REV-ERB in GABAergic neurons controls diurnal hepatic insulin sensitivity
Ding, G;Li, X;Hou, X;Zhou, W;Gong, Y;Liu, F;He, Y;Song, J;Wang, J;Basil, P;Li, W;Qian, S;Saha, P;Wang, J;Cui, C;Yang, T;Zou, K;Han, Y;Amos, CI;Xu, Y;Chen, L;Sun, Z;
PMID: 33762728 | DOI: 10.1038/s41586-021-03358-w
Systemic insulin sensitivity shows a diurnal rhythm with a peak upon waking1,2. The molecular mechanism that underlies this temporal pattern is unclear. Here we show that the nuclear receptors REV-ERB-α and REV-ERB-β (referred to here as 'REV-ERB') in the GABAergic (γ-aminobutyric acid-producing) neurons in the suprachiasmatic nucleus (SCN) (SCNGABA neurons) control the diurnal rhythm of insulin-mediated suppression of hepatic glucose production in mice, without affecting diurnal eating or locomotor behaviours during regular light-dark cycles. REV-ERB regulates the rhythmic expression of genes that are involved in neurotransmission in the SCN, and modulates the oscillatory firing activity of SCNGABA neurons. Chemogenetic stimulation of SCNGABA neurons at waking leads to glucose intolerance, whereas restoration of the temporal pattern of either SCNGABA neuron firing or REV-ERB expression rescues the time-dependent glucose metabolic phenotype caused by REV-ERB depletion. In individuals with diabetes, an increased level of blood glucose after waking is a defining feature of the 'extended dawn phenomenon'3,4. Patients with type 2 diabetes with the extended dawn phenomenon exhibit a differential temporal pattern of expression of REV-ERB genes compared to patients with type 2 diabetes who do not have the extended dawn phenomenon. These findings provide mechanistic insights into how the central circadian clock regulates the diurnal rhythm of hepatic insulin sensitivity, with implications for our understanding of the extended dawn phenomenon in type 2 diabetes.
Dowall, S;Salguero, FJ;Wiblin, N;Fotheringham, S;Hatch, G;Parks, S;Gowan, K;Harris, D;Carnell, O;Fell, R;Watson, R;Graham, V;Gooch, K;Hall, Y;Mizen, S;Hewson, R;
PMID: 34835057 | DOI: 10.3390/v13112251
The global pandemic of coronavirus disease (COVID-19) caused by infection with severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) has led to an international thrust to study pathogenesis and evaluate interventions. Experimental infection of hamsters and the resulting respiratory disease is one of the preferred animal models since clinical signs of disease and virus shedding are similar to more severe cases of human COVID-19. The main route of challenge has been direct inoculation of the virus via the intranasal route. To resemble the natural infection, we designed a bespoke natural transmission cage system to assess whether recipient animals housed in physically separate adjacent cages could become infected from a challenged donor animal in a central cage, with equal airflow across the two side cages. To optimise viral shedding in the donor animals, a low and moderate challenge dose were compared after direct intranasal challenge, but similar viral shedding responses were observed and no discernible difference in kinetics. The results from our natural transmission set-up demonstrate that most recipient hamsters are infected within the system developed, with variation in the kinetics and levels of disease between individual animals. Common clinical outputs used for the assessment in directly-challenged hamsters, such as weight loss, are less obvious in hamsters who become infected from naturally acquiring the infection. The results demonstrate the utility of a natural transmission model for further work on assessing the differences between virus strains and evaluating interventions using a challenge system which more closely resembles human infection.
