Population coding of predator imminence in the hypothalamus.

Hypothalamic VMHdm SF1 neurons are activated by predator cues and are necessary and sufficient for instinctive defensive responses. However, such data do not distinguish which features of a predator encounter are encoded by VMHdm SF1 neural activity. To address this issue, we imaged VMHdm SF1 neurons at single-cell resolution in freely behaving mice exposed to a natural predator in varying contexts. Our results reveal that VMHdm SF1 neurons do not represent different defensive behaviors, but rather encode predator identity and multiple predator-evoked internal states, including threat-evoked fear/anxiety; neophobia or arousal; predator imminence; and safety. Notably, threat and safety are encoded bi-directionally by anti-correlated subpopulations. Finally, individual differences in predator defensiveness are correlated with differences in VMHdm SF1 response dynamics. Thus, different threat-related internal state variables are encoded by distinct neuronal subpopulations within a genetically defined, anatomically restricted hypothalamic cell class. Highlights: Distinct subsets of VMHdm SF1 neurons encode multiple predator-evoked internal states. Anti-correlated subsets encode safety vs. threat in a bi-directional mannerA population code for predator imminence is identified using a novel assay VMHdm SF1 dynamics correlate with individual variation in predator defensiveness.

Encoding of female mating dynamics by a hypothalamic line attractor.

Females exhibit complex, dynamic behaviours during mating with variable sexual receptivity depending on hormonal status1-4. However, how their brains encode the dynamics of mating and receptivity remains largely unknown. The ventromedial hypothalamus, ventrolateral subdivision contains oestrogen receptor type 1-positive neurons that control mating receptivity in female mice5,6. Here, unsupervised dynamical system analysis of calcium imaging data from these neurons during mating uncovered a dimension with slow ramping activity, generating a line attractor in neural state space. Neural perturbations in behaving females demonstrated relaxation of population activity back into the attractor. During mating, population activity integrated male cues to ramp up along this attractor, peaking just before ejaculation. Activity in the attractor dimension was positively correlated with the degree of receptivity. Longitudinal imaging revealed that attractor dynamics appear and disappear across the oestrus cycle and are hormone dependent. These observations suggest that a hypothalamic line attractor encodes a persistent, escalating state of female sexual arousal or drive during mating. They also demonstrate that attractors can be reversibly modulated by hormonal status, on a timescale of days.

Jellyfish for the study of nervous system evolution and function.

Jellyfish comprise a diverse clade of free-swimming predators that arose prior to the Cambrian explosion. They play major roles in ocean ecosystems via a suite of complex foraging, reproductive, and defensive behaviors. These behaviors arise from decentralized, regenerative nervous systems composed of body parts that generate the appropriate part-specific behaviors autonomously following excision. Here, we discuss the organization of jellyfish nervous systems and opportunities afforded by the recent development of a genetically tractable jellyfish model for systems and evolutionary neuroscience.

A line attractor encoding a persistent internal state requires neuropeptide signaling.

Internal states drive survival behaviors, but their neural implementation is poorly understood. Recently, we identified a line attractor in the ventromedial hypothalamus (VMH) that represents a state of aggressiveness. Line attractors can be implemented by recurrent connectivity or neuromodulatory signaling, but evidence for the latter is scant. Here, we demonstrate that neuropeptidergic signaling is necessary for line attractor dynamics in this system by using cell-type-specific CRISPR-Cas9-based gene editing combined with single-cell calcium imaging. Co-disruption of receptors for oxytocin and vasopressin in adult VMH Esr1+ neurons that control aggression diminished attack, reduced persistent neural activity, and eliminated line attractor dynamics while only slightly reducing overall neural activity and sex- or behavior-specific tuning. These data identify a requisite role for neuropeptidergic signaling in implementing a behaviorally relevant line attractor in mammals. Our approach should facilitate mechanistic studies in neuroscience that bridge different levels of biological function and abstraction.

Causal evidence of a line attractor encoding an affective state.

