Shi MM, Fan KM, Qiao YN, Xu JH, Qiu LJ, Li X, Liu Y, Qian ZQ, Wei CL, Han J, Fan J, Tian YF, Ren W, Liu ZQ.
PMID: 31142818 | DOI: 10.1038/s41380-019-0435-z
Stressful life events induce abnormalities in emotional and cognitive behaviour. The endogenous opioid system plays an essential role in stress adaptation and coping strategies. In particular, the µ-opioid receptor (μR), one of the major opioid receptors, strongly influences memory processing in that alterations in μR signalling are associated with various neuropsychiatric disorders. However, it remains unclear whether μR signalling contributes to memory impairments induced by acute stress. Here, we utilized pharmacological methods and cell-type-selective/non-cell-type-selective μR depletion approaches combined with behavioural tests, biochemical analyses, and in vitro electrophysiological recordings to investigate the role of hippocampal μR signalling in memory-retrieval impairment induced by acute elevated platform (EP) stress in mice. Biochemical and molecular analyses revealed that hippocampal μRs were significantly activated during acute stress. Blockage of hippocampal μRs, non-selective deletion of μRs or selective deletion of μRs on GABAergic neurons (μRGABA) reversed EP-stress-induced impairment of memory retrieval, with no effect on the elevation of serum corticosterone after stress. Electrophysiological results demonstrated that stress depressed hippocampal GABAergic synaptic transmission to CA1 pyramidal neurons, thereby leading to excitation/inhibition (E/I) imbalance in a μRGABA-dependent manner. Pharmaceutically enhancing hippocampal GABAAreceptor-mediated inhibitory currents in stressed mice restored their memory retrieval, whereas inhibiting those currents in the unstressed mice mimicked the stress-induced impairment of memory retrieval. Our findings reveal a novel pathway in which endogenous opioids recruited by acute stress predominantly activate μRGABA to depress GABAergic inhibitory effects on CA1 pyramidal neurons, which subsequently alters the E/I balance in the hippocampus and results in impairment of memory retrieval.
Brain Struct Funct. 2018 Oct 28.
Albert-Gasco H, Sanchez-Sarasua S, Ma S, García-Díaz C, Gundlach AL, Sanchez-Perez AM, Olucha-Bordonau FE.
PMID: 30368554 | DOI: 10.1007/s00429-018-1763-5
In mammals, the extended amygdala is a neural hub for social and emotional information processing. In the rat, the extended amygdala receives inhibitory GABAergic projections from the nucleus incertus (NI) in the pontine tegmentum. NI neurons produce the neuropeptide relaxin-3, which acts via the Gi/o-protein-coupled receptor, RXFP3. A putative role for RXFP3 signalling in regulating social interaction was investigated by assessing the effect of intracerebroventricular infusion of the RXFP3 agonist, RXFP3-A2, on performance in the 3-chamber social interaction paradigm. Central RXFP3-A2, but not vehicle, infusion, disrupted the capacity to discriminate between a familiar and novel conspecific subject, but did not alter differentiation between a conspecific and an inanimate object. Subsequent studies revealed that agonist-infused rats displayed increased phosphoERK(pERK)-immunoreactivity in specific amygdaloid nuclei at 20 min post-infusion, with levels similar to control again after 90 min. In parallel, we used immunoblotting to profile ERK phosphorylation dynamics in whole amygdala after RXFP3-A2 treatment; and multiplex histochemical labelling techniques to reveal that after RXFP3-A2 infusion and social interaction, pERK-immunopositive neurons in amygdala expressed vesicular GABA-transporter mRNA and displayed differential profiles of RXFP3 and oxytocin receptor mRNA. Overall, these findings demonstrate that central relaxin-3/RXFP3 signalling can modulate social recognition in rats via effects within the amygdala and likely interactions with GABA and oxytocin signalling.
