Flanigan, ME;Hon, OJ;D'Ambrosio, S;Boyt, KM;Hassanein, L;Castle, M;Haun, HL;Pina, MM;Kash, TL;
PMID: 37002196 | DOI: 10.1038/s41467-023-36808-2
Binge alcohol consumption induces discrete social and arousal disturbances in human populations that promote increased drinking and accelerate the progression of Alcohol Use Disorder. Here, we show in a mouse model that binge alcohol consumption disrupts social recognition in females and potentiates sensorimotor arousal in males. These negative behavioral outcomes were associated with sex-specific adaptations in serotonergic signaling systems within the lateral habenula (LHb) and the bed nucleus of the stria terminalis (BNST), particularly those related to the receptor 5HT2c. While both BNST and LHb neurons expressing this receptor display potentiated activation following binge alcohol consumption, the primary causal mechanism underlying the effects of alcohol on social and arousal behaviors appears to be excessive activation of LHb5HT2c neurons. These findings may have valuable implications for the development of sex-specific treatments for mood and alcohol use disorders targeting the brain's serotonin system.
Chirila, AM;Rankin, G;Tseng, SY;Emanuel, AJ;Chavez-Martinez, CL;Zhang, D;Harvey, CD;Ginty, DD;
PMID: 36334588 | DOI: 10.1016/j.cell.2022.10.012
The encoding of touch in the spinal cord dorsal horn (DH) and its influence on tactile representations in the brain are poorly understood. Using a range of mechanical stimuli applied to the skin, large-scale in vivo electrophysiological recordings, and genetic manipulations, here we show that neurons in the mouse spinal cord DH receive convergent inputs from both low- and high-threshold mechanoreceptor subtypes and exhibit one of six functionally distinct mechanical response profiles. Genetic disruption of DH feedforward or feedback inhibitory motifs, comprised of interneurons with distinct mechanical response profiles, revealed an extensively interconnected DH network that enables dynamic, flexible tuning of postsynaptic dorsal column (PSDC) output neurons and dictates how neurons in the primary somatosensory cortex respond to touch. Thus, mechanoreceptor subtype convergence and non-linear transformations at the earliest stage of the somatosensory hierarchy shape how touch of the skin is represented in the brain.
Yao, Y;Barger, Z;Saffari Doost, M;Tso, CF;Darmohray, D;Silverman, D;Liu, D;Ma, C;Cetin, A;Yao, S;Zeng, H;Dan, Y;
PMID: 36170850 | DOI: 10.1016/j.neuron.2022.08.027
Sleep disturbances are strongly associated with cardiovascular diseases. Baroreflex, a basic cardiovascular regulation mechanism, is modulated by sleep-wake states. Here, we show that neurons at key stages of baroreflex pathways also promote sleep. Using activity-dependent genetic labeling, we tagged neurons in the nucleus of the solitary tract (NST) activated by blood pressure elevation and confirmed their barosensitivity with optrode recording and calcium imaging. Chemogenetic or optogenetic activation of these neurons promoted non-REM sleep in addition to decreasing blood pressure and heart rate. GABAergic neurons in the caudal ventrolateral medulla (CVLM)-a downstream target of the NST for vasomotor baroreflex-also promote non-REM sleep, partly by inhibiting the sympathoexcitatory and wake-promoting adrenergic neurons in the rostral ventrolateral medulla (RVLM). Cholinergic neurons in the nucleus ambiguous-a target of the NST for cardiac baroreflex-promoted non-REM sleep as well. Thus, key components of the cardiovascular baroreflex circuit are also integral to sleep-wake brain-state regulation.
Xiao L, Priest MF, Nasenbeny J, Lu T, Kozorovitskiy Y.