Glucagon-like peptide 1 receptor-mediated stimulation of a GABAergic projection from the bed nucleus of the stria terminalis to the hypothalamic paraventricular nucleus
Povysheva, N;Zheng, H;Rinaman, L;
PMID: 34277897 | DOI: 10.1016/j.ynstr.2021.100363
We previously reported that GABAergic neurons within the ventral anterior lateral bed nucleus of the stria terminalis (alBST) express glucagon-like peptide 1 receptor (GLP1R) in rats, and that virally-mediated "knock-down" of GLP1R expression in the alBST prolongs the hypothalamic-pituitary-adrenal axis response to acute stress. Given other evidence that a GABAergic projection pathway from ventral alBST serves to limit stress-induced activation of the HPA axis, we hypothesized that GLP1 signaling promotes activation of GABAergic ventral alBST neurons that project directly to the paraventricular nucleus of the hypothalamus (PVN). After PVN microinjection of fluorescent retrograde tracer followed by preparation of ex vivo rat brain slices, whole-cell patch clamp recordings were made in identified PVN-projecting neurons within the ventral alBST. Bath application of Exendin-4 (a specific GLP1R agonist) indirectly depolarized PVN-projecting neurons in the ventral alBST and adjacent hypothalamic parastrial nucleus (PS) through a network-dependent increase in excitatory synaptic inputs, coupled with a network-independent reduction in inhibitory inputs. Additional retrograde tracing experiments combined with in situ hybridization confirmed that PVN-projecting neurons within the ventral alBST/PS are GABAergic, and do not express GLP1R mRNA. Conversely, GLP1R mRNA is expressed by a subset of neurons that project into the ventral alBST and were likely contained within coronal ex vivo slices, including GABAergic neurons within the oval subnucleus of the dorsal alBST and glutamatergic neurons within the substantia innominata. Our novel findings reveal potential GLP1R-mediated mechanisms through which the alBST exerts inhibitory control over the endocrine HPA axis.
An amygdala circuit that suppresses social engagement
Kwon, JT;Ryu, C;Lee, H;Sheffield, A;Fan, J;Cho, DH;Bigler, S;Sullivan, HA;Choe, HK;Wickersham, IR;Heiman, M;Choi, GB;
PMID: 33790466 | DOI: 10.1038/s41586-021-03413-6
Innate social behaviours, such as mating and fighting, are fundamental to animal reproduction and survival1. However, social engagements can also put an individual at risk2. Little is known about the neural mechanisms that enable appropriate risk assessment and the suppression of hazardous social interactions. Here we identify the posteromedial nucleus of the cortical amygdala (COApm) as a locus required for the suppression of male mating when a female mouse is unhealthy. Using anatomical tracing, functional imaging and circuit-level epistatic analyses, we show that suppression of mating with an unhealthy female is mediated by the COApm projections onto the glutamatergic population of the medial amygdalar nucleus (MEA). We further show that the role of the COApm-to-MEA connection in regulating male mating behaviour relies on the neuromodulator thyrotropin-releasing hormone (TRH). TRH is expressed in the COApm, whereas the TRH receptor (TRHR) is found in the postsynaptic MEA glutamatergic neurons. Manipulating neural activity of TRH-expressing neurons in the COApm modulated male mating behaviour. In the MEA, activation of the TRHR pathway by ligand infusion inhibited mating even towards healthy female mice, whereas genetic ablation of TRHR facilitated mating with unhealthy individuals. In summary, we reveal a neural pathway that relies on the neuromodulator TRH to modulate social interactions according to the health status of the reciprocating individual. Individuals must balance the cost of social interactions relative to the benefit, as deficits in the ability to select healthy mates may lead to the spread of disease.
Signal transduction and targeted therapy
Zheng, Y;Xu, C;Sun, J;Ming, W;Dai, S;Shao, Y;Qiu, X;Li, M;Shen, C;Xu, J;Fei, F;Fang, J;Jiang, X;Zheng, G;Hu, W;Wang, Y;Wang, S;Ding, M;Chen, Z;
PMID: 37193687 | DOI: 10.1038/s41392-023-01404-9
Seizures due to cortical dysplasia are notorious for their poor prognosis even with medications and surgery, likely due to the widespread seizure network. Previous studies have primarily focused on the disruption of dysplastic lesions, rather than remote regions such as the hippocampus. Here, we first quantified the epileptogenicity of the hippocampus in patients with late-stage cortical dysplasia. We further investigated the cellular substrates leading to the epileptic hippocampus, using multiscale tools including calcium imaging, optogenetics, immunohistochemistry and electrophysiology. For the first time, we revealed the role of hippocampal somatostatin-positive interneurons in cortical dysplasia-related seizures. Somatostatin-positive were recruited during cortical dysplasia-related seizures. Interestingly, optogenetic studies suggested that somatostatin-positive interneurons paradoxically facilitated seizure generalization. By contrast, parvalbumin-positive interneurons retained an inhibitory role as in controls. Electrophysiological recordings and immunohistochemical studies revealed glutamate-mediated excitatory transmission from somatostatin-positive interneurons in the dentate gyrus. Taken together, our study reveals a novel role of excitatory somatostatin-positive neurons in the seizure network and brings new insights into the cellular basis of cortical dysplasia.
