NeuroPAL: A Multicolor Atlas for Whole-Brain Neuronal Identification in C. elegans.

Comprehensively resolving neuronal identities in whole-brain images is a major challenge. We achieve this in C. elegans by engineering a multicolor transgene called NeuroPAL (a neuronal polychromatic atlas of landmarks). NeuroPAL worms share a stereotypical multicolor fluorescence map for the entire hermaphrodite nervous system that resolves all neuronal identities. Neurons labeled with NeuroPAL do not exhibit fluorescence in the green, cyan, or yellow emission channels, allowing the transgene to be used with numerous reporters of gene expression or neuronal dynamics. We showcase three applications that leverage NeuroPAL for nervous-system-wide neuronal identification. First, we determine the brainwide expression patterns of all metabotropic receptors for acetylcholine, GABA, and glutamate, completing a map of this communication network. Second, we uncover changes in cell fate caused by transcription factor mutations. Third, we record brainwide activity in response to attractive and repulsive chemosensory cues, characterizing multimodal coding for these stimuli.

Molecular Pharmacology of Gelsemium Alkaloids on Inhibitory Receptors.

Indole alkaloids are the main bioactive molecules of the Gelsemium genus plants. Diverse reports have shown the beneficial actions of Gelsemium alkaloids on the pathological states of the central nervous system (CNS). Nevertheless, Gelsemium alkaloids are toxic for mammals. To date, the molecular targets underlying the biological actions of Gelsemium alkaloids at the CNS remain poorly defined. Functional studies have determined that gelsemine is a modulator of glycine receptors (GlyRs) and GABAA receptors (GABAARs), which are ligand-gated ion channels of the CNS. The molecular and physicochemical determinants involved in the interactions between Gelsemium alkaloids and these channels are still undefined. We used electrophysiological recordings and bioinformatic approaches to determine the pharmacological profile and the molecular interactions between koumine, gelsemine, gelsevirine, and humantenmine and these ion channels. GlyRs composed of α1 subunits were inhibited by koumine and gelsevirine (IC50 of 31.5 ± 1.7 and 40.6 ± 8.2 µM, respectively), while humantenmine did not display any detectable activity. The examination of GlyRs composed of α2 and α3 subunits showed similar results. Likewise, GABAARs were inhibited by koumine and were insensitive to humantenmine. Further assays with chimeric and mutated GlyRs showed that the extracellular domain and residues within the orthosteric site were critical for the alkaloid effects, while the pharmacophore modeling revealed the physicochemical features of the alkaloids for the functional modulation. Our study provides novel information about the molecular determinants and functional actions of four major Gelsemium indole alkaloids on inhibitory receptors, expanding our knowledge regarding the interaction of these types of compounds with protein targets of the CNS.

Evidence of introgression, ecological divergence and adaptation in Asterias sea stars.

Hybrid zones are important windows into the evolutionary dynamics of populations, revealing how processes like introgression and adaptation structure population genomic variation. Importantly, they are useful for understanding speciation and how species respond to their environments. Here, we investigate two closely related sea star species, Asterias rubens and A. forbesi, distributed along rocky European and North American coastlines of the North Atlantic, and use genome-wide molecular markers to infer the distribution of genomic variation within and between species in this group. Using genomic data and environmental niche modelling, we document hybridization occurring between northern New England and the southern Canadian Maritimes. We investigate the factors that maintain this hybrid zone, as well as the environmental variables that putatively drive selection within and between species. We find that the two species differ in their environmental niche breadth; Asterias forbesi displays a relatively narrow environmental niche while conversely, A. rubens has a wider niche breadth. Species distribution models accurately predict hybrids to occur within environmental niche overlap, thereby suggesting environmental selection plays an important role in the maintenance of the hybrid zone. Our results imply that the distribution of genomic variation in North Atlantic sea stars is influenced by the environment, which will be crucial to consider as the climate changes.

Understanding the Role of ATP Release through Connexins Hemichannels during Neurulation.

