Pharmacology
pharmacology
Prof. Carmen Varela
The Varela lab is hiring a full-time research assistant to perform electrophysiology and pharmacology experiments in rats to investigate the link between sleep architecture, memory consolidation and thalamic neural activity. This project is part of a wider research program in the lab that seeks to provide mechanistic insight on the role of sleep dysfunction in Alzheimer’s Disease and related disorders. This is a great opportunity for students looking to strengthen their research skills and academic competitiveness for PhD and MD-PhD Programs in Neuroscience. Start date flexible in the Fall of 2023 or early 2024; 1 year with possibility of renewal. The Varela laboratory investigates the cellular and network mechanisms of learning and memory in rodents. We use a broad range of state-of-the-art methods, including multi-site extracellular recordings in freely behaving rats, closed-loop manipulations of brain activity, optogenetics, and computational approaches http://www.varelalab.org/
Assistant Prof Yao Chen
Are you looking for immersion in exciting science and cutting-edge technology? Yao Chen’s Laboratory in the Department of Neuroscience at Washington University School of Medicine is seeking a highly motivated individual for a full-time research technician position. Our laboratory conducts basic research to understand how dynamics of molecular signals contribute to neuromodulator actions and sleep functions. We employ a wide variety of techniques ex vivo and in vivo, including two-photon fluorescence lifetime imaging microscopy, electrophysiology, biosensor design, opto/chemogenetics, molecular biology, pharmacology, and behavior analysis. For a complete job description and to apply, please visit https://jobs.wustl.edu and search for Job ID number “51507” for Research Technician II - Neuroscience – 51507.
Prof Zoe Kourtzi
Post-doctoral position in Cognitive Computational Neuroscience at the Adaptive Brain Lab. The role involves combining high field brain imaging (7T fMRI, MR Spectroscopy), electrophysiology (EEG), computational modelling (machine learning, reinforcement learning) and interventions (TMS, tDCS, pharmacology) to understand network dynamics for learning and brain plasticity. The research programme bridges work across scales (local circuits, global networks) and species (humans, rodents) to uncover the neurocomputations that support learning and brain plasticity.
Alberto Bacci
The successful candidate will work on inhibitory circuits of the prefrontal cortex of mice. In particular, they will study the properties and plasticity of synapses connecting a rich diversity of prefrontal cortical neuron subtypes. The candidate will also perform and analyze electrophysiological recordings in vivo, using high-density Neuropixels probes. This project is part of an ERA-Net NEURON international consortium and focuses on the rich diversity of GABAergic interneurons and their impact on the functional states of prefrontal cortical networks in healthy and diseased states.
How the presynapse forms and functions”
Nervous system function relies on the polarized architecture of neurons, established by directional transport of pre- and postsynaptic cargoes. While delivery of postsynaptic components depends on the secretory pathway, the identity of the membrane compartment(s) that supply presynaptic active zone (AZ) and synaptic vesicle (SV) proteins is largely unknown. I will discuss our recent advances in our understanding of how key components of the presynaptic machinery for neurotransmitter release are transported and assembled focussing on our studies in genome-engineered human induced pluripotent stem cell-derived neurons. Specifically, I will focus on the composition and cell biological identity of the axonal transport vesicles that shuttle key components of neurotransmission to nascent synapses and on machinery for axonal transport and its control by signaling lipids. Our studies identify a crucial mechanism mediating the delivery of SV and active zone proteins to developing synapses and reveal connections to neurological disorders. In the second part of my talk, I will discuss how exocytosis and endocytosis are coupled to maintain presynaptic membrane homeostasis. I will present unpublished data regarding the role of membrane tension in the coupling of exocytosis and endocytosis at synapses. We have identified an endocytic BAR domain protein that is capable of sensing alterations in membrane tension caused by the exocytotic fusion of SVs to initiate compensatory endocytosis to restore plasma membrane area. Interference with this mechanism results in defects in the coupling of presynaptic exocytosis and SV recycling at human synapses.
