Primary Neurotransmitter Research Articles

Research Progress of Isoxazoline Insecticides

Abstract: Isoxazoline insecticides constitute a class of compounds featuring the isoxazoline structure, which primarily exert their effects by inhibiting the γ-aminobutyric acid (GABA)- gated chloride channel in insects. GABA serves as the primary inhibitory neurotransmitter in invertebrates, with its receptor composed of subunits encoded by the Rdl gene. By selectively inhibiting the GABA-Cl receptor subunit in invertebrates, isoxazolines block inhibitory neurotransmission, ultimately resulting in insect mortality. This unique mechanism of action endows isoxazolines with a high degree of selective toxicity toward insects while maintaining relative safety for mammals. Recently, isoxazoline insecticides have garnered considerable attention due to their broad-spectrum efficacy, high potency, and environmentally friendly profile. These compounds have emerged as promising solutions in crop protection and animal health management, offering innovative means to combat insect pests and parasites. Their development represents a significant advancement in pesticides, offering farmers and veterinarians effective and sustainable options for managing agricultural and animal health challenges. This review mainly introduces the current commercialized and under-development isoxazoline insecticides, the research progress on the mechanism of action of isoxazoline insecticides, the study of synthetic methods, as well as the research progress in structural derivation and structure-activity relationship.

GABALAGEN Alleviates Stress-Induced Sleep Disorders in Rats.

(1) Background: Gamma-aminobutyric acid (GABA) is an amino acid and the primary inhibitory neurotransmitter in the brain. GABA has been shown to reduce stress and promote sleep. GABALAGEN (GBL) is the product of fermented fish collagen by Lactobacillus brevis BJ20 and Lactobacillus plantarum BJ21, naturally enriched with GABA through the fermentation process and characterized by low molecular weight. (2) Methods: The present study evaluated the GABAA affinity of GBL through receptor binding assay. The sedative effects of GBL were investigated through electroencephalography (EEG) analysis in an animal model of electro foot shock (EFS) stress-induced sleep disorder, and then we examined the expression of orexin and the GABAA receptor in the brain region using immunohistochemistry and an enzyme-linked immunosorbent assay (ELISA). (3) Results: We found that on the binding assay, GBL displayed high affinity to the GABAA receptor. Also, after treatment with GBL, the percentage of the total time in rapid eye movement (REM) and non-rapid eye movement (NREM) sleep was significantly and dose-dependently increased in EFS-induced rats. Consistent with behavioral results, the GBL-treated groups showed that the expression of GABAA receptor immune-positive cells in the VLPO was markedly and dose-dependently increased. Also, the GBL-treated groups showed that the expression of the orexin-A level in LH was significantly decreased. (4) Conclusions: GBL showed efficacy and potential to be used as an anti-stress therapy to treat sleep deprivation through the stimulation of GABAA receptors and the consequent inhibition of orexin activity.

Displacement of extracellular chloride by immobile anionic constituents of the brain's extracellular matrix.

GABA is the primary inhibitory neurotransmitter. Membrane currents evoked by GABAA receptor activation have uniquely small driving forces: their reversal potential (EGABA) is very close to the resting membrane potential. As a consequence, GABAA currents can flow in either direction, depending on both the membrane potential and the local intra and extracellular concentrations of the primary permeant ion, chloride (Cl). Local cytoplasmic Cl concentrations vary widely because of displacement of mobile Cl ions by relatively immobile anions. Here, we use new reporters of extracellular chloride (Cl- o) to demonstrate that Cl is displaced in the extracellular space by high and spatially heterogenous concentrations of immobile anions including sulfated glycosaminoglycans (sGAGs). Cl- o varies widely, and the mean Cl- o is only half the canonical concentration (i.e. the Cl concentration in the cerebrospinal fluid). These unexpectedly low and heterogenous Cl- o domains provide a mechanism to link the varied but highly stable distribution of sGAGs and other immobile anions in the brain's extracellular space to neuronal signal processing via the effects on the amplitude and direction of GABAA transmembrane Cl currents. KEY POINTS: Extracellular chloride concentrations in the brain were measured using a new chloride-sensitive organic fluorophore and two-photon fluorescence lifetime imaging. In vivo, the extracellular chloride concentration was spatially heterogenous and only half of the cerebrospinal fluid chloride concentration Stable displacement of extracellular chloride by immobile extracellular anions was responsible for the low extracellular chloride concentration The changes in extracellular chloride were of sufficient magnitude to alter the conductance and reversal potential of GABAA chloride currents The stability of the extracellular matrix, the impact of the component immobile anions, including sulfated glycosaminoglycans on extracellular chloride concentrations, and the consequent effect on GABAA signalling suggests a previously unappreciated mechanism for modulating GABAA signalling.

