Biology subjects

Palmiter, R.

Publications and source records attributed to Palmiter, R..

8 recordsLinked to original sources

bioRxiv2026

Genetic Identification of Dopamine Neurons Required for Circadian Food Anticipatory Activity in Mice

Anticipating daily food availability is a conserved circadian behavior that persists even in animals lacking the suprachiasmatic nucleus, yet its neural substrates remain poorly defined. Previous studies implicated dopamine signaling in food anticipatory activity (FAA) but lacked the resolution to identify the responsible neuronal population. Here, we conditionally deleted tyrosine hydroxylase (Th) from molecularly defined dopamine neuron populations in mice. Broad deletion of Th in dopamine transporter-expressing neurons nearly abolished FAA, whereas restoration of Th in substantia nigra dopamine neurons rescued anticipatory locomotion. Surprisingly, deletion of Th from several large dopamine neuron populations had little effect on FAA. In contrast, deletion using Calb1Cre, targeting only [~]25% of substantia nigra dopamine neurons, produced a profound FAA deficit. Notably, these mice exhibited a profound loss of anticipatory locomotion while retaining substantial anticipatory food-seeking behavior. These findings identify a small Calbindin1+ dopamine population required for anticipatory locomotion and demonstrate that distinct behavioral components of food anticipation can be genetically dissociated.

neuroscience↗

bioRxiv2026

Parabrachial Ntsr1 neurons modulate food intake and anxiety through a projection to the ventromedial hypothalamus

The parabrachial nucleus (PBN) is an important hub located in the pons that relays sensory signals from peripheral regions. It is genetically diverse and contains many populations that modulate feeding and responses to threatening situations. A small Ntsr1-expressing population of neurons was identified that projects selectively to the ventromedial hypothalamus (VMH). The Ntsr1 neurons are scattered throughout the lateral PBN with a cluster of cells along the border to the nucleus of the lateral lemniscus (NLL) that overlap with Cck and Foxp2 expression. Chemogenetic activation of PBN Ntsr1 neurons results in Fos induction in Nr5a1 (SF1) and Bdnf neurons in the VMH. Activation of PBN Ntsr1 neurons or their terminals in the VMH reduces food intake after fasting and increases anxiety-like behaviors. In anxiogenic feeding assays, activation of PBN Ntsr1 neurons increases latency to feed as well as reducing food intake. Photometry showed that PBN Ntsr1-neuronal activity increases during anxiogenic situations but is suppressed during food consumption, suggesting a role in threat-induced suppression of feeding. Silencing PBN Ntsr1 neurons with tetanus toxin light-chain increased food intake and reduced anxiety. These findings reveal a genetically defined PBN to VMH circuit that responds to threats and suppresses feeding behavior. SignificanceThis study explored a population of Ntsr1 mRNA-expressing neurons in the parabrachial nucleus (PBN) that project selectively to the ventromedial hypothalamus (VMH). Stimulation of PBN Ntsr1 neurons and their terminals in the VMH decreased feeding and increased anxiety, results that resemble those achieved by activating VMH neurons, implicating the Ntsr1 neurons as part of the circuitry that controls feeding and anxiety. Because PBN Ntsr1 neurons are activated by aversive stimuli, they are posited to help mice suppress feeding in risky environments.

neuroscience↗

bioRxiv2024

Parabrachial Calca neurons mediate second-order conditioning

Learning to associate cues, both directly and indirectly, with biologically significant events is essential for survival. Second-order conditioning (SOC) involves forming an association between a previously reinforced conditioned stimulus (CS1) and a new conditioned stimulus (CS2) without the presence of an unconditioned stimulus (US). The neural substrates mediating SOC, however, remain unclear. In the parabrachial nucleus, Calca gene-expressing neurons, which react to the noxious US, also respond to a CS after its pairing with a US. This observation led us to hypothesize their involvement in SOC. To explore this possibility, we established an aversive SOC behavioral paradigm in mice and monitored Calca neuron activity via single-cell calcium imaging during SOC and subsequent recall phases. These neurons were activated not only by CS1 following its association with the US but also by CS2 after SOC. Chemogenetically inhibiting these neurons during second-order associations attenuated SOC. These findings suggest that activating the US pathway in response to a learned CS plays an important role in forming the association between the old and a new CS, promoting the formation of second-order memories.

neuroscience↗

bioRxiv2021

Vestibular CCK neurons drive motion-induced malaise

Travel can induce motion sickness (MS) in susceptible individuals. MS is an evolutionary conserved mechanism caused by mismatches between motion-related sensory information and past visual and motion memory, triggering a malaise accompanied by hypolocomotion, hypothermia, hypophagia and nausea. Vestibular nuclei (VN) are critical for the processing of movement input from the inner ear. Motion-induced activation of VN neurons recapitulates MS-related signs. However, the genetic identity of VN neurons mediating MS- related autonomic and aversive responses remains unknown. Here, we identify a central role of cholecystokinin (CCK)-expressing VN neurons in motion-induced malaise. Moreover, we show that CCK VN inputs onto the parabrachial nucleus activate Calca- expressing neurons and are sufficient to establish avoidance to novel food, which is prevented by CCK-A receptor antagonism. These observations provide greater insight into the neurobiological regulation of MS by identifying the neural substrates of MS and providing potential targets for treatment. SIGNIFICANCE STATEMENTWe live in an age where travel is paramount. However, one of the most disabling conditions inherent to traveling is motion sickness (MS). While studies have underscored the role of the vestibular system in the development of MS, the neuronal populations involved in motion-induced malaise remain largely unknown. Here, we describe the vestibular pathways eliciting MS responses, and identify a key role for cholecystokinin (CCK)-expressing vestibular neurons. We reveal that a vestibulo-parabrachial (PBN) CCKergic projection is sufficient to induce conditioned taste aversion, likely through the activation of calcitonin gene-related peptide-expressing PBN neurons. Finally, we underscore the role of CCK-A receptor signaling as a novel druggable target to treat MS, providing novel insight on the neurobiological substrates of MS.