Decoding ketamine: Neurobiological mechanisms underlying its rapid antidepressant efficacy
Unlike traditional monoamine-based antidepressants that require weeks to exert effects, ketamine alleviates depression within hours, though its clinical use is limited by side effects. While ketamine was initially thought to work primarily through NMDA receptor (NMDAR) inhibition, our research reveals a more complex mechanism. We demonstrate that NMDAR inhibition alone cannot explain ketamine's sustained antidepressant effects, as other NMDAR antagonists like MK-801 lack similar efficacy. Instead, the (2R,6R)-hydroxynorketamine (HNK) metabolite appears critical, exhibiting antidepressant effects without ketamine's side effects. Paradoxically, our findings suggest an inverted U-shaped dose-response relationship where excessive NMDAR inhibition may actually impede antidepressant efficacy, while some level of NMDAR activation is necessary. The antidepressant actions of ketamine and (2R,6R)-HNK require AMPA receptor activation, leading to synaptic potentiation and upregulation of AMPA receptor subunits GluA1 and GluA2. Furthermore, NMDAR subunit GluN2A appears necessary and possibly sufficient for these effects. This research establishes NMDAR-GluN2A activation as a common downstream effector for rapid-acting antidepressants, regardless of their initial targets, offering promising directions for developing next-generation antidepressants with improved efficacy and reduced side effects.
Pharmacological exploitation of neurotrophins and their receptors to develop novel therapeutic approaches against neurodegenerative diseases and brain trauma
Neurotrophins (NGF, BDNF, NT-3) are endogenous growth factors that exert neuroprotective effects by preventing neuronal death and promoting neurogenesis. They act by binding to their respective high-affinity, pro-survival receptors TrkA, TrkB or TrkC, as well as to p75NTR death receptor. While these molecules have been shown to significantly slow or prevent neurodegeneration, their reduced bioavailability and inability to penetrate the blood-brain-barrier limit their use as potential therapeutics. To bypass these limitations, our research team has developed and patented small-sized, lipophilic compounds which selectively resemble neurotrophins’ effects, presenting preferable pharmacological properties and promoting neuroprotection and repair against neurodegeneration. In addition, the combination of these molecules with 3D cultured human neuronal cells, and their targeted delivery in the brain ventricles through soft robotic systems, could offer novel therapeutic approaches against neurodegenerative diseases and brain trauma.
The Neurobiology of the Addicted Brain
Rodents to Investigate the Neural Basis of Audiovisual Temporal Processing and Perception
To form a coherent perception of the world around us, we are constantly processing and integrating sensory information from multiple modalities. In fact, when auditory and visual stimuli occur within ~100 ms of each other, individuals tend to perceive the stimuli as a single event, even though they occurred separately. In recent years, our lab, and others, have developed rat models of audiovisual temporal perception using behavioural tasks such as temporal order judgments (TOJs) and synchrony judgments (SJs). While these rodent models demonstrate metrics that are consistent with humans (e.g., perceived simultaneity, temporal acuity), we have sought to confirm whether rodents demonstrate the hallmarks of audiovisual temporal perception, such as predictable shifts in their perception based on experience and sensitivity to alterations in neurochemistry. Ultimately, our findings indicate that rats serve as an excellent model to study the neural mechanisms underlying audiovisual temporal perception, which to date remains relativity unknown. Using our validated translational audiovisual behavioural tasks, in combination with optogenetics, neuropharmacology and in vivo electrophysiology, we aim to uncover the mechanisms by which inhibitory neurotransmission and top-down circuits finely control ones’ perception. This research will significantly advance our understanding of the neuronal circuitry underlying audiovisual temporal perception, and will be the first to establish the role of interneurons in regulating the synchronized neural activity that is thought to contribute to the precise binding of audiovisual stimuli.
How can we treat visceral pain?
Chronic pain is a leading cause of morbidity, common to patients with gastrointestinal diseases such as irritable bowel syndrome (IBS) and inflammatory bowel disease (IBD). Most pain killers are largely ineffective against this type of pain or restricted for use in these patients due to gut related complications and risk of addition. A significant unmet clinical need therefore exists to develop novel non-opioid based visceral analgesics.
Ebselen: a lithium-mimetic without lithium side-effects?