PMID: 28669546 | DOI: 10.1016/j.neuron.2017.06.003
The release of dopamine (DA) regulates rewarding behavior and motor actions through striatum-targeting efferents from ventral tegmental area (VTA) and substantia nigra pars compacta (SNc). Here, we map and functionally characterize axonal projections from oxytocin neurons in the hypothalamic paraventricular nucleus to midbrain DA regions. Electrophysiological recordings of DA neurons reveal that both the application of oxytocin and optogenetic stimulation of oxytocinergic terminals suffice to increase DA neuron activity in the VTA but downregulate it in SNc. This biased modulation is mediated by oxytocin and vasopressin G-protein-coupled receptors. Oxytocin release directly activates DA neurons and indirectly inhibits them through local GABA neurons, but the relative magnitudes of the two mechanisms differ in VTA and SNc. Oxytocin-modulated DA neurons give rise to canonical striatal projections. Since hypothalamic oxytocinergic projections also target the striatum, oxytocin is poised to bias the balance of DA tone through multiple sites in vertebrate reward circuits.
Keller JA, Chen J, Simpson S, Wang EHJ, Lilascharoen V, George O, Lim BK, Stowers L.
PMID: 30104734 | DOI: 10.1038/s41593-018-0204-3
Voluntary urination ensures that waste is eliminated when safe and socially appropriate, even without a pressing urge. Uncontrolled urination, or incontinence, is a common problem with few treatment options. Normal urine release requires a small region in the brainstem known as Barrington's nucleus (Bar), but specific neurons that relax the urethral sphincter and enable urine flow are unknown. Here we identify a small subset of Bar neurons that control the urethral sphincter in mice. These excitatory neurons express estrogen receptor 1 (BarESR1), project to sphincter-relaxing interneurons in the spinal cord and are active during natural urination. Optogenetic stimulation of BarESR1 neurons rapidly initiates sphincter bursting and efficient voiding in anesthetized and behaving animals. Conversely, optogenetic and chemogenetic inhibition reveals their necessity in motivated urination behavior. The identification of these cells provides an expanded model for the control of urination and its dysfunction.
Chen, W;Mehlkop, O;Scharn, A;Nolte, H;Klemm, P;Henschke, S;Steuernagel, L;Sotelo-Hitschfeld, T;Kaya, E;Wunderlich, CM;Langer, T;Kononenko, NL;Giavalisco, P;Brüning, JC;
PMID: 37075752 | DOI: 10.1016/j.cmet.2023.03.019
Autophagy represents a key regulator of aging and metabolism in sensing energy deprivation. We find that fasting in mice activates autophagy in the liver paralleled by activation of hypothalamic AgRP neurons. Optogenetic and chemogenetic activation of AgRP neurons induces autophagy, alters phosphorylation of autophagy regulators, and promotes ketogenesis. AgRP neuron-dependent induction of liver autophagy relies on NPY release in the paraventricular nucleus of the hypothalamus (PVH) via presynaptic inhibition of NPY1R-expressing neurons to activate PVHCRH neurons. Conversely, inhibiting AgRP neurons during energy deprivation abrogates induction of hepatic autophagy and rewiring of metabolism. AgRP neuron activation increases circulating corticosterone concentrations, and reduction of hepatic glucocorticoid receptor expression attenuates AgRP neuron-dependent activation of hepatic autophagy. Collectively, our study reveals a fundamental regulatory principle of liver autophagy in control of metabolic adaptation during nutrient deprivation.
Shin, S;You, IJ;Jeong, M;Bae, Y;Wang, XY;Cawley, ML;Han, A;Lim, BK;
PMID: 36510113 | DOI: 10.1038/s41593-022-01208-0
Early-life trauma (ELT) is a risk factor for binge eating and obesity later in life, yet the neural circuits that underlie this association have not been addressed. Here, we show in mice that downregulation of the leptin receptor (Lepr) in the lateral hypothalamus (LH) and its effect on neural activity is crucial in causing ELT-induced binge-like eating and obesity upon high-fat diet exposure. We also found that the increased activity of Lepr-expressing LH (LHLepr) neurons encodes sustained binge-like eating in ELT mice. Inhibition of LHLepr neurons projecting to the ventrolateral periaqueductal gray normalizes these behavioral features of ELT mice. Furthermore, activation of proenkephalin-expressing ventrolateral periaqueductal gray neurons, which receive inhibitory inputs from LHLepr neurons, rescues ELT-induced maladaptive eating habits. Our results identify a circuit pathway that mediates ELT-induced maladaptive eating and may lead to the identification of novel therapeutic targets for binge eating and obesity.