Cryo-electron tomographic investigation of native hippocampal glutamatergic synapses

Chemical synapses are the major sites of communication between neurons in the nervous system and mediate either excitatory or inhibitory signaling. At excitatory synapses, glutamate is the primary neurotransmitter and upon release from presynaptic vesicles, is detected by postsynaptic glutamate receptors, which include ionotropic AMPA and NMDA receptors. Here, we have developed methods to identify glutamatergic synapses in brain tissue slices, label AMPA receptors with small gold nanoparticles (AuNPs), and prepare lamella for cryo-electron tomography studies. The targeted imaging of glutamatergic synapses in the lamella is facilitated by fluorescent pre- and postsynaptic signatures, and the subsequent tomograms allow for the identification of key features of chemical synapses, including synaptic vesicles, the synaptic cleft, and AuNP-labeled AMPA receptors. These methods pave the way for imaging brain regions at high resolution, using unstained, unfixed samples preserved under near-native conditions.

Cryo-electron tomographic investigation of native hippocampal glutamatergic synapses.

Chemical synapses are the major sites of communication between neurons in the nervous system and mediate either excitatory or inhibitory signaling. At excitatory synapses, glutamate is the primary neurotransmitter and upon release from presynaptic vesicles, is detected by postsynaptic glutamate receptors, which include ionotropic AMPA and NMDA receptors. Here, we have developed methods to identify glutamatergic synapses in brain tissue slices, label AMPA receptors with small gold nanoparticles (AuNPs), and prepare lamella for cryo-electron tomography studies. The targeted imaging of glutamatergic synapses in the lamella is facilitated by fluorescent pre- and postsynaptic signatures, and the subsequent tomograms allow for the identification of key features of chemical synapses, including synaptic vesicles, the synaptic cleft, and AuNP-labeled AMPA receptors. These methods pave the way for imaging brain regions at high resolution, using unstained, unfixed samples preserved under near-native conditions.

Altered functional connectivity within the primary visual networks and neurotransmitter activity in male smokers: A group ICA study

Smoking puts patients at high risk for cognitive and psychiatric disorders. The aim of this study was to explore the effects of nicotine use on primary visual network (PVN) and its association with neurotransmitters. A total of 59 tobacco use disorder (TUD) patients and 51 healthy controls (HC) participated in this study and underwent resting state functional magnetic resonance imaging scans. Functional connectivity (FC) within the network was explored using independent component analysis. In addition, the spatial correlations of PVN changes with neurotransmitters and their correlations with clinical characteristics of patients were evaluated using the JuSpace toolbox and SPSS. We found reduced FC within the PVN in patients with TUD compared with HC. In terms of relevant analysis, there is a spatial correlation between FC changes in the patient's PVN and a higher distribution of dopamine receptor and gamma-aminobutyric acid receptor. This study revealed changes in the FC and neurotransmitters of the PVN in patients with TUD, expanding the potential neural mechanisms underlying sensory perception and psychiatric disorders.

Whole Nervous System Expression of Glutamate Receptors Reveals Distinct Receptor Roles in Sensorimotor Circuits.

The goal of connectomics is to reveal the links between neural circuits and behavior. Larvae of the primitive chordate Ciona are well-suited to make contributions in this area. In addition to having a described connectome, Ciona larvae have a range of readily quantified behaviors. Moreover, the small number of neurons in the larval CNS (∼180) holds the promise of a comprehensive characterization of individual neurons. We present single-neuron predictions for glutamate receptor (GlutR) expression based on in situ hybridization. Included are both ionotropic receptors (AMPA, NMDA, and kainate) and metabotropic receptors. The predicted glutamate receptor expression dataset is discussed in the context of known circuits driving behaviors such as phototaxis, mechanosensation, and looming shadow response. The predicted expression of AMPA and NMDA receptors may help resolve issues regarding the co-production of GABA and glutamate by a subset of photoreceptors. The targets of these photoreceptors in the midbrain appear to express NMDA receptors, but not AMPA receptors. This is in agreement with previous results indicating that GABA is the primary neurotransmitter from the photoreceptors evoking a swimming response through a disinhibition mechanism and that glutamate may, therefore, have only a modulatory action in this circuit. Other findings reported here are more unexpected. For example, many of the targets of glutamatergic epidermal sensory neurons (ESNs) do not express any of the ionotropic receptors, yet the ESNs themselves express metabotropic receptors. Thus, we speculate that their production of glutamate may be for communication with neighboring ESNs, rather than to their interneuron targets.

