Reduced Neurotransmitter Release Research Articles

Group III metabotropic glutamate receptors: guardians against excitotoxicity in ischemic brain injury, with implications for neonatal contexts

AbstractThe group III metabotropic glutamate receptors (mGluRs), comprising mGluR4, mGluR6, mGluR7, and mGluR8, offer neuroprotective potential in mitigating excitotoxicity during ischemic brain injury, particularly in neonatal contexts. They are G-protein coupled receptors that inhibit adenylyl cyclase and reduce neurotransmitter release, mainly located presynaptically and acting as autoreceptors. This review aims to examine the differential expression and function of group III mGluRs across various brain regions such as the cortex, hippocampus, and cerebellum, with a special focus on the neonatal stage of development. Glutamate excitotoxicity plays a crucial role in the pathophysiology of brain ischemia in neonates. While ionotropic glutamate receptors are traditional targets for neuroprotection, their direct inhibition often leads to severe side effects due to their critical roles in normal neurotransmission and synaptic plasticity. Group III mGluRs provide a more nuanced and potentially safer approach by modulating rather than blocking glutamatergic transmission. Their downstream signaling cascade results in the regulation of intracellular calcium levels, neuronal hyperpolarization, and reduced neurotransmitter release, effectively decreasing excitotoxic signaling without completely suppressing essential glutamatergic functions. Importantly, the neuroprotective effects of group III mGluRs extend beyond direct modulation of glutamate release influencing glial cell function, neuroinflammation, and oxidative stress, all of which contribute to secondary injury cascades in brain ischemia. This comprehensive analysis of group III mGluRs multifaceted neuroprotective potential provides valuable insights for developing novel therapeutic strategies to combat excitotoxicity in neonatal ischemic brain injury.

Synaptotagmin-11 facilitates assembly of a presynaptic signaling complex in post-Golgi cargo vesicles

GABAB receptors (GBRs), the G protein-coupled receptors for GABA, regulate synaptic transmission throughout the brain. A main synaptic function of GBRs is the gating of Cav2.2-type Ca2+ channels. However, the cellular compartment where stable GBR/Cav2.2 signaling complexes form remains unknown. In this study, we demonstrate that the vesicular protein synaptotagmin-11 (Syt11) binds to both the auxiliary GBR subunit KCTD16 and Cav2.2 channels. Through these dual interactions, Syt11 recruits GBRs and Cav2.2 channels to post-Golgi vesicles, thus facilitating assembly of GBR/Cav2.2 signaling complexes. In addition, Syt11 stabilizes GBRs and Cav2.2 channels at the neuronal plasma membrane by inhibiting constitutive internalization. Neurons of Syt11 knockout mice exhibit deficits in presynaptic GBRs and Cav2.2 channels, reduced neurotransmitter release, and decreased GBR-mediated presynaptic inhibition, highlighting the critical role of Syt11 in the assembly and stable expression of GBR/Cav2.2 complexes. These findings support that Syt11 acts as a vesicular scaffold protein, aiding in the assembly of signaling complexes from low-abundance components within transport vesicles. This mechanism enables insertion of pre-assembled functional signaling units into the synaptic membrane.

Aagab is required for zebrafish larval development by regulating neural activity

Clathrin-mediated endocytosis has been implicated in various physiological processes, including nutrient uptake, signal transduction, synaptic vesicle recycling, maintenance of cell polarity, and antigen presentation. Despite prior knowledge of its importance as a key regulator in promoting clathrin-mediated endocytosis, the physiological function of α- and γ-adaptin binding protein (aagab) remains elusive. In this study, we investigate the biological function of aagab during zebrafish development. We establish a loss-of-function mutant of aagab in zebrafish, revealing impaired swimming and early larval mortality. Given the high expression level of aagab in the brain, we probe into its physiological role in the nervous system. aagab mutants display subdued calcium responses and local field potential in the optic tectal neurons, aligning with reduced neurotransmitter release (e.g., norepinephrine) in the tectal neuropil of aagab mutants. Overexpressing aagab mRNA or nervous stimulant treatment in mutants restores neurotransmitter release, calcium responses, swimming ability, and survival. Furthermore, our observations show delayed release of FM 1–43 in AAGAB knockdown differentiated neuroblastoma cells, pointing towards a probable link to defective clathrin-mediated synaptic vesicle recycling. In conclusion, our study underscores the significance of Aagab in neurobiology and suggests its potential impacts on neurological disorders.