Neurulation is a crucial process in the formation of the central nervous system (CNS), which begins with the folding and fusion of the neural plate, leading to the generation of the neural tube and subsequent development of the brain and spinal cord. Environmental and genetic factors that interfere with the neurulation process promote neural tube defects (NTDs). Connexins (Cxs) are transmembrane proteins that form gap junctions (GJs) and hemichannels (HCs) in vertebrates, allowing cell-cell (GJ) or paracrine (HCs) communication through the release of ATP, glutamate, and NAD+; regulating processes such as cell migration and synaptic transmission. Changes in the state of phosphorylation and/or the intracellular redox potential activate the opening of HCs in different cell types. Cxs such as Cx43 and Cx32 have been associated with proliferation and migration at different stages of CNS development. Here, using molecular and cellular biology techniques (permeability), we demonstrate the expression and functionality of HCs-Cxs, including Cx46 and Cx32, which are associated with the release of ATP during the neurulation process in Xenopus laevis. Furthermore, applications of FGF2 and/or changes in intracellular redox potentials (DTT), well known HCs-Cxs modulators, transiently regulated the ATP release in our model. Importantly, the blockade of HCs-Cxs by carbenoxolone (CBX) and enoxolone (ENX) reduced ATP release with a concomitant formation of NTDs. We propose two possible and highly conserved binding sites (N and E) in Cx46 that may mediate the pharmacological effect of CBX and ENX on the formation of NTDs. In summary, our results highlight the importance of ATP release mediated by HCs-Cxs during neurulation.

The Effect of Amino-Phosphate Interactions on the Biosensing Performance of Enzymatic Graphene Field-Effect Transistors.

The interaction between polyamines and phosphate species is found in a wide range of biological and abiotic systems, yielding crucial consequences that range from the formation of supramolecular colloids to structure determination. In this work, the occurrence of phosphate-amino interactions is evidenced from changes in the electronic response of graphene field effect transistors (gFETs). First, the surface of the transistors is modified with poly(allylamine), and the effect of phosphate binding on the transfer characteristics is interpreted in terms of its impact on the surface charge density. The electronic response of the polyamine-functionalized gFETs is shown to be sensitive to the presence of different phosphate anions, such as orthophosphate, adenosine triphosphate, and tripolyphosphate, and a simple binding model is developed to explain the dependence of the shift of the Dirac point potential on the phosphate species concentration. Afterward, the impact of phosphate-amino interactions on the immobilization of enzymes to polyamine-modified graphene surfaces is investigated, and a decrease in the amount of anchored enzyme as the phosphate concentration increases is found. Finally, multilayer polyamine-urease biosensors are fabricated while increasing the phosphate concentration in the enzyme solution, and the sensing properties of the gFETs toward urea are evaluated. It is found that the presence of simple phosphate anions alters the nanoarchitecture of the polyelectrolyte-urease assemblies, with direct implications on urea sensing.

Proteome-wide covalent ligand discovery in native biological systems.

Small molecules are powerful tools for investigating protein function and can serve as leads for new therapeutics. Most human proteins, however, lack small-molecule ligands, and entire protein classes are considered 'undruggable'. Fragment-based ligand discovery can identify small-molecule probes for proteins that have proven difficult to target using high-throughput screening of complex compound libraries. Although reversibly binding ligands are commonly pursued, covalent fragments provide an alternative route to small-molecule probes, including those that can access regions of proteins that are difficult to target through binding affinity alone. Here we report a quantitative analysis of cysteine-reactive small-molecule fragments screened against thousands of proteins in human proteomes and cells. Covalent ligands were identified for >700 cysteines found in both druggable proteins and proteins deficient in chemical probes, including transcription factors, adaptor/scaffolding proteins, and uncharacterized proteins. Among the atypical ligand-protein interactions discovered were compounds that react preferentially with pro- (inactive) caspases. We used these ligands to distinguish extrinsic apoptosis pathways in human cell lines versus primary human T cells, showing that the former is largely mediated by caspase-8 while the latter depends on both caspase-8 and -10. Fragment-based covalent ligand discovery provides a greatly expanded portrait of the ligandable proteome and furnishes compounds that can illuminate protein functions in native biological systems.

Betel quid: New insights into an ancient addiction.