Zhang, L;Koller, J;Gopalasingam, G;Qi, Y;Herzog, H;
PMID: 35691527 | DOI: 10.1016/j.molmet.2022.101525
Neuropeptide FF (NPFF) group peptides belong to the evolutionary conserved RF-amide peptide family. While they have been assigned a role as pain modulators, their roles in other aspects of physiology have received much less attention. NPFF peptides and their receptor NPFFR2 have strong and localized expression within the dorsal vagal complex that has emerged as the key centre for regulating glucose homeostasis. Therefore, we investigated the role of the NPFF system in the control of glucose metabolism and the histochemical and molecular identities of NPFF and NPFFR2 neurons.We examined glucose metabolism in Npff-/- and wild type (WT) mice using intraperitoneal (i.p.) glucose tolerance and insulin tolerance tests. Body composition and glucose tolerance was further examined in mice after 1-week and 3-week of high-fat diet (HFD). Using RNAScope double ISH, we investigated the neurochemical identity of NPFF and NPFFR2 neurons in the caudal brainstem, and the expression of receptors for peripheral factors in NPFF neurons.Lack of NPFF signalling in mice leads to improved glucose tolerance without significant impact on insulin excursion after the i.p. glucose challenge. In response to an i.p. bolus of insulin, Npff-/- mice have lower glucose excursions than WT mice, indicating an enhanced insulin action. Moreover, while HFD has rapid and potent detrimental effects on glucose tolerance, this diet-induced glucose intolerance is ameliorated in mice lacking NPFF signalling. This occurs in the absence of any significant impact of NPFF deletion on lean or fat masses, suggesting a direct effect of NPFF signalling on glucose metabolism. We further reveal that NPFF neurons in the subpostrema area (SubP) co-express receptors for peripheral factors involved in glucose homeostasis regulation such as insulin and GLP1. Furthermore, Npffr2 is expressed in the glutamatergic NPFF neurons in the SubP, and in cholinergic neurons of the dorsal motor nucleus of the vagus (DMV), indicating that central NPFF signalling is likely modulating vagal output to innervated peripheral tissues including those important for glucose metabolic control.NPFF signalling plays an important role in the regulation of glucose metabolism. NPFF neurons in the SubP are likely to receive peripheral signals and mediate the control of whole-body glucose homeostasis via centrally vagal pathways. Targeting NPFF and NPFFR2 signalling may provide a new avenue for treating type 2 diabetes and obesity.
Biological Psychiatry Global Open Science
Funayama, Y;Li, H;Ishimori, E;Kawatake-Kuno, A;Inaba, H;Yamagata, H;Seki, T;Nakagawa, S;Watanabe, Y;Murai, T;Oishi, N;Uchida, S;
| DOI: 10.1016/j.bpsgos.2021.12.009
Background A key challenge in the understanding and treatment of depression is identifying cell types and molecular mechanisms that mediate behavioral responses to antidepressant drugs. As treatment responses in clinical depression are heterogeneous, it is crucial to examine treatment responders and nonresponders in preclinical studies. Methods We utilized the large variance in behavioral responses to chronic treatment with multiple class of antidepressant drugs in different inbred mouse strains and classified the mice into responders and nonresponders based on their response in the forced swim test. Medial prefrontal cortex tissues were subjected to RNA sequencing to identify molecules that are consistently associated across antidepressant responders. We developed and employed virus-mediated gene transfer to induce the gene of interest in specific cell types and performed forced swim test, sucrose preference, social interaction, and open field tests to investigate antidepressant-like and anxiety behaviors. Results Cocaine- and amphetamine-regulated transcript peptide (Cartpt) expression was consistently upregulated in responders to four types of antidepressants but not in nonresponders in different mice strains. Responder mice given a single dose of ketamine, a fast-acting non-monoamine-based antidepressant, exhibited high CART peptide expression. CART peptide overexpression in the GABAergic neurons of the anterior cingulate cortex (aCC) led to antidepressant-like behavior and drove chronic stress resiliency independently of mouse genetic background. Conclusions These data demonstrate that activation of CART peptide signaling in GABAergic neurons of the aCC is a common molecular mechanism across antidepressant responders and that this pathway also drives stress resilience.
Domi E, Uhrig S, Soverchia L, Spanagel R, Hansson AC, Barbier E, Heilig M, Ciccocioppo R, Ubaldi M.
PMID: 27810934 | DOI: 10.1523/JNEUROSCI.4127-15.2016
PPARγ is one of the three isoforms of the Peroxisome Proliferator-Activated Receptors (PPARs). PPARγ is activated by thiazolidinediones such as pioglitazone, and it is targeted to treat insulin resistance. PPARγ is densely expressed in brain areas involved in regulation of motivational and emotional processes.Here, we investigated the role of PPARγ in the brain and explored its role in anxiety and stress responses in mice. The results show that stimulation of PPARγ by pioglitazone did not affect basal anxiety but fully prevented the anxiogenic effect of acute stress. Using mice with genetic ablation of neuronal PPARγ (PPARγNestinCre), we demonstrated that a lack of receptors, specifically in neurons, exacerbated basal anxiety and enhanced stress sensitivity. The administration of GW9662, a selective PPARγ antagonist, elicited a marked anxiogenic response in PPARγ wild-type (Wt) but not in PPARγNestinCre KO mice. Using c-Fos immunohistochemistry we observed that acute stress exposure resulted in a different pattern of neuronal activation in the amygdala and the hippocampus of PPARγNestinCre KO mice compared with Wt mice. No differences were found between Wt and KO mice in hypothalamic regions responsible for hormonal response to stress, nor in blood corticosterone levels. Microinjection of pioglitazone, into the amygdala but not into the hippocampus abolished the anxiogenic response elicited by acute stress. Results also showed that in both regions PPARγ co-localizes with GABAergic cells. These findings demonstrate that neuronal PPARγ is involved the regulation of the stress response, and that the amygdala is a key substrate for the anxiolytic effect of PPARγ.
