed Mical1 expression in the cerebellum, which plays a prominent role in the coordination of motor movements, with reduced Mical1 expression in Mical1 mice co-expressing Tyr::Cre. Analysis of the gaits of mice running on a treadmill showed that both male and female Mical1, Tyr::Cre mutant mice had significant alterations to their striding patterns relative to wild-type mice, although the specific aspects of their altered gaits differed between the sexes. Additional motor tests that involved movement on a rotating rod, descending a vertical pole, or crossing a balance beam did not show significant differences between the genotypes, suggesting that the effect of the Mical1, Tyr::Cre genetic modifications was only manifested during specific highly coordinated movements that contribute to running. These findings indicate that there is a behavioral consequence in Mical1, Tyr::Cre mutant mice that affects motor control as manifested by alterations in their gait.
A GWAS for grip strength in cohorts of children-Advantages of analysing young participants for this trait
Grip strength (GS) is a proxy measure for muscular strength and a predictor for bone fracture risk among other diseases. Previous genome-wide association studies (GWASs) have been conducted in large cohorts of adults focusing on scores collected for the dominant hand, therefore increasing the likelihood of confounding effects by environmental factors. Here, we perform the first GWAS meta-analyses on maximal GS with the dominant (GSD) and non-dominant (GSND) hand in two cohorts of children (ALSPAC, N = 5450; age range = 10.65-13.61; Raine Study, N = 1162, age range: 9.42-12.38 years). We identified a novel significant association for GSND (rs9546244, LINC02465, p = 3.43e-08) and replicated associations previously reported in adults including with a HOXB3 gene marker that shows an expression quantitative trait locus (eQTL) effect. Despite a much smaller sample (~3%) compared with the UK Biobank we replicated correlation analyses previously reported in this much larger adult cohort, such as a negative correlation with coronary artery disease. Although the results from the polygenic risk score (PRS) analyses did not survive multiple testing correction, we observed nominally significant associations between GS and risk of overall fracture, as previously reported, as well ADHD which will require further investigations. Finally, we observed a higher SNP-heritability (24%-41%) compared with previous studies (4%-24%) in adults. Overall, our results suggest that cohorts of children might be better suited for genetic studies of grip strength, possibly due to the shorter exposure to confounding environmental factors compared with adults.
Concentration- and time-dependent behavioural effects of ethanol on Lumbriculus variegatus
Ethanol is one of the most widely used drugs in the world. Ethanol induces profound physiological and behavioural responses in invertebrate model organisms, such as Caenorhabditis elegans and Drosophila melanogaster. Lumbriculus variegatus (Annelida, Oligochaete) is an aquatic worm which shows behavioural responses to common drugs and thus is potentially useful in pharmacological research. The effects of ethanol are unknown in this organism. In this study, we examine the effects of acute exposure to ethanol (0-500 mM) on the stereotypical movements and locomotor activity of L. variegatus and examine the concentration- (0-500 mM) and time-dependent (0-210 min) effects of ethanol in L. variegatus. We show that ≥250 mM ethanol reversibly reduced the ability of tactile stimulation to elicit stereotypical movements, namely body reversal and helical swimming and locomotor activity (p < 0.05, N = 8). We also found that 2 min of exposure to ≥250 mM ethanol rapidly induces steady-state hypokinesis (p < 0.05, N = 11) and confirm ethanol absorption into L. variegatus tissues. Additionally, we also observed acute ethanol tolerance after 150 min of exposure to 500 mM ethanol (p < 0.05, N = 24). This study is the first to report the behavioural effects of ethanol in L. variegatus. Our results show that this is a model organism for use in ethanol studies, providing further evidence for its utility in pharmacological research.
