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Proceedings of the National Academy of... Feb 2024Neuropeptide S (NPS) was postulated to be a wake-promoting neuropeptide with unknown mechanism, and a mutation in its receptor (NPSR1) causes the short sleep duration...
Neuropeptide S (NPS) was postulated to be a wake-promoting neuropeptide with unknown mechanism, and a mutation in its receptor (NPSR1) causes the short sleep duration trait in humans. We investigated the role of different NPS nuclei in sleep/wake regulation. Loss-of-function and chemogenetic studies revealed that NPS neurons in the parabrachial nucleus (PB) are wake-promoting, whereas peri-locus coeruleus (peri-LC) NPS neurons are not important for sleep/wake modulation. Further, we found that a NPS nucleus in the central gray of the pons (CGPn) strongly promotes sleep. Fiber photometry recordings showed that NPS neurons are wake-active in the CGPn and wake/REM-sleep active in the PB and peri-LC. Blocking NPS-NPSR1 signaling or knockdown of supported the function of the NPS-NPSR1 pathway in sleep/wake regulation. Together, these results reveal that NPS and NPS neurons play dichotomous roles in sleep/wake regulation at both the molecular and circuit levels.
Topics: Humans; Sleep; Pons; Locus Coeruleus; Neurons; Neuropeptides; Receptors, G-Protein-Coupled
PubMed: 38381789
DOI: 10.1073/pnas.2320276121 -
The Journal of Neuroscience : the... Nov 2023The parabrachial nucleus (PBN) interfaces between taste and feeding systems and is also an important hub for relaying distress information and threats. Despite that the...
The parabrachial nucleus (PBN) interfaces between taste and feeding systems and is also an important hub for relaying distress information and threats. Despite that the PBN sends projections to the ventral tegmental area (VTA), a heterogeneous brain region that regulates motivational behaviors, the function of the PBN-to-VTA connection remains elusive. Here, by using male mice in several behavioral paradigms, we discover that VTA-projecting PBN neurons are significantly engaged in contextual fear, restraint or mild stress but not palatable feeding, visceral malaise, or thermal pain. These results suggest that the PBN-to-VTA input may relay negative emotions under threat. Consistent with this notion, optogenetic activation of PBN-to-VTA glutamatergic input results in aversion, which is sufficient to override palatable feeding. Moreover, in a palatable food-reinforced operant task, we demonstrate that transient optogenetic activation of PBN-to-VTA input during food reward retrieval disengages instrumental food-seeking behaviors but spares learned action-outcome association. By using an activity-dependent targeting approach, we show that VTA DA neurons are disengaged by the PBN afferent activation, implicating that VTA non-DA neurons may mediate PBN afferent regulation. We further show that optogenetic activation of VTA neurons functionally recruited by the PBN input results in aversion, dampens palatable feeding, and disengages palatable food self-administration behavior. Finally, we demonstrate that transient activation of VTA glutamatergic, but not GABAergic, neurons recapitulates the negative regulation of the PBN input on food self-administration behavior. Together, we reveal that the PBN-to-VTA input conveys negative affect, likely through VTA glutamatergic neurons, to disengage instrumental food-seeking behaviors. The PBN receives multiple inputs and thus is well positioned to route information of various modalities to engage different downstream circuits to attend or respond accordingly. We demonstrate that the PBN-to-VTA input conveys negative affect and then triggers adaptive prioritized responses to address pertinent needs by withholding ongoing behaviors, such as palatable food seeking or intake shown in the present study. It has evolutionary significance because preparing to cope with stressful situations or threats takes priority over food seeking to promote survival. Knowing how appropriate adaptive responses are generated will provide new insights into circuitry mechanisms of various coping behaviors to changing environmental stimuli.
Topics: Mice; Male; Animals; Ventral Tegmental Area; Parabrachial Nucleus; Food; GABAergic Neurons; Emotions; Reward
PubMed: 37684032
DOI: 10.1523/JNEUROSCI.2114-22.2023 -
BioRxiv : the Preprint Server For... May 2024The parabrachial nucleus (PB), located in the dorsolateral pons, contains primarily glutamatergic neurons which regulate responses to a variety of interoceptive and...
