Neurotensin inversely modulates maternal aggression

A protein-coding gene expression atlas from the brain of pregnant and non-pregnant goats

Background: The brain is an extraordinarily complex organ with multiple anatomical structures involved in highly specialized functions related with behavior and physiological homeostasis. Our goal was to build an atlas of protein-coding gene expression in the goat brain by sequencing the transcriptomes of 12 brain regions in seven female Murciano-Granadina goats, from which three of them were 1-month pregnant. Results: Between 14,889 (cerebellar hemisphere) and 15,592 (pineal gland) protein-coding genes were expressed in goat brain regions, and most of them displayed ubiquitous or broad patterns of expression across tissues. Principal component analysis and hierarchical clustering based on the patterns of mRNA expression revealed that samples from certain brain regions tend to group according to their position in the anterior-posterior axis of the neural tube, i.e., hindbrain (pons and medulla oblongata), midbrain (rostral colliculus) and forebrain (frontal neocortex, olfactory bulb, hypothalamus, and hippocampus). Exceptions to this observation were cerebellum and glandular tissues (pineal gland and hypophysis), which showed highly divergent mRNA expression profiles. Differential expression analysis between pregnant and non-pregnant goats revealed moderate changes of mRNA expression in the frontal neocortex, hippocampus, adenohypophysis and pons, and very dramatic changes in the olfactory bulb. Many genes showing differential expression in this organ are related to olfactory function and behavior in humans. Conclusion: With the exception of cerebellum and glandular tissues, there is a relationship between the cellular origin of sampled regions along the anterior-posterior axis of the neural tube and their mRNA expression patterns in the goat adult brain. Gestation induces substantial changes in the mRNA expression of the olfactory bulb, a finding consistent with the key role of this anatomical structure on the development of maternal behavior.

Transcriptomic changes associated with maternal care in the brain of mouthbrooding cichlid Astatotilapia burtoni reflect adaptation to self-induced metabolic stress

Parental care in Astatotilapia burtoni entails females protecting eggs and developing fry in a specialized buccal cavity in the mouth. During this mouthbrooding behavior, which can last 2-3 weeks, mothers undergo voluntary fasting accompanied by loss of body mass and major metabolic changes. Following release of fry, females resume normal feeding behavior and quickly recover body mass as they become reproductively active once again. In order to investigate the molecular underpinnings of such dramatic behavioral and metabolic changes, we sequenced whole-brain transcriptomes from females at four time points throughout their reproductive cycle: 2 days after the start of mouthbrooding, 14 days after the start of mouthbrooding, 2 days after the release of fry and 14 days after the release of fry. Differential expression analysis and clustering of expression profiles revealed a number of neuropeptides and hormones, including the strong candidate gene neurotensin, suggesting that molecular mechanisms underlying parental behaviors may be common across vertebrates despite de novo evolution of parental care in these lineages. In addition, oxygen transport pathways were found to be dramatically downregulated, particularly later in the mouthbrooding stage, while certain neuroprotective pathways were upregulated, possibly to mitigate negative consequences of metabolic depression brought about by fasting. Our results offer new insights into the evolution of parental behavior as well as revealing candidate genes that would be of interest for the study of hypoxic ischemia and eating disorders.

Neurotranscriptomic changes associated with chick-directed parental care in adult non-reproductive Japanese quail

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.

Lack of NPY in neurotensin neurons leads to a lean phenotype

Neuropeptide Y (NPY) producing neurons in the arcuate nucleus (Arc) of the hypothalamus are essential to the regulation of food intake and energy homeostasis. Whilst they have classically been thought to co-express agouti-related peptide (AgRP), it is now clear that there is a sub-population of NPY neurons in the Arc that do not. Here, we show that a subset of AgRP-negative, NPY-positive neurons in the Arc also express neurotensin (NTS) and we use an NTS-Cre line to investigate the function of this sub-population of NPY neurons. The lack of NPY in NTS-positive neurons led to a marked reduction in fat mass and bodyweight as well as a significant reduction in food intake in male NPY^lox/lox; NTS^cre/+ mice compared to controls. Despite the reduction in food intake, overall energy expenditure was similar between genotypes due to concomitant reduction in activity in NPY^lox/lox; NTS^cre/+ mice. Furthermore, cortical bone mass was significantly reduced in NPY^lox/lox;NTS^cre/+ mice with no evident alterations in the cancellous bone compartment, likely due to reduced leptin levels as a result of their reduced adiposity. Taken together, these data suggest that the sub-population of Arc NPY neurons expressing NTS are critical for regulating food intake, activity and fat mass but are not directly involved in the control of bone mass.