SIGNIFICANCE STATEMENT:
PPARγ is a classical target for antidiabetic therapies with thiazolidinedione compounds. PPARγ agonists, such as rosiglitazone and pioglitazone, are in clinical use for the treatment of insulin resistance. PPARγ has recently attracted attention for its involvement in the regulation of CNS immune response and functions. Here, we demonstrate that neuronal PPARγ activation prevented the negative emotional effects of stress and exerted anxiolytic actions without influencing HPA axis function. Conversely, pharmacological blockade or genetic deletion of PPARγ enhanced anxiogenic responses and increased vulnerability to stress. These effects appear to be controlled by PPARγ neuronal-mediated mechanisms in the amygdala.
Calafate, S;Özturan, G;Thrupp, N;Vanderlinden, J;Santa-Marinha, L;Morais-Ribeiro, R;Ruggiero, A;Bozic, I;Rusterholz, T;Lorente-Echeverría, B;Dias, M;Chen, WT;Fiers, M;Lu, A;Vlaeminck, I;Creemers, E;Craessaerts, K;Vandenbempt, J;van Boekholdt, L;Poovathingal, S;Davie, K;Thal, DR;Wierda, K;Oliveira, TG;Slutsky, I;Adamantidis, A;De Strooper, B;de Wit, J;
PMID: 37188873 | DOI: 10.1038/s41593-023-01325-4
Early Alzheimer's disease (AD) is associated with hippocampal hyperactivity and decreased sleep quality. Here we show that homeostatic mechanisms transiently counteract the increased excitatory drive to CA1 neurons in AppNL-G-F mice, but that this mechanism fails in older mice. Spatial transcriptomics analysis identifies Pmch as part of the adaptive response in AppNL-G-F mice. Pmch encodes melanin-concentrating hormone (MCH), which is produced in sleep-active lateral hypothalamic neurons that project to CA1 and modulate memory. We show that MCH downregulates synaptic transmission, modulates firing rate homeostasis in hippocampal neurons and reverses the increased excitatory drive to CA1 neurons in AppNL-G-F mice. AppNL-G-F mice spend less time in rapid eye movement (REM) sleep. AppNL-G-F mice and individuals with AD show progressive changes in morphology of CA1-projecting MCH axons. Our findings identify the MCH system as vulnerable in early AD and suggest that impaired MCH-system function contributes to aberrant excitatory drive and sleep defects, which can compromise hippocampus-dependent functions.
bioRxiv : the preprint server for biology
François, M;Delgado, IC;Lafond, A;Lewis, EM;Kuromaru, M;Hassouna, R;Deng, S;Thaker, VV;Dölen, G;Zeltser, LM;
PMID: 36824966 | DOI: 10.1101/2023.02.15.528679
Females are more sensitive to social exclusion, which could contribute to their heightened susceptibility to anxiety disorders. Chronic social isolation stress (CSIS) for at least 7 weeks after puberty induces anxiety-related behavioral adaptations in female mice. Here, we show that Arginine vasopressin receptor 1a ( Avpr1a )-expressing neurons in the central nucleus of the amygdala (CeA) mediate these sex-specific effects, in part, via projections to the caudate putamen. Loss of function studies demonstrate that AVPR1A signaling in the CeA is required for effects of CSIS on anxiety-related behaviors in females but has no effect in males or group housed females. This sex-specificity is mediated by AVP produced by a subpopulation of neurons in the posterodorsal medial nucleus of the amygdala that project to the CeA. Estrogen receptor alpha signaling in these neurons also contributes to preferential sensitivity of females to CSIS. These data support new therapeutic applications for AVPR1A antagonists in women.