The parabrachial nucleus (PB), located in the dorsolateral pons, contains primarily glutamatergic neurons which regulate responses to a variety of interoceptive and cutaneous sensory signals. The lateral PB subpopulation expressing the gene which produces the neuropeptide calcitonin gene-related peptide (CGRP) relays signals related to threatening stimuli such as hypercarbia, pain, and nausea, yet the afferents to these neurons are only partially understood. We mapped the afferent projections to the lateral part of the PB in mice using conventional cholera toxin B subunit (CTb) retrograde tracing, and then used conditional rabies virus retrograde tracing to map monosynaptic inputs specifically targeting the PB neurons. Using vesicular GABA (vGAT) and glutamate (vGLUT2) transporter reporter mice, we found that lateral PB neurons receive GABAergic afferents from regions such as the lateral part of the central nucleus of the amygdala, lateral dorsal subnucleus of the bed nucleus of the stria terminalis, substantia innominata, and the ventrolateral periaqueductal gray. Additionally, they receive glutamatergic afferents from the infralimbic and insular cortex, paraventricular nucleus, parasubthalamic nucleus, trigeminal complex, medullary reticular nucleus, and nucleus of the solitary tract. Using anterograde tracing and confocal microscopy, we then identified close axonal appositions between these afferents and PB neurons. Finally, we used channelrhodopsin-assisted circuit mapping to test whether some of these inputs directly synapse upon the PB neurons. These findings provide a comprehensive neuroanatomical framework for understanding the afferent projections regulating the PB neurons.
PubMed: 38766214
DOI: 10.1101/2024.05.07.593004 -
CNS Neuroscience & Therapeutics Nov 2023Neuropathic pain after spinal cord injury (SCI) remains a common and thorny problem, influencing the life quality severely. This study aimed to elucidate the...
Neuropathic pain following spinal cord hemisection induced by the reorganization in primary somatosensory cortex and regulated by neuronal activity of lateral parabrachial nucleus.
AIMS
Neuropathic pain after spinal cord injury (SCI) remains a common and thorny problem, influencing the life quality severely. This study aimed to elucidate the reorganization of the primary sensory cortex (S1) and the regulatory mechanism of the lateral parabrachial nucleus (lPBN) in the presence of allodynia or hyperalgesia after left spinal cord hemisection injury (LHS).
METHODS
Through behavioral tests, we first identified mechanical allodynia and thermal hyperalgesia following LHS. We then applied two-photon microscopy to observe calcium activity in S1 during mechanical or thermal stimulation and long-term spontaneous calcium activity after LHS. By slice patch clamp recording, the electrophysiological characteristics of neurons in lPBN were explored. Finally, exploiting chemogenetic activation or inhibition of the neurons in lPBN, allodynia or hyperalgesia was regulated.
RESULTS
The calcium activity in left S1 was increased during mechanical stimulation of right hind limb and thermal stimulation of tail, whereas in right S1 it was increased only with thermal stimulation of tail. The spontaneous calcium activity in right S1 changed more dramatically than that in left S1 after LHS. The lPBN was also activated after LHS, and exploiting chemogenetic activation or inhibition of the neurons in lPBN could induce or alleviate allodynia and hyperalgesia in central neuropathic pain.
CONCLUSION
The neuronal activity changes in S1 are closely related to limb pain, which has accurate anatomical correspondence. After LHS, the spontaneously increased functional connectivity of calcium transient in left S1 is likely causing the mechanical allodynia in right hind limb and increased neuronal activity in bilateral S1 may induce thermal hyperalgesia in tail. This state of allodynia and hyperalgesia can be regulated by lPBN.
Topics: Humans; Hyperalgesia; Parabrachial Nucleus; Calcium; Somatosensory Cortex; Spinal Cord; Neuralgia; Neurons; Spinal Cord Injuries
PubMed: 37170721
DOI: 10.1111/cns.14258 -
BioRxiv : the Preprint Server For... Aug 2023In the brain, connectivity determines function. Neurons in the parabrachial nucleus (PB) relay diverse information to widespread brain regions, but the connections and...
In the brain, connectivity determines function. Neurons in the parabrachial nucleus (PB) relay diverse information to widespread brain regions, but the connections and functions of PB neurons that express (neuropeptide S) remain mysterious. Here, we use Cre-dependent anterograde tracing and whole-brain analysis to map their output connections. While many other PB neurons project ascending axons through the central tegmental tract, NPS axons reach the forebrain via distinct periventricular and ventral pathways. Along the periventricular pathway, NPS axons target the tectal longitudinal column and periaqueductal gray then continue rostrally to target the paraventricular nucleus of the thalamus. Along the ventral pathway, NPS axons blanket much of the hypothalamus but avoid the ventromedial and mammillary nuclei. They also project prominently to the ventral bed nucleus of the stria terminalis, A13 cell group, and magnocellular subparafasciular nucleus. In the hindbrain, NPS axons have fewer descending projections, targeting primarily the superior salivatory nucleus, nucleus of the lateral lemniscus, and periolivary region. Combined with what is known about NPS and its receptor, the output pattern of -expressing neurons in the PB region predicts a role in threat response and circadian behavior.
PubMed: 37645772
DOI: 10.1101/2023.08.13.553140 -
Neuropsychopharmacology : Official... Feb 2024The spino-ponto-amygdaloid pathway is a major ascending circuit relaying nociceptive information from the spinal cord to the brain. Potentiation of excitatory synaptic...