Neurotensin in reward processes

Neurotensin (NTS) is a neuropeptide neurotransmitter expressed in the central and peripheral nervous systems. Many studies over the years have revealed a number of roles for this neuropeptide in body temperature regulation, feeding, analgesia, ethanol sensitivity, psychosis, substance use, and pain. This review provides a general survey of the role of neurotensin with a focus on modalities that we believe to be particularly relevant to the study of reward. We focus on NTS signaling in the ventral tegmental area, nucleus accumbens, lateral hypothalamus, bed nucleus of the stria terminalis, and central amygdala. Studies on the role of NTS outside of the ventral tegmental area are still in their relative infancy, yet they reveal a complex role for neurotensinergic signaling in reward-related behaviors that merits further study. This article is part of the special issue on 'Neuropeptides'.

Gender Related Changes in Gene Expression Induced by Valproic Acid in A Mouse Model of Autism and the Correction by S-adenosyl Methionine. Does It Explain the Gender Differences in Autistic Like Behavior?

In previous studies we produced autism like behavioral changes in mice by Valproic acid (VPA) with significant differences between genders. S-adenosine methionine (SAM) prevented the autism like behavior in both genders. The expression of 770 genes of pathways involved in neurophysiology and neuropathology was studied in the prefrontal cortex of 60 days old male and female mice using the NanoString nCounter. In females, VPA induced statistically significant changes in the expression of 146 genes; 71 genes were upregulated and 75 downregulated. In males, VPA changed the expression of only 19 genes, 16 were upregulated and 3 downregulated. Eight genes were similarly changed in both genders. When considering only the genes that were changed by at least 50%, VPA changed the expression of 15 genes in females and 3 in males. Only Nts was similarly downregulated in both genders. SAM normalized the expression of most changed genes in both genders. We presume that genes that are involved in autism like behavior in our model were similarly changed in both genders and corrected by SAM. The behavioral and other differences between genders may be related to genes that were differently affected by VPA in males and females and/or differently affected by SAM.

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Neurotensin (Nts) is a neuropeptide implicated in the regulation of many facets of physiology, including cardiovascular tone, pain processing, ingestive behaviors, locomotor drive, sleep, addiction and social behaviors. Yet, there is incomplete understanding about how the various populations of Nts neurons distributed throughout the brain mediate such physiology. This knowledge gap largely stemmed from the inability to simultaneously identify Nts cell bodies and manipulate them in vivo. One means of overcoming this obstacle is to study Nts^Cre mice crossed onto a Cre-inducible green fluorescent reporter line (Nts^Cre;GFP mice), as these mice permit both visualization and in vivo modulation of specific populations of Nts neurons (using Cre-inducible viral and genetic tools) to reveal their function. Here we provide a comprehensive characterization of the distribution and relative densities of the Nts-GFP populations observed throughout the male Nts^Cre;GFP mouse brain, which will pave the way for future work to define their physiologic roles. We also compared the distribution of Nts-GFP neurons with Nts-In situ Hybridization (Nts-ISH) data from the adult mouse brain. By comparing these data sets we can distinguish Nts-GFP populations that may only transiently express Nts during development but not in the mature brain, and hence which populations may not be amenable to Cre-mediated manipulation in adult Nts^Cre;GFP mice. This atlas of Nts-GFP neurons will facilitate future studies using the Nts^Cre;GFP line to describe the physiological functions of individual Nts populations and how modulating them may be useful to treat disease.