Lactate as a supplemental fuel for synaptic transmission and neuronal network oscillations: Potentials and limitations.

Lactate shuttled from the blood circulation, astrocytes, oligodendrocytes or even activated microglia (resident macrophages) to neurons has been hypothesized to represent a major source of pyruvate compared to what is normally produced endogenously by neuronal glucose metabolism. However, the role of lactate oxidation in fueling neuronal signaling associated with complex cortex function, such as perception, motor activity, and memory formation, is widely unclear. This issue has been experimentally addressed using electrophysiology in hippocampal slice preparations (ex vivo) that permit the induction of different neural network activation states by electrical stimulation, optogenetic tools or receptor ligand application. Collectively, these studies suggest that lactate in the absence of glucose (lactate only) impairs gamma (30-70 Hz) and theta-gamma oscillations, which feature high energy demand revealed by the cerebral metabolic rate of oxygen (CMRO2, set to 100%). The impairment comprises oscillation attenuation or moderate neural bursts (excitation-inhibition imbalance). The bursting is suppressed by elevating the glucose fraction in energy substrate supply. By contrast, lactate can retain certain electric stimulus-induced neural population responses and intermittent sharp wave-ripple activity that features lower energy expenditure (CMRO2 of about 65%). Lactate utilization increases the oxygen consumption by about 9% during sharp wave-ripples reflecting enhanced adenosine-5'-triphosphate (ATP) synthesis by oxidative phosphorylation in mitochondria. Moreover, lactate attenuates neurotransmission in glutamatergic pyramidal cells and fast-spiking, γ-aminobutyric acid (GABA)ergic interneurons by reducing neurotransmitter release from presynaptic terminals. By contrast, the generation and propagation of action potentials in the axon is regular. In conclusion, lactate is less effective than glucose and potentially detrimental during neural network rhythms featuring high energetic costs, likely through the lack of some obligatory ATP synthesis by aerobic glycolysis at excitatory and inhibitory synapses. High lactate/glucose ratios might contribute to central fatigue, cognitive impairment, and epileptic seizures partially seen, for instance, during exhaustive physical exercise, hypoglycemia and neuroinflammation.

Homeostatic synaptic plasticity rescues neural coding reliability

To survive, animals must recognize reoccurring stimuli. This necessitates a reliable stimulus representation by the neural code. While synaptic transmission underlies the propagation of neural codes, it is unclear how synaptic plasticity can maintain coding reliability. By studying the olfactory system of Drosophila melanogaster, we aimed to obtain a deeper mechanistic understanding of how synaptic function shapes neural coding in the live, behaving animal. We show that the properties of the active zone (AZ), the presynaptic site of neurotransmitter release, are critical for generating a reliable neural code. Reducing neurotransmitter release probability of olfactory sensory neurons disrupts both neural coding and behavioral reliability. Strikingly, a target-specific homeostatic increase of AZ numbers rescues these defects within a day. These findings demonstrate an important role for synaptic plasticity in maintaining neural coding reliability and are of pathophysiological interest by uncovering an elegant mechanism through which the neural circuitry can counterbalance perturbations.

Opioid Receptor-Mediated Regulation of Neurotransmission in the Brain.