Continuous attractors are an emergent property of neural population dynamics that have been hypothesized to encode continuous variables such as head direction and eye position1-4. In mammals, direct evidence of neural implementation of a continuous attractor has been hindered by the challenge of targeting perturbations to specific neurons within contributing ensembles2,3. Dynamical systems modelling has revealed that neurons in the hypothalamus exhibit approximate line-attractor dynamics in male mice during aggressive encounters5. We have previously hypothesized that these dynamics may encode the variable intensity and persistence of an aggressive internal state. Here we report that these neurons also showed line-attractor dynamics in head-fixed mice observing aggression6. This allowed us to identify and manipulate line-attractor-contributing neurons using two-photon calcium imaging and holographic optogenetic perturbations. On-manifold perturbations yielded integration of optogenetic stimulation pulses and persistent activity that drove the system along the line attractor, while transient off-manifold perturbations were followed by rapid relaxation back into the attractor. Furthermore, single-cell stimulation and imaging revealed selective functional connectivity among attractor-contributing neurons. Notably, individual differences among mice in line-attractor stability were correlated with the degree of functional connectivity among attractor-contributing neurons. Mechanistic recurrent neural network modelling indicated that dense subnetwork connectivity and slow neurotransmission7 best recapitulate our empirical findings. Our work bridges circuit and manifold levels3, providing causal evidence of continuous attractor dynamics encoding an affective internal state in the mammalian hypothalamus.

Intrinsic Dynamics and Neural Implementation of a Hypothalamic Line Attractor Encoding an Internal Behavioral State.

Line attractors are emergent population dynamics hypothesized to encode continuous variables such as head direction and internal states. In mammals, direct evidence of neural implementation of a line attractor has been hindered by the challenge of targeting perturbations to specific neurons within contributing ensembles. Estrogen receptor type 1 (Esr1)-expressing neurons in the ventrolateral subdivision of the ventromedial hypothalamus (VMHvl) show line attractor dynamics in male mice during fighting. We hypothesized that these dynamics may encode continuous variation in the intensity of an internal aggressive state. Here, we report that these neurons also show line attractor dynamics in head-fixed mice observing aggression. We exploit this finding to identify and perturb line attractor-contributing neurons using 2-photon calcium imaging and holographic optogenetic perturbations. On-manifold perturbations demonstrate that integration and persistent activity are intrinsic properties of these neurons which drive the system along the line attractor, while transient off-manifold perturbations reveal rapid relaxation back into the attractor. Furthermore, stimulation and imaging reveal selective functional connectivity among attractor-contributing neurons. Intriguingly, individual differences among mice in line attractor stability were correlated with the degree of functional connectivity among contributing neurons. Mechanistic modelling indicates that dense subnetwork connectivity and slow neurotransmission are required to explain our empirical findings. Our work bridges circuit and manifold paradigms, shedding light on the intrinsic and operational dynamics of a behaviorally relevant mammalian line attractor.

Anatomically distributed neural representations of instincts in the hypothalamus.

Artificial activation of anatomically localized, genetically defined hypothalamic neuron populations is known to trigger distinct innate behaviors, suggesting a hypothalamic nucleus-centered organization of behavior control. To assess whether the encoding of behavior is similarly anatomically confined, we performed simultaneous neuron recordings across twenty hypothalamic regions in freely moving animals. Here we show that distinct but anatomically distributed neuron ensembles encode the social and fear behavior classes, primarily through mixed selectivity. While behavior class-encoding ensembles were spatially distributed, individual ensembles exhibited strong localization bias. Encoding models identified that behavior actions, but not motion-related variables, explained a large fraction of hypothalamic neuron activity variance. These results identify unexpected complexity in the hypothalamic encoding of instincts and provide a foundation for understanding the role of distributed neural representations in the expression of behaviors driven by hardwired circuits.

Neuropeptide Signaling is Required to Implement a Line Attractor Encoding a Persistent Internal Behavioral State.