Determination of neurotensin projections to the ventral tegmental area in mice

Pharmacologic treatment with the neuropeptide neurotensin (Nts) modifies motivated behaviors such as feeding, locomotor activity, and reproduction. Dopamine (DA) neurons of the ventral tegmental area (VTA) control these behaviors, and Nts directly modulates the activity of DA neurons via Nts receptor-1. While Nts sources to the VTA have been described in starlings and rats, the endogenous sources of Nts to the VTA of mice remain incompletely understood, impeding determination of which Nts circuits orchestrate specific behaviors in this model. To overcome this obstacle we injected the retrograde tracer Fluoro-Gold into the VTA of mice that express GFP in Nts neurons. Identification of GFP-Nts cells that accumulate Fluoro-Gold revealed the Nts afferents to the VTA in mice. Similar to rats, most Nts afferents to the VTA of mice arise from the medial and lateral preoptic areas (POA) and the lateral hypothalamic area (LHA), brain regions that are critical for coordination of feeding and reproduction. Additionally, the VTA receives dense input from Nts neurons in the nucleus accumbens shell (NAsh) of mice, and minor Nts projections from the amygdala and periaqueductal gray area. Collectively, our data reveal multiple populations of Nts neurons that provide direct afferents to the VTA and which may regulate specific aspects of motivated behavior. This work lays the foundation for understanding endogenous Nts actions in the VTA, and how circuit-specific Nts modulation may be useful to correct motivational and affective deficits in neuropsychiatric disease.

Song in an Affiliative Context Relates to the Neural Expression of Dopamine- and Neurotensin-Related Genes in Male European Starlings

Some animals, including songbirds, vocalize at high rates when alone or in large groups. In songbirds, vocal behavior in these contexts is important for song learning and group cohesion. It is not obviously targeted at any particular individual and is described as 'undirected'. Studies suggest a role for dopamine (DA) in undirected song. The neuropeptide neurotensin (NT) can enhance dopaminergic signaling upon binding to the NT receptor 1 (NTR1) and is found in regions where DA can influence song, including the ventral tegmental area (VTA), septum, and the song control nucleus Area X. To begin to test the hypothesis that NT and DA in these regions interact to influence undirected song, we used quantitative real-time PCR to relate undirected singing to mRNA expression of NT, NTR1, tyrosine hydroxylase (TH; a synthetic enzyme for DA) and D1 and D2 receptors in male European starlings. TH and NT expression in VTA, and NT and D1 expression in Area X, positively correlated with song. NT markers also correlated positively with DA markers in VTA. Given the role of VTA projections to Area X in song learning, these results suggest that interactions between NT and DA in these regions may contribute to vocal learning. In septum, NTR1 expression positively correlated with song and NT and DA markers were correlated, suggesting that NT in this region may influence dopaminergic transmission to facilitate undirected vocalizations. Overall, these findings implicate interactions between NT and DA in affiliative communication.

Neurotensin neural mRNA expression correlates with vocal communication and other highly-motivated social behaviors in male European starlings

Vocalizations coordinate social interactions in many species and often are important for behaviors such as mate attraction or territorial defense. Although the neural circuitry underlying vocal communication is well-known for some animal groups, such as songbirds, the motivational processes that regulate vocal signals are not as clearly understood. Neurotensin (NT) is a neuropeptide implicated in motivation that can modulate the activity of dopaminergic neurons. Dopaminergic projections from the ventral tegmental area (VTA) are key to mediating highly motivated, goal-directed behaviors, including sexually-motivated birdsong. However, the role of NT in modifying vocal communication or other social behaviors has not been well-studied. Here in European starlings (Sturnus vulgaris) we analyzed relationships between sexually-motivated song and NT and NT1 receptor (NTSR1) expression in VTA. Additionally, we examined NT and NTSR1 expression in four regions that receive dopaminergic projections from VTA and are involved in courtship song: the medial preoptic nucleus (POM), the lateral septum (LS), Area X, and HVC. Relationships between NT and NTSR1 expression and non-vocal courtship and agonistic behaviors were also examined. NT expression in Area X positively related to sexually-motivated song production. NT expression in POM positively correlated with non-vocal courtship behavior and agonistic behavior. NT expression in POM was greatest in males owning nesting sites, and the opposite pattern was observed for NTSR1 expression in LS. These results are the first to implicate NT in Area X in birdsong, and further highlight NT as a potential neuromodulator for the control of vocal communication and other social behaviors.

Maternally responsive neurons in the bed nucleus of the stria terminalis and medial preoptic area: Putative circuits for regulating anxiety and reward

Postpartum neuropsychiatric disorders are a major source of morbidity and mortality and affect at least 10% of childbearing women. Affective dysregulation within this context has been identified in association with changes in reproductive steroids. Steroids promote maternal actions and modulate affect, but can also destabilize mood in some but not all women. Potential brain regions that mediate these effects include the medial preoptic area (mPOA) and ventral bed nucleus of the stria terminalis (vBNST). Herein, we review the regulation of neural activity in the mPOA/vBNST by environmental and hormonal concomitants in puerperal females. Such activity may influence maternal anxiety and motivation and have significant implications for postpartum affective disorders. Future directions for research are also explored, including physiological circuit-level approaches to gain insight into the functional connectivity of hormone-responsive maternal circuits that modulate affect.

