Publications using the RZ5P

The bed nuclei of the stria terminalis (BST) is a nuclear complex that coordinates neuroendocrine, autonomic, and behavioral responses associated with maintaining homeostasis. Here, we demonstrate that melanocortin 3 receptor (MC3R) neurons in the BST (BST MC3R ) play a key role in modulating feeding behaviors and responses to stressful events. BST MC3R neurons are primarily GABAergic and colocalize with neuropeptides known to regulate feeding and affective behaviors. Chemogenetic activation of BST MC3R neurons causes reduced feeding, particularly in males. BST MC3R neurons are also robustly activated by stress and can control responses to stress and defensive behaviors in both sexes. Whole-brain monosynaptic rabies tracing identified multiple sexually dimorphic inputs to BST MC3R neurons that may contribute to observed functional sexual dimorphisms. Altogether, these data reveal that BST MC3R neurons participate in sexually dimorphic circuits that influence feeding and defensive behaviors, responses to stress, and may represent a potential therapeutic target for stress- and eating-related disorders.

Cytokines and their receptors play important roles in brain development and aging-related disease, but their functions within the healthy adult brain remain poorly understood. Here, we show that pyramidal neurons in hippocampal CA1 induce Fn14 expression in response to activity and environmental enrichment. Once expressed, Fn14 dampens the activity of these neurons most prominently at the daily transition between light and dark. Fn14 expression in CA1 neurons is regulated by the circadian transcription factor Bmal1, and mice lacking Fn14 exhibit disrupted sleep-wake patterns in vivo. At the cellular level, microglia contact fewer excitatory synapses in the absence of Fn14, while neuronal overexpression of Fn14 induces rod-like microglia and recruits them to excitatory synapses. Beyond a homeostatic context, mice lacking Fn14 exhibit heightened susceptibility to chemically induced seizures. These findings reveal that pro-inflammatory cytokine receptors such as Fn14 can play major roles in healthy neurological function in the adult brain.

The entorhinal-hippocampal system constitutes a pivotal neural circuit in the central nervous system. It is critically involved in processing spatial learning and memory. However, the specific neural interactions between entorhinal inputs and intra-hippocampal subcircuits that underlie spatial coding remain elusive. To address this gap, we integrated multimodal approaches including in vivo calcium imaging, dual-color optogenetic manipulation, chemogenetic intervention, electrophysiological recordings, immunohistochemistry, and Morris water maze (MWM) behavior to dissect how entorhinal-hippocampal afferents modulate hippocampal computations. Intriguingly, CA1-projecting CA3 neurons exhibited pronounced hyperactivity during early spatial learning, with activity gradually declining after sustained task performance. Chemogenetic inactivation of medial entorhinal-hippocampal afferents attenuated both neural responses of CA1-projecting CA3 neurons and the performance of spatial learning, hinting that medial entorhinal cortex (MEC) inputs to the hippocampus are essential for animals to execute spatial tasks precisely. By implementing dual-light theta-burst stimulation to co-activate ChrimsonR-expressing CA3-CA1 afferents and Chronos-expressing MEC-CA1 terminals, we observed robust heterosynaptic long-term potentiation in the dorsal CA1 region in vitro brain slice. This neuroplasticity was mediated synergistically by activating both NMDA receptors and voltage-gated calcium channels. Our findings establish that entorhinohippocampal afferents exert multilevel regulatory control over hippocampal function, thereby advancing mechanistic understanding of memory-related neurological pathologies.

Reward processes have traditionally been ascribed to dopamine (DA)–associated circuits. While external stimuli, such as food and drugs of abuse, are activators of DA-neuron activity, growing evidence indicates that interoceptive signals also play a critical role. Among these, the gut-brain vagal axis has emerged as a key regulator, although its precise contribution to mesolimbic DA signaling and behavior remains unclear. Here, we combine complementary ex vivo and in vivo approaches across multiple scales to show that gut-brain vagal tone is essential for gating mesolimbic DA system activity and functions, modulating DA-dependent molecular and cellular processes, and scaling both food- and drug-induced reinforcement. These findings challenge the traditional brain-centric view of reward processing, supporting a more integrated model in which vagus-mediated interoceptive signals intrinsically shape motivation and reinforcement. By uncovering the influence of gut-brain vagal communication on DA functions, this work provides insights into the neurobiology of adaptive and maladaptive reward, with broad relevance for eating disorders and addiction.