The role of cerebellar FOXP1 in the development of motor and communicative behaviors in mice
The gene FOXP2 is well established for a role in human speech and language; far less is known about FOXP1. However, this related gene has also been implicated in human language development as well as disorders associated with features of autism spectrum disorder (ASD). FOXP1 protein expression has also recently been identified in the cerebellum-a neural structure previously shown to express FOXP2 protein. The current study sought to elucidate the behavioral implications of a conditional knock-out of Foxp1 using an En1-Cre driver, which is active in the entirety of the cerebellum and a subset of neurons in the midbrain and spinal cord, in mice using a test battery including motor tasks associated with cerebellar dysfunction, as well as communicative and autistic-relevant behaviors. Male and female mice with a conditional knock-out (cKO, n = 31) and wildtype littermate controls (WT, n = 34) were assessed for gross and orofacial motor control, motor-coordination learning, locomotion, social behavior, anxiety, auditory processing and expressive vocalizations. Overall results suggest Foxp1 plays a specific role in the development of communicative systems, and phenotypic expression of disruptions may interact with sex. Robust motor deficits associated with Foxp1 protein loss may particularly affect vocalizations based on significant orofacial motor deficits in cKO subjects could also contribute to vocalization anomalies. In summary, the current study provides key insights into the role of Foxp1 in cerebellar function and associated behaviors in mice, with implications for an improved understanding of communicative and motor-based neurodevelopmental disabilities in humans.
Genome-wide association study of delay discounting in Heterogeneous Stock rats
Delay discounting refers to the behavioral tendency to devalue rewards as a function of their delay in receipt. Heightened delay discounting has been associated with substance use disorders and multiple co-occurring psychopathologies. Human and animal genetic studies have established that delay discounting is heritable, but only a few associated genes have been identified. We aimed to identify novel genetic loci associated with delay discounting through a genome-wide association study (GWAS) using Heterogeneous Stock (HS) rats, a genetically diverse outbred population derived from eight inbred founder strains. We assessed delay discounting in 650 male and female HS rats using an adjusting amount procedure in which rats chose between smaller immediate sucrose rewards or a larger reward at various delays. Preference switch points were calculated and both exponential and hyperbolic functions were fitted to these indifference points. Area under the curve (AUC) and the discounting parameter k of both functions were used as delay discounting measures. GWAS for AUC, exponential k, and one indifference point identified significant loci on chromosomes 20 and 14. The gene Slc35f1, which encodes a member of the solute carrier family, was the sole gene within the chromosome 20 locus. That locus also contained an eQTL for Slc35f1, suggesting that heritable differences in the expression might be responsible for the association with behavior. Adgrl3, which encodes a latrophilin subfamily G-protein coupled receptor, was the sole gene within the chromosome 14 locus. These findings implicate novel genes in delay discounting and highlight the need for further exploration.
Transcriptomics analysis reveals potential regulatory role of nSMase2 (Smpd3) in nervous system development and function of middle-aged mouse brains
Neutral sphingomyelinase-2 (nSMase2), gene name sphingomyelin phosphodiesterase-3 (Smpd3), is a key regulatory enzyme responsible for generating the sphingolipid ceramide. The function of nSMase2 in the brain is still controversial. To better understand the functional roles of nSMase2 in the aging mouse brain, we applied RNA-seq analysis, which identified a total of 1462 differentially abundant mRNAs between +/fro and fro/fro, of which 891 were increased and 571 were decreased in nSMase2-deficient mouse brains. The most strongly enriched GO and KEGG annotation terms among transcripts increased in fro/fro mice included synaptogenesis, synapse development, synaptic signaling, axon development, and axonogenesis. Among decreased transcripts, enriched annotations included ribosome assembly and mitochondrial protein complex functions. KEGG analysis of decreased transcripts also revealed overrepresentation of annotations for Alzheimer's disease (AD), Parkinson's disease (PD), and Huntington disease (HD). Ingenuity Pathway Analysis (IPA) tools predicted lower susceptibility to these neurodegenerative disorders, as well as predictions agreeing with stronger synaptic function, learning, and memory in fro/fro mice. The IPA tools identified signaling proteins, epigenetic regulators, and microRNAs as likely upstream regulators of the broader set of genes encoding the affected transcripts. It also revealed 16 gene networks, each linked to biological processes identified as overrepresented annotations among the affected transcripts by multiple analysis methods. Therefore, the analysis of these RNA-seq data indicates that nSMase2 impacts synaptic function and neural development, and may contribute to the onset and development of neurodegenerative diseases in middle-aged mice.
