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Theranostics 2021Inflammatory cytokines produced by muscularis macrophages largely contribute to the pathological signs of postoperative ileus (POI). Electroacupuncture (EA) can suppress...
Inflammatory cytokines produced by muscularis macrophages largely contribute to the pathological signs of postoperative ileus (POI). Electroacupuncture (EA) can suppress inflammation, mainly or partly via activation of vagal efferent. The goal of this study was to investigate the mechanisms by which EA stimulation at an hindlimb region ameliorates inflammation in POI. Intestinal motility and inflammation were examined after 24 h after intestinal manipulation (IM)-induced POI in mice. Local immune response in the intestinal muscularis, expression of macrophages, α7 nicotinic acetylcholine receptor (α7nAChR), Janus kinase 2 (JAK2) and signal transducer and activator of transcription 3 (STAT3) were determined by flow cytometry, Western Blot, qPCR and immunofluorescence. The effects of α7nAChR antagonists (methyllycaconitine and α-bungarotoxin) and JAK2/STAT3 inhibitors (AG490 and WP1066) were also administered in a subset of mice prior to EA. In the parasympathetic pathways, intestinal motility and inflammation were determined after cervical vagotomy and sub-diaphragmatic vagotomy. The expression of gamma absorptiometry aminobutyric acid (GABA) receptor in dorsal motor nucleus of vagal (DMV) cholinergic neurons was assessed by immunofluorescence and the response to DMV microinjection of bicuculine (antagonist of GABA receptor) or muscimol (agonist of GABA receptor) were assessed. EA suppressed intestinal inflammation and promoted gastrointestinal motility. Mechanistically, EA activated the α7nAChR-mediated JAK2/STAT3 signaling pathway in macrophages which reduced the production of inflammatory cytokines. Furthermore, we also demonstrated that hindlimb region stimulation drove vagal efferent output by inhibiting the expression of GABA receptor in DMV to ameliorate inflammation. The present study revealed that EA of hindlimb regions inhibited the expression of GABA receptor in DMV neurons, whose excited vagal nerve, in turn suppressed IM-induced inflammation via activation of α7nAChR-mediated JAK2/STAT3 signaling pathway.
Topics: Animals; Cytokines; Electroacupuncture; Ileus; Inflammation; Intestines; Janus Kinase 2; Macrophages; Mice; Mice, Inbred C57BL; Parasympathetic Nervous System; Postoperative Complications; STAT3 Transcription Factor; Signal Transduction; Vagus Nerve; alpha7 Nicotinic Acetylcholine Receptor
PubMed: 33754049
DOI: 10.7150/thno.52574 -
The New Phytologist Sep 2022
PubMed: 35616133
DOI: 10.1111/nph.18214 -
Nature Neuroscience Nov 2019Microglia dynamically survey the brain parenchyma. Microglial processes interact with neuronal elements; however, what role neuronal network activity plays in regulating...
Microglia dynamically survey the brain parenchyma. Microglial processes interact with neuronal elements; however, what role neuronal network activity plays in regulating microglial dynamics is not entirely clear. Most studies of microglial dynamics use either slice preparations or in vivo imaging in anesthetized mice. Here we demonstrate that microglia in awake mice have a relatively reduced process area and surveillance territory and that reduced neuronal activity under general anesthesia increases microglial process velocity, extension and territory surveillance. Similarly, reductions in local neuronal activity through sensory deprivation or optogenetic inhibition increase microglial process surveillance. Using pharmacological and chemogenetic approaches, we demonstrate that reduced norepinephrine signaling is necessary for these increases in microglial process surveillance. These findings indicate that under basal physiological conditions, noradrenergic tone in awake mice suppresses microglial process surveillance. Our results emphasize the importance of awake imaging for studying microglia-neuron interactions and demonstrate how neuronal activity influences microglial process dynamics.
Topics: Animals; Brain; CX3C Chemokine Receptor 1; Clozapine; Isoflurane; Mice; Mice, Knockout; Mice, Transgenic; Microglia; Microinjections; Muscimol; Neurons; Norepinephrine; Optogenetics; Propanolamines; Propranolol; Receptors, Purinergic P2Y12; Sensory Deprivation; Somatosensory Cortex; Tetrodotoxin; Wakefulness
PubMed: 31636449
DOI: 10.1038/s41593-019-0511-3 -
Communications Biology Oct 2023Pyroptosis is a cell death process that causes inflammation and contributes to numerous diseases. Pyroptosis is mediated by caspase-1 family proteases that cleave the...