Interoceptive predictions are internal models that guide behavior by anticipating physiological needs based on past experiences and environmental cues. The paraventricular nucleus of the thalamus (PVT), which receives both interoceptive and exteroceptive inputs, is well-positioned to integrate these signals. Using fiber photometry and bulk calcium imaging in mice performing a reward-based linear maze task, we found that dopamine receptor 2-expressing PVT neurons (PVTD2R+) are engaged in behaviors leading to physiologically relevant outcomes, with their activity highly dependent on the interoceptive state of the mice and the expected outcome. Furthermore, we show that the chronic inhibition of PVTD2R+ neurons impairs the long-term performance of interoceptive-guided motivated behavior. Collectively, these findings identify PVTD2R+ neurons as critical integrators of internal states, external cues, and experiential factors, all of which contribute to interoceptive predictions that facilitate adaptive, goal-directed behavior.

The mammillary body (MB) has traditionally been regarded as a relay station for the hippocampus and plays a pivotal role in the Papez circuit. However, its molecular and cellular organization remains inadequately characterized. This study focuses on the horizontally symmetrically distributed neurotensin (Nts)-expressing and nitric oxide synthase 1 (Nos1)-expressing neurons in the MB, demonstrating that Grik4 (encoding a high-affinity kainate receptor subunit) underlies their distinct electrophysiological properties. Within neural circuits, Nts and Nos1 neurons receive excitatory inputs from the ventral subiculum and send parallel excitatory projections to the dorsomedial and ventrolateral subdivisions of the anteroventral thalamus (AV). These 2 cell type-specific circuits are essential for working memory and exhibit selective activation during the maintenance phase with a marked temporal difference. Together, our findings establish a direct link from molecular identity to circuit architecture and cognitive processing by demonstrating that molecularly distinct Nts and Nos1 neurons constitute differential circuits with convergent inputs, divergent outputs, and dissociable roles in working memory maintenance. This work thus reveals a fundamental cross-scale organizational principle—molecule, cell, circuit, function—within the MB.

Maternal obesity predisposes offspring to metabolic diseases. Here, we show that non-nutritive sensory components of a high-fat diet (HFD), beyond its hypercaloric, obesogenic effects, are sufficient to alter metabolic health in the offspring. To dissociate the caloric and sensory components of HFD, we fed dams a bacon-flavoured diet, isonutritional to a normal chow diet but enriched with fat-related odours. Offspring exposed to these fat-related odours during development display metabolic inflexibility and increased adiposity when fed HFD in adulthood independently of maternal metabolic health. Developmental exposure to fat-related odours shifts mesolimbic dopaminergic circuits and Agouti-related peptide (AgRP) hunger neurons’ responses to phenocopy those of obese mice, including a desensitization of AgRP neurons to dietary fat. While neither neonatal optogenetic activation of sensory circuits nor passive exposure to fat-related odours is sufficient to alter metabolic responses to HFD, coupling optogenetic stimulation of sensory circuits with caloric intake exacerbates obesity. Collectively, we report that fat-related sensory cues during development act as signals that can prime central responses to food cues and whole-body metabolism regulation.

The anterior-lateral motor cortex (ALM) has been extensively studied as a model for understanding the cortical mechanisms involved in planning directional movements. ALM neurons show preparatory activity that predict whether the mouse will produce a left- or right-directed lick. While the neural mechanisms underlying ALM dynamics and their links to behavior are beginning to be elucidated, the sources of this directional activity remain unclear. Here, we examined the role of ALM dopaminergic circuits in mice performing a directional licking task. We report that dopamine (DA) signals and the activity of neurons expressing D1 receptors (D1R + ) tracked the preparation and execution of licking and demonstrated a bias for planning of licks aimed at the direction contralateral to the recording site. Unilateral optogenetic manipulations of D1R + neurons or DA afferents affected lateral licking in a way consistent with their role in planning contralateral movements. Together, these results show that cortical DA modulation plays an important role in the motor preparation of directional movements.