Development of new medications for mental health conditions is a pressing need given the high proportion of people not responding to available treatments. We hope that presenting ebselen to a wider audience will inspire further studies on this promising agent with a benign side-effects profile. Laboratory research, animal research and human studies suggest that ebselen shares many features with the mood stabilising drug lithium, creating a promise of a drug that would have a similar clinical effect but without lithium’s troublesome side-effect profile and toxicity. Both drugs have a common biological target, inositol monophosphatase, whose inhibition is thought key to lithium’s therapeutic effect. Both drugs have neuroprotective action and reduce oxidative stress. In animal studies, ebselen affected neurotransmitters involved in the development of mental health symptoms, and in particular, produced effects of serotonin function very similar to lithium. Both ebselen and lithium share behavioural effects: antidepressant-like effects in rodent models of depression and decrease in behavioural impulsivity, a property associated with lithium's anti-suicidal action. Human neuropsychological studies support an antidepressant profile for ebselen based on its positive impact on emotional processing and reward seeking. Our group currently is exploring ebselen’s effects in patients with mood disorders. A completed ‘add-on’ clinical trial in mania showed ebselen’s superiority over placebo after three weeks of treatment. Our ongoing experimental research explores ebselen’s antidepressant profile in patients with treatment resistant depression. If successful, this will lead to a clinical trial of ebselen as an antidepressant augmentation agent, similar to lithium.
Chemistry of the adaptive mind: lessons from dopamine
The human brain faces a variety of computational dilemmas, including the flexibility/stability, the speed/accuracy and the labor/leisure tradeoff. I will argue that striatal dopamine is particularly well suited to dynamically regulate these computational tradeoffs depending on constantly changing task demands. This working hypothesis is grounded in evidence from recent studies on learning, motivation and cognitive control in human volunteers, using chemical PET, psychopharmacology, and/or fMRI. These studies also begin to elucidate the mechanisms underlying the huge variability in catecholaminergic drug effects across different individuals and across different task contexts. For example, I will demonstrate how effects of the most commonly used psychostimulant methylphenidate on learning, Pavlovian and effortful instrumental control depend on fluctuations in current environmental volatility, on individual differences in working memory capacity and on opportunity cost respectively.
The 15th David Smith Lecture in Anatomical Neuropharmacology: Professor Tim Bliss, "Memories of long term potentiation
The David Smith Lectures in Anatomical Neuropharmacology, Part of the 'Pharmacology, Anatomical Neuropharmacology and Drug Discovery Seminars Series', Department of Pharmacology, University of Oxford. The 15th David Smith Award Lecture in Anatomical Neuropharmacology will be delivered by Professor Tim Bliss, Visiting Professor at UCL and the Frontier Institutes of Science and Technology, Xi’an Jiaotong University, China, and is hosted by Professor Nigel Emptage. This award lecture was set up to celebrate the vision of Professor A David Smith, namely, that explanations of the action of drugs on the brain requires the definition of neuronal circuits, the location and interactions of molecules. Tim Bliss gained his PhD at McGill University in Canada. He joined the MRC National Institute for Medical Research in Mill Hill, London in 1967, where he remained throughout his career. His work with Terje Lømo in the late 1960’s established the phenomenon of long-term potentiation (LTP) as the dominant synaptic model of how the mammalian brain stores memories. He was elected as a Fellow of the Royal Society in 1994 and is a founding fellow of the Academy of Medical Sciences. He shared the Bristol Myers Squibb award for Neuroscience with Eric Kandel in 1991, the Ipsen Prize for Neural Plasticity with Richard Morris and Yadin Dudai in 2013. In May 2012 he gave the annual Croonian Lecture at the Royal Society on ‘The Mechanics of Memory’. In 2016 Tim, with Graham Collingridge and Richard Morris shared the Brain Prize, one of the world's most coveted science prizes. Abstract: In 1966 there appeared in Acta Physiologica Scandinavica an abstract of a talk given by Terje Lømo, a PhD student in Per Andersen’s laboratory at the University of Oslo. In it Lømo described the long-lasting potentiation of synaptic responses in the dentate gyrus of the anaesthetised rabbit that followed repeated episodes of 10-20Hz stimulation of the perforant path. Thus, heralded and almost entirely unnoticed, one of the most consequential discoveries of 20th century neuroscience was ushered into the world. Two years later I arrived in Oslo as a visiting post-doc from the National Institute for Medical Research in Mill Hill, London. In this talk I recall the events that led us to embark on a systematic reinvestigation of the phenomenon now known as long-term potentiation (LTP) and will then go on to describe the discoveries and controversies that enlivened the early decades of research into synaptic plasticity in the mammalian brain. I will end with an observer’s view of the current state of research in the field, and what we might expect from it in the future.