The use of areca nuts (areca) in the form of betel quids constitutes the fourth most common addiction in the world, associated with high risk for oral disease and cancer. Areca is a complex natural product, making it difficult to identify specific components associated with the addictive and carcinogenic properties. It is commonly believed that the muscarinic agonist arecoline is at the core of the addiction. However, muscarinic receptor activation is not generally believed to support drug-taking behaviour. Subjective accounts of areca use include descriptions of both sedative and stimulatory effects, consistent with the presence of multiple psychoactive agents. We have previously reported partial agonism of α4-containing nicotinic acetylcholine receptors by arecoline and subsequent inhibition of those receptors by whole areca broth. In the present study, we report the inhibition of nicotinic acetylcholine receptors and other types of neurotransmitter receptors with compounds of high molecular weight in areca and the ability of low molecular weight areca extract to activate GABA and glutamate receptors. We confirm the presence of a high concentration of GABA and glutamate in areca. Additionally, data also indicate the presence of a dopamine and serotonin transporter blocking activity in areca that could account for the reported stimulant and antidepressant activity. Our data suggest that toxic elements of high molecular weight may contribute to the oral health liability of betel quid use, while two distinct low molecular weight components may provide elements of reward, and the nicotinic activity of arecoline contributes to the physical dependence of addiction.

Roles of the Unsaturated Fatty Acid Docosahexaenoic Acid in the Central Nervous System: Molecular and Cellular Insights.

Fatty acids (FAs) are essential components of the central nervous system (CNS), where they exert multiple roles in health and disease. Among the FAs, docosahexaenoic acid (DHA) has been widely recognized as a key molecule for neuronal function and cell signaling. Despite its relevance, the molecular pathways underlying the beneficial effects of DHA on the cells of the CNS are still unclear. Here, we summarize and discuss the molecular mechanisms underlying the actions of DHA in neural cells with a special focus on processes of survival, morphological development, and synaptic maturation. In addition, we examine the evidence supporting a potential therapeutic role of DHA against CNS tumor diseases and tumorigenesis. The current results suggest that DHA exerts its actions on neural cells mainly through the modulation of signaling cascades involving the activation of diverse types of receptors. In addition, we found evidence connecting brain DHA and ω-3 PUFA levels with CNS diseases, such as depression, autism spectrum disorders, obesity, and neurodegenerative diseases. In the context of cancer, the existing data have shown that DHA exerts positive actions as a coadjuvant in antitumoral therapy. Although many questions in the field remain only partially resolved, we hope that future research may soon define specific pathways and receptor systems involved in the beneficial effects of DHA in cells of the CNS, opening new avenues for innovative therapeutic strategies for CNS diseases.

19S Proteasome Subunits as Oncogenes and Prognostic Biomarkers in FLT3-Mutated Acute Myeloid Leukemia (AML).

26S proteasome non-ATPase subunits 1 (PSMD1) and 3 (PSMD3) were recently identified as prognostic biomarkers and potential therapeutic targets in chronic myeloid leukemia (CML) and multiple solid tumors. In the present study, we analyzed the expression of 19S proteasome subunits in acute myeloid leukemia (AML) patients with mutations in the FMS-like tyrosine kinase 3 (FLT3) gene and assessed their impact on overall survival (OS). High levels of PSMD3 but not PSMD1 expression correlated with a worse OS in FLT3-mutated AML. Consistent with an oncogenic role for PSMD3 in AML, shRNA-mediated PSMD3 knockdown impaired colony formation of FLT3+ AML cell lines, which correlated with increased OS in xenograft models. While PSMD3 regulated nuclear factor-kappa B (NF-κB) transcriptional activity in CML, we did not observe similar effects in FLT3+ AML cells. Rather, proteomics analyses suggested a role for PSMD3 in neutrophil degranulation and energy metabolism. Finally, we identified additional PSMD subunits that are upregulated in AML patients with mutated versus wild-type FLT3, which correlated with worse outcomes. These findings suggest that different components of the 19S regulatory complex of the 26S proteasome can have indications for OS and may serve as prognostic biomarkers in AML and other types of cancers.

Addition of clinoptilolite in the diet reduces uterine PMN leukocytes and open days in multiparous lactating dairy cows managed in a mountain tropical pasture-based system.

This study aimed to assess the effect of adding clinoptilolite in the diet on uterine health and reproductive performance in multiparous lactating dairy cows managed in a tropical pasture-based system above 2500 m of altitude. Seventy-seven multiparous Holstein crossbred cows from two farms were allocated randomly into two groups: clinoptilolite supplemented cows (CLG, n = 42) and non-supplemented cows as control (CG, n = 35). Cows from CLG were supplemented with clinoptilolite from 30 days (50 g/cow/day) before to 60 days after calving (200 g/cow/day). In CLG cows, percentages of uterine PMN leukocytes (P < 0.0001) and proportion of subclinical endometritis (P = 0.0187) were lower than in CG. The interval calving to first corpus luteum was shorter (P = 0.0759) in CLG than CG, and calving to first service interval was similar between treatments. Cows from CLG became pregnant 35 days earlier than CG cows (P = 0.0224). On farm A, calving to conception interval was 18.1 days longer in CLG than in CG (P = 0.3750); in farm B, this interval was 86.2 days shorter in CLG than in CG (P = 0.0002). In conclusion, daily addition of clinoptilolite in the diet decreased the percentage of uterine PMN leukocytes, the proportion of cows with subclinical endometritis, and shortened the calving-conception interval in multiparous lactating dairy cows.