Aguilar, K;Comes, G;Canal, C;Quintana, A;Sanz, E;Hidalgo, J;
PMID: 35770802 | DOI: 10.1002/glia.24234
Leigh syndrome is a mitochondrial disease characterized by neurodegeneration, neuroinflammation, and early death. Mice lacking NDUFS4, a mitochondrial complex I subunit (Ndufs4 KO mice), have been established as a good animal model for studying human pathology associated with Leigh syndrome. As the disease progresses, there is an increase in neurodegeneration and neuroinflammation, thereby leading to deteriorating neurological symptoms, including motor deficits, breathing alterations, and eventually, death of the animal. However, despite the magnitude of neuroinflammation associated with brain lesions, the role of neuroinflammatory pathways and their main cellular components have not been addressed directly as relevant players in the disease pathology. Here, we investigate the role of microglial cells, the main immune cells of the CNS, in Leigh-like syndrome pathology, by pharmacologically depleting them using the colony-stimulating factor 1 receptor antagonist PLX3397. Microglial depletion extended lifespan and delayed motor symptoms in Ndufs4 KO mice, likely by preventing neuronal loss. Next, we investigated the role of the major cytokine interleukin-6 (IL-6) in the disease progression. IL-6 deficiency partially rescued breathing abnormalities and modulated gliosis but did not extend the lifespan or rescue motor decline in Ndufs4 KO mice. The present results show that microglial accumulation is pathogenic, in a process independent of IL-6, and hints toward a contributing role of neuroinflammation in the disease of Ndufs4 KO mice and potentially in patients with Leigh syndrome.
Jin, XT;Drenan, RM;
PMID: 35167902 | DOI: 10.1016/j.neuropharm.2022.108987
The interpeduncular nucleus (IPN) plays a key role in nicotine dependence and is involved in regulation of fear responses, affective states, and novelty processing. IPN neurons express nicotinic acetylcholine receptors (nAChR) and receive strong cholinergic innervation from the ventral medial habenula. Dorsal medial habenula neurons are primarily peptidergic, releasing substance P (SP) mainly onto IPN neurons in the lateral subnucleus (IPL). IPL neurons are sensitive to SP, but it is not known if they are involved in cholinergic transmission like other IPN neurons. We examined nAChR subunit gene expression in IPL neurons, revealing that Chrna7 (α7 nAChR subunit) is expressed in a subset of GABAergic IPL neurons. In patch-clamp recordings from IPL neurons, ACh-evoked inward currents were attenuated by methyllycaconitine (α7 nAChR antagonist) and potentiated by NS1738 (α7 Type I positive allosteric modulator). We confirmed α7 functional expression in IPL neurons by also showing that ACh-evoked currents were potentiated by PNU-120596 (Type II positive allosteric modulator). Additional pharmacological experiments show that IPN neurons expressing α7 nAChRs also express α3β4 nAChRs. Finally, we used 2-photon laser scanning microscopy and nicotine uncaging to directly examine the morphology of IPL neurons that express α7 nAChRs. These results highlight a novel aspect of α7 nAChR neurobiology, adding to the complexity of cholinergic modulation by nAChRs in the IPN.
Shi, Z;Stornetta, DS;Stornetta, RL;Brooks, VL;
PMID: 34937769 | DOI: 10.1523/ENEURO.0404-21.2021
The arcuate nucleus (ArcN) is an integrative hub for the regulation of energy balance, reproduction, and arterial pressure (AP), all of which are influenced by Angiotensin II (AngII); however, the cellular mechanisms and downstream neurocircuitry are unclear. Here we show that ArcN AngII increases AP in female rats via two phases, both of which are mediated via activation of AngII type 1 receptors (AT1aR): initial vasopressin-induced vasoconstriction, followed by slowly developing increases in sympathetic nerve activity (SNA) and heart rate (HR). In male rats, ArcN AngII evoked a similarly slow increase in SNA, but the initial pressor response was variable. In females, the effects of ArcN AngII varied during the estrus cycle, with significant increases in SNA, HR, and AP occurring during diestrus and estrus, but only increased AP during proestrus. Pregnancy markedly increased the expression of AT1aR in the ArcN with parallel substantial AngII-induced increases in SNA and MAP. In both sexes, the sympathoexcitation relied on suppression of tonic ArcN sympathoinhibitory Neuropeptide Y inputs, and activation of pro-opiomelanocortin (POMC) projections, to the paraventricular nucleus (PVN). Few or no NPY or POMC neurons expressed the AT1aR, suggesting that AngII increases AP and SNA at least in part indirectly via local interneurons, which express tyrosine hydroxylase (TH) and VGat (i.e. GABAergic). ArcN TH neurons release GABA locally, and central AT1aR and TH neurons mediate stress responses; therefore, we propose that TH AT1aR neurons are well situated to locally coordinate the regulation of multiple modalities within the ArcN in response to stress.SIGNIFICANCEThe arcuate nucleus (ArcN) is an integrative hub for the regulation of energy balance, reproduction, and arterial pressure (AP), all of which are influenced by Angiotensin II (AngII). Here we show that ArcN AngII activates AT1aR to increase AP in male and female rats by slowly increasing sympathetic nerve activity. In females, ArcN AngII also evoked an initial pressor response mediated by vasopressin-induced vasoconstriction. Pregnant and estrus females responded more than males, in association with higher ArcN AT1aR expression. AT1aR were identified in ArcN interneurons that express tyrosine hydroxylase (TH) and GABA. Since brain AT1aR and TH mediate stress responses, ArcN AT1aR TH neurons are well situated to locally coordinate autonomic, hormonal, and behavioral responses to stress.