A draft connectome for ganglion cell types of the mouse retina
The visual system of the brain is highly parallel in its architecture. This is clearly evident in the outputs of the retina, which arise from neurons called ganglion cells. Work in our lab has shown that mammalian retinas contain more than a dozen distinct types of ganglion cells. Each type appears to filter the retinal image in a unique way and to relay this processed signal to a specific set of targets in the brain. My students and I are working to understand the meaning of this parallel organization through electrophysiological and anatomical studies. We record from light-responsive ganglion cells in vitro using the whole-cell patch method. This allows us to correlate directly the visual response properties, intrinsic electrical behavior, synaptic pharmacology, dendritic morphology and axonal projections of single neurons. Other methods used in the lab include neuroanatomical tracing techniques, single-unit recording and immunohistochemistry. We seek to specify the total number of ganglion cell types, the distinguishing characteristics of each type, and the intraretinal mechanisms (structural, electrical, and synaptic) that shape their stimulus selectivities. Recent work in the lab has identified a bizarre new ganglion cell type that is also a photoreceptor, capable of responding to light even when it is synaptically uncoupled from conventional (rod and cone) photoreceptors. These ganglion cells appear to play a key role in resetting the biological clock. It is just this sort of link, between a specific cell type and a well-defined behavioral or perceptual function, that we seek to establish for the full range of ganglion cell types. My research concerns the structural and functional organization of retinal ganglion cells, the output cells of the retina whose axons make up the optic nerve. Ganglion cells exhibit great diversity both in their morphology and in their responses to light stimuli. On this basis, they are divisible into a large number of types (>15). Each ganglion-cell type appears to send its outputs to a specific set of central visual nuclei. This suggests that ganglion cell heterogeneity has evolved to provide each visual center in the brain with pre-processed representations of the visual scene tailored to its specific functional requirements. Though the outline of this story has been appreciated for some time, it has received little systematic exploration. My laboratory is addressing in parallel three sets of related questions: 1) How many types of ganglion cells are there in a typical mammalian retina and what are their structural and functional characteristics? 2) What combination of synaptic networks and intrinsic membrane properties are responsible for the characteristic light responses of individual types? 3) What do the functional specializations of individual classes contribute to perceptual function or to visually mediated behavior? To pursue these questions, we label retinal ganglion cells by retrograde transport from the brain; analyze in vitro their light responses, intrinsic membrane properties and synaptic pharmacology using the whole-cell patch clamp method; and reveal their morphology with intracellular dyes. Recently, we have discovered a novel ganglion cell in rat retina that is intrinsically photosensitive. These ganglion cells exhibit robust light responses even when all influences from classical photoreceptors (rods and cones) are blocked, either by applying pharmacological agents or by dissociating the ganglion cell from the retina. These photosensitive ganglion cells seem likely to serve as photoreceptors for the photic synchronization of circadian rhythms, the mechanism that allows us to overcome jet lag. They project to the circadian pacemaker of the brain, the suprachiasmatic nucleus of the hypothalamus. Their temporal kinetics, threshold, dynamic range, and spectral tuning all match known properties of the synchronization or "entrainment" mechanism. These photosensitive ganglion cells innervate various other brain targets, such as the midbrain pupillary control center, and apparently contribute to a host of behavioral responses to ambient lighting conditions. These findings help to explain why circadian and pupillary light responses persist in mammals, including humans, with profound disruption of rod and cone function. Ongoing experiments are designed to elucidate the phototransduction mechanism, including the identity of the photopigment and the nature of downstream signaling pathways. In other studies, we seek to provide a more detailed characterization of the photic responsiveness and both morphological and functional evidence concerning possible interactions with conventional rod- and cone-driven retinal circuits. These studies are of potential value in understanding and designing appropriate therapies for jet lag, the negative consequences of shift work, and seasonal affective disorder.
Mechanisms of visual circuit development: aligning topographic maps of space
Dissecting the neural circuits underlying prefrontal regulation of reward and threat responsivity in a primate
Gaining insight into the overlapping neural circuits that regulate positive and negative emotion is an important step towards understanding the heterogeneity in the aetiology of anxiety and depression and developing new treatment targets. Determining the core contributions of the functionally heterogenous prefrontal cortex to these circuits is especially illuminating given its marked dysregulation in affective disorders. This presentation will review a series of studies in a new world monkey, the common marmoset, employing pathway-specific chemogenetics, neuroimaging, neuropharmacology and behavioural and cardiovascular analysis to dissect out prefrontal involvement in the regulation of both positive and negative emotion. Highlights will include the profound shift of sensitivity away from reward and towards threat induced by localised activations within distinct regions of vmPFC, namely areas 25 and 14 as well as the opposing contributions of this region, compared to orbitofrontal and dorsolateral prefrontal cortex, in the overall responsivity to threat. Ongoing follow-up studies are identifying the distinct downstream pathways that mediate some of these effects as well as their differential sensitivity to rapidly acting anti-depressants.