Chikungunya and the Heart.

INTRODUCTION: Neglected tropical diseases are a group of communicable diseases that occur in tropical and subtropical conditions and are closely related to poverty and inadequate sanitation conditions. Among these entities, chikungunya remains one of the most widely spread diseases. Although the main symptoms are related to a febrile syndrome, cardiovascular (CV) involvement has been reported, with short- and long-term implications. As part of the "Neglected Tropical Diseases and other Infectious Diseases involving the Heart" (NET-Heart) Project, the aim of this review is to compile all the information available regarding CV involvement of this disease, to help healthcare providers gain knowledge in this field, and contribute to improving early diagnosis, treatment, and prevention strategies. METHODS: We adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement in conducting and reporting this systematic review. The search was conducted using MEDLINE/PubMed, SciELO, and LILACS databases to identify any relevant studies or reviews detailing an association between chikungunya and cardiac involvement published from January 1972 to May 31, 2020. RESULTS: Despite its mechanism not being fully understood, CV involvement has been described as the most frequent atypical presentation of chikungunya (54.2%). Myocarditis is the most prevalent CV complication. Different rhythm disturbances have been reported in 52% of cases, whereas heart failure was reported in 15% of cases, pericarditis in 5%, and acute myocardial infarction in 2%. Overall estimated CV mortality is 10%, although in patients with other comorbidities, it may increase up to 20%. In the proper clinical setting, the presence of fever, polyarthralgia, and new-onset arrhythmia suggests chikungunya virus-related myocarditis. CONCLUSION: Although most cases are rarely fatal, CV involvement in chikungunya infection remains the most frequent atypical presentation of this disease and may have severe manifestations. Timely diagnosis and appropriate management are necessary to improve patient outcomes.

A multi-objective formulation of improving flexibility in the operation of electric power systems: Application to mitigation measures during the coronavirus pandemic.

The coronavirus pandemic has infected more than 23 million people worldwide by August 2020 along with more than 800,000 deaths. To face this pandemic, a joint effort among different areas has been required. In this context, the correct supply of basic services is the key to enhance the complex circumstance. The operation of the electric power systems is needed to ensure the answer to the situation. Basic services in areas of health, security, food, and communications depend on the electricity supply. Consequently, this paper introduces a multi-objective procedure that enhances the operations of power systems under these circumstances. It considers geographical areas that are affected by coronavirus cases and their effects on the personnel of power plants. To obtain the best combinations of total cost and protection of the workers, lexicographic optimization is implemented. The effectiveness of this approach is studied by solving two test cases: a 6-bus system and the Argentine Electric System with real data about the infection cases. The effects on the electricity generation and transportation stages are studied. The results allow identifying critical areas and proposing corrective actions. The method can reach feasible solutions with a low computational requirement.

Evidence for the Role of Mitochondrial DNA Release in the Inflammatory Response in Neurological Disorders.

Mitochondria are regarded as the metabolic centers of cells and are integral in many other cell processes, including the immune response. Each mitochondrion contains numerous copies of mitochondrial DNA (mtDNA), a small, circular, and bacterial-like DNA. In response to cellular damage or stress, mtDNA can be released from the mitochondrion and trigger immune and inflammatory responses. mtDNA release into the cytosol or bloodstream can occur as a response to hypoxia, sepsis, traumatic injury, excitatory cytotoxicity, or drastic mitochondrial membrane potential changes, some of which are hallmarks of neurodegenerative and mood disorders. Released mtDNA can mediate inflammatory responses observed in many neurological and mood disorders by driving the expression of inflammatory cytokines and the interferon response system. The current understanding of the role of mtDNA release in affective mood disorders and neurodegenerative diseases will be discussed.

Clustered Kv2.1 decreases dopamine transporter activity and internalization.