Feng, C;Wang, Y;Zha, X;Cao, H;Huang, S;Cao, D;Zhang, K;Xie, T;Xu, X;Liang, Z;Zhang, Z;
PMID: 35675799 | DOI: 10.1016/j.cmet.2022.05.002
Homeostatic thermogenesis is an essential protective feature of endotherms. However, the specific neuronal types involved in cold-induced thermogenesis remain largely unknown. Using functional magnetic resonance imaging and in situ hybridization, we screened for cold-sensitive neurons and found preprodynorphin (PDYN)-expressing cells in the dorsal medial region of the ventromedial hypothalamus (dmVMH) to be a candidate. Subsequent in vivo calcium recording showed that cold temperature activates dmVMHPdyn neurons, whereas hot temperature suppresses them. In addition, optogenetic activation of dmVMHPdyn neurons increases the brown adipose tissue and core body temperature, heart rate, and blood pressure, whereas optogenetic inhibition shows opposite effects, supporting their role in homeostatic thermogenesis. Furthermore, we found that dmVMHPdyn neurons are linked to known thermoregulatory circuits. Importantly, dmVMHPdyn neurons also show activation during mouse social interaction, and optogenetic inhibition suppresses social interaction and associated hyperthermia. Together, our study describes dual functions of dmVMHPdyn neurons that allow coordinated regulation of body temperature and social behaviors.
Somatostatin-expressing parafacial neurons are CO2/H+ sensitive and regulate baseline breathing
Cleary, CM;Milla, BM;Kuo, FS;James, S;Flynn, WF;Robson, P;Mulkey, DK;
PMID: 34013884 | DOI: 10.7554/eLife.60317
Glutamatergic neurons in the retrotrapezoid nucleus (RTN) function as respiratory chemoreceptors by regulating breathing in response to tissue CO2/H+. The RTN and greater parafacial region may also function as a chemosensing network composed of CO2/H+-sensitive excitatory and inhibitory synaptic interactions. In the context of disease, we showed that loss of inhibitory neural activity in a mouse model of Dravet syndrome disinhibited RTN chemoreceptors and destabilized breathing (Kuo et al., 2019). Despite this, contributions of parafacial inhibitory neurons to control of breathing are unknown, and synaptic properties of RTN neurons have not been characterized. Here, we show the parafacial region contains a limited diversity of inhibitory neurons including somatostatin (Sst)-, parvalbumin (Pvalb)-, and cholecystokinin (Cck)-expressing neurons. Of these, Sst-expressing interneurons appear uniquely inhibited by CO2/H+. We also show RTN chemoreceptors receive inhibitory input that is withdrawn in a CO2/H+-dependent manner, and chemogenetic suppression of Sst+ parafacial neurons, but not Pvalb+ or Cck+ neurons, increases baseline breathing. These results suggest Sst-expressing parafacial neurons contribute to RTN chemoreception and respiratory activity.
Claypool, SM;Behdin, S;Applebey, SV;Orihuel, J;Ma, Z;Reiner, DJ;
PMID: 35768212 | DOI: 10.1523/ENEURO.0496-21.2022
The orbitofrontal cortex (OFC) and piriform cortex (Pir) play a role in fentanyl relapse after food choice-induced voluntary abstinence, a procedure mimicking abstinence because of availability of alternative nondrug rewards. We used in situ hybridization and pharmacology to determine the role of OFC and Pir cannabinoid and dopamine receptors in fentanyl relapse. We trained male and female rats to self-administer food pellets for 6 d (6 h/d) and intravenous fentanyl (2.5 µg/kg/infusion) for 12 d (6 h/d). We assessed fentanyl relapse after 12 discrete choice sessions between fentanyl and food (20 trials/d), in which rats voluntarily reduced fentanyl self-administration. We used RNAscope to determine whether fentanyl relapse is associated with activity (indicated by Fos) in OFC and Pir cells expressing Cnr1 [which encodes cannabinoid 1 (CB1) receptors] or Drd1 and Drd2 (which encode dopamine D1 and D2 receptors). We injected a CB1 receptor antagonist or agonist (0.3 or 1.0 µg AM251 or WIN55,212-2/hemisphere) into OFC or a dopamine D1 receptor antagonist (1.0 or 3.0 µg SCH39166/hemisphere) into Pir to determine the effect on fentanyl relapse. Fentanyl relapse was associated with OFC cells co-expressing Fos and Cnr1 and Pir cells co-expressing Fos and Drd1 However, injections of the CB1 receptor antagonist AM251 or agonist WIN55,212-2 into OFC or the dopamine D1 receptor antagonist SCH39166 into Pir had no effect on fentanyl relapse. Fentanyl relapse is associated with activation of Cnr1-expressing OFC cells and Drd1-expressing Pir cells, but pharmacological manipulations do not support causal roles of OFC CB1 receptors or Pir dopamine D1 receptors in fentanyl relapse.