Xu Y, Chang JT, Myers MG Jr, Xu Y, Tong Q.
PMID: 26822087 | DOI: -
Central leptin action is sufficient to restore euglycemia in insulinopenic type 1 diabetes (T1D); however, the underlying mechanism remains poorly understood. To examine the role of intracellular STAT3 pathways, we used LepRs/s mice with disrupted leptin-pSTAT3 signaling to test the effect of central leptin on euglycemia restoration. These mice developed STZ-induced T1D, which was surprisingly not associated with hyperglucagonemia, a typical manifestation in T1D. Further, leptin action on euglycemia restoration was abrogated in these mice, which was associated with refractory hypercorticosteronemia. To examine the role of fast-acting neurotransmitters glutamate and γ-aminobutyric acid (GABA), two major neurotransmitters in the brain, from LepR neurons, we used mice with disrupted release of glutamate, GABA or both from LepR neurons. Surprisingly, all mice responded normally to leptin-mediated euglycemia restoration, which was associated with expected correction from hyperglucagonemia and hyperphagia. In contrast, mice with loss of glutamate and GABA appeared to develop an additive obesity effect over those with loss of single neurotransmitter release. Thus, our study reveals that STAT3 signaling, but not fast-acting neurotransmitter release, is required for leptin action on euglycemia restoration, and that hyperglucagonemia is not required for T1D.
Ahrlund-Richter S, Xuan Y, van Lunteren JA, Kim H, Ortiz C, Pollak Dorocic I, Meletis K and Carlen M
PMID: 30886408 | DOI: 10.1038/s41593-019-0354-y
The local and long-range connectivity of cortical neurons are considered instrumental to the functional repertoire of the cortical region in which they reside. In cortical networks, distinct cell types build local circuit structures enabling computational operations. Computations in the medial prefrontal cortex (mPFC) are thought to be central to cognitive operation, including decision-making and memory. We used a retrograde trans-synaptic rabies virus system to generate brain-wide maps of the input to excitatory neurons as well as three inhibitory interneuron subtypes in the mPFC. On the global scale the input patterns were found to be mainly cell type independent, with quantitative differences in key brain regions, including the basal forebrain. Mapping of the local mPFC network revealed high connectivity between the different subtypes of interneurons. The connectivity mapping gives insight into the information that the mPFC processes and the structural architecture underlying the mPFC's unique functions.
SARS-CoV-2 infection and transmission in the North American deer mouse
Griffin, BD;Chan, M;Tailor, N;Mendoza, EJ;Leung, A;Warner, BM;Duggan, AT;Moffat, E;He, S;Garnett, L;Tran, KN;Banadyga, L;Albietz, A;Tierney, K;Audet, J;Bello, A;Vendramelli, R;Boese, AS;Fernando, L;Lindsay, LR;Jardine, CM;Wood, H;Poliquin, G;Strong, JE;Drebot, M;Safronetz, D;Embury-Hyatt, C;Kobasa, D;
PMID: 34127676 | DOI: 10.1038/s41467-021-23848-9
Widespread circulation of SARS-CoV-2 in humans raises the theoretical risk of reverse zoonosis events with wildlife, reintroductions of SARS-CoV-2 into permissive nondomesticated animals. Here we report that North American deer mice (Peromyscus maniculatus) are susceptible to SARS-CoV-2 infection following intranasal exposure to a human isolate, resulting in viral replication in the upper and lower respiratory tract with little or no signs of disease. Further, shed infectious virus is detectable in nasal washes, oropharyngeal and rectal swabs, and viral RNA is detectable in feces and occasionally urine. We further show that deer mice are capable of transmitting SARS-CoV-2 to naïve deer mice through direct contact. The extent to which these observations may translate to wild deer mouse populations remains unclear, and the risk of reverse zoonosis and/or the potential for the establishment of Peromyscus rodents as a North American reservoir for SARS-CoV-2 remains unknown.