Neurotensin immunolabeling relates to sexually-motivated song and other social behaviors in male European starlings (Sturnus vulgaris)

The brain regions involved in vocal communication are well described for some species, including songbirds, but less is known about the neural mechanisms underlying motivational aspects of communication. Mesolimbic dopaminergic projections from the ventral tegmental area (VTA) are central to mediating motivated behaviors. In songbirds, VTA provides dopaminergic innervation to brain regions associated with motivation and social behavior that are also involved in sexually-motivated song production. Neurotensin (NT) is a neuropeptide that strongly modulates dopamine activity, co-localizes with dopamine in VTA, and is found in regions where dopaminergic cells project from VTA. Yet, little is known about how NT contributes to vocal communication or other motivated behaviors. We examined the relationships between sexually-motivated song produced by male European starlings (Sturnus vulgaris) and NT immunolabeling in brain regions involved in social behavior and motivation. Additionally, we observed relationships between NT labeling, non-vocal courtship behaviors (another measure of sexual motivation), and agonistic behavior to begin to understand NT's role in socially-motivated behaviors. NT labeling in VTA, lateral septum, and bed nucleus of the stria terminalis correlated with sexually-motivated singing and non-vocal courtship behaviors. NT labeling in VTA, lateral septum, medial preoptic nucleus, and periaqueductal gray was associated with agonistic behavior. This study is the first to suggest NT's involvement in song, and one of the few to implicate NT in social behaviors more generally. Additionally, our results are consistent with the idea that distinct patterns of neuropeptide activity in brain areas involved in social behavior and motivation underlie differentially motivated behaviors.

Brain serotonin determines maternal behavior and offspring survival

Maternal care is an indispensable component of offspring survival and development in all mammals and necessary for reproductive success. Although brain areas regulating maternal behaviors are innervated by serotonergic afferents, very little is known about the role of this neurotransmitter in these behaviors. To evaluate the contribution of serotonin to maternal care, we used mice with a null mutation in the gene for tryptophan hydroxylase-2 (TPH2), which results in a genetic depletion of brain serotonin, and tested them in a wide range of maternal behavior paradigms. We found that litters born to and reared by TPH2(-/-) mothers showed decreased survival, lower weaning weights and increased cannibalization. In addition, TPH2(-/-) mothers performed poorly in pup retrieval, huddling, nest construction and high-arched back nursing. Aggression in TPH2(-/-) dams was not triggered by lactation and was steadily high. Survival and weaning weight deficits of TPH2(-/-) pups were rescued by cross-fostering and in litters of mixed genotype (TPH2(-/-) and TPH2(-/+) ). However, the maternal behaviors of TPH2(-/-) dams did not improve when rearing either TPH2(+/+) pups or mixed-genotype litters. In addition, TPH2(-/-) pups significantly worsened the behavior of TPH2(+/+) dams with respect to cannibalism, weaning weight and latency to attack. Olfactory and auditory functions of TPH2(-/-) females or anxiety-like behaviors did not account for these maternal alterations as they were equal to their TPH2(+/+) counterparts. These findings illustrate a profound influence of brain serotonin on virtually all elements of maternal behavior and establish that TPH2(-/-) pups can engender maladaptive mothering in dams of both genotypes.

Endogenous CNS expression of neurotensin and neurotensin receptors is altered during the postpartum period in outbred mice