Heather C. Rice, Gabriele Marcassa, Iordana Chrysidou,Katrien Horr�Tracy L. Young-Pearse, Ulrike C. M�ller, Takashi Saito Takaomi C. Saido, Robert Vassar, Joris de Wit,and Bart De Strooper
PMID: 31915042 | DOI: 10.1186/s13024-019-0356-y
The amyloid-? (A?) peptide, the primary constituent of amyloid plaques found in Alzheimer�s disease (AD) brains, is derived from sequential proteolytic processing of the Amyloid Precursor Protein (APP). However, the contribution of different cell types to A? deposition has not yet been examined in an in vivo, non-overexpression system. Here, we show that endogenous APP is highly expressed in a heterogeneous subset of GABAergic interneurons throughout various laminae of the hippocampus, suggesting that these cells may have a profound contribution to AD plaque pathology. We then characterized the laminar distribution of amyloid burden in the hippocampus of an APP knock-in mouse model of AD. To examine the contribution of GABAergic interneurons to plaque pathology, we blocked A? production specifically in these cells using a cell type-specific knock-out of BACE1. We found that during early stages of plaque deposition, interneurons contribute to approximately 30% of the total plaque load in the hippocampus. The greatest contribution to plaque load (75%) occurs in the stratum pyramidale of CA1, where plaques in human AD cases are most prevalent and where pyramidal cell bodies and synaptic boutons from perisomatic-targeting interneurons are located. These findings reveal a crucial role of GABAergic interneurons in the pathology of AD. Our study also highlights the necessity of using APP knock-in models to correctly evaluate the cellular contribution to amyloid burden since APP overexpressing transgenic models drive expression in cell types according to the promoter and integration site and not according to physiologically relevant expression mechanisms.
Ziminski J, Hessler S, Margetts-Smith G, Sieburg MC, Crombag HS, Koya E.
PMID: 28213443 | DOI: 10.1523/JNEUROSCI.3766-16.2017
Cues that predict the availability of food rewards influence motivational states and elicit food-seeking behaviors. If a cue no longer predicts food availability, animals may adapt accordingly by inhibiting food seeking responses. Sparsely activated sets of neurons, coined neuronal ensembles, have been shown to encode the strength of reward-cue associations. While alterations in intrinsic excitability have been shown to underlie many learning and memory processes, little is known about these properties specifically on cue-activated neuronal ensembles. We examined the activation patterns of cue-activated orbitofrontal cortex (OFC) and nucleus accumbens (NAc) shell ensembles using wild-type and Fos-GFP mice following appetitive conditioning with sucrose and extinction learning. We also investigated the neuronal excitability of recently activated, GFP+ neurons in these brain areas using whole-cell electrophysiology in brain slices. Exposure to a sucrose cue elicited activation of neurons in both the NAc shell and OFC. In the NAc shell, but not the OFC, these activated GFP+ neurons were more excitable than surrounding GFP- neurons. Following extinction, the number of neurons activated in both areas was reduced and activated ensembles in neither area exhibited altered excitability. These data suggest that learning-induced alterations in the intrinsic excitability of neuronal ensembles is regulated dynamically across different brain areas. Furthermore, we show that changes in associative strength modulate the excitability profile of activated ensembles in the NAc shell.SIGNIFICANCE STATEMENTSparsely distributed sets of neurons called 'neuronal ensembles' encode learned associations about food and cues predictive of its availability. Widespread changes in neuronal excitability have been observed in limbic brain areas after associative learning, but little is known about the excitability changes that occur specifically on neuronal ensembles that encode appetitive associations. Here we reveal that sucrose cue exposure recruited a more excitable ensemble in the nucleus accumbens, but not orbitofrontal cortex compared to their surrounding neurons. This excitability difference was not observed when the cue's salience was diminished following extinction learning. These novel data provide evidence that the intrinsic excitability of appetitive memory-encoding ensembles is differentially regulated across brain areas and dynamically adapts to changes in associative strength.