Internal states drive survival behaviors, but their neural implementation is not well understood. Recently we identified a line attractor in the ventromedial hypothalamus (VMH) that represents an internal state of aggressiveness. Line attractors can be implemented by recurrent connectivity and/or neuromodulatory signaling, but evidence for the latter is scant. Here we show that neuropeptidergic signaling is necessary for line attractor dynamics in this system, using a novel approach that integrates cell type-specific, anatomically restricted CRISPR/Cas9-based gene editing with microendoscopic calcium imaging. Co-disruption of receptors for oxytocin and vasopressin in adult VMH Esr1 + neurons that control aggression suppressed attack, reduced persistent neural activity and eliminated line attractor dynamics, while only modestly impacting neural activity and sex- or behavior-tuning. These data identify a requisite role for neuropeptidergic signaling in implementing a behaviorally relevant line attractor. Our approach should facilitate mechanistic studies in neuroscience that bridge different levels of biological function and abstraction.

HI-FISH: WHOLE BRAIN IN SITU MAPPING OF NEURONAL ACTIVATION IN DROSOPHILA DURING SOCIAL BEHAVIORS AND OPTOGENETIC STIMULATION.

Monitoring neuronal activity at single-cell resolution in freely moving Drosophila engaged in social behaviors is challenging because of their small size and lack of transparency. Extant methods, such as Flyception, are highly invasive. Whole-brain calcium imaging in head-fixed, walking flies is feasible but the animals cannot perform the consummatory phases of social behaviors like aggression or mating under these conditions. This has left open the fundamental question of whether neurons identified as functionally important for such behaviors using loss- or gain-of-function screens are actually active during the natural performance of such behaviors, and if so during which phase(s). Here we describe a method, called HI-FISH, for brain-wide mapping of active cells expressing the Immediate Early Gene hr38 using a high-sensitivity/low background amplification method called HCR-3.0. Using double-labeling for hr38 mRNA and for GFP, we describe the activity of several classes of aggression-promoting neurons during courtship and aggression, including P1a cells, an intensively studied population of male-specific interneurons. Using HI-FISH in combination with optogenetic activation of aggression-promoting neurons (opto-HI-FISH) we identify candidate downstream functional targets of these cells in a brain-wide, unbiased manner. Finally we compare the activity of P1a neurons during sequential performance of courtship and aggression, using intronic vs. exonic hr38 probes to differentiate newly synthesized nuclear transcripts from cytoplasmic transcripts synthesized at an earlier time. These data provide evidence suggesting that different subsets of P1a neurons may be active during courtship vs. aggression. HI-FISH and associated methods may help to fill an important lacuna in the armamentarium of tools for neural circuit analysis in Drosophila.

Evaluation and comparison of pharmacokinetic profiles and safety of two extended-release buprenorphine formulations in common marmosets (Callithrix jacchus).

While sustained-release buprenorphine (BSR) is used as a long-lasting opioid analgesic in common marmosets (Callithrix jacchus), there are no published studies on pharmaceutical-grade extended-release buprenorphine options such as Ethiqa XR (EXR) for this species. However, BSR is a compounded product and has been reported to cause injection site reactions in multiple species, including marmosets. Additionally, now with the availability of EXR, a pharmaceutical-grade veterinary product, the use of BSR in laboratory animals is not compliant with the Guide for the Care and Use of Laboratory Animals (Guide) unless scientifically justified and approved by the IACUC. We compared pharmacokinetic and safety profiles of BSR (0.15 mg/kg) and EXR (0.1-0.2 mg/kg) administered subcutaneously to adult marmosets. Blood was collected by venipuncture of the saphenous vein at multiple time points (0.25-72 h) and analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). EXR between 0.1 and 0.2 mg/kg resulted in a dose-dependent increase in Cmax (1.43-2.51 ng/mL) and were not statistically different from BSR (1.82 ng/mL). Tmax, lambdaz, and t1/2 were not statistically different between formulations. Mean plasma buprenorphine concentrations for BSR and EXR exceeded the therapeutic threshold (0.1 ng/mL) within 0.25 h and lasted for > 72 h. Mild sedation, but neither respiratory depression nor ataxia, was observed for both formulations. BSR injection sites had significantly higher histopathological scores compared to EXR. Video recordings for monitoring drug-induced behavioral changes showed increased animal activity levels after BSR and EXR versus saline controls. Norbuprenorphine, a buprenorphine metabolite associated with respiratory depression, was detected in the plasma after BSR and EXR administration as well as by in vitro liver microsome assays. In conclusion, we recommend using EXR over BSR as a long-lasting buprenorphine analgesic in marmosets because EXR is a pharmaceutical-grade formulation that is compliant with FDA guidelines and the Guide as well as exhibits comparable PK and safety profiles as BSR.