Glutamate uptake is transiently compromised in the perilesional cortex following controlled cortical impact.

Glutamate, the primary excitatory neurotransmitter in the CNS, is regulated by the excitatory amino acid transporters (EAATs) GLT-1 and GLAST. Following traumatic brain injury (TBI), extracellular glutamate levels increase, contributing to excitotoxicity, circuit dysfunction, and morbidity. Increased neuronal glutamate release and compromised astrocyte-mediated uptake contribute to elevated glutamate, but the mechanistic and spatiotemporal underpinnings of these changes are not well established. Using the controlled cortical impact (CCI) model of TBI and iGluSnFR glutamate imaging, we quantified extracellular glutamate dynamics after injury. Three days post-injury, glutamate release was increased, and glutamate uptake and GLT-1 expression were reduced. 7- and 14-days post-injury, glutamate dynamics were comparable between sham and CCI animals. Changes in peak glutamate response were unique to specific cortical layers and proximity to injury. This was likely driven by increases in glutamate release, which was spatially heterogenous, rather than reduced uptake, which was spatially uniform. The astrocyte K + channel, Kir4.1, regulates activity-dependent slowing of glutamate uptake. Surprisingly, Kir4.1 was unchanged after CCI and accordingly, activity-dependent slowing of glutamate uptake was unaltered. This dynamic glutamate dysregulation after TBI underscores a brief period in which disrupted glutamate uptake may contribute to dysfunction and highlights a potential therapeutic window to restore glutamate homeostasis.

Use of p-methoxy cinnamaldehyde in label-assisted laser desorption/ionization mass spectrometry (LALDI-MS) for detection of different classes of primary amines, amino acids and neurotransmitters

Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS), useful for the detection of macromolecules, is generally not suitable for recording the mass spectrum of small molecules, especially within the range of m/z 500, because of the appearance of matrix cluster peaks in the small molecular weight range. To circumvent this problem, a matrix-free variant of MALDI-MS, namely Label-assisted laser desorption/ionization mass spectrometry (LALDI-MS) has been developed in recent years where analytes get covalently attached to a laser absorbing label which induces the desorption/ionization process thus facilitating the recording the mass spectra and avoiding the problem of formation of cluster peaks. In general, the probes used for such detections are all pyrene-based scaffolds which despite being a good laser-active chromophore have both reactivity and solubility problems. Inspired by the right chromophoric nature, we have undertaken a systematic study to design and optimize cinnamaldehyde derivatives and have found that p-methoxy cinnamaldehyde (PMC) as a simpler, cost-effective, less hydrophobic laser-active label, which can detect a series of primary amines, including the neurotransmitters and amino acids. The label PMC can also discriminate between aliphatic and aromatic primary amines.

The interaction between cannabinoids and long-term synaptic plasticity: A survey on memory formation and underlying mechanisms.

Synaptic plasticity, including long-term potentiation (LTP) and long-term depression (LTD), is an essential phenomenon in memory formation as well as maintenance along with many other cognitive functions, such as those needed for coping with external stimuli. Synaptic plasticity consists of gradual changes in the biochemistry and morphology of pre- and postsynaptic neurons, particularly in the hippocampus. Consuming marijuana as a primary source of exocannabinoids immediately impairs attention and working memory-related tasks. Evidence regarding the effects of cannabinoids on LTP and memory is contradictory. While cannabinoids can affect a variety of specific cannabinoid receptors (CBRs) and nonspecific receptors throughout the body and brain, they exert miscellaneous systemic and local cerebral effects. Given the increasing use of cannabis, mainly among the young population, plus its potential adverse long-term effects on learning and memory processes, it could be a future global health challenge. Indeed, the impact of cannabinoids on memory is multifactorial and depends on the dosage, timing, formula, and route of consumption, plus the background complex interaction of the endocannabinoids system with other cerebral networks. Herein, we review how exogenously administrated organic cannabinoids, CBRs agonists or antagonists, and endocannabinoids can affect LTP and synaptic plasticity through various receptors in interaction with other cerebral pathways and primary neurotransmitters.

Glutamate transporters are involved in direct inhibitory synaptic transmission in the vertebrate retina.