Pyroptosis is a cell death process that causes inflammation and contributes to numerous diseases. Pyroptosis is mediated by caspase-1 family proteases that cleave the pore-forming protein gasdermin D, causing plasma membrane rupture and release of pathogenic cellular contents. We previously identified muscimol as a small molecule that prevents plasma membrane rupture during pyroptosis via an unidentified mechanism. Here, we show that muscimol has reversible activity to prevent cellular lysis without affecting earlier pyroptotic events. Although muscimol is a well-characterized agonist for neuronal GABA receptors, muscimol protection is not altered by GABA receptor antagonists or recapitulated by other GABA agonists, suggesting that muscimol acts via a novel mechanism. We find that muscimol blocks oligomerization of ninjurin-1, which is required for plasma membrane rupture downstream of gasdermin D pore formation. Our structure-activity relationship studies reveal distinct molecular determinants defining inhibition of pyroptotic lysis compared to GABA binding. In addition, we demonstrate that muscimol reduces lethality during LPS-induced septic shock. Together, these findings demonstrate that ninjurin-1-mediated plasma membrane rupture can be pharmacologically modulated and pave the way toward identification of therapeutic strategies for pathologic conditions associated with pyroptosis.
Topics: Pyroptosis; Muscimol; Gasdermins; Intracellular Signaling Peptides and Proteins; Cell Membrane; Receptors, GABA-A; gamma-Aminobutyric Acid
PubMed: 37798443
DOI: 10.1038/s42003-023-05354-4 -
Nature Neuroscience Oct 2021Compromised placental function or premature loss has been linked to diverse neurodevelopmental disorders. Here we show that placenta allopregnanolone (ALLO), a...
Compromised placental function or premature loss has been linked to diverse neurodevelopmental disorders. Here we show that placenta allopregnanolone (ALLO), a progesterone-derived GABA-A receptor (GABAR) modulator, reduction alters neurodevelopment in a sex-linked manner. A new conditional mouse model, in which the gene encoding ALLO's synthetic enzyme (akr1c14) is specifically deleted in trophoblasts, directly demonstrated that placental ALLO insufficiency led to cerebellar white matter abnormalities that correlated with autistic-like behavior only in male offspring. A single injection of ALLO or muscimol, a GABAR agonist, during late gestation abolished these alterations. Comparison of male and female human preterm infant cerebellum also showed sex-linked myelination marker alteration, suggesting similarities between mouse placental ALLO insufficiency and human preterm brain development. This study reveals a new role for a placental hormone in shaping brain regions and behaviors in a sex-linked manner. Placental hormone replacement might offer novel therapeutic opportunities to prevent later neurobehavioral disorders.
Topics: Aldehyde Reductase; Animals; Autism Spectrum Disorder; Cerebellum; Endocrine Glands; Female; GABA Agonists; GABA Modulators; Gene Deletion; Humans; Infant; Infant, Newborn; Male; Mice; Muscimol; Placenta; Pregnancy; Pregnanolone; Receptors, GABA-A; Sex Characteristics; Social Behavior; Trophoblasts; White Matter
PubMed: 34400844
DOI: 10.1038/s41593-021-00896-4 -
Frontiers in Pharmacology 2022Oligodendrocytes are the myelin forming cells of the central nervous system, and their vulnerability to excitotoxicity induced by glutamate contributes to the...
Oligodendrocytes are the myelin forming cells of the central nervous system, and their vulnerability to excitotoxicity induced by glutamate contributes to the pathogenesis of neurological disorders including brain ischemia and neurodegenerative diseases, such as multiple sclerosis. In addition to glutamate receptors, oligodendrocytes express GABA receptors (GABAR) that are involved in their survival and differentiation. The interactions between glutamate and GABAergic systems are well documented in neurons, under both physiological and pathological conditions, but this potential crosstalk in oligodendrocytes has not been studied in depth. Here, we evaluated the protective effect of GABAR agonists, baclofen (GABA) and muscimol (GABA), against AMPA-induced excitotoxicity in cultured rat oligodendrocytes. First, we observed that both baclofen and muscimol reduced cell death and caspase-3 activation after AMPA insult, proving their oligoprotective potential. Interestingly, analysis of the cell-surface expression of calcium-impermeable GluR2 subunits in oligodendrocytes revealed that GABAergic agonists significantly reverted GluR2 internalization induced by AMPA. We determined that baclofen and muscimol also impaired AMPA-induced intracellular calcium increase and subsequent mitochondrial membrane potential alteration, ROS generation, and calpain activation. However, AMPA-triggered activation of Src, Akt, JNK and CREB was not affected by baclofen or muscimol. Overall, our results suggest that GABAR activation initiates alternative molecular mechanisms that attenuate AMPA-mediated apoptotic excitotoxicity in oligodendrocytes by interfering with expression of GluR subunits in membranes and with calcium-dependent intracellular signaling pathways. Together, these findings provide evidence of GABAR agonists as potential oligodendroglial protectants in central nervous system disorders.