The ventral tegmental area (VTA) is classically linked to learning and reinforcement via the actions of dopamine neurons. Intermingled VTA GABA neurons are positioned to regulate dopamine, but we lack detailed insight into how this population contributes to behavior. Recording calcium activity in VTA dopamine and GABA neurons, we show that, while dopamine neurons were only responsive to appetitive events, GABA neurons actively encoded both appetitive and aversive stimuli. Critically, GABA neuron activity selectively integrated events when both valences were present. In a motivational conflict task, where rats weighed decisions to avoid shock or seek reward, GABA neuron activity scaled with escalating cost and predicted reward seeking. Optogenetic inhibition of GABA neurons disrupted reward seeking specifically under conditions of motivational conflict. Together, our data show that VTA GABA neurons reflect a broader learning signal, compared to dopamine neurons, that is important for directing economic decision making in complex, multivalent environments.

Persistent maladaptive drug-context associations are a key component of relapse vulnerability and pose a major obstacle in treating opioid use disorder. Although the dorsal hippocampus (dHPC) is critical for contextual memory formation, the synaptic mechanisms by which opioids alter hippocampal circuits to sustain these associations remain unclear. We previously found that repeated context-paired morphine exposure impairs dHPC long-term potentiation (LTP) through enhanced activity of small-conductance calcium-activated potassium (SK2) channels. Here, we investigated the role of SK2 channels in morphine-context associative learning and memory by combining in vivo electrophysiology, molecular analyses, and behavioral pharmacology with the morphine-conditioned place preference (MorCPP) paradigm in male mice. Manipulation of SK2 channels with either SK2 blocker Lei-Dab7 or activator NS309 before MorCPP post-test dose-dependently reduced MorCPP preference, despite no changes observed in SK2 mRNA or protein expression following MorCPP post-test. Interestingly, SK2 blockade during conditioning instead facilitated morphine-context memory formation, suggesting a distinct SK2 role in drug-context memory acquisition versus retrieval. Electrophysiology data suggest that modulation of dHPC neuronal activity by SK2 channels could be a potential mechanism underlying these observations. Our findings demonstrate that dHPC SK2 channels regulate morphine-context memory formation and retrieval, identifying them as a candidate for mitigating context-driven drug behaviors.

Dopamine release in the nucleus accumbens is classically linked to associative learning, signaling relationships between predictive cues and outcomes. Yet, dopamine is also strongly modulated by novelty, a nonassociative factor that has received comparatively little attention. Here, we used optical dopamine sensors in awake, behaving male and female mice to define how novelty alters the temporal dynamics of dopamine release during aversive learning. We manipulated novelty in three ways: (1) omitting expected footshocks, (2) introducing novel neutral cues concurrently with shock-predictive stimuli, and (3) presenting novel stimuli in an unpaired fashion within a context. Across all conditions, manipulations robustly increased dopamine release and in some cases altered the directionality of cue-evoked dopamine responses. Notably, these effects extended beyond the immediate stimulus window, altering subsequent responses to both conditioned cues and footshocks. Together, these findings demonstrate that changes in the environment that extend beyond prediction-based learning can exert a powerful and sustained influence on dopamine signaling, reshaping how aversive cues and outcomes are represented in the brain.

A central mechanism of exposure-based cognitive behavioral therapy for anxiety and trauma-related disorders is fear extinction. However, the mechanisms underlying fear extinction are deficient in some individuals, leading to treatment resistance. Recent animal studies demonstrate that upon omission of the aversive, unconditioned stimulus (US) during fear extinction, dopamine (DA) neurons in the ventral tegmental area (VTA) produce a prediction error (PE)-like signal. However, whether this VTA-DA neuronal PE-like signal is altered in animals exhibiting deficient fear extinction has not been studied. Here, we used a mouse model of impaired fear extinction [129S1/SvImJ (S1) inbred mouse strain] to monitor and manipulate VTA-DA neurons during extinction. Male DAT-Cre mice backcrossed onto an S1 background (S1-DAT-Cre) exhibited impaired extinction but normal VTA-DA neuron number, as compared with BL6-DAT-Cre mice. In vivo fiber photometry showed that impaired extinction in male S1-DAT-Cre mice was associated with abnormally sustained US omission-related VTA-DA neuronal calcium activity during extinction training and retrieval. Neither in vivo optogenetic photoexcitation of VTA-DA neuronal cell bodies nor their axons in the infralimbic cortex was sufficient to rescue deficient extinction in male S1-DAT-Cre mice, at least within the optogenetic and behavioral parameters used. These data suggest that alterations in the activity of VTA-DA neurons during extinction learning and retrieval may be associated with deficient fear extinction in male S1 mice and could potentially contribute to extinction impairments in patient populations.

