Receptor Tyrosine Kinases as Therapeutic Targets for Alcohol Use Disorder

A single-cell genomic atlas for the effects of chronic ethanol exposure in the mouse dorsal striatum

Alcohol use disorder (AUD) is characterized by compulsive drinking, which is thought to be mediated by effects of chronic intermittent ethanol exposure on the dorsal striatum, the input nucleus of the basal ganglia. Despite significant efforts to understand the impact of ethanol on the dorsal striatum, the rich diversity of striatal cell types and multitude of ethanol targets expressed by them necessitates an unbiased, discovery-based approach. In this study, we used single-nuclei RNA-sequencing (snRNA-seq; n = 86,715 cells) to examine the impact of chronic intermittent ethanol exposure on the dorsal striatum in C57BL/6 male and female mice. We detected 462 differentially expressed genes at FDR < 0.05, the majority of which were mapped to spiny projection neurons (SPNs), the most prominent cell type in the striatum. Gene co-expression network analysis and functional annotation of differentially expressed genes revealed down-regulation of postsynaptic intracellular signaling cascades in SPNs. Inflammation-related genes were down-regulated across many neuronal and non-neuronal cell types. Gene set enrichment analyses also pointed to altered states of rare cell types, including the induction of angiogenesis-related genes in vascular cells. A gene module down-regulated specifically in canonical SPNs was enriched for calcium-signaling genes and components of glutamatergic synapses, as well as for genes associated with genetic risk for AUD. Genetic perturbations of six of this module's hub genes - Foxp1, Bcl11b, Pde10a, Rarb, Rgs9, and Itgr1 - had causal effects on its expression in the mouse striatum and/or on the broader set of differentially expressed genes in alcohol-exposed mice. These data provide important clues as to the impact of ethanol on striatal biology and provide a key resource for future investigation.

Candidate Key Proteins in Tinnitus: A Bioinformatic Study of Synaptic Transmission in Spiral Ganglion Neurons

To study key proteins associated with changes in synaptic transmission in the spiral ganglion in tinnitus, we build three gene lists from the GeneCard database: 1. Perception of sound (PoS), 2. Acoustic stimulation (AcouStim), and 3. Tinnitus (Tin). Enrichment analysis by the DAVID database resulted in similar Gene Ontology (GO) terms for cellular components in all gene lists, reflecting synaptic structures known to be involved in auditory processing. The STRING protein-protein interaction (PPI) network and the Cytoscape data analyzer were used to identify the top two high-degree proteins (HDPs) and their high-score interaction proteins (HSIPs) identified by the combined score (CS) of the corresponding edges. The top two protein pairs (key proteins) for the PoS are BDNF-GDNF and OTOF-CACNA1D and for the AcouStim process BDNF-NTRK2 and TH-CALB1. The Tin process showed BDNF and NGF as HDPs, with high-score interactions with NTRK1 and NGFR at a comparable level. Compared to the PoS and AcouStim process, the number of HSIPs of key proteins (CS > 90. percentile) increases strongly in Tin. In the PoS and AcouStim networks, BDNF receptor signaling is the dominant pathway, and in the Tin network, the NGF-signaling pathway is of similar importance. Key proteins and their HSIPs are good indicators of biological processes and of signaling pathways characteristic for the normal hearing on the one hand and tinnitus on the other.

Neurotoxicology of alcohol: a bibliometric and science mapping analysis

Alcohol consumption is common in many societies and has increased considerably, resulting in many socioeconomic and public health problems. In this sense, studies have been carried out in order to understand the mechanisms involved in alcohol consumption and related harmful effects. This study aimed to identify and map the knowledge and to perform bibliometric analysis of the neurotoxicology of alcohol based on the 100 most cited articles. A search was carried out in the Web of Science Core Collection database and information was extracted regarding the journal, authors, keywords, year of publication, number of citations, country and continent of the corresponding author. For each selected manuscript, the study design, alcohol exposure model, dose, period of exposure, and effect on the central nervous system and research hotspots were mapped. The journal with the highest number of publications was Alcoholism: Clinical and Experimental Research (n = 11 papers), the author who contributed the most was Crews FT (n = 8 papers), the studies had a total of 288 keywords and 75% of the publications were from the United States of America. The experimental studies evaluated the effects of prenatal and postnatal exposure and were conducted in rats and mice using doses ranging from 2.5 to 14 g/kg/day, with administration by subcutaneous, intraperitoneal, intragastric, or inhalation route or with free access through drinking bottles. Among the studies mapped, the oldest one (1989) aimed to understand the systemic damage and mechanisms of action involved, while the most recent focused on understanding the receptors and mechanisms involved in addiction, as well as genetic factors. Our results show the panorama of the most widespread scientific production in the scientific community on the neurotoxicology of ethanol, a high prevalence was observed in studies that addressed fetal alcohol syndrome and/or the effects of ethanol on neurodevelopment.