Opioids mediate their effects via opioid receptors: mu, delta, and kappa. At the neuronal level, opioid receptors are generally inhibitory, presynaptically reducing neurotransmitter release and postsynaptically hyperpolarizing neurons. However, opioid receptor-mediated regulation of neuronal function and synaptic transmission is not uniform in expression pattern and mechanism across the brain. The localization of receptors within specific cell types and neurocircuits determine the effects that endogenous and exogenous opioids have on brain function. In this review we will explore the similarities and differences in opioid receptor-mediated regulation of neurotransmission across different brain regions. We discuss how future studies can consider potential cell-type, regional, and neural pathway-specific effects of opioid receptors in order to better understand how opioid receptors modulate brain function.

Chemobrain: A review on mechanistic insight, targets and treatments.

Chemo-brain refers to the thinking and memory problems that occur in cancer patients during and after chemotherapy. It is also known as cognitive dysfunction or chemo-fog. Risk factors include brain malignancies, either primary or metastatic, radiotherapy and chemotherapy, either systemic or brain targeted. There are various mechanisms by which chemo-brain occurs in patients post-chemotherapy, including inflammation of neurons, stress due to free radical generation, and alterations in normal neuronal cell process due to biochemical changes. While chemotherapy drugs that are non-brain targeted, usually fail to cross the blood-brain barrier (BBB), this is not the case for inflammatory cytokines that are released, which easily cross the BBB. These inflammatory neurotoxic agents may represent the primary mediators of chemobrain and include the pro-inflammatory cytokines such as interleukins 1 and 6 and tumor necrosis factor. The pronounced rise in oxidative stress due to continuous chemotherapy also leads to a reduction in neurogenesis and gliogenesis, loss of spine and dendritic cells, and a reduction in neurotransmitter release. Based on recent research, potential agents to prevent and treat chemo brain have been identified, which include Lithium, Fluoxetine, Metformin, Rolipram, Astaxanthin, and microglial inhibitors. However, more defined animal models for cognitive dysfunction are required to study in detail the mechanisms involved in chemo-brain; furthermore, well-defined clinical trials are required to identify drug targets and their therapeutic significance. With these focused approaches, the future for improved therapies is promising.

Peripherally Administered Botulinum Toxin Type A Localizes Bilaterally in Trigeminal Ganglia of Animal Model.

Peripheral nerve injury leads to sensory ganglion hyperexcitation, which increases neurotransmitter release and neuropathic pain. Botulinum toxin type A (BoNT/A) regulates pain transmission by reducing neurotransmitter release, thereby attenuating neuropathic pain. Despite multiple studies on the use of BoNT/A for managing neuropathic pain in the orofacial region, its exact mechanism of transport remains unclear. In this study, we investigated the effects of BoNT/A in managing neuropathic pain in two different animal models and its transport mechanism in the trigeminal nerve. Intraperitoneal administration of cisplatin induced bilateral neuropathic pain in the orofacial region, reducing the head withdrawal threshold to mechanical stimulation. Unilateral infraorbital nerve constriction (IONC) also reduced the ipsilateral head withdrawal threshold to mechanical stimulation. Unilateral peripheral administration of BoNT/A to the rat whisker pad attenuated cisplatin-induced pain behavior bilaterally. Furthermore, contralateral peripheral administration of BoNT/A attenuated neuropathy-induced behavior caused by IONC. We also noted the presence of BoNT/A in the blood using the mouse bioassay. In addition, the Alexa Fluor-488-labeled C-terminal half of the heavy chain of BoNT/A (BoNT/A-Hc) was localized in the neurons of the bilateral trigeminal ganglia following its unilateral administration. These findings suggest that axonal and hematogenous transport are involved in the therapeutic effects of peripherally administered BoNT/A in the orofacial region.

Reader Response: What Is the Mechanism of Therapeutic and Adverse Effects of Gabapentinoids?

Dr. Benarroch's article about gabapentinoids describes that the α2δ subunit of voltage-gated calcium channels (VGCC) allows for neuronal calcium influx. A2δ is expressed in Purkinje cells, which use gamma aminobutyric acid (GABA) as a neurotransmitter. The author states that gabapentinoids inhibit the α2δ subunit and reduce neurotransmitter release, resulting in the induction of cerebellar ataxia.1,2

The Frequency-Dependence of Pre- and Postganglionic Nerve Stimulation of Pig and Rat Bladder.