neuroscience↗

bioRxiv2021

Pubertal sex hormones control transcriptional trajectories in the medial preoptic area

Pubertal maturation aids development of emotion, cognition, and reproduction. We investigated transcriptional dynamics in the medial preoptic area (MPOA), a hypothalamic center for reproductive behaviors, in male and female mice at single-cell resolution (scRNAseq) during puberty. Defined subsets of neurons expressing Slc32a1 and Esr1 (Vgat+ Esr1+) were the most transcriptionally dynamic compared to other cell types throughout puberty. These cell type specific transcriptional progressions towards adulthood were bidirectionally controlled by the levels of circulating testosterone and estradiol. Selective deletion of Esr1 in Slc32a1-expressing cells in the MPOA prior to puberty arrested transcriptional progression and revealed a sexually dimorphic gene-regulatory network governed by Esr1. Deletion of Esr1 in Vgat+ cells prevented the development of mating behavior in both sexes. These analyses reveal both sexually common and dimorphic transcriptional progressions during puberty as well as their regulatory mechanisms, which have important implications towards understanding adaptative and maladaptive processes governing adolescent brain development.

neuroscience↗

bioRxiv2021

PD-1 in hippocampal neurons regulates excitability, synaptic plasticity, and cognition

Immunotherapy using monoclonal antibodies against programmed cell death protein 1 (PD-1) demonstrated improved survival in cancer patients through immune activation. Here we show that functional PD-1 is expressed in mouse and primate hippocampal neurons and PD-1 inhibition improves cognition in physiological and pathological conditions. Mice lacking the Pdcd1 gene encoding PD-1 exhibit enhanced long-term potentiation (LTP) and learning and memory. These behavioral and cellular changes can be recapitulated by selective deletion of Pdcd1 in hippocampal excitatory neurons but not in microglia. Perfusion of mouse or nonhuman primate brain slices with anti-PD-1 antibody is sufficient to increase excitability in CA1 hippocampal neurons. Conversely, re-expression of Pdcd1 in PD-1 deficient hippocampal neurons suppresses memory and LTP. Traumatic brain injury impairs learning and memory, which is improved by intraventricular administration of anti-PD-1. These findings suggest that anti-PD-1 treatment has therapeutic potential to counteract cognitive decline. HighlightsO_LIAdult mice lacking Pdcd1 in hippocampal neurons exhibit enhanced memory and LTP C_LIO_LIAnti-PD-1 antibody treatment increases CA1 neuron excitability in brain slices of mice and primates C_LIO_LIRe-expression of Pdcd1 in PD-1 deficient hippocampal neurons impairs memory and LTP C_LIO_LICognitive deficits after traumatic brain injury are improved by anti-PD-1 treatment C_LI

neuroscience↗

bioRxiv2021

Continuous Polony Gels for Tissue Mapping with High Resolution and RNA Capture Efficiency

Current technologies for acquiring spatial transcript information from tissue sections rely on either RNA probes or spatial barcodes. The former methods require a priori knowledge for probeset formulation; the latter have yet to achieve single cell resolution and/or transcript capture efficiencies approaching dissociative, single-cell methods. Here, we describe a novel spatial transcriptome assay called polony (or DNA cluster)-indexed library-sequencing (PIXEL-seq). It improves upon other spatial barcoding methods by employing "continuous" polony oligos arrayed across a customized gel surface. In terms of assay performance, PIXEL-seq attains [≤] 1 {micro}m resolution and captures >1,000 unique molecular identifiers/10x10 {micro}m2. In other words, this global, naive platform achieves subcellular spatial transcriptome mapping while maintaining high transcript capture efficiencies.

genomics↗

bioRxiv2020

Cold-induced hyperphagia requires AgRP-neuron activation in mice

To maintain energy homeostasis during cold exposure, the increased energy demands of thermogenesis must be counterbalanced by increased energy intake. To investigate the neurobiological mechanisms underlying this cold-induced hyperphagia, we asked whether agouti-related peptide (AgRP) neurons are activated when animals are placed in a cold environment and, if so, whether this response is required for the associated hyperphagia. We report that AgRP-neuron activation occurs rapidly upon acute cold exposure, as do increases of both energy expenditure and energy intake, suggesting the mere perception of cold is sufficient to engage each of these responses. We further report that silencing of AgRP neurons selectively blocks the effect of cold exposure to increase food intake. Together, these findings establish a physiologically important role for AgRP neurons in the hyperphagic response to cold exposure.

neuroscience↗