Nonlinear spatial integration in retinal bipolar cells shapes the encoding of artificial and natural stimuli
Vision begins in the eye, and what the “retina tells the brain” is a major interest in visual neuroscience. To deduce what the retina encodes (“tells”), computational models are essential. The most important models in the retina currently aim to understand the responses of the retinal output neurons – the ganglion cells. Typically, these models make simplifying assumptions about the neurons in the retinal network upstream of ganglion cells. One important assumption is linear spatial integration. In this talk, I first define what it means for a neuron to be spatially linear or nonlinear and how we can experimentally measure these phenomena. Next, I introduce the neurons upstream to retinal ganglion cells, with focus on bipolar cells, which are the connecting elements between the photoreceptors (input to the retinal network) and the ganglion cells (output). This pivotal position makes bipolar cells an interesting target to study the assumption of linear spatial integration, yet due to their location buried in the middle of the retina it is challenging to measure their neural activity. Here, I present bipolar cell data where I ask whether the spatial linearity holds under artificial and natural visual stimuli. Through diverse analyses and computational models, I show that bipolar cells are more complex than previously thought and that they can already act as nonlinear processing elements at the level of their somatic membrane potential. Furthermore, through pharmacology and current measurements, I illustrate that the observed spatial nonlinearity arises at the excitatory inputs to bipolar cells. In the final part of my talk, I address the functional relevance of the nonlinearities in bipolar cells through combined recordings of bipolar and ganglion cells and I show that the nonlinearities in bipolar cells provide high spatial sensitivity to downstream ganglion cells. Overall, I demonstrate that simple linear assumptions do not always apply and more complex models are needed to describe what the retina “tells” the brain.
Astrocytes and oxytocin interaction regulates amygdala neuronal network activity and related behaviors”
Oxytocin orchestrates social and emotional behaviors through modulation of neural circuits in brain structures such as the central amygdala (CeA). In this structure, the release of oxytocin modulates inhibitory circuits and subsequently suppresses fear responses and decreases anxiety levels. Using astrocyte-specific gain and loss of function approaches and pharmacology, we demonstrate that oxytocin signaling in the central amygdala relies on a subpopulation of astrocytes that represent a prerequisite for proper function of CeA circuits and adequate behavioral responses, both in rats and mice. Our work identifies astrocytes as crucial cellular intermediaries of oxytocinergic modulation in emotional behaviors related to anxiety or positive reinforcement. To our knowledge, this is the first demonstration of a direct role of astrocytes in oxytocin signaling and challenges the long-held dogma that oxytocin signaling occurs exclusively via direct action on neurons in the central nervous system.
Synapses, Shadows and Stress Contagion
Survival is predicated on the ability of an organism to respond to stress. The reliability of this response is ensured by a synaptic architecture that is relatively inflexible (i.e. hard-wired). Our work has shown that in naive animals, synapses on CRH neurons in the paraventricular nucleus of the hypothalamus are very reluctant to modification. If animals are stressed, however, these synapses become willing to learn. This seminar will focus on mechanisms linking acute stress to metaplastic changes at glutamate synapses, and also show how stress, and these synaptic changes can be transmitted from one individual to another.
Will it keep me awake? Common caffeine intake habits and sleep in real life situations
Daily caffeine consumption and chronic sleep restriction are highly prevalent in society. It is well established that acute caffeine intake under controlled conditions enhances vigilance and promotes wakefulness but can also delay sleep initiation and reduce electroencephalographic (EEG) markers of sleep intensity, particularly in susceptible individuals. To investigate whether these effects are also present during chronic consumption of coffee/caffeine, we recently conducted several complementary studies. We examined whether repeated coffee intake in dose and timing mimicking ‘real world’ habits maintains simple and complex attentional processes during chronic sleep restriction, such as during a busy work week. We found in genetically caffeine-sensitive individuals that regular coffee (300 mg caffeine/day) benefits most attentional tasks for 3-4 days when compared to decaffeinated coffee. Genetic variants were also used in the population-based HypnoLaus cohort, to investigate whether habitual caffeine consumption causally affects time to fall asleep, number of awakenings during sleep, and EEG-derived sleep intensity. The multi-level statistical analyses consistently showed that sleep quality was virtually unaffected when >3 caffeine-containing beverages/day were compared to 0-3 beverages/day. This conclusion was further corroborated by quantifying the sleep EEG in the laboratory in habitual caffeine consumers. Compared to placebo, daily intake of 3 x 150 mg caffeine over 10 days did not strongly impair nocturnal sleep nor subjective sleep quality in good sleepers. Finally, we tested whether an engineered delayed, pulsatile-release caffeine formula can improve the quality of morning awakening in sleep-restricted volunteers. We found that 160 mg caffeine taken at bedtime ameliorated the quality of awakening, increased positive and reduced negative affect scores, and promoted sustained attention immediately upon scheduled wake-up. Such an approach could prevent over-night caffeine withdrawal and provide a proactive strategy to attenuate disabling sleep inertia. Taken together, the studies suggest that common coffee/caffeine intake habits can transiently attenuate detrimental consequences of reduced sleep virtually without disturbing subjective and objective markers of sleep quality. Nevertheless, coffee/caffeine consumption cannot compensate for chronic sleep restriction.