RNA-sequencing reveals a shared neurotranscriptomic profile in the medial preoptic area of highly social songbirds and rats
Rough-and-tumble play in juvenile rats and song in flocks of adult songbirds outside a breeding context (gregarious song) are two distinct forms of non-sexual social behavior. Both are believed to play roles in the development of sociomotor skills needed for later life-history events, including reproduction, providing opportunities for low-stakes practice. Additionally, both behaviors are thought to be intrinsically rewarded and are associated with a positive affective state. Given the functional similarities of these behaviors, this study used RNA-sequencing to identify commonalities in their underlying neurochemical systems within the medial preoptic area. This brain region is implicated in multiple social behaviors, including song and play, and is highly conserved across vertebrates. DESeq2 and rank-rank hypergeometric overlap analyses identified a shared neurotranscriptomic profile in adult European starlings singing high rates of gregarious song and juvenile rats playing at high rates. Transcript levels for several glutamatergic receptor genes, such as GRIN1, GRIN2A, and GRIA1, were consistently upregulated in highly gregarious (i.e., playful/high singing) animals. This study is the first to directly investigate shared neuromodulators of positive, non-sexual social behaviors across songbirds and mammals. It provides insight into a conserved brain region that may regulate similar behaviors across vertebrates.
The activity-regulated cytoskeleton-associated protein (Arc) functions in a cell type- and sex-specific manner in the adult nucleus accumbens to regulate non-contingent cocaine behaviors
Repeated cocaine use produces adaptations in brain function that contribute to long-lasting behaviors associated with cocaine use disorder (CUD). In rodents, the activity-regulated cytoskeleton-associated protein (Arc) can regulate glutamatergic synaptic transmission, and cocaine regulates Arc expression and subcellular localization in multiple brain regions, including the nucleus accumbens (NAc)-a brain region linked to CUD-related behavior. We show here that repeated, non-contingent cocaine administration in global Arc KO male mice produced a dramatic hypersensitization of cocaine locomotor responses and drug experience-dependent sensitization of conditioned place preference (CPP). In contrast to the global Arc KO mice, viral-mediated reduction of Arc in the adult male, but not female, NAc (shArc) reduced both CPP and cocaine-induced locomotor activity, but without altering basal miniature or evoked glutamatergic synaptic transmission. Interestingly, cell type-specific knockdown of Arc in D1 dopamine receptor-expressing NAc neurons reduced cocaine-induced locomotor sensitization, but not cocaine CPP; whereas, Arc knockdown in D2 dopamine receptor-expressing NAc neurons reduced cocaine CPP, but not cocaine-induced locomotion. Taken together, our findings reveal that global, developmental loss of Arc produces hypersensitized cocaine responses; however, these effects cannot be explained by Arc's function in the adult mouse NAc since Arc is required in a cell type- and sex-specific manner to support cocaine-context associations and locomotor responses.
Correction to "Anxiety-related defensive behavioral responses in mice selectively bred for High and Low Activity"
Memory, mood and associated neuroanatomy in individuals with steroid sulphatase deficiency (X-linked ichthyosis)
Steroid sulphatase (STS) cleaves sulphate groups from steroid hormones, and steroid (sulphate) levels correlate with mood and age-related cognitive decline. In animals, STS inhibition or deletion of the associated gene, enhances memory/neuroprotection and alters hippocampal neurochemistry. Little is known about the consequences of constitutive STS deficiency on memory-related processes in humans. We investigated self-reported memory performance (Multifactorial Memory Questionnaire), word-picture recall and recent mood (Kessler Psychological Distress Scale, K10) in adult males with STS deficiency diagnosed with the dermatological condition X-linked ichthyosis (XLI; n = 41) and in adult female carriers of XLI-associated genetic variants (n = 79); we compared results to those obtained from matched control subjects [diagnosed with ichthyosis vulgaris (IV, n = 98) or recruited from the general population (n = 250)]. Using the UK Biobank, we compared mood/memory-related neuroanatomy in carriers of genetic deletions encompassing STS (n = 28) and non-carriers (n = 34,522). We found poorer word-picture recall and lower perceived memory abilities in males with XLI and female carriers compared with control groups. XLI-associated variant carriers and individuals with IV reported more adverse mood symptoms, reduced memory contentment and greater use of memory aids, compared with general population controls. Mood and memory findings appeared largely independent. Neuroanatomical analysis only indicated a nominally-significantly larger molecular layer in the right hippocampal body of deletion carriers relative to non-carriers. In humans, constitutive STS deficiency appears associated with mood-independent impairments in memory but not with large effects on underlying brain structure; the mediating psychobiological mechanisms might be explored further in individuals with XLI and in new mammalian models lacking STS developmentally.