In the central nervous system of vertebrates, glutamate serves as the primary excitatory neurotransmitter. However, in the retina, glutamate released from photoreceptors causes hyperpolarization in post-synaptic ON-bipolar cells through a glutamate-gated chloride current, which seems paradoxical. Our research reveals that this current is modulated by two excitatory glutamate transporters, EAAT5b and EAAT7. In the zebrafish retina, these transporters are located at the dendritic tips of ON-bipolar cells and interact with all four types of cone photoreceptors. The absence of these transporters leads to a decrease in ON-bipolar cell responses, with eaat5b mutants being less severely affected than eaat5b/eaat7 double mutants, which also exhibit altered response kinetics. Biophysical investigations establish that EAAT7 is an active glutamate transporter with a predominant anion conductance. Our study is the first to demonstrate the direct involvement of post-synaptic glutamate transporters in inhibitory direct synaptic transmission at a central nervous system synapse.

Prospects for using N-acetylcysteine in the treatment of obsessive-compulsive disorder

Obsessive-compulsive disorder (OCD) primarily has its clinical manifestations due to dysfunction in the glutamatergic system and modulation of inflammatory cytokines. Dysregulation of the glutamatergic system, the primary excitatory neurotransmitter system in the human brain, is directly related to the pathophysiology of OCD. Indeed, this system is critical for neuroplasticity, learning and memory, and recent studies have identified glutamatergic abnormalities in people with OCD. The worldwide prevalence of OCD is estimated at 2-3%, and this figure may be underestimated due to frequent misdiagnosis. Current first-line treatments include selective serotonin reuptake inhibitors (SSRIs) and cognitive behavioral therapy (CBT). However, a significant proportion of patients remain refractory to these treatments, necessitating the search for alternative therapeutic strategies. This article examines the potential use of N-acetylcysteine (NAC) as an alternative treatment for obsessive-compulsive disorder.

Mechanistic Evaluation of miRNAs and Their Targeted Genes in the Pathogenesis and Therapeutics of Parkinson's Disease.

MicroRNA (miRNA) are usually 18-25 nucleotides long non-coding RNA targeting post-transcriptional regulation of genes involved in various biological processes. The function of miRNA is essential for maintaining a homeostatic cellular condition, regulating autophagy, cellular motility, and inflammation. Dysregulation of miRNA is responsible for multiple disorders, including neurodegeneration, which has emerged as a severe problem in recent times and has verified itself as a life-threatening condition that can be understood by the continuous destruction of neurons affecting various cognitive and motor functions. Parkinson's disease (PD) is the second most common, permanently debilitating neurodegenerative disorder after Alzheimer's, mainly characterized by uncontrolled tremor, stiffness, bradykinesia or akinesia (slowness in movement), and post-traumatic stress disorder. PD is mainly caused by the demolition of the primary dopamine neurotransmitter secretory cells and dopaminergic or dopamine secretory neurons in the substantia nigra pars compacta of the midbrain, which are majorly responsible for motor functions. In this study, a systematic evaluation of research articles from year 2017 to 2022 was performed on multiple search engines, and lists of miRNA being dysregulated in PD in different body components were generated. This study highlighted miR-7, miR-124, miR-29 family, and miR-425, showing altered expression levels during PD's progression, further regulating the expression of multiple genes responsible for PD.

Development of Germinated-Brown-Rice-Based Novel Functional Beverage Enriched with γ-Aminobutyric Acid: Nutritional and Bio-Functional Characterization.

γ-aminobutyric acid (GABA), recognized as a primary inhibitory neurotransmitter within the brain, serves a crucial role in the aging process and in neurodegenerative conditions such as Alzheimer's disease. Research has demonstrated the beneficial effects of GABA, particularly for elderly individuals. Given that elderly individuals often encounter challenges with swallowing food, beverages designed to address dysphagia represent a preferable option for this demographic. Among the different processing techniques, the germination process triggers biochemical changes, leading to an increase in certain nutrients and bioactive compounds (e.g., GABA). Therefore, we attempted to develop a novel functional beverage utilizing germinated brown rice enriched with GABA and studied its nutritional and bio-functional characterization. The optimal conditions (X1, X2, X3 and X4.) were determined: powdered sugar (40 g), chocolate powder (20 g), sodium carboxymethyl cellulose (0.5 g), GBR (220 g), and water (440 mL). The results of storage studies indicated that the germinated-brown-rice-based beverage exhibited favorable nutritional attributes, including increased γ-oryzanol (52.73 ± 1.56%), total phenolic content (26.68 ± 1.56 mg GAE/100 g), niacin (5.17 ± 0.14%), and GABA (42.12 ± 0.63 mg/100 g) levels. Additionally, the beverage demonstrated notable antioxidant activity (74.23 ± 2.37 µmol TE/100 g), suggesting potential health-promoting effects. Sensory evaluation revealed satisfactory acceptability among consumers, highlighting its palatability. Overall, this study elucidates the development of a novel functional beverage utilizing germinated brown rice enriched with GABA, offering promising nutritional and bio-functional characteristics for health-conscious consumers.