PurposeThe urinary bladder generates phasic contractions via action potentials generated in pre- and then postganglionic neurons. Whilst the frequency-dependence of postganglionic neurons to generate contractions has been quantified, the dynamic range of preganglionic neurons is less clear and if intramural ganglia exert frequency-dependent modulation of transmission between pre- and postganglionic neurons. The phosphodiesterase type 5 inhibitor sildenafil reduces neurotransmitter release from postganglionic fibres to detrusor smooth muscle and an additional question was if there was also a preganglionic action. This study aimed to compare the frequency range of bladder contractile activation by pre- and postganglionic stimulation in pig and rat bladders and if sildenafil exerted additional preganglionic actions.MethodsAn arterially-perfused ex vivo pig bladder preparation was used for preganglionic (pelvic nerve) and mixed pre-and postganglionic (direct bladder wall) stimulation at 36°C and postganglionic mediated contractions achieved by field-stimulation of in vitro isolated detrusor strips. With rats, pelvic nerve stimulation was carried out in vivo and postganglionic stimulation also with isolated detrusor strips.ResultsAll contractions were abolished by 2% lignocaine indicating they are nerve-mediated. Stimulation targets were verified with hexamethonium that completely abolished pelvic nerve responses by had no effect on detrusor strips; responses to mixed bladder wall stimulation were partially reduced. The frequency-dependence of contractile activation was similar whether by pre- or postganglionic stimulation in both pigs and rats. Sildenafil reduced contractions to preganglionic stimulation significantly more than to postganglionic stimulation. Mixed pre- and postganglionic stimulation were reduced by an intermediate extent.ConclusionsIntramural ganglia offer no frequency-dependent modulation under the experimental conditions used here and the sildenafil data are consistent with multiple sites of action underlying generation of bladder contractions. A translational aspect of these findings is discussed in terms of setting stimulation parameters for neuromodulation protocols.

Input-dependent synaptic suppression by pregabalin in the central amygdala in male mice with inflammatory pain

Pregabalin (PGB) is a synthetic amino acid compound most widely prescribed for chronic peripheral and central neuropathic pain. PGB is a ligand for the α2δ1 subunit of voltage-dependent calcium channels, and its binding reduces neurotransmitter release and thus inhibits synaptic transmission. The central nucleus of the amygdala (CeA) is a kernel site for the enhanced nociception-emotion link in chronic pain. The nociceptive information is conveyed to the CeA via the following two pathways: 1) the pathway arising from the basolateral amygdala (BLA), which carries nociceptive information mediated by the thalamocortical system, and 2) that arising from the external part of the pontine lateral parabrachial nucleus (LPB), that forms the final route of the spino-parabrachio-amygdaloid pathway that conveys nociceptive information directly from the superficial layer of the spinal dorsal horn. We compared the effects of PGB on the excitatory postsynaptic currents of neurons in the right CeA in response to electrical stimulation of BLA and LPB pathways using the whole-cell patch-clamp technique. Inflammatory pain was induced by intraplantar injection of formalin solution at the left hind paw.At eight hours post-formalin, PGB reduced EPSCs amplitude of the BLA-to-CeA synaptic transmission, accompanied by a significant increase in the PPR, suggesting a decreased release probability from the presynaptic terminals. In addition, these effects of PGB were only seen in inflammatory conditions. PGB did not affect the synaptic transmission at the LPB-to-CeA pathway, even in formalin-treated mice. These results suggest PGB improves not simply the aberrantly enhanced nociception but also various pain-associated cognitive and affective consequences in patients with chronic nociplastic pain.

The role of voltage-gated ion channels in visual function and disease in mammalian photoreceptors.