Epigenetic regulation of alternative splicing in the context of cocaine reward
Neuronal alternative splicing is a key gene regulatory mechanism in the brain. However, the spliceosome machinery is insufficient to fully specify splicing complexity. In considering the role of the epigenome in activity-dependent alternative splicing, we and others find the histone modification H3K36me3 to be a putative splicing regulator. In this study, we found that mouse cocaine self-administration caused widespread differential alternative splicing, concomitant with the enrichment of H3K36me3 at differentially spliced junctions. Importantly, only targeted epigenetic editing can distinguish between a direct role of H3K36me3 in splicing and an indirect role via regulation of splice factor expression elsewhere on the genome. We targeted Srsf11, which was both alternatively spliced and H3K36me3 enriched in the brain following cocaine self-administration. Epigenetic editing of H3K36me3 at Srsf11 was sufficient to drive its alternative splicing and enhanced cocaine self-administration, establishing the direct causal relevance of H3K36me3 to alternative splicing of Srsf11 and to reward behavior.
Sleepless in Vienna - how to rescue folding-deficient dopamine transporters by pharmacochaperoning
Diseases that arise from misfolding of an individual protein are rare. However, collectively, these folding diseases represent a large proportion of hereditary and acquired disorders. In fact, the term "Molecular Medicine" was coined by Linus Pauling in conjunction with the study of a folding disease, i.e. sickle cell anemia. In the past decade, we have witnessed an exponential growth in the number of mutations, which have been identified in genes encoding solute carriers (SLC). A sizable faction - presumably the majority - of these mutations result in misfolding of the encoded protein. While studying the export of the GABA transporter (SLC6A1) and of the serotonin transporter (SLC6A4), from the endoplasmic reticulum (ER), we discovered by serendipity that some ligands can correct the folding defect imparted by point mutations. These bind to the inward facing state. The most effective compound is noribogaine, the metabolite of ibogaine (an alkaloid first isolated from the shrub Tabernanthe iboga). There are 13 mutations in the human dopamine transporter (DAT, SLC6A3), which give rise to a syndrome of infantile Parkinsonism and dystonia. We capitalized on our insights to explore, if the disease-relevant mutant proteins were amenable to pharmacological correction. Drosopohila melanogaster, which lack the dopamine transporter, are hyperactive and sleepless (fumin in Japanese). Thus, mutated human DAT variants can be introduced into fumin flies. This allows for examining the effect of pharmacochaperones on delivery of DAT to the axonal territory and on restoring sleep. We explored the chemical space populated by variations of the ibogaine structure to identify an analogue (referred to as compound 9b), which was highly effective: compound 9b also restored folding in DAT variants, which were not amenable to rescue by noribogaine. Deficiencies in the human creatine transporter-1 (CrT1, SLC6A8) give rise to a syndrome of intellectual disability and seizures and accounts for 5% of genetically based intellectual disabilities in boys. Point mutations occur, in part, at positions, which are homologous to those of folding-deficient DAT variants. CrT1 lacks the rich pharmacology of monoamine transporters. Nevertheless, our insights are also applicable to rescuing some disease-related variants of CrT1. Finally, the question arises how one can address the folding problem. We propose a two-pronged approach: (i) analyzing the effect of mutations on the transport cycle by electrophysiological recordings; this allows for extracting information on the rates of conformational transitions. The underlying assumption posits that - even when remedied by pharmacochaperoning - folding-deficient mutants must differ in the conformational transitions associated with the transport cycle. (ii) analyzing the effect of mutations on the two components of protein stability, i.e. thermodynamic and kinetic stability. This is expected to provide a glimpse of the energy landscape, which governs the folding trajectory.