The spino-ponto-amygdaloid pathway is a major ascending circuit relaying nociceptive information from the spinal cord to the brain. Potentiation of excitatory synaptic transmission in the parabrachial nucleus (PBN) to central amygdala (CeA) pathway has been reported in rodent models of persistent pain. However, the functional significance of this pathway in the modulation of the somatosensory component of pain was recently challenged by studies showing that spinal nociceptive neurons do not target CeA-projecting PBN cells and that manipulations of this pathway have no effect on reflexive-defensive somatosensory responses to peripheral noxious stimulation. Here, we showed that activation of CeA-projecting PBN neurons is critical to increase both stimulus-evoked and spontaneous nociceptive responses following an injury in male and female mice. Using optogenetic-assisted circuit mapping, we confirmed a functional excitatory projection from PBN→CeA that is independent of the genetic or firing identity of CeA cells. We then showed that peripheral noxious stimulation increased the expression of the neuronal activity marker Fos in CeA-projecting PBN neurons and that chemogenetic inactivation of these cells decreased behavioral hypersensitivity in models of neuropathic and inflammatory pain without affecting baseline nociception. Lastly, we showed that chemogenetic activation of CeA-projecting PBN neurons is sufficient to induced bilateral hypersensitivity without injury. Together, our results indicate that the PBN→CeA pathway is a key modulator of pain-related behaviors that can increase reflexive-defensive and affective-motivational responses to somatosensory stimulation in injured states without affecting nociception under normal physiological conditions.
Topics: Mice; Male; Female; Animals; Central Amygdaloid Nucleus; Pain; Parabrachial Nucleus; Neurons; Synaptic Transmission
PubMed: 37542159
DOI: 10.1038/s41386-023-01673-6 -
Brain Research Bulletin Sep 2023The nucleus tractus solitarii (NTS) is the primary central station that integrates visceral afferent information and regulates respiratory, gastrointestinal,...
The nucleus tractus solitarii (NTS) is the primary central station that integrates visceral afferent information and regulates respiratory, gastrointestinal, cardiovascular, and other physiological functions. Leptin receptor b (LepRb)-expressing neurons of the NTS (NTS neurons) are implicated in central respiration regulation, respiratory facilitation, and respiratory drive enhancement. Furthermore, LepRb dysfunction is involved in obesity, insulin resistance, and sleep-disordered breathing. However, the monosynaptic inputs and outputs of NTS neurons in whole-brain mapping remain to be elucidated. Therefore, the exploration of its whole-brain connection system may provide strong support for comprehensively understanding the physiological and pathological functions of NTS neurons. In the present study, we used a cell type-specific, modified rabies virus and adeno-associated virus with the Cre-loxp system to map monosynaptic inputs and outputs of NTS neurons in LepRb-Cre mice. The results showed that NTS neurons received inputs from 48 nuclei in the whole brain from five brain regions, including especially the medulla. We found that NTS neurons received inputs from nuclei associated with respiration, such as the pre-Bötzinger complex, ambiguus nucleus, and parabrachial nucleus. Interestingly, some brain areas related to cardiovascular regulation-i.e., the ventrolateral periaqueductal gray and locus coeruleus-also sent a small number of inputs to NTS neurons. In addition, anterograde tracing results demonstrated that NTS neurons sent efferent projections to 15 nuclei, including the dorsomedial hypothalamic nucleus and arcuate hypothalamic nucleus, which are involved in regulation of energy metabolism and feeding behaviors. Quantitative statistical analysis revealed that the inputs of the whole brain to NTS neurons were significantly greater than the outputs. Our study comprehensively revealed neuronal connections of NTS neurons in the whole brain and provided a neuroanatomical basis for further research on physiological and pathological functions of NTS neurons.
Topics: Mice; Animals; Solitary Nucleus; Receptors, Leptin; Neurons; Brain Mapping; Obesity
PubMed: 37348822
DOI: 10.1016/j.brainresbull.2023.110693 -
Biological Psychiatry Global Open... Oct 2023The neuropeptide PACAP (pituitary adenylate cyclase-activating polypeptide) is a master regulator of central and peripheral stress responses, yet it is not clear how...
BACKGROUND
The neuropeptide PACAP (pituitary adenylate cyclase-activating polypeptide) is a master regulator of central and peripheral stress responses, yet it is not clear how PACAP projections throughout the brain execute endocrine and behavioral stress responses.
METHODS
We used AAV (adeno-associated virus) neuronal tracing, an acute restraint stress (ARS) paradigm, and intersectional genetics, in C57BL/6 mice, to identify PACAP-containing circuits controlling stress-induced behavior and endocrine activation.