Light activation of the classical light-sensing retinal neurons, the photoreceptors, results in a graded change in membrane potential that ultimately leads to a reduction in neurotransmitter release to the post-synaptic retinal neurons. Photoreceptors show striking powers of adaptation, and for visual processing to function optimally, they must adjust their gain to remain responsive to different levels of ambient light intensity. The presence of a tightly controlled balance of inward and outward currents modulated by several different types of ion channels is what gives photoreceptors their remarkably dynamic operating range. Part of the resetting and modulation of this operating range is controlled by potassium and calcium voltage-gated channels, which are involved in setting the dark resting potential and synapse signal processing, respectively. Their essential contribution to visual processing is further confirmed in patients suffering from cone dystrophy with supernormal rod response (CDSRR) and congenital stationary night blindness type 2 (CSNB2), both conditions that lead to irreversible vision loss. This review will discuss these two types of voltage-gated ion channels present in photoreceptors, focussing on their structure and physiology, and their role in visual processing. It will also discuss the use and benefits of knockout mouse models to further study the function of these channels and what routes to potential treatments could be applied for CDSRR and CSNB2.

Amitriptyline Decreases GABAergic Transmission in Basal Forebrain Neurons Using an Optogenetic Model of Aging.

The antidepressant drug amitriptyline is used in the treatment of clinical depression and a variety of neurological conditions such as anxiety, neuropathic pain disorders and migraine. Antidepressants are associated with both therapeutic and untoward effects, and their use in the elderly has tripled since the mid-1990s. Because of this widespread use, we are interested in testing the acute effects of amitriptyline on synaptic transmission at therapeutic concentrations well below those that block voltage-gated calcium channels. We found that 3 μM amitriptyline reduced the frequency of spontaneous GABAergic inhibitory postsynaptic currents (IPSCs) and reduced quantal content in mice at ages of 7–10 mo. and 23–25 mo., suggesting a presynaptic mechanism of action that does not diminish with age. We employed a reduced synaptic preparation of the basal forebrain (BF) and a new optogenetic aging model utilizing a bacterial artificial chromosome (BAC) transgenic mouse line with stable expression of the channelrhodopsin-2 (ChR2) variant H134R specific for GABAergic neurons [VGAT-ChR2(H134R)-EYFP]. This model enables optogenetic light stimulation of specific GABAergic synaptic terminals across aging. Age-related impairment of circadian behavior was used to confirm predictable age-related changes associated with this model. Our results suggest that low concentrations of amitriptyline act presynaptically to reduce neurotransmitter release and that this action is maintained during aging.

Detrusor underactivity causes neurogenic voiding dysfunction in a rat bilateral accessory nerve-injury model

We aimed to investigate detrusor function in a previously developed rat neurogenic voiding dysfunction model that we have developed previously. We performed sham or bilateral accessory nerve injury (BACNI) surgeries on ten-week-old male Wistar/ST rats. One week after surgery, we evaluated detrusor contractility in the bladder using isometric tension and mRNA expression assays. Cholinergic contraction was attenuated in the injury model, whereas carbachol-evoked contraction was enhanced, and mRNA expression of the cholinergic receptor increased. These findings suggest that there was a reduction in neurotransmitter release causing detrusor underactivity.

Decreased excitatory drive onto hilar neuronal nitric oxide synthase expressing interneurons in chronic models of epilepsy

Excitation-inhibition imbalance of GABAergic interneurons is predisposed to develop chronic temporal lobe epilepsy (TLE). We have previously shown that virtually every neuronal nitric oxide synthase (nNOS)-positive cell is a GABAergic inhibitory interneuron in the denate gyrus. The present study was designed to quantify the number of nNOS-containing hilar interneurons using stereology in pilocapine- and kainic acid (KA)-exposed transgenic adult mice that expressed GFP under the nNOS promoter. In addition, we studied the properties of miniature excitatory postsynaptic current (mEPSC) and paired-pulse response ratio (PPR) of evoked EPSC in nNOS interneurons using whole cell recording techniques. Results showed that there were fewer nNOS-immunoreactive interneurons of chronically epileptic animals. Importantly, patch-clamp recordings revealed reduction in mEPSC frequency, indicating diminished global excitatory input. In contrast, PPR of evoked EPSC following the granule cell layer stimulation was increased in epileptic animals suggesting reduced neurotransmitter release from granule cell input. In summary, we propose that impaired excitatory drive onto hippocampal nNOS interneurons may be implicated in the development of refractory epilepsy.