Bedside to bench and back again, a path to translational pain research?
Pain has both a sensory and emotional component and is driven by activation of sensory neurones called nociceptors that are tuned to detect noxious stimuli in a process called nociception. Although nociception functions as a detect and protect mechanism. and is found in many organisms, this system becomes dysregulated in a number of conditions where chronic pain presents as a key symptom, for example osteoarthritis. Nociceptors do not innervate empty space though and do not act alone. Going beyond the neurone, other cell types, such as fibroblast-like synoviocytes interact with and modify the function of nociceptors, which is likely a key contributor to the chronification of pain. In this talk, I will look at how combining pre-clinical mouse work with human tissue and genetics might provide a way to accelerate new analgesics from bench to bedside, giving examples from our work in joint pain, bowel pain and labour pain.
SCN1A/Nav1.1 sodium channel: loss and gain of function in epilepsy and migraine
Genetic mutations of the SCN1A gene, the voltage gated sodium channel NaV1.1, cause well-defined epilepsies, including the severe developmental and epileptic encephalopathy Dravet syndrome and genetic epilepsy with febrile seizures plus (GEFS+), as well as a severe form of migraine with aura, familial hemiplegic migraine (FHM). More recently, they have been identified in an extremely severe early infantile encephalopathy. Functional studies and animal models have contributed to disclose pathological mechanisms, which can be often linked to a straightforward loss- vs gain- of channel function. However, although this simple dichotomy is pertinent and useful, detailed pathological mechanisms in neuronal circuits can be more complex, sometimes because of unexpected homeostatic or pathologic responses. I will compare pathological mechanisms of epilepsy and migraine mutations studied with cellular, animal and computational models, highlighting a novel homeostatic response implemented by CCK-positive GABAergic neurons in a mouse model of Dravet syndrome, which may be boosted in therapeutic approaches.
Psychedelics and the Pharmacology of Consciousness
The study of altered states of consciousness has long had the potential to provide important insight into the nature of consciousness. In recent years there has been a resurgence of research and public interest in atypical or altered states of consciousness. These have focused both on conditions in which consciousness is considered to be impaired due to brain trauma or enhanced in some way through mediation practices or ingestion of psychedelics. The talk will begin with a brief overview of recent scientific approaches to understanding these different types of altered consciousness. The remainder of the talk will focus on lab-based experiments conducted by myself and others looking at the effects of serotoninergic hallucinogens (i.e. psilocybin and LSD) on perceptual and cognitive function. Together this body of research provides important new insights for the scientific study of consciousness and an initial understanding of the neuropharmacological mechanisms underlying conscious experience.
The pharmacology of consciousness
My research uses a range of methods to better understand how the brain’s natural chemicals control complex behaviours, thoughts and perceptions. I also have a particular fascination about the factors that determine the contents of an individual’s conscious experience. In this talk I will present work that sits at the intersection of these two research areas looking at the role of different neurotransmitter systems in driving changes in conscious state. Specifically, I will discuss a series of studies using ambiguous stimuli to explore the neuropharmacological processes that underly alternations in perceptual awareness. By comparing different methods and neurotransmitter systems including: serotonin (psychedelics), noradrenaline (pupillometry) and Glutamate/GABA (Magnetic Resonance Spectroscopy MRS) we can start to tease apart the distinct role that different neurotransmitter systems play in coordinating conscious experience across time.
Cellular and circuit-based mechanisms regulating daily sleep
Circuit mechanisms underlying the dynamic control of cortical processing by subcortical neuromodulators
Behavioral states such as arousal and attention can have profound effects on sensory processing, determining how – sometimes whether – a stimulus is processed. This state-dependence is believed to arise, at least in part, as a result of inputs to cortex from subcortical structures that release neuromodulators such as acetylcholine, noradrenaline, and serotonin, often non-synaptically. The mechanisms that underlie the interaction between these “wireless” non-synaptic signals and the “wired” cortical circuit are not well understood. Furthermore, neuromodulatory signaling is traditionally considered broad in its impact across cortex (within a species) and consistent in its form and function across species (at least in mammals). The work I will present approaches the challenge of understanding neuromodulatory action in the cortex from a number of angles: anatomy, physiology, pharmacology, and chemistry. The overarching goal of our effort is to elucidate the mechanisms behind local neuromodulation in the cortex of non-human primates, and to reveal differences in structure and function across cortical model systems.