Low, AYT;Goldstein, N;Gaunt, JR;Huang, KP;Zainolabidin, N;Yip, AKK;Carty, JRE;Choi, JY;Miller, AM;Ho, HST;Lenherr, C;Baltar, N;Azim, E;Sessions, OM;Ch'ng, TH;Bruce, AS;Martin, LE;Halko, MA;Brady, RO;Holsen, LM;Alhadeff, AL;Chen, AI;Betley, JN;
PMID: 34789878 | DOI: 10.1038/s41586-021-04143-5
The brain is the seat of body weight homeostasis. However, our inability to control the increasing prevalence of obesity highlights a need to look beyond canonical feeding pathways to broaden our understanding of body weight control1-3. Here we used a reverse-translational approach to identify and anatomically, molecularly and functionally characterize a neural ensemble that promotes satiation. Unbiased, task-based functional magnetic resonance imaging revealed marked differences in cerebellar responses to food in people with a genetic disorder characterized by insatiable appetite. Transcriptomic analyses in mice revealed molecularly and topographically -distinct neurons in the anterior deep cerebellar nuclei (aDCN) that are activated by feeding or nutrient infusion in the gut. Selective activation of aDCN neurons substantially decreased food intake by reducing meal size without compensatory changes to metabolic rate. We found that aDCN activity terminates food intake by increasing striatal dopamine levels and attenuating the phasic dopamine response to subsequent food consumption. Our study defines a conserved satiation centre that may represent a novel therapeutic target for the management of excessive eating, and underscores the utility of a 'bedside-to-bench' approach for the identification of neural circuits that influence behaviour.
Gastrointestinal Pathology in Samples from Coronavirus Disease 2019 (COVID-19)-Positive Patients
Archives of pathology & laboratory medicine
Westerhoff, M;Jones, D;Hrycaj, SM;Chan, MP;Pantanowitz, L;Tu, H;Choi, K;Greenson, J;Lamps, L;
PMID: 33961007 | DOI: 10.5858/arpa.2021-0137-SA
-Although primarily considered a respiratory illness, coronavirus disease 2019 (COVID-19) can cause gastrointestinal manifestations. -To evaluate histopathology and in situ hybridization for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in gastrointestinal samples from patients with recent and remote COVID-19. -Patients with positive SARS-CoV-2 nasopharyngeal tests and a gastrointestinal tissue specimen were included. SARS-CoV-2 in situ hybridization (ISH) was performed on each sample. A subset had SARS-CoV-2 next generation sequencing (NGS) performed. -Twenty-five patients met inclusion criteria. Five had positive SARS-CoV-2 nasopharyngeal tests within 7 days of their gastrointestinal procedure. Two were ulcerative colitis patients on steroid therapy who lacked typical COVID-19 symptoms. Their colectomies showed severe ulcerative colitis; one demonstrated SARS-CoV-2 by NGS but a negative ISH. Another had an ischemic colon resected as a complication of the COVID-19 course; however, both ISH and NGS were negative. A fourth had a normal-appearing terminal ileum but positive ISH and NGS. The fifth patient had ileal ulcers with SARS-CoV-2 negativity by both modalities. The remaining 20 patients had positive nasopharyngeal tests an average of 53 days prior to procedure. None of their samples demonstrated SARS-CoV-2 ISH positivity, but one was positive on NGS despite a negative nasopharyngeal test. -Gastrointestinal findings from SARS-CoV-2-infected patients ranged from normal with virus detected by ISH and NGS, to bowel ischemia secondary to systemic viral effects, without evidence of virus in the tissue. No distinct histologic finding was identified in those with gastrointestinal tissue specimens demonstrating SARS-CoV-2 positivity in this cohort.