Age effects on Nazca booby foraging performance are largely constant across variation in the marine environment: Results from a 5-year study in Galápagos.

Foraging outcomes dictate the nutritional resources available to an organism and may vary with intrinsic factors, like age. Thus, understanding how age affects foraging performance, alone or in interaction with extrinsic factors (like environmental quality), improves our understanding of aging processes in the wild. We examined how foraging traits, measured across five breeding seasons, change with age, environmental variation, and their interaction in Nazca boobies (Sula granti), a pelagic seabird in Galápagos. We evaluated the hypotheses that (1) foraging performance is better in middle-aged birds than in young ones, and that (2) foraging performance is better in middle-aged birds than in old ones. Furthermore, favorable environmental conditions will either (3) attenuate age differences in foraging performance (by relieving constraints on young, inexperienced and old, senescent age classes), or (4) accentuate age differences (if middle-aged birds can exploit abundant resources better than other age classes can). Incubating birds tagged with GPS loggers (N = 815) provided data on foraging performance (e.g., total distance traveled, mass gained) to evaluate interactions between age and environmental variation (e.g., sea surface temperature). Poor environmental conditions associated with the cool phase of the El Niño-Southern Oscillation increased foraging effort, including foraging distance and duration, for example. Across age classes, foraging boobies responded similarly to environmental variation except for female mass gain rate: age-related declines in mass gain rate were reduced under favorable environmental conditions. Birds of different ages also searched in somewhat distinct areas in the poor conditions of 2016, but not in other years. In several foraging traits, including foraging duration and distance, female boobies showed predicted early-life improvement and late-life decline, following the established pattern for reproductive traits in this species. Thus, deficits in resource acquisition (this study) may contribute to the poor survival and reproductive outcomes previously observed in old Nazca boobies, particularly in females.

Los resultados del forrajeo determinan los recursos nutricionales disponibles de un organismo, los cuales pueden variar por factores intrínsecos, como la edad. Por lo tanto, el entendimiento de cómo la edad afecta el rendimiento de forrajeo, sola o en interacción con factores extrínsecos (como la calidad ambiental), mejora nuestro entendimiento de los procesos del envejecimiento en la naturaleza. Nosotros examinamos como las características de forrajeo, a lo largo de cinco temporadas reproductivas, cambian con la edad, la variabilidad ambiental y sus interacciones en el Piquero de Nazca (Sula granti), un ave marina pelágica en las Islas Galápagos. Evaluamos las hipótesis que (1) el desempeño de búsqueda de alimentación es mejor en aves adultas que en las jóvenes, y que (2) este desempeño es mejor en aves adultas que en las viejas. Además, las condiciones ambientales favorables (3) atenuaran las diferencias de edades en el rendimiento de forrajeo (aliviando las restricciones en los jóvenes, inexpertos, y viejos), o (4) acentuaran las diferencias de edad (sí los adultos pueden explotar recursos abundantes de mejor forma que otros grupos etarios). Colocamos dispositivos GPS en aves incubadoras (N = 815), para colectar datos sobre el rendimiento del forrajeo (p. ej. distancia total de viaje, incremento de peso) para evaluar las interacciones entre edad y la variación ambiental (p. ej. temperatura superficial del mar). Las condiciones ambientales adversas relacionadas a la fase fría de El Niño Oscilación del Sur incrementaron el esfuerzo de forrajeo (la distancia de forrajeo y su duración, por ejemplo). En todos los grupos etarios, los piqueros respondieron de forma similar a la variación ambiental, excepto la tasa de ganancia de peso de las hembras. Las reducciones relacionadas a la edad en la tasa de ganancia de peso fueron menores durante condiciones ambientales favorables. Las aves de diferentes grupos etarios buscaron alimento en zonas levemente diferentes durante las condiciones adversas de 2016, pero no en otros años. En varias características de forrajeo, incluyendo la duración y la distancia, las hembras mostraron un esperado mejoramiento en los primeros años y un declive en su vida tardía, mostrando el patrón establecido en rasgos reproductivos en esta especie. Por lo tanto, el déficit en la adquisición de recursos (este estudio), puede contribuir a la reducida supervivencia y los resultados reproductivos previamente observados en piqueros de Nazca viejos, especialmente en las hembras.