Palmer MV, Wiarda J, Kanipe C and Thacker TC
PMID: 30895908 | DOI: 10.1177/0300985819833454
Mycobacterium bovis is a serious zoonotic pathogen and the cause of tuberculosis in many mammalian species, most notably, cattle. The hallmark lesion of tuberculosis is the granuloma. It is within the developing granuloma where host and pathogen interact; therefore, it is critical to understand host-pathogen interactions at the granuloma level. Cytokines and chemokines drive cell recruitment, activity, and function and ultimately determine the success or failure of the host to control infection. In calves, early lesions (ie, 15 and 30 days) after experimental aerosol infection were examined microscopically using in situ hybridization and immunohistochemistry to demonstrate early infiltrates of CD68+ macrophages within alveoli and alveolar interstitium, as well as the presence of CD4, CD8, and gammadelta T cells. Unlike lesions at 15 days, lesions at 30 days after infection contained small foci of necrosis among infiltrates of macrophages, lymphocytes, neutrophils, and multinucleated giant cells and extracellular acid-fast bacilli within necrotic areas. At both time points, there was abundant expression of the chemokines CXCL9, MCP-1/CCL2, and the cytokine transforming growth factor (TGF)-beta. The proinflammatory cytokines tumor necrosis factor (TNF)-alpha and interleukin (IL)-1beta, as well as the anti-inflammatory cytokine IL-10, were expressed at moderate levels at both time points, while expression of IFN-gamma was limited. These findings document the early pulmonary lesions after M. bovis infection in calves and are in general agreement with the proposed pathogenesis of tuberculosis described in laboratory animal and nonhuman primate models of tuberculosis.
Bullock BL, Kimball AK, Poczobutt JM, Neuwelt AJ, Li HY, Johnson AM, Kwak JW, Kleczko EK, Kaspar RE, Wagner EK, Hopp K, Schenk EL, Weiser-Evans MC, Clambey ET, Nemenoff RA.
PMID: 31133614 | DOI: 10.26508/lsa.201900328
Targeting PD-1/PD-L1 is only effective in ∼20% of lung cancer patients, but determinants of this response are poorly defined. We previously observed differential responses of two murine K-Ras-mutant lung cancer cell lines to anti-PD-1 therapy: CMT167 tumors were eliminated, whereas Lewis Lung Carcinoma (LLC) tumors were resistant. The goal of this study was to define mechanism(s) mediating this difference. RNA sequencing analysis of cancer cells recovered from lung tumors revealed that CMT167 cells induced an IFNγ signature that was blunted in LLC cells. Silencing Ifngr1 in CMT167 resulted in tumors resistant to IFNγ and anti-PD-1 therapy. Conversely, LLC cells had high basal expression of SOCS1, an inhibitor of IFNγ. Silencing Socs1 increased response to IFNγ in vitro and sensitized tumors to anti-PD-1. This was associated with a reshaped tumor microenvironment, characterized by enhanced T cell infiltration and enrichment of PD-L1hi myeloid cells. These studies demonstrate that targeted enhancement of tumor-intrinsic IFNγ signaling can induce a cascade of changes associated with increased therapeutic vulnerability