Neurotensin (NT) is a neuropeptide identical in mice and humans that is produced and released in many CNS regions associated with maternal behavior. NT has been linked to aspects of maternal care and previous studies have indirectly suggested that endogenous NT signaling is altered in the postpartum period. In the present study, we directly examine whether NT and its receptors exhibit altered gene expression in maternal relative to virgin outbred mice using real time quantitative PCR (qPCR) across multiple brain regions. We also examine NT protein levels using anti-NT antibodies and immunohistochemistry in specific brain regions. In the medial preoptic area (MPOA), which is critical for maternal behaviors, mRNA of NT and NT receptor 3 (Sort1) were significantly up-regulated in postpartum mice compared to virgins. NT mRNA was also elevated in postpartum females in the bed nucleus of the stria terminalis dorsal. However, in the lateral septum, NT mRNA was down-regulated in postpartum females. In the paraventricular nucleus of the hypothalamus (PVN), Ntsr1 expression was down-regulated in postpartum females. Neurotensin receptor 2 (Ntsr2) expression was not altered in any brain region tested. In terms of protein expression, NT immunohistochemistry results indicated that NT labeling was elevated in the postpartum brain in the MPOA, lateral hypothalamus, and two subregions of PVN. Together, these findings indicate that endogenous changes occur in NT and its receptors across multiple brain regions, and these likely support the emergence of some maternal behaviors.

Vascular calcification in diabetes: mechanisms and implications

Cardiovascular disease (CVD) remains the leading cause of death among adults with diabetes, and CVD prevention remains a major challenge. Coronary artery calcium (CAC) score measured by electron beam tomography (EBT) or multi-slice detector computed tomography correlates closely with plaque burden and coronary angiography, and predicts coronary events independently of other risk factors. Further, progression of CAC over several years has been shown to predict increased mortality. Coronary calcification is an active process strongly associated with atherosclerotic plaque evolution and is an accepted surrogate endpoint in studies of patients with diabetes older than 30. In this review, recent findings regarding the mechanisms and implications of vascular calcification in diabetes will be discussed.

Both oxytocin and vasopressin are mediators of maternal care and aggression in rodents: from central release to sites of action

In the mammalian peripartum period, the activity of both the brain oxytocin and vasopressin system is elevated as part of the physiological adaptations occurring in the mother. This is reflected by increased expression and intracerebral release of oxytocin and vasopressin, as well as increased neuropeptide receptor expression and binding. In this review we discuss the functional role of the brain oxytocin and vasopressin system in the context of maternal behavior, specifically maternal care and maternal aggression in rodents. In order to enable the identification of significant and peptide-specific contributions to the display of maternal behavior, various complementary animal models of maternal care and/or maternal aggression were studied, including rats selectively bred for differences in anxiety-related behavior (HAB and LAB dams), monitoring of local neuropeptide release during ongoing maternal behavior, and local pharmacological or genetic manipulations of the neuropeptide systems. The medial preoptic area was identified as a major site for oxytocin- and vasopressin-mediated maternal care. Furthermore, both oxytocin and vasopressin release and receptor activation in the central amygdala and the bed nucleus of the stria terminalis play an important role for maternal aggression. This article is part of a Special Issue entitled Oxytocin, Vasopressin, and Social Behavior.

Neurotensin induced Egr-1 activity is altered in the postpartum period in mice

Neurotensin (NT) is a 13 amino acid neuropeptide that is identical in mice and humans and is released from and acts upon a number of social brain regions. Recent work indicates NT neurotransmission may be altered in postpartum females and support the onset of some maternal behaviors. In a recent study, we highlighted how virgin and postpartum brains from mice selected for high offspring protection differ in response to injected NT (0.1 μg) relative to vehicle when examining c-Fos profiles across the CNS. In this companion study we use a second marker for brain activity, Egr-1, and evaluate multiple brain regions. Common significant increased Egr-1 responses to NT (relative to vehicle) were found in both female groups only in ventromedial hypothalamus. In lateral periaqueductal gray, virgin mice showed a significant Egr-1 increase with NT (relative to vehicle), but maternal mice did not. When comparing NT injections, virgin (relative to maternal) mice had significantly higher activity in five regions, including anterior hypothalamus, lateral hypothalamus, somatosensory cortex, paraventricular nucleus, and zona incerta; no regions were higher in maternal mice. A Principal Components Analysis was also used for data mining and in virgin mice, greater changes in activity hubs were found with NT (relative to vehicle) than for maternal mice. Overall, a lower sensitivity to NT in terms of Egr-1 reactivity in the maternal state was highlighted and this is consistent with previous c-Fos results. These findings provide additional insight into the mechanisms by which NT functions in the CNS.