Periodic hypothalamic attractor-like dynamics during the estrus cycle.

Cyclic changes in hormonal state are well-known to regulate mating behavior during the female reproductive cycle, but whether and how these changes affect the dynamics of neural activity in the female brain is largely unknown. The ventromedial hypothalamus, ventro-lateral subdivision (VMHvl) contains a subpopulation of VMHvl Esr1+,Npy2r- neurons that controls female sexual receptivity. Longitudinal single cell calcium imaging of these neurons across the estrus cycle revealed that overlapping but distinct subpopulations were active during proestrus (mating-accepting) vs. non-proestrus (rejecting) phases. Dynamical systems analysis of imaging data from proestrus females uncovered a dimension with slow ramping activity, which generated approximate line attractor-like dynamics in neural state space. During mating, the neural population vector progressed along this attractor as male mounting and intromission proceeded. Attractor-like dynamics disappeared in non-proestrus states and reappeared following re-entry into proestrus. They were also absent in ovariectomized females but were restored by hormone priming. These observations reveal that hypothalamic line attractor-like dynamics are associated with female sexual receptivity and can be reversibly regulated by sex hormones, demonstrating that attractor dynamics can be flexibly modulated by physiological state. They also suggest a potential mechanism for the neural encoding of female sexual arousal.

Pharmacokinetics of intranasal amiloride in healthy volunteers.

Anxiety and panic disorders are the most common mental illnesses in the United States and lack effective treatment options. Acid-sending ion channels (ASICs) in the brain were shown to be associated with fear conditioning and anxiety responses and therefore are potential targets for treating panic disorder. Amiloride is an inhibitor of the ASICs in the brain and was shown to reduce panic symptoms in preclinical animal models. An intranasal formulation of amiloride will be highly beneficial to treat acute panic attacks due to advantages such as the rapid onset of action and patient compliance. The aim of this single-center, open-label trial was to evaluate the basic pharmacokinetics (PKs) and safety of amiloride after intranasal administration in healthy human volunteers at three doses (0.2, 0.4, and 0.6 mg). Amiloride was detected in plasma within 10 min of intranasal administration and showed a biphasic PK profile with an initial peak within 10 min of administration followed by a second peak between 4 and 8 h of administration. The biphasic PKs indicate an initial rapid absorption via the nasal pathway and later slower absorption by non-nasal pathways. Intranasal amiloride exhibited a dose-proportional increase in the area under the curve and did not exhibit any systemic toxicity. These data indicate that intranasal amiloride is rapidly absorbed and safe at the doses evaluated and can be further considered for clinical development as a portable, rapid, noninvasive, and nonaddictive anxiolytic agent to treat acute panic attacks.

Seabird morphology determines operational wind speeds, tolerable maxima, and responses to extremes.

Storms can cause widespread seabird stranding and wrecking,1,2,3,4,5 yet little is known about the maximum wind speeds that birds are able to tolerate or the conditions they avoid. We analyzed >300,000 h of tracking data from 18 seabird species, including flapping and soaring fliers, to assess how flight morphology affects wind selectivity, both at fine scales (hourly movement steps) and across the breeding season. We found no general preference or avoidance of particular wind speeds within foraging tracks. This suggests seabird flight morphology is adapted to a "wind niche," with higher wing loading being selected in windier environments. In support of this, wing loading was positively related to the median wind speeds on the breeding grounds, as well as the maximum wind speeds in which birds flew. Yet globally, the highest wind speeds occur in the tropics (in association with tropical cyclones) where birds are morphologically adapted to low median wind speeds. Tropical species must therefore show behavioral responses to extreme winds, including long-range avoidance of wind speeds that can be twice their operable maxima. By contrast, Procellariiformes flew in almost all wind speeds they encountered at a seasonal scale. Despite this, we describe a small number of cases where albatrosses avoided strong winds at close range, including by flying into the eye of the storm. Extreme winds appear to pose context-dependent risks to seabirds, and more information is needed on the factors that determine the hierarchy of risk, given the impact of global change on storm intensity.6,7.