The dopamine transporter (DAT) regulates dopamine neurotransmission via reuptake of dopamine released into the extracellular space. Interactions with partner proteins alter DAT function and thereby dynamically shape dopaminergic tone important for normal brain function. However, the extent and nature of these interactions are incompletely understood. Here, we describe a novel physical and functional interaction between DAT and the voltage-gated K+ channel Kv2.1 (potassium voltage-gated channel subfamily B member 1 or KCNB1). To examine the functional consequences of this interaction, we employed a combination of immunohistochemistry, immunofluorescence live-cell microscopy, co-immunoprecipitation, and electrophysiological approaches. Consistent with previous reports, we found Kv2.1 is trafficked to membrane-bound clusters observed both in vivo and in vitro in rodent dopamine neurons. Our data provide evidence that clustered Kv2.1 channels decrease DAT's lateral mobility and inhibit its internalization, while also decreasing canonical transporter activity by altering DAT's conformational equilibrium. These results suggest that Kv2.1 clusters exert a spatially discrete homeostatic braking mechanism on DAT by inducing a relative increase in inward-facing transporters. Given recent reports of Kv2.1 dysregulation in neurological disorders, it is possible that alterations in the functional interaction between DAT and Kv2.1 affect dopamine neuron activity.

Phosphorylation of mitochondrial transcription factor B2 controls mitochondrial DNA binding and transcription.

Mammalian cells contain genetic information in two compartments, the nucleus and the mitochondria. Mitochondrial gene expression must be coordinated with nuclear gene expression to respond to cellular energetic needs. To gain insight into the coordination between the nucleus and mitochondria, there is a need to understand the regulation of transcription of mitochondrial DNA (mtDNA). Reversible protein post-translational modifications of the mtDNA transcriptional machinery may be one way to control mtDNA transcription. Here we focus on a member of the mtDNA transcription initiation complex, mitochondrial transcription factor B2 (TFB2M). TFB2M melts mtDNA at the promoter to allow the RNA polymerase (POLRMT) to access the DNA template and initiate transcription. Three phosphorylation sites have been previously identified on TFB2M by mass spectrometry: threonine 184, serine 197, and threonine 313. Phosphomimetics were established at these positions. Proteins were purified and analyzed for their ability to bind mtDNA and initiate transcription in vitro. Our results indicate phosphorylation at threonine 184 and threonine 313 impairs promoter binding and prevents transcription. These findings provide a potential regulatory mechanism of mtDNA transcription and help clarify the importance of protein post-translational modifications in mitochondrial function.

Mechanisms involved in the adaptation of Escherichia coli O157:H7 to the host intestinal microenvironment.

Host adaptation of pathogens may increase intra- and interspecies transmission. We showed previously that the passage of a clinically isolated enterohemorrhagic Escherichia coli (EHEC) O157 strain (125/99) through the gastrointestinal tract of mice increases its pathogenicity in the same host. In this work, we aimed to elucidate the underlying mechanism(s) involved in the patho-adaptation of the stool-recovered (125RR) strain. We assessed the global transcription profile by microarray and found almost 100 differentially expressed genes in 125RR strain compared with 125/99 strain. We detected an overexpression of Type Three Secretion System (TTSS) proteins at the mRNA and protein levels and demonstrated increased adhesion to epithelial cell lines for the 125RR strain. Additional key attributes of the 125RR strain were: increased motility on semisolid agar, which correlated with an increased fliC mRNA level; reduced Stx2 production at the mRNA and protein levels; increased survival at pH 2.5, as determined by acid resistance assays. We tested whether the overexpression of the LEE-encoded regulator (ler) in trans in the 125/99 strain could recreate the increased pathogenicity observed in the 125RR strain. As anticipated ler overexpression led to increased expression of TTSS proteins and bacterial adhesion to epithelial cells in vitro but also increased mortality and intestinal colonization in vivo. We conclude that this host-adaptation process required changes in several mechanisms that improved EHEC O157 fitness in the new host. The research highlights some of the bacterial mechanisms required for horizontal transmission of these zoonotic pathogens between their animal and human populations.

Intrauterine therapy with ozone reduces subclinical endometritis and improves reproductive performance in postpartum dairy cows managed in pasture-based systems.