Changes in CNS response to neurotensin accompany the postpartum period in mice

Neurotensin (NT) is a highly conserved neuropeptide in mammals. Recent studies suggest that altered NT neurotransmission in postpartum females could promote the emergence of some maternal behaviors, including offspring protection. Here we evaluated how virgin and postpartum brains from mice selected for high maternal defense differ in response to NT. Virgin and postpartum mice were injected with either vehicle or 0.1 μg NT icv and brains were evaluated for c-Fos immunoreactivity, an indirect marker of neuronal activity. Using ANOVA analysis, common significant responses to NT were found in both female groups in four brain regions, including supraoptic nucleus, ventromedial nucleus, bed nucleus of stria terminalis dorsal, and a subregion of lateral septum (LS). For postpartum mice, only one additional region showed a significant response to NT relative to vehicle, whereas for virgin mice seven unique brain regions showed a significant c-Fos response: nucleus accumbens shell, paraventricular nucleus, central amygdala, and substantia nigra. Using a principal components analysis of c-Fos, we identified regions within each group with highly correlated activity. As expected, virgin and postpartum mice (vehicle conditions) showed different activity hubs and in the postpartum group the hubs matched regions linked to maternal care. The response to injected NT was different in the maternal and virgin groups with maternal mice showing a stronger coordinated activity in periaqueductal gray whereas virgin mice showed a stronger septal and amygdala linking of activity. Together, these results indicate neuronal responses of virgin and postpartum mice to NT and highlight pathways by which NT can alter maternal responses.

GABAA receptor signaling in caudal periaqueductal gray regulates maternal aggression and maternal care in mice

Maternal aggression (maternal defense) is exhibited by lactating females towards intruders and contributes to the protection of offspring. Enhancement of Gamma-Aminobutyric acid (GABA)(A) receptor signaling by benzodiazepines elevates maternal aggression, and we previously found indirect evidence (via c-Fos immunohistochemistry) that caudal periaqueductal gray (cPAG) and lateral septum (LS) could be sites where benzodiazepines increase aggression. We recently found that GABA(A) receptor signaling in LS modulates maternal aggression, and in this study, we tested the hypothesis that GABA(A) receptor signaling in cPAG also regulates this behavior. Site-directed injections to cPAG were made in lactating mice using the GABA(A) receptor antagonist, bicuculline (3-9 ng) or the GABA(A) receptor positive modulator, chlordiazepoxide (CDP), a benzodiazepine (2.5-20 microg). Maternal aggression, other maternal behaviors, and anxiety-like measures (using the light-dark box) were then examined. GABA(A) receptor positive modulator did not increase aggression, which could have resulted from a ceiling effect. However, 8 ng and 9 ng of bicuculline in cPAG significantly decreased maternal aggression without altering other maternal behaviors or light-dark box performance, suggesting some GABA(A) receptor signaling in cPAG is required for full maternal aggression expression. Additionally, 7 ng of bicuculline significantly increased licking/grooming of pups, and decreased the number of transitions between the light and dark compartments of the light-dark box without affecting aggression. Given these results indicating that antagonizing GABA(A) receptor in cPAG dose-dependently promotes offspring grooming behavior while impairing aggression, it is possible that the cPAG represents a key site for decision making (aggression versus other behaviors) in the lactating female.

GABA(A) receptor signaling in the lateral septum regulates maternal aggression in mice

Maternal aggression (maternal defense) is a fierce aggression produced by lactating females toward intruders that plays an important role in protection of vulnerable offspring. Enhancement of GABA(A) receptor signaling by benzodiazepines increases maternal aggression, and we recently found indirect evidence that lateral septum (LS) could be a key site where benzodiazepines elevate aggression. In this study, we directly tested the hypothesis that activation of GABA(A) receptors in LS would promote maternal aggression while inhibition of this receptor would decrease aggression. Site-directed injections to LS were made using the GABA(A) receptor antagonist, bicuculline (3-30 ng), or the GABA(A) receptor agonists, chlordiazepoxide, a benzodiazepine (2.5-5 microg), and muscimol (0.05-5 ng). Maternal aggression and other behavioral measures were then evaluated in lactating mice. Neither GABA(A) receptor agonist elevated aggression, which could reflect a ceiling effect. However, 7 ng of the GABA(A) receptor antagonist, bicuculline, in LS significantly decreased maternal aggression without altering other maternal behaviors or light-dark box performance, suggesting some GABA(A) receptor signaling in LS is required for full maternal aggression expression. Together, these results confirm a role for GABA(A) receptor signaling in LS in the regulation of maternal aggression.