An approximate line attractor in the hypothalamus encodes an aggressive state.

The hypothalamus regulates innate social behaviors, including mating and aggression. These behaviors can be evoked by optogenetic stimulation of specific neuronal subpopulations within MPOA and VMHvl, respectively. Here, we perform dynamical systems modeling of population neuronal activity in these nuclei during social behaviors. In VMHvl, unsupervised analysis identified a dominant dimension of neural activity with a large time constant (>50 s), generating an approximate line attractor in neural state space. Progression of the neural trajectory along this attractor was correlated with an escalation of agonistic behavior, suggesting that it may encode a scalable state of aggressiveness. Consistent with this, individual differences in the magnitude of the integration dimension time constant were strongly correlated with differences in aggressiveness. In contrast, approximate line attractors were not observed in MPOA during mating; instead, neurons with fast dynamics were tuned to specific actions. Thus, different hypothalamic nuclei employ distinct neural population codes to represent similar social behaviors.

Use of point of care ultrasound (POCUS) by intensive care paramedics to achieve peripheral intravenous access in patients predicted to be difficult: An out-of-hospital pilot study.

INTRODUCTION: Intravenous cannulation is a common procedure for paramedics. Difficulty is often encountered and may result in escalation of care to an intensive care paramedic (ICP). Ultrasound-guided peripheral intravenous access (USGPIVA) is used in-hospital as an alternative approach. Historically limited to physicians, it is increasingly embraced by non-physicians, with point of care ultrasound (POCUS) devices more affordable, portable, and suited to the out of hospital environment. OBJECTIVE: To explore the utility of ICP-performed USGPIVA for patients who are predicted to be difficult according to a difficult intravenous access scoring tool. METHODS: This was a prospective observational pilot study of ICPs who used the adult difficult intravenous access (A-DIVA) scale to predict difficulty and perform USGPIVA using a contemporary POCUS device. RESULTS: For the 32 patients enroled, the overall success rate was 50% of which 87% were successful on the first attempt. Mean A-DIVA score was 4.1/5, and paradoxically, success improved with A-DIVA-predicted difficulty. CONCLUSION: ICPs can perform USGPIVA with moderate success. The A-DIVA score could be useful for paramedics to predict difficult cannulation. Future research should focus on increasing exposure, training time and enhancing feedback to paramedics performing USGPIVA.

Apparent Homozygosity for a gr/gr AZFc Deletion in A 47,XYY Man with Oligozoospermia and Secondary Infertility.

Background: Approximately 1 in 1000 men have a 47,XYY karyotype. Previous publications have presented cases of infertile XYY men and have suggested that the additional Y chromosome may cause disrupted meiosis leading to sperm apoptosis. The purpose of the current study was to determine whether XYY men are over-represented in infertility cohorts. Methods: In this paper, an ongoing infertility cohort was evaluated for Y chromosome microdeletions using the MLPA technique and the data from the first 2000 referrals were recorded. Moreover, the MLPA technique detected 47,XYY karyotypes. Results: Four XYY individuals were identified within the cohort. One of the four XYY men was shown to have an apparent gr/gr partial AZFc deletion on both Y chromosomes while Sertoli cell only syndrome was detected in another case. The other two cases (out of 2000) might, therefore, represent an incidental finding. Conclusion: The gr/gr deletion is not detectable by the multiplex PCR method; therefore, there might be additional explanations for the fertility problems of infertile XYY men reported in previously published articles. It seems that among other cases, their XYY karyotype may be coincidental, rather than causative of their fertility issues.

Transformations of neural representations in a social behaviour network.