Obesity is characterized by insulin resistance, motivational impairments, and, in some cases, reduced availability of dopamine D2 receptors in the brain. However, whether the low D2 receptor levels represent a predisposing factor or a consequence of obesity, and how these processes are mechanistically linked, remains unclear. Here, we directly tested this causal relationship by selectively reducing D2 receptor density in striatal neurons. Male, but not female, mice with a low density of striatal D2 receptors consumed more food, gained more weight, and developed metabolic features of peripheral insulin resistance despite being maintained on standard chow. Motivational deficits preceded weight gain, manifesting as delayed circadian locomotor onset, reduced physical activity, and diminished effort to obtain food. In the brain, male mice with low D2 receptor density showed reduced dopamine release capacity and age-dependent alterations in brain insulin sensitivity. Prior to weight gain, brain insulin responses were blunted compared to those of controls, in which insulin potentiates dopamine release and enhances striatal acetylcholine signaling. Once overweight, however, these mice exhibited brain insulin hypersensitivity, with insulin strongly restoring dopamine release capacity. Together, these findings demonstrate that low striatal D2 receptor density predisposes male mice to an obesity-like phenotype through early dopaminergic dysfunction that precedes weight gain and is later compensated by insulin hypersensitivity in the brain.

Long-term sustained pain following acute physical injury is a prominent feature of chronic pain conditions1. Populations of neurons that rapidly respond to noxious stimuli or tissue damage have been identified in the spinal cord and several nuclei in the brain2-4. Understanding the central mechanisms that signal ongoing sustained pain, including after tissue healing, remains a challenge5. Here we use spatial transcriptomics, neural manipulations, activity recordings and computational modelling to demonstrate that activity in an ensemble of anatomically and molecularly diverse parabrachial neurons that express the neuropeptide Y (NPY) receptor Y1 (Y1R neurons) is increased following injury and predicts functional coping behaviour. Hunger, thirst or predator cues suppressed sustained pain, regardless of the injury type, by inhibiting parabrachial Y1R neurons via the release of NPY. Together, our results demonstrate an endogenous analgesic hub at pain-responsive parabrachial Y1R neurons.

Olfactory perception of food odors is a key determinant of eating behavior, including triggering appetite, facilitating food seeking and influencing food choice. While transient food-related olfactory cues stimulate appetite and provoke cravings in states of hunger, emerging evidence implies that prolonged and sustained exposure to food-derived odor (FO) suppresses feeding. However, the mechanisms by which olfaction induces hypophagia remain elusive. In this study, we show that prolonged FO exposure significantly suppresses food intake in male mice. We identified a subset of neurons in the ventral subiculum (vSub) that are specifically activated by FO. We further discovered that these FO-activated neurons in the vSub receive excitatory inputs from the olfactory bulb (OB) and send glutamatergic projections to the ventromedial hypothalamus (VMH). Inhibition of the OB → vSub → VMH circuit abolished the FO-induced reduction in food intake, while activation of this circuit suppressed feeding and reduced body weight. Together, these findings reveal a neurobiological circuitry that mediates the influence of olfactory signals on food intake regulation.

Glutamatergic neuronal activity promotes proliferation of both oligodendrocyte precursor cells (OPCs) and gliomas, including diffuse midline glioma (DMG). However, the role of neuromodulatory brainstem neurons projecting to midline structures where DMGs arise remains unexplored. Here, we demonstrate that midbrain cholinergic neuronal activity modulates OPC and DMG proliferation in a circuit-dependent manner. Optogenetic stimulation of the cholinergic pedunculopontine nucleus (PPN) promotes glioma growth in pons, while stimulation of the laterodorsal tegmentum nucleus (LDT) drives proliferation in thalamus. DMG-bearing mice exhibit higher acetylcholine release and increased cholinergic neuronal activity over the disease course. In co-culture, cholinergic neurons enhance DMG proliferation, and acetylcholine directly acts on DMG cells. Single-cell RNA sequencing revealed high CHRM1 and CHRM3 expression in primary DMG samples. Pharmacological or genetic blockade of M1/M3 receptors abolished cholinergic activity-driven DMG proliferation. Taken together, these findings demonstrate that midbrain cholinergic long-range projections promote activity-dependent DMG growth, mirroring a parallel proliferative effect on healthy OPCs.