Human-specific insights into candidate genes and boosted discoveries of novel loci illuminate roles of neuroglia in reading disorders
Reading disorders (RD) are human-specific neuropsychological conditions associated with decoding printed words and/or reading comprehension. So far only a handful of candidate genes segregated in families and 42 loci from genome-wide association study (GWAS) have been identified that jointly provided little clues of pathophysiology. Leveraging human-specific genomic information, we critically assessed the RD candidates for the first time and found substantial human-specific features within. The GWAS candidates (i.e., population signals) were distinct from the familial counterparts and were more likely pleiotropic in neuropsychiatric traits and to harbor human-specific regulatory elements (HSREs). Candidate genes associated with human cortical morphology indeed showed human-specific expression in adult brain cortices, particularly in neuroglia likely regulated by HSREs. Expression levels of candidate genes across human brain developmental stages showed a clear pattern of uplifted expression in early brain development crucial to RD development. Following the new insights and loci pleiotropic in cognitive traits, we identified four novel genes from the GWAS sub-significant associations (i.e., FOXO3, MAPT, KMT2E and HTT) and the Semaphorin gene family with functional priors (i.e., SEMA3A, SEMA3E and SEMA5B). These novel genes were related to neuronal plasticity and disorders, mostly conserved the pattern of uplifted expression in early brain development and had evident expression in cortical neuroglial cells. Our findings jointly illuminated the association of RD with neuroglia regulation-an emerging hotspot in studying neurodevelopmental disorders, and highlighted the need of improving RD phenotyping to avoid jeopardizing future genetic studies of RD.
Behavioral transcriptomic effects of triploidy and probiotic therapy (Bifidobacterium, Lactobacillus, and Lactococcus mixture) on juvenile Chinook salmon (Oncorhynchus tshawytscha)
Aquaculturists use polyploid fish to maximize production albeit with some unintended consequences including compromised behaviors and physiological function. Given benefits of probiotic therapies (e.g., improved immune response, growth, and metabolism), we explored probiotic supplementation (mixture of Bifidobacterium, Lactobacillus, and Lactococcus), to overcome drawbacks. We first examined fish gut bacterial community composition using 16S metabarcoding (via principal coordinate analyses and PERMANOVA) and determined probiotics significantly impacted gut bacteria composition (p = 0.001). Secondly, we examined how a genomic disruptor (triploidy) and diet supplements (probiotics) impact gene transcription and behavioral profiles of hatchery-reared Chinook salmon (Oncorhynchus tshawytscha). Juveniles from four treatment groups (diploid-regular feed, diploid-probiotic feed, triploid-regular feed, and triploid-probiotic feed; n = 360) underwent behavioral assays to test activity, exploration, neophobia, predator evasion, aggression/sociality, behavioral sensitivity, and flexibility. In these fish, transcriptional profiles for genes associated with neural functions (neurogenesis/synaptic plasticity) and biomarkers for stress response and development (growth/appetite) were (i) examined across treatments and (ii) used to describe behavioral phenotypes via principal component analyses and general linear mixed models. Triploids exhibited a more active behavioral profile (p = 0.002), and those on a regular diet had greater Neuropeptide Y transcription (p = 0.02). A growth gene (early growth response protein 1, p = 0.02) and long-term neural development genes (neurogenic differentiation factor, p = 0.003 and synaptysomal-associated protein 25-a, p = 0.005) impacted activity and reactionary profiles, respectively. Overall, our probiotic treatment did not compensate for triploidy. Our research highlights novel applications of behavioral transcriptomics for identifying candidate genes and dynamic, mechanistic associations with complex behavioral repertoires.
Learning, memory and blood-brain barrier pathology in Duchenne muscular dystrophy mice lacking Dp427, or Dp427 and Dp140
Duchenne muscular dystrophy is a severe neuromuscular disorder that is caused by mutations in the DMD gene, resulting in a disruption of dystrophin production. Next to dystrophin expression in the muscle, different isoforms of the protein are also expressed in the brain and lack of these isoforms leads to cognitive and behavioral deficits in patients. It remains unclear how the loss of the shorter dystrophin isoform Dp140 affects these processes. Using a variety of behavioral tests, we found that mdx and mdx mice (which lack Dp427 or Dp427 + Dp140, respectively) exhibit similar deficits in working memory, movement patterns and blood-brain barrier integrity. Neither model showed deficits in spatial learning and memory, learning flexibility, anxiety or spontaneous behavior, nor did we observe differences in aquaporin 4 and glial fibrillary acidic protein. These results indicate that in contrast to Dp427, Dp140 does not play a crucial role in processes of learning, memory and spontaneous behavior.