Mating and aggression are innate social behaviours that are controlled by subcortical circuits in the extended amygdala and hypothalamus1-4. The bed nucleus of the stria terminalis (BNSTpr) is a node that receives input encoding sex-specific olfactory cues from the medial amygdala5,6, and which in turn projects to hypothalamic nuclei that control mating7-9 (medial preoptic area (MPOA)) and aggression9-14 (ventromedial hypothalamus, ventrolateral subdivision (VMHvl)), respectively15. Previous studies have demonstrated that male aromatase-positive BNSTpr neurons are required for mounting and attack, and may identify conspecific sex according to their overall level of activity16. However, neural representations in BNSTpr, their function and their transformations in the hypothalamus have not been characterized. Here we performed calcium imaging17,18 of male BNSTprEsr1 neurons during social behaviours. We identify distinct populations of female- versus male-tuned neurons in BNSTpr, with the former outnumbering the latter by around two to one, similar to the medial amygdala and MPOA but opposite to VMHvl, in which male-tuned neurons predominate6,9,19. Chemogenetic silencing of BNSTprEsr1 neurons while imaging MPOAEsr1 or VMHvlEsr1 neurons in behaving animals showed, unexpectedly, that the male-dominant sex-tuning bias in VMHvl was inverted to female-dominant whereas a switch from sniff- to mount-selective neurons during mating was attenuated in MPOA. Our data also indicate that BNSTprEsr1 neurons are not essential for conspecific sex identification. Rather, they control the transition from appetitive to consummatory phases of male social behaviours by shaping sex- and behaviour-specific neural representations in the hypothalamus.

Pre-clinical safety and therapeutic efficacy of a plant-based alkaloid in a human colon cancer xenograft model.

A high-throughput drug screen revealed that veratridine (VTD), a natural plant alkaloid, induces expression of the anti-cancer protein UBXN2A in colon cancer cells. UBXN2A suppresses mortalin, a heat shock protein, with dominant roles in cancer development including epithelial-mesenchymal transition (EMT), cancer cell stemness, drug resistance, and apoptosis. VTD-dependent expression of UBXN2A leads to the deactivation of mortalin in colon cancer cells, making VTD a potential targeted therapy in malignant tumors with high levels of mortalin. VTD was used clinically for the treatment of hypertension in decades past. However, the discovery of newer antihypertensive drugs and concerns over potential neuro- and cardiotoxicity ended the use of VTD for this purpose. The current study aims to determine the safety and efficacy of VTD at doses sufficient to induce UBXN2A expression in a mouse model. A set of flow-cytometry experiments confirmed that VTD induces both early and late apoptosis in a dose-dependent manner. In vivo intraperitoneal (IP) administration of VTD at 0.1 mg/kg every other day (QOD) for 4 weeks effectively induced expression of UBXN2A in the small and large intestines of mice. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) assays on tissues collected from VTD-treated animals demonstrated VTD concentrations in the low pg/mg range. To address concerns regarding neuro- and cardiotoxicity, a comprehensive set of behavioral and cardiovascular assessments performed on C57BL/6NHsd mice revealed that VTD generates no detectable neurotoxicity or cardiotoxicity in animals receiving 0.1 mg/kg VTD QOD for 30 days. Finally, mouse xenograft experiments in athymic nude mice showed that VTD can suppress tumor growth. The main causes for the failure of experimental oncologic drug candidates are lack of sufficient safety and efficacy. The results achieved in this study support the potential utility of VTD as a safe and efficacious anti-cancer molecule.

Make war not love: The neural substrate underlying a state-dependent switch in female social behavior.

Female mice exhibit opposing social behaviors toward males depending on their reproductive state: virgins display sexual receptivity (lordosis behavior), while lactating mothers attack. How a change in reproductive state produces a qualitative switch in behavioral response to the same conspecific stimulus is unknown. Using single-cell RNA-seq, we identify two distinct subtypes of estrogen receptor-1-positive neurons in the ventrolateral subdivision of the female ventromedial hypothalamus (VMHvl) and demonstrate that they causally control sexual receptivity and aggressiveness in virgins and lactating mothers, respectively. Between- and within-subject bulk-calcium recordings from each subtype reveal that aggression-specific cells acquire an increased responsiveness to social cues during the transition from virginity to maternity, while the responsiveness of the mating-specific population appears unchanged. These results demonstrate that reproductive-state-dependent changes in the relative activity of transcriptomically distinct neural subtypes can underlie categorical switches in behavior associated with physiological state changes.