Dopaminergic signaling is essential for regulating movement, learning, and reward. Disruptions in this system are linked to neuropsychiatric disorders such as ADHD. ADGRL3, an adhesion G protein-coupled receptor highly expressed in the brain, is genetically associated with increased ADHD risk. ADGRL3 knockout in animals alters expression of dopaminergic markers and induces dopamine-related behavioral changes. However, its precise role in modulating dopamine signaling remains unclear. We investigated how ADGRL3 knockout affects striatal dopamine release in mice using ex vivo fast-scan cyclic voltammetry and in vivo fiber photometry with a dopamine sensor. Ex vivo measurements showed increased electrically-evoked dopamine release across the striatum. Conversely, in vivo recordings revealed reduced task-induced dopamine signals in the nucleus accumbens during an operant fixed interval task. This reduction was not due to impaired dopamine availability, as amphetamine-evoked release was unchanged. These findings suggest ADGRL3 modulates dopamine release in complex ways via different pre- and postsynaptic mechanisms.

The stress axis is always active, even in the absence of any threat. This manifests as hourly pulses of corticosteroid stress hormone secretion over the day. Corticotropin-releasing hormone (CRH) neurons in the paraventricular nucleus of the hypothalamus (CRH PVN ) control both the neuroendocrine stress axis as well as stress-associated behaviors. However, it is currently unclear how the resting activity of these neurons is coordinated with both spontaneous behavior and ultradian pulses of corticosteroid secretion. To investigate this, we performed fiber photometry recordings of CRH PVN neuron activity in Crh-Ires-Cre mice and a newly generated line of Crh-Ires-Cre rats. In both mice and rats, CRH PVN neurons displayed an ultradian rhythm of activity with reoccurring upstates of activity approximately once per hour over the 24-h day. Upstates in activity were coordinated with increases in animal activity/arousal. Chemogenetic activation of CRH PVN neurons was also sufficient to induce behavioral arousal. In rats, increases in CRH neural activity preceded some pulses of corticosteroid secretion but not others. Thus, while CRH PVN neurons display an ultradian rhythm of activity over the 24-h day that is coordinated with behavioral arousal, the relationship between CRH PVN activity and pulses of corticosteroid secretion is not one-to-one.

MDMA is a promising adjunct to psychotherapy and has well-known abuse liability, although less than other amphetamine analogs. While the reinforcing dopamine (DA)-releasing properties of MDMA are on par with methamphetamine (METH), MDMA is a far more potent serotonin (5-HT) releaser, via the 5-HT transporter (SERT). MDMA-mediated 5-HT release in a major reward center, the nucleus accumbens (NAc), drives prosocial behaviors via 5-HT1BR activation. We hypothesized that this prosocial mechanism contributes to the reduced reinforcing properties of MDMA compared to METH and used a platform of assays to predict the balance of prosocial and abuse-linked effects of (R)-MDMA, a novel entactogen in clinical development. NAc DA release, measured by GRAB-DA photometry in vivo, increased in proportion to MDMA (7.5 and 15 mg/kg, i.p.) and METH (2 mg/kg i.p.)-conditioned place preference (CPP). Using conditional knockouts (cKOs) for DAT and SERT, microdialysis, and photometry, we found that MDMA-released 5-HT limited MDMA-released DA through actions in the NAc, rather than at ventral tegmental area DAergic cell bodies. SERT cKO reduced the MDMA dose required for CPP three-fold. This enhanced MDMA-CPP and increased DA release were replicated by intra-NAc infusion of either a 5-HT reuptake inhibitor (escitalopram) to prevent MDMA interaction with SERT, or a 5-HT2CR antagonist (SB242084), but not by the 5-HT1BR antagonist NAS-181. These data support separate mechanisms for the low abuse potential versus prosocial effect of MDMA. Using this platform of assays, (R)-MDMA is predicted to have prosocial effects and low abuse potential.