Targeting the Endocannabinoid System for Management of Chemotherapy, HIV and Antiretroviral-Induced Neuropathic Pain
Chemotherapeutic drugs (used for treating cancer), HIV infection and antiretroviral therapy (ART) can independently cause difficult-to-manage painful neuropathy. Paclitaxel, a chemotherapeutic drug, for example is associated with high incidence of peripheral neuropathy, around 71% of the patients of which 27% of these develop neuropathic pain. Use of cannabis or phytocannabinoids has been reported to improve pain measures in patients with neuropathic pain, including painful HIV-associated sensory neuropathy and cancer pain. Phytocannabinoids and endocannabinoids, such as anandamide and 2-arachidonoylglycerol (2-AG), produce their effects via cannabinoid (CB) receptors, which are present both in the periphery and central nervous system. Endocannabinoids are synthesized in an “on demand” fashion and are degraded by various enzymes such as fatty acid amide hydrolase (FAAH) and monoacylglycerol lipase (MGL). Various studies, including those from our group, suggest that there are changes in gene and protein expression of endocannabinoid molecules during chemotherapy-induced neuropathic pain (CINP), HIV and antiretroviral-induced neuropathic pain. Analysis of endocannabinoid molecule expression in the brain, spinal cord and paw skin using LC-MS/MS show that there is a specific deficiency of the endocannabinoids 2-AG and/or anandamide in the periphery during CINP. Various drugs including endocannabinoids, cannabidiol, inhibitors of FAAH and MGL, CB receptor agonists, desipramine and coadministered indomethacin plus minocycline have been found to either prevent the development and/or attenuate established CINP, HIV and antiretroviral-induced neuropathic pain in a CB receptor-dependent manner. The results available suggest that targeting the endocannabinoid system for prevention and treatment of CINP, HIV-associated neuropathic pain and antiretroviral-induced neuropathic pain is a plausible therapeutic option.
Neuroscience tools for the 99%: On the low-fi development of high-tech lab gear for hands-on neuroscience labs and exploratory research
The public has a fascination with the brain, but little attention is given to neuroscience education prior to graduate studies in brain-related fields. One reason may be the lack of low cost and engaging teaching materials. To address this, we have developed a suite of open-source tools which are appropriate for amateurs and for use in high school, undergraduate, and graduate level educational and research programs. This lecture will provide an overview of our mission to re-engineer research-grade lab equipment using first principles and will highlight basic principles of neuroscience in a "DIY" fashion: neurophysiology, functional electrical stimulation, micro-stimulation effect on animal behavior, neuropharmacology, even neuroprosthesis and optogenetics! Finally, with faculty academic positions becoming a scarce resource, I will discuss an alternative academic career path: entrepreneurship. It is possible to be an academic, do research, publish papers, present at conferences and train students all outside the traditional university setting. I will close by discussing my career path from graduate student to PI/CEO of a startup neuroscience company.
Neural Circuit Mechanisms of Emotional and Social Processing
How does our brain rapidly determine if something is good or bad? How do we know our place within a social group? How do we know how to behave appropriately in dynamic environments with ever-changing conditions? The Tye Lab is interested in understanding how neural circuits important for driving positive and negative motivational valence (seeking pleasure or avoiding punishment) are anatomically, genetically and functionally arranged. We study the neural mechanisms that underlie a wide range of behaviours ranging from learned to innate, including social, feeding, reward-seeking and anxiety-related behaviours. We have also become interested in “social homeostasis” -- how our brains establish a preferred set-point for social contact, and how this maintains stability within a social group. How are these circuits interconnected with one another, and how are competing mechanisms orchestrated on a neural population level? We employ optogenetic, electrophysiological, electrochemical, pharmacological and imaging approaches to probe these circuits during behaviour.
Insights into the pharmacology of GluN3A receptors: Exploring the mechanism of action of selective inhibitors and their activity at native receptors
FENS Forum 2024
Photopharmacology in the spotlight: Spatially selective adenosinergic modulation of hippocampal excitability in the pursuit of therapeutic innovation in temporal lobe epilepsy
FENS Forum 2024
Using photopharmacology as a tool to study mGlu5 hippocampal asymmetry in AD mice
FENS Forum 2024