PubMed: 35959434
DOI: 10.3389/fphar.2022.897056 -
Sleep Jan 2021The substantia nigra pars reticulata (SNR) is a major output nucleus of the basal ganglia. Animal studies have shown that lesions of the SNR cause hyposomnia and motor...
STUDY OBJECTIVES
The substantia nigra pars reticulata (SNR) is a major output nucleus of the basal ganglia. Animal studies have shown that lesions of the SNR cause hyposomnia and motor hyperactivity, indicating that the SNR may play a role in the control of sleep and motor activity.
METHODS
Eight 8- to 10-week-old adult male Sprague-Dawley rats were used. After 3 days of baseline polysomnographic recording, dialysates were collected from the lateral SNR across natural sleep-wake states. Muscimol and bicuculline were microinfused into the lateral SNR.
RESULTS
We found that GABA release in the lateral SNR is negatively correlated with slow wave sleep (SWS; R = -0.266, p < 0.01, n = 240) and positively correlated with waking (R = 0.265, p < 0.01, n = 240) in rats. Microinfusion of muscimol into the lateral SNR decreased sleep time and sleep quality, as well as eliciting motor hyperactivity in wake and increased periodic leg movement in SWS, while bicuculline infused into the lateral SNR increased sleep and decreased motor activity in SWS in rats. Muscimol infusion skewed the distribution of inter-movement intervals, with most between 10 and 20 s, while a flat distribution of intervals between 10 and 90 s was seen in baseline conditions.
CONCLUSIONS
Activation of the lateral SNR is important for inducing sleep and inhibiting motor activity prior to and during sleep, and thus to the maintenance of sleep. Abnormal function of the lateral SNR may cause hyposomnia and motor hyperactivity in quiet wake and in sleep.
Topics: Animals; GABA Antagonists; Male; Motor Activity; Pars Reticulata; Rats; Rats, Sprague-Dawley; Sleep; Substantia Nigra; gamma-Aminobutyric Acid
PubMed: 32808987
DOI: 10.1093/sleep/zsaa151 -
Neuron Oct 2023The persistence of play after decortication points to a subcortical mechanism of play control. We found that global blockade of the rat periaqueductal gray with either...
The persistence of play after decortication points to a subcortical mechanism of play control. We found that global blockade of the rat periaqueductal gray with either muscimol or lidocaine interfered with ticklishness and play. We recorded vocalizations and neural activity from the periaqueductal gray of young, playful rats during interspecific touch, play, and tickling. Rats vocalized weakly to touch and more strongly to play and tickling. Periaqueductal gray units showed diverse but strong modulation to tickling and play. Hierarchical clustering based on neuronal responses to play and tickling revealed functional clusters mapping to different periaqueductal gray columns. Specifically, we observed play-neutral/tickling-inhibited and tickling/play-neutral units in dorsolateral and dorsomedial periaqueductal gray columns. In contrast, strongly play/tickling-excited units mapped to the lateral columns and were suppressed by anxiogenic conditions. Optogenetic inactivation of lateral periaqueductal columns disrupted ticklishness and play. We conclude that the lateral periaqueductal gray columns are decisive for play and laughter.