The role of the GABAergic system on insomnia.

Sleep is an essential activity for the survival of mammals. Good sleep quality helps promote the performance of daily functions. In contrast, insufficient sleep reduces the efficiency of daily activities, causes various chronic diseases like Alzheimer's disease, and increases the risk of having accidents. The GABAergic system is the primary inhibitory neurotransmitter system in the central nervous system. It transits the gamma-aminobutyric acid (GABA) neurotransmitter via GABAA and GABAB receptors to counterbalance excitatory neurotransmitters, such as glutamate, noradrenaline, serotonin, acetylcholine, orexin, and dopamine, which release and increase arousal activities during sleep. Several studies emphasized that dysfunction of the GABAergic system is related to insomnia, the most prevalent sleep-related disorder. The GABAergic system comprises the GABA neurotransmitter, GABA receptors, GABA synthesis, and degradation. Many studies have demonstrated that GABA levels correlate with sleep quality, suggesting that modulating the GABAergic system may be a promising therapeutic approach for insomnia. In this article, we highlight the significance of sleep, the classification and pathology of insomnia, and the impact of the GABAergic system changes on sleep. In addition, we also review the medications that target the GABAergic systems for insomnia, including benzodiazepines (BZDs), non-BZDs, barbiturates, GABA supplements, and Chinese herbal medicines.

Nicotinic Acetylcholine Receptors in Glial Cells as Molecular Target for Parkinson's Disease.

Parkinson's disease (PD) is a progressive neurodegenerative disease characterized by resting tremor, bradykinesia, rigidity, and postural instability that also includes non-motor symptoms such as mood dysregulation. Dopamine (DA) is the primary neurotransmitter involved in this disease, but cholinergic imbalance has also been implicated. Current intervention in PD is focused on replenishing central DA, which provides remarkable temporary symptomatic relief but does not address neuronal loss and the progression of the disease. It has been well established that neuronal nicotinic cholinergic receptors (nAChRs) can regulate DA release and that nicotine itself may have neuroprotective effects. Recent studies identified nAChRs in nonneuronal cell types, including glial cells, where they may regulate inflammatory responses. Given the crucial role of neuroinflammation in dopaminergic degeneration and the involvement of microglia and astrocytes in this response, glial nAChRs may provide a novel therapeutic target in the prevention and/or treatment of PD. In this review, following a brief discussion of PD, we focus on the role of glial cells and, specifically, their nAChRs in PD pathology and/or treatment.

Nystagmus and Imbalance as the Presenting Symptoms of AntiGad Antibody Syndrome in A 67-Year-Old Female

Autoimmune encephalitis is a serious condition that causes brain inflammation, usually mediated by antibodies to various neuronal antigens [1]. One of the many antigens that may generate an immune response and cause this type of inflammation is the glutamic acid decarboxylase enzyme (GAD). AntiGAD (glutamic acid decarboxylase) antibodies are targeted against the GAD enzyme that converts glutamate to GABA, which is the nervous system’s primary inhibitory neurotransmitter [2]. With the body’s primary inhibitory neurotransmitter compromised, anti-GAD antibody syndrome is a rare type of autoimmune encephalitis that results in various symptoms related to prolonged excitation, such as seizures or nystagmus [3]. We present a rare case of autoimmune encephalitis caused by significantly elevated Anti-GAD antibody, with concomitant rheumatoid arthritis in the hands/wrists; symptoms of downbeat nystagmus, diplopia, headaches, and joint pain are improved with rituximab and IVIG infusion, following an unsuccessful treatment with oral prednisone.