New postpartum strategies have been developed in dairy cows to ameliorate uterine health and reproductive performance, especially the first service conception rates. This study aimed to assess the effect of intrauterine therapy with ozone (IUTO) in early postpartum on subclinical endometritis prevalence and reproductive parameters in dairy cows under commercial farm conditions. For this purpose, eighty clinically healthy cows with a body condition score between 3.0 and 3.5, from four dairy farms, were randomly allocated into two groups: ozone therapy group (OG, n = 40), which were subjected to IUTO, and control group (CG, n = 40). Content of uterine polymorphonuclear (PMN) leukocytes and subclinical endometritis (SE) percentage were assessed at 35 days after calving by uterine cytology. A second cytology was performed 72 h after IUTO. Reproductive parameters such as interval calving to first service (IFS), number of services per conception (nSC), interval calving to conception (ICC) and first service conception rate (FSCR) were analysed. The second endometrial cytology demonstrated that IUTO reduced (P < 0.01) both PMN (3.7 ± 1.4 vs. 7.6 ± 1.1%) and SE (5.0 vs. 50.0%) percentages compared with CG. Likewise, after ozone treatment, both nSC (2.1 ± 0.3 vs. 3.1 ± 0.2; P < 0.01) and ICC (126.2 ± 9.7 vs. 149.0 ± 9.0; P = 0.0672) decreased, and FSCR increased (50.0 vs. 16.2%; P < 0.01) compared with CG. In conclusion, intrauterine ozone therapy applied at 35 days after calving reduced subclinical endometritis prevalence and improved reproductive performance in postpartum dairy cows managed in a pasture-based system.

X-ray Structures of Two Bacteroides thetaiotaomicron C11 Proteases in Complex with Peptide-Based Inhibitors.

Commensal bacteria secrete proteins and metabolites to influence host intestinal homeostasis, and proteases represent a significant constituent of the components at the host:microbiome interface. Here, we determined the structures of the two secreted C11 cysteine proteases encoded by the established gut commensal Bacteroides thetaiotaomicron. We employed mutational analysis to demonstrate the two proteases, termed "thetapain" and "iotapain", undergo in trans autoactivation after lysine and/or arginine residues, as observed for other C11 proteases. We determined the structures of the active forms of thetapain and iotapain in complex with irreversible peptide inhibitors, Ac-VLTK-AOMK and biotin-VLTK-AOMK, respectively. Structural comparisons revealed key active-site interactions important for peptide recognition are more extensive for thetapain; however, both proteases employ a glutamate residue to preferentially bind small polar residues at the P2 position. Our results will aid in the design of protease-specific probes to ultimately understand the biological role of C11 proteases in bacterial fitness, elucidate their host and/or microbial substrates, and interrogate their involvement in microbiome-related diseases.

Fast synaptic inhibition in spinal sensory processing and pain control.

The two amino acids GABA and glycine mediate fast inhibitory neurotransmission in different CNS areas and serve pivotal roles in the spinal sensory processing. Under healthy conditions, they limit the excitability of spinal terminals of primary sensory nerve fibers and of intrinsic dorsal horn neurons through pre- and postsynaptic mechanisms, and thereby facilitate the spatial and temporal discrimination of sensory stimuli. Removal of fast inhibition not only reduces the fidelity of normal sensory processing but also provokes symptoms very much reminiscent of pathological and chronic pain syndromes. This review summarizes our knowledge of the molecular bases of spinal inhibitory neurotransmission and its organization in dorsal horn sensory circuits. Particular emphasis is placed on the role and mechanisms of spinal inhibitory malfunction in inflammatory and neuropathic chronic pain syndromes.

Glycine receptors and glycine transporters: targets for novel analgesics?

Glycinergic neurotransmission has long been known for its role in spinal motor control. During the last two decades, additional functions have become increasingly recognized-among them is a critical contribution to spinal pain processing. Studies in rodent pain models provide proof-of-concept evidence that enhancing inhibitory glycinergic neurotransmission reduces chronic pain symptoms. Apparent strategies for pharmacological intervention include positive allosteric modulators of glycine receptors and modulators or inhibitors of the glial and neuronal glycine transporters GlyT1 and GlyT2. These prospects have led to drug discovery efforts in academia and in industry aiming at compounds that target glycinergic neurotransmission with high specificity. Available data show promising analgesic efficacy. Less is currently known about potential unwanted effects but the presence of glycinergic innervation in CNS areas outside the nociceptive system prompts for a careful evaluation not only of motor function, but also of potential respiratory impairment and addictive properties.