Liu, X;Wang, Y;Zeng, Y;Wang, D;Wen, Y;Fan, L;He, Y;Zhang, J;Sun, W;Liu, Y;Tao, A;
PMID: 36876522 | DOI: 10.1111/all.15699
Spinal astrocytes contribute to chronic itch via sensitization of itch-specific neurons expressing gastrin-releasing peptide receptor (GRPR). However, whether microglia-neuron interactions contribute to itch remains unclear. In this study, we aimed to explore how microglia interact with GRPR+ neurons and promote chronic itch.RNA sequencing, quantitative real-time PCR, western blot, immunohistochemistry, RNAscope ISH, pharmacologic and genetic approaches were performed to examine the roles of spinal NLRP3 (The NOD-like receptor family, pyrin-containing domain 3) inflammasome activation and IL-1β-IL1R1 signaling in chronic itch. Grpr-eGFP and Grpr KO mice were used to investigate microglia-GRPR+ neuron interactions.We observed NLRP3 inflammasome activation and IL-1β production in spinal microglia under chronic itch conditions. Blockade of microglial activation and the NLRP3/caspase-1/IL-1β axis attenuated chronic itch and neuronal activation. Type 1 IL-1 receptor (IL-1R1) was expressed in GRPR+ neurons, which are essential for the development of chronic itch. Our studies also find that IL-1β+ microglia are localized in close proximity to GRPR+ neurons. Consistently, intrathecal injection of IL1R1 antagonist or exogenous IL-1β indicate that the IL-1β-IL-1R1 signaling pathway enhanced the activation of GRPR+ neurons. Furthermore, our results demonstrate that the microglial NLRP3/caspase-1/IL-1β axis contributes to several different chronic itches triggered by small molecules and protein allergens from the environment and drugs.Our findings reveal a previously unknown mechanism in which microglia enhances the activation of GRPR+ neurons through the NLRP3/caspase-1/IL-1β/IL1R1 axis. These results will provide new insights into the pathophysiology of pruritus and novel therapeutic strategies for patients with chronic itch.
Proceedings of the National Academy of Sciences of the United States of America
Zhong, W;Barde, S;Mitsios, N;Adori, C;Oksvold, P;Feilitzen, KV;O'Leary, L;Csiba, L;Hortobágyi, T;Szocsics, P;Mechawar, N;Maglóczky, Z;Renner, É;Palkovits, M;Uhlén, M;Mulder, J;Hökfelt, T;
PMID: 35947618 | DOI: 10.1073/pnas.2123146119
Human prefrontal cortex (hPFC) is a complex brain region involved in cognitive and emotional processes and several psychiatric disorders. Here, we present an overview of the distribution of the peptidergic systems in 17 subregions of hPFC and three reference cortices obtained by microdissection and based on RNA sequencing and RNAscope methods integrated with published single-cell transcriptomics data. We detected expression of 60 neuropeptides and 60 neuropeptide receptors in at least one of the hPFC subregions. The results reveal that the peptidergic landscape in PFC consists of closely located and functionally different subregions with unique peptide/transmitter-related profiles. Neuropeptide-rich PFC subregions were identified, encompassing regions from anterior cingulate cortex/orbitofrontal gyrus. Furthermore, marked differences in gene expression exist between different PFC regions (>5-fold; cocaine and amphetamine-regulated transcript peptide) as well as between PFC regions and reference regions, for example, for somatostatin and several receptors. We suggest that the present approach allows definition of, still hypothetical, microcircuits exemplified by glutamatergic neurons expressing a peptide cotransmitter either as an agonist (hypocretin/orexin) or antagonist (galanin). Specific neuropeptide receptors have been identified as possible targets for neuronal afferents and, interestingly, peripheral blood-borne peptide hormones (leptin, adiponectin, gastric inhibitory peptide, glucagon-like peptides, and peptide YY). Together with other recent publications, our results support the view that neuropeptide systems may play an important role in hPFC and underpin the concept that neuropeptide signaling helps stabilize circuit connectivity and fine-tune/modulate PFC functions executed during health and disease.