What Is the Mechanism of Therapeutic and Adverse Effects of Gabapentinoids?

Voltage-gated calcium channels (VGCCs) are essential for the function of excitable cells by permitting Ca2+ entry in response to membrane depolarization. The high-voltage-activated channels, including the presynaptic P/Q-type (Cav2.1) and N-type (Cav 2.2) channels, comprise the main pore-forming subunit, α1, along with the auxiliary subunits β and α2δ. Although not directly involved in Ca2+ transport, Cavβ and Cavα2δ are critical for VGCC function by regulating kinetics and cell surface expression of these channels. Gabapentinoids, including gabapentin and pregabalin, are extensively used for treatment of neuropathic pain, restless legs syndrome, and focal seizures. Their efficacy in these disorders is primarily attributed to their effects in inhibiting the functions of the α2δ subunit of presynaptic VGCCs, thereby reducing neurotransmitter release. Recent studies on Cα2δ function and effects of gabapentinoids provide further insight into both the therapeutic and adverse effects of these drugs (figure).

Neurexin1⍺ differentially regulates synaptic efficacy within striatal circuits

SUMMARYMutations in genes essential for synaptic function, such as the presynaptic adhesion molecule Neurexin1α (Nrxn1α), are strongly implicated in neuropsychiatric pathophysiology. As the input nucleus of the basal ganglia, the striatum integrates diverse excitatory projections governing cognitive and motor control, and its impairment may represent a recurrent pathway to disease. Here, we test the functional relevance of Nrxn1α in striatal circuits by employing optogenetic-mediated afferent recruitment of dorsal prefrontal cortical (dPFC) and parafascicular thalamic connections onto dorsomedial striatal (DMS) spiny projection neurons (SPNs). For dPFC-DMS circuits, we find decreased synaptic strength specifically onto indirect pathway SPNs in both Nrxn1α+/− and Nrxn1α−/− mice, driven by reductions in neurotransmitter release. In contrast, thalamic excitatory inputs to DMS exhibit relatively normal excitatory synaptic strength despite changes in synaptic N-methyl-D-aspartate receptor (NMDAR) content. These findings suggest that dysregulation of Nrxn1α modulates striatal function in an input- and target-specific manner.

Impaired Pre‐Motor Circuit Activity and Movement in a Drosophila Model of KCNMA1‐Linked Dyskinesia

BackgroundParoxysmal dyskinesias (PxDs) are characterized by involuntary movements and altered pre‐motor circuit activity. Causative mutations provide a means to understand the molecular basis of PxDs. Yet in many cases, animal models harboring corresponding mutations are lacking. Here we utilize the fruit fly, Drosophila, to study a PxD linked to a gain‐of‐function (GOF) mutation in the KCNMA1/hSlo1 BK potassium channel.ObjectivesWe aimed to recreate the equivalent BK (big potassium) channel mutation in Drosophila. We sought to determine how this mutation altered action potentials (APs) and synaptic release in vivo; to test whether this mutation disrupted pre‐motor circuit function and locomotion; and to define neural circuits involved in locomotor disruption.MethodsWe generated a knock‐in Drosophila model using homologous recombination. We used electrophysiological recordings and calcium‐imaging to assess AP shape, neurotransmission, and the activity of the larval pre‐motor central pattern generator (CPG). We used video‐tracking and automated systems to measure movement, and developed a genetic method to limit BK channel expression to defined circuits.ResultsNeuronal APs exhibited reduced width and an enhanced afterhyperpolarization in the PxD model. We identified calcium‐dependent reductions in neurotransmitter release, dysfunction of the CPG, and corresponding alterations in movement, in model larvae. Finally, we observed aberrant locomotion and dyskinesia‐like movements in adult model flies, and partially mapped the impact of GOF BK channels on movement to cholinergic neurons.ConclusionOur model supports a link between BK channel GOF and hyperkinetic movements, and provides a platform to dissect the mechanistic basis of PxDs. © 2021 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society