Re-wiring of the bonded brain: Gene expression among pair bonded female prairie voles changes as they transition to motherhood
Motherhood is a costly life-history transition accompanied by behavioral and neural plasticity necessary for offspring care. Motherhood in the monogamous prairie vole is associated with decreased pair bond strength, suggesting a trade-off between parental investment and pair bond maintenance. Neural mechanisms governing pair bonds and maternal bonds overlap, creating possible competition between the two. We measured mRNA expression of genes encoding receptors for oxytocin (oxtr), dopamine (d1r and d2r), mu-opioids (oprm1a), and kappa-opioids (oprk1a) within three brain areas processing salience of sociosensory cues (anterior cingulate cortex; ACC), pair bonding (nucleus accumbens; NAc), and maternal care (medial preoptic area; MPOA). We compared gene expression differences between pair bonded prairie voles that were never pregnant, pregnant (~day 16 of pregnancy), and recent mothers (day 3 of lactation). We found greater gene expression in the NAc (oxtr, d2r, oprm1a, and oprk1a) and MPOA (oxtr, d1r, d2r, oprm1a, and oprk1a) following the transition to motherhood. Expression for all five genes in the ACC was greatest for females that had been bonded for longer. Gene expression within each region was highly correlated, indicating that oxytocin, dopamine, and opioids comprise a complimentary gene network for social signaling. ACC-NAc gene expression correlations indicated that being a mother (oxtr and d1r) or maintaining long-term pair bonds (oprm1a) relies on the coordination of different signaling systems within the same circuit. Our study suggests the maternal brain undergoes changes that prepare females to face the trade-off associated with increased emotional investment in offspring, while also maintaining a pair bond.
Differentially expressed genes of esophageal tissue in male acute and chronic sleep deprivation mice
Gastroesophageal reflux disease (GERD) is associated with sleep disturbances. However, mechanisms underlying these interactions remain unclear. Male acute and chronic sleep deprivation (SD) mice were used for this study. Mice in the chronic SD group exhibited anxiety- and depression-like behaviors. We further performed high-throughput genome sequencing and bioinformatics analysis to screen for featured differentially expressed genes (DEGs) in the esophageal tissue. The acute SD group, comprised 25 DEGs including 14 downregulated and 11 upregulated genes. Compared with the acute SD group, more DEGs were present in the chronic SD group, with a total of 169 DEGs, including 88 downregulated and 81 upregulated genes. Some DEGs that were closely related to GERD and associated esophageal diseases were significantly different in the chronic SD group. Quantitative real-time polymerase chain reaction verified the downregulation of Krt4, Krt13, Krt15 and Calml3 and upregulation of Baxl1 and Per3. Notably, these DEGs are involved in biological processes, which might be the pathways of the neuroregulatory mechanisms of DEGs expression.
Large analysis of genetic manipulations reveals an inverse correlation between initial alcohol resistance and rapid tolerance phenotypes
Tolerance occurs when, following an initial experience with a substance, more of the substance is required subsequently to induce identical behavioral effects. Tolerance is not well-understood, and numerous researchers have turned to model organisms, particularly Drosophila melanogaster, to unravel its mechanisms. Flies have high translational relevance for human alcohol responses, and there is substantial overlap in disease-causing genes between flies and humans, including those associated with Alcohol Use Disorder. Numerous Drosophila tolerance mutants have been described; however, approaches used to identify and characterize these mutants have varied across time and labs and have mostly disregarded any impact of initial resistance/sensitivity to ethanol on subsequent tolerance development. Here, we analyzed our own, as well as data published by other labs to uncover an inverse correlation between initial ethanol resistance and tolerance phenotypes. This inverse correlation suggests that initial resistance phenotypes can explain many 'perceived' tolerance phenotypes, thus classifying such mutants as 'secondary' tolerance mutants. Additionally, we show that tolerance should be measured as a relative increase in time to sedation between an initial and second exposure rather than an absolute change in time to sedation. Finally, based on our analysis, we provide a method for using a linear regression equation to assess the residuals of potential tolerance mutants. These residuals provide predictive insight into the likelihood of a mutant being a 'primary' tolerance mutant, where a tolerance phenotype is not solely a consequence of initial resistance, and we offer a framework for understanding the relationship between initial resistance and tolerance.