RESULTS
PACAP deletion from forebrain excitatory neurons, including a projection directly from medial prefrontal cortex to hypothalamus, impairs c-fos activation and corticotropin-releasing hormone (CRH) messenger RNA elevation in the paraventricular nucleus after 2 hours of restraint, without affecting ARS-induced hypophagia, or c-fos elevation in nonhypothalamic brain. Elimination of PACAP within projections from lateral parabrachial nucleus to extended amygdala, on the other hand, attenuates ARS-induced hypophagia, along with extended amygdala fos induction, without affecting ARS-induced CRH messenger RNA elevation in the paraventricular nucleus. PACAP projections to extended amygdala terminate at protein kinase C delta type (PKCδ) neurons in both the central amygdala and the oval bed nucleus of the stria terminalis. Silencing of PKCδ neurons in the central amygdala, but not in the oval bed nucleus of the stria terminalis, attenuates ARS-induced hypophagia. Experiments were carried out in mice of both sexes with ≥ 3 per group.
CONCLUSIONS
A frontocortical descending PACAP projection controls paraventricular nucleus CRH messenger RNA production to maintain hypothalamic-pituitary-adrenal axis activation and regulate the endocrine response to stress. An ascending PACAPergic projection from the external lateral parabrachial nucleus to PKCδ neurons in the central amygdala regulates behavioral responses to stress. Defining two separate limbs of the acute stress response provides broader insight into the specific brain circuitry engaged by the psychogenic stress response.
PubMed: 37881538
DOI: 10.1016/j.bpsgos.2023.04.001 -
Zoological Research May 2024Painful stimuli elicit first-line reflexive defensive reactions and, in many cases, also evoke second-line recuperative behaviors, the latter of which reflects the...
Painful stimuli elicit first-line reflexive defensive reactions and, in many cases, also evoke second-line recuperative behaviors, the latter of which reflects the sensing of tissue damage and the alleviation of suffering. The lateral parabrachial nucleus (lPBN), composed of external- (elPBN), dorsal- (dlPBN), and central/superior-subnuclei (jointly referred to as slPBN), receives sensory inputs from spinal projection neurons and plays important roles in processing affective information from external threats and body integrity disruption. However, the organizational rules of lPBN neurons that provoke diverse behaviors in response to different painful stimuli from cutaneous and deep tissues remain unclear. In this study, we used region-specific neuronal depletion or silencing approaches combined with a battery of behavioral assays to show that slPBN neurons expressing substance P receptor ( ) (lPBN ) are crucial for driving pain-associated self-care behaviors evoked by sustained noxious thermal and mechanical stimuli applied to skin or bone/muscle, while elPBN neurons are dispensable for driving such reactions. Notably, lPBN neurons are specifically required for forming sustained somatic pain-induced negative teaching signals and aversive memory but are not necessary for fear-learning or escape behaviors elicited by external threats. Lastly, both lPBN and elPBN neurons contribute to chemical irritant-induced nocifensive reactions. Our results reveal the functional organization of parabrachial substrates that drive distinct behavioral outcomes in response to sustained pain versus external danger under physiological conditions.
Topics: Animals; Parabrachial Nucleus; Mice; Nociception; Neurons; Pain; Male; Behavior, Animal
PubMed: 38766746
DOI: 10.24272/j.issn.2095-8137.2023.412 -
Neuroscience Jan 2024The paraventricular nucleus of the thalamus (PVT) sends dense projections to the shell of the nucleus accumbens (NAcSh), dorsolateral region of the bed nucleus of the...
The paraventricular nucleus of the thalamus (PVT) sends dense projections to the shell of the nucleus accumbens (NAcSh), dorsolateral region of the bed nucleus of the stria terminalis (BSTDL) and the lateral region of central nucleus of the amygdala (CeL). Projection specific modulation of these pathways has been shown to regulate appetitive and aversive behavioral responses. The present investigation applied an intersectional monosynaptic rabies tracing approach to quantify the brain-wide sources of afferent input to PVT neurons that primarily project to the NAcSh, BSTDL and CeL. The results demonstrate that these projection neurons receive monosynaptic input from similar brain regions. The prefrontal cortex and the ventral subiculum of the hippocampus were major sources of input to the PVT projection neurons. In addition, the lateral septal nucleus, thalamic reticular nucleus and the hypothalamic medial preoptic area, dorsomedial, ventromedial, and arcuate nuclei were sources of input. The subfornical organ, parasubthalamic nucleus, periaqueductal gray matter, lateral parabrachial nucleus, and nucleus of the solitary tract were consistent but lesser sources of input. This input-output relationship is consistent with recent observations that PVT neurons have axons that bifurcate extensively to divergently innervate the NAcSh, BSTDL and CeL.
Topics: Nucleus Accumbens; Central Amygdaloid Nucleus; Paraventricular Hypothalamic Nucleus; Hypothalamus; Neurons; Neural Pathways
PubMed: 38056620
DOI: 10.1016/j.neuroscience.2023.11.033