Establishment of animal model manifested as bladder neurogenic changes generated by bilateral pelvic nerve injury in male rats.

To establish a male rat model of neurogenic bladder after bilateral pelvic nerve injury (BPNI) and investigate the factors associated with onset of neurogenic bladder. Twenty-four 8-week-old male Sprague-Dawley rats were randomly divided into three groups (n = 8 rats per group). Rats in 4-week and 8-week nerve injury group underwent BPNI, while rats in the sham group underwent a sham operation. Bladder functional analysis were performed and then bladders tissues were harvested for morphological examination and investigating the mRNA expression levels of target genes in all rats. The bladder weight significantly increased in rats following BPNI. Functional analysis revealed non-voiding contractions and decreased detrusor contractility following BPNI, manifested as elevated post-void residual and bladder capacity while reduced maximum voiding pressure and voiding efficiency. The collagen area in bladder tissue and mRNA expression levels of target genes significantly increased at 4or 8weeks post-BPNI except Smad3. At 4weeks post-BPNI, expression levels of vesicular acetylcholine transporter were reduced, then returned to baseline at 8weeks. Expression levels of tyrosine hydroxylase were reduced at both 4 and 8weeks post-BPNI. A neurogenic bladder animal model was successfully established by performing BPNI in male rats, characterized by impaired voiding function, bladder detrusor fibrosis, and reduced neurotransmitter release.

Development and Validation of CRISPR Activator Systems for Overexpression of CB1 Receptors in Neurons

Gene therapy approaches using viral vectors for the overexpression of target genes have been for several years the focus of gene therapy research against neurological disorders. These approaches deliver robust expression of therapeutic genes, but are typically limited to the delivery of single genes and often do not manipulate the expression of the endogenous locus. In the last years, the advent of CRISPR-Cas9 technologies have revolutionized many areas of scientific research by providing novel tools that allow simple and efficient manipulation of endogenous genes. One of the applications of CRISPR-Cas9, termed CRISPRa, based on the use of a nuclease-null Cas9 protein (dCas9) fused to transcriptional activators, enables quick and efficient increase in target endogenous gene expression. CRISPRa approaches are varied, and different alternatives exist with regards to the type of Cas9 protein and transcriptional activator used. Several of these approaches have been successfully used in neurons in vitro and in vivo, but have not been so far extensively applied for the overexpression of genes involved in synaptic transmission. Here we describe the development and application of two different CRISPRa systems, based on single or dual Lentiviral and Adeno-Associated viral vectors and VP64 or VPR transcriptional activators, and demonstrate their efficiency in increasing mRNA and protein expression of the Cnr1 gene, coding for neuronal CB1 receptors. Both approaches were similarly efficient in primary neuronal cultures, and achieved a 2–5-fold increase in Cnr1 expression, but the AAV-based approach was more efficient in vivo. Our dual AAV-based VPR system in particular, based on Staphylococcus aureus dCas9, when injected in the hippocampus, displayed almost complete simultaneous expression of both vectors, high levels of dCas9 expression, and good efficiency in increasing Cnr1 mRNA as measured by in situ hybridization. In addition, we also show significant upregulation of CB1 receptor protein in vivo, which is reflected by an increased ability in reducing neurotransmitter release, as measured by electrophysiology. Our results show that CRISPRa techniques could be successfully used in neurons to target overexpression of genes involved in synaptic transmission, and can potentially represent a next-generation gene therapy approach against neurological disorders.