Topics: Rats; Animals; Periaqueductal Gray; Touch; Neurons; Touch Perception
PubMed: 37516112
DOI: 10.1016/j.neuron.2023.06.018 -
European Neuropsychopharmacology : the... Nov 2023Alzheimer's Disease (AD) is a currently incurable but increasingly prevalent fatal and progressive neurodegenerative disease, demanding consideration of therapeutically... (Review)
Review
Alzheimer's Disease (AD) is a currently incurable but increasingly prevalent fatal and progressive neurodegenerative disease, demanding consideration of therapeutically relevant natural products and their synthetic analogues. This paper reviews evidence for effectiveness of natural and synthetic psychedelics in the treatment of AD causes and symptoms. The plastogenic effects of serotonergic psychedelics illustrate that they have efficacy for addressing multiple facets of AD pathology. We review findings illustrating neuroplasticity mechanisms of classic (serotonergic) and non-classic psychedelics that indicate their potential as treatments for AD and related dementias. Classic psychedelics modulate glutamatergic neurotransmission and stimulate synaptic and network remodeling that facilitates synaptic, structural and behavioral plasticity. Up-regulation of neurotrophic factors enable psychedelics to promote neuronal survival and glutamate-driven neuroplasticity. Muscimol modulation of GABAR reduces Aβ-induced neurotoxicity and psychedelic Sig-1R agonists provide protective roles in Aβ toxicity. Classic psychedelics also activate mTOR intracellular effector pathways in brain regions that show atrophy in AD. The potential of psychedelics to treat AD involves their ability to induce structural and functional neural plasticity in brain circuits and slow or reverse brain atrophy. Psychedelics stimulate neurotrophic pathways, increase neurogenesis and produce long-lasting neural changes through rewiring pathological neurocircuitry. Psychedelic effects on 5-HT receptor target genes and induction of synaptic, structural, and functional changes in neurons and networks enable them to promote and enhance brain functional connectivity and address diverse mechanisms underlying degenerative neurological disorders. These findings provide a rationale for immediate investigation of psychedelics as treatments for AD patients.
Topics: Humans; Alzheimer Disease; Hallucinogens; Neurodegenerative Diseases; Brain; Atrophy
PubMed: 37451163
DOI: 10.1016/j.euroneuro.2023.07.003 -
Molecular Pain 2022GABAergic system disinhibition played an important role in the pathogenesis of remifentanil-induced hyperalgesia (RIH). K-Cl-cotransporter-2 (KCC2) has the potential to...
GABAergic system disinhibition played an important role in the pathogenesis of remifentanil-induced hyperalgesia (RIH). K-Cl-cotransporter-2 (KCC2) has the potential to enhance the strength of GABAergic signaling function. However, few reports have focused on the additive analgesic effect of KCC2 enhancer and GABAA receptor agonist on the spinal dorsal horn. Therefore, we evaluated the role of GABA type A receptor (GABAAR) agonist (muscimol), KCC2 enhancer (CLP257) in remifentanil-induced hyperalgesia, as well as GABA and KCC2 receptors responses in the dorsal spinal horn. Remifentanil started to reduce paw withdrawal mechanical thresholds at postoperative 4 h and lasted to 72 h. The RIH associated decreases in spinal GABA release was transient. The amount of spinal GABA transmitter by microdialysis was observed to be decreased at the beginning and reached bottom at 150 min, then returned to the baseline level at 330 min. The synthesis and transportation of GABA transmitter were inhibited, characterized as spinal GAD67 and GAT1 downregulation after the establishment of RIH model. The effect of RIH on GABA receptor downregulation was linked to the reduced expression of spinal KCC2 receptor. This decrease in KCC2 expression has coincided with an early loss of GABA inhibition. KCC2 enhancer, which is reported to lead to a reduction in intracellular Cl, can enhance GABA-mediated inhibitory function. Both muscimol and CLP257 could dose-dependently inhibit mechanical hypersensitivity caused by remifentanil-induced downregulation of GABAAα2R and KCC2, respectively. Compared with muscimol acting alone, the joint action of CLP257 and muscimol showed a higher pain threshold and less c-fos expression via upregulation of KCC2 and GABAAα2R. Taken together, these findings suggested that the RIH was initiated by decreased GABA release. Downregulation of GABAAα2R and KCC2 receptor contributed to spinally mediated hyperalgesia in RIH. KCC2 enhancer was proved to potentiate antinociceptive effect of GABAAR agonist in RIH.
Topics: Analgesics; Animals; GABA-A Receptor Agonists; Hyperalgesia; Rats; Rats, Sprague-Dawley; Receptors, GABA-A; Remifentanil; Symporters; Up-Regulation
PubMed: 35352582
DOI: 10.1177/17448069221082880