Inherited Pediatric Neurotransmitter Disorders: Case Studies and Long-Term Outcomes

AbstractPrimary pediatric neurotransmitter disorders include genetic defects of neurotransmitter metabolism that may mimic common neurological conditions in children. Our objective was to evaluate the clinical experience and outcomes of affected patients. Five patients with primary neurotransmitter defects were identified in the neurometabolic database between 2004 and 2022. Two patients with 6-pyruvoyltetrahydropterin synthase deficiency and one with pyridoxine-dependent epilepsy (PDE) presented in the neonatal period. One patient with succinic semialdehyde dehydrogenase (SSADH) deficiency and one with aromatic l-amino acid decarboxylase (AADC) deficiency presented in later life. A diagnosis of cerebral palsy was revised following biochemical confirmation of SSADH deficiency. AADC deficiency was confirmed via exome sequencing and reduced activity on enzyme assay. Late diagnosis in the latter two cases was likely due to a low index of suspicion and lack of access to diagnostic tests in the country of origin. In two children with tetrahydrobiopterin deficiency, newborn screening results and atypical clinical features prompted investigations. An early diagnosis of PDE was established based on presenting features, a high index of suspicion, the presence of an identifiable biochemical marker and molecular genetic testing. Pediatric neurotransmitter disorders can be diagnosed based on a high clinical index of suspicion, availability of biochemical markers, and molecular genetic testing. These disorders, though rare, need to be included in the differential diagnosis of common neurological presentations in children as they may be potentially treatable. Outcomes and influencing factors in the present series are discussed in comparison to published data.

A paradoxical switch: the implications of excitatory GABAergic signaling in neurological disorders.

Gamma-aminobutyric acid (GABA) is the primary inhibitory neurotransmitter in the central nervous system. In the mature brain, inhibitory GABAergic signaling is critical in maintaining neuronal homeostasis and vital human behaviors such as cognition, emotion, and motivation. While classically known to inhibit neuronal function under physiological conditions, previous research indicates a paradoxical switch from inhibitory to excitatory GABAergic signaling that is implicated in several neurological disorders. Various mechanisms have been proposed to contribute to the excitatory switch such as chloride ion dyshomeostasis, alterations in inhibitory receptor expression, and modifications in GABAergic synaptic plasticity. Of note, the hypothesized mechanisms underlying excitatory GABAergic signaling are highlighted in a number of neurodevelopmental, substance use, stress, and neurodegenerative disorders. Herein, we present an updated review discussing the presence of excitatory GABAergic signaling in various neurological disorders, and their potential contributions towards disease pathology.

Morphological, molecular, and functional characterization of mouse glutamatergic myenteric neurons.

The enteric nervous system (ENS) functions largely independently of the central nervous system (CNS). Glutamate, the dominant neurotransmitter in the CNS and sensory afferents, is not a primary neurotransmitter in the ENS. Only a fraction (∼2%) of myenteric neurons in the mouse distal colon and rectum (colorectum) are positive for vesicular glutamate transporter type 2 (VGLUT2), the structure and function of which remain undetermined. Here, we systematically characterized VGLUT2-positive enteric neurons (VGLUT2-ENs) through sparse labeling with adeno-associated virus, single-cell mRNA sequencing (scRNA-seq), and GCaMP6f calcium imaging. Our results reveal that the majority of VGLUT2-ENs (29 of 31, 93.5%) exhibited Dogiel type I morphology with a single aborally projecting axon; most axons (26 of 29, 89.7%) are between 4 and 10 mm long, each traversing 19 to 34 myenteric ganglia. These anatomical features exclude the VGLUT2-ENs from being intrinsic primary afferent or motor neurons. The scRNA-seq conducted on 52 VGLUT2-ENs suggests different expression profiles from conventional descending interneurons. Ex vivo GCaMP6f recordings from flattened colorectum indicate that almost all VGLUT2-EN (181 of 215, 84.2%) are indirectly activated by colorectal stretch via nicotinic cholinergic neural transmission. In conclusion, VGLUT2-ENs are a functionally unique group of enteric neurons with single aborally projecting long axons that traverse multiple myenteric ganglia and are activated indirectly by colorectal mechanical stretch. This knowledge will provide a solid foundation for subsequent studies on the potential interactions of VGLUT2-EN with extrinsic colorectal afferents via glutamatergic neurotransmission.NEW & NOTEWORTHY We reveal that VGLUT2-positive enteric neurons (EN), although constituting a small fraction of total EN, are homogeneously expressed in the myenteric ganglia, with a slight concentration at the intermediate region between the colon and rectum. Through anatomic, molecular, and functional analyses, we demonstrated that VGLUT2-ENs are activated indirectly by noxious circumferential colorectal stretch via nicotinic cholinergic transmission, suggesting their participation in mechanical visceral nociception.