Peripheral control of psychiatric disorders: Focus on OCD. Are we there yet?

"We are all in this together" - we often hear this phrase when we want to flag up a problem that is not for a single individual but concerns us all. A similar reflection has been recently made in the field of mental disorders where brain-centric scientists have started to zoom out their brain-focused graphical representations of the mechanisms regulating psychiatric diseases to include other organs or mediators that did not belong historically to the world of neuroscience. The brain itself - that has long been seen as a master in command secluded in its fortress (the blood brain barrier), has now become a collection of Airbnb(s) where all sorts of cells come in and out and sometimes even rearrange the furniture! Under this new framework of reference, mental disorders have become multisystem pathologies where different biological systems - not just the CNS -contribute 'all together' to the development and severity of the disease. In this narrative review article, we will focus on one of the most popular biological systems that has been shown to influence the functioning of the CNS: the immune system. We will specifically highlight the two main features of the immune system and the CNS that we think are important in the context of mental disorders: plasticity and memory.

OECs Prevented Neuronal Cells from Apoptosis Partially Through Exosome-derived BDNF

It is known that neurotrophic factors are a major source of the neuroprotective effects of olfactory ensheathing cells (OECs). However, the form of neurotrophic factors that originate from OECs is not fully understood. Our previous study demonstrated that OECs could secrete exosome (OECs-Exo), which provided neuroprotection by switching the phenotype of macrophages/microglia. Considering that exosomes could also be taken up by neurons, we explored the direct effect of OECs-Exo on neuronal survival and the underlying mechanism. Electron microscopy, nano-traffic analysis, and Western blotting were applied to identify the OECs-Exo. The effect of OECs-Exo on neuronal survival was tested by flow cytometry and TUNEL staining. Western blotting and ELISA were used to detect neurotrophic factors in purified OECs-Exo. We first isolated OECs-Exo and found that OECs-Exo exerted protective effects on neuronal survival in response to TNF-α challenge. Brain-derived neurotrophic factor (BDNF) was then identified in OECs-Exo, and its receptor TrkB in neurons was activated by OECs-Exo treatment. Furthermore, we demonstrated that OECs prevented TNF-α-induced apoptosis in neurons partially through exosome-derived BDNF. Our data showed that OECs attenuated TNF-α-induced apoptosis in neurons partially through OEC-Exo-derived BDNF, which might provide a novel strategy for the neuroprotective effect of OEC-Exo-based treatment.

New developments in the biology of fibroblast growth factors

The fibroblast growth factor (FGF) family is composed of 18 secreted signaling proteins consisting of canonical FGFs and endocrine FGFs that activate four receptor tyrosine kinases (FGFRs 1-4) and four intracellular proteins (intracellular FGFs or iFGFs) that primarily function to regulate the activity of voltage-gated sodium channels and other molecules. The canonical FGFs, endocrine FGFs, and iFGFs have been reviewed extensively by us and others. In this review, we briefly summarize past reviews and then focus on new developments in the FGF field since our last review in 2015. Some of the highlights in the past 6 years include the use of optogenetic tools, viral vectors, and inducible transgenes to experimentally modulate FGF signaling, the clinical use of small molecule FGFR inhibitors, an expanded understanding of endocrine FGF signaling, functions for FGF signaling in stem cell pluripotency and differentiation, roles for FGF signaling in tissue homeostasis and regeneration, a continuing elaboration of mechanisms of FGF signaling in development, and an expanding appreciation of roles for FGF signaling in neuropsychiatric diseases. This article is categorized under: Cardiovascular Diseases > Molecular and Cellular Physiology Neurological Diseases > Molecular and Cellular Physiology Congenital Diseases > Stem Cells and Development Cancer > Stem Cells and Development.

Alcohol and the brain: from genes to circuits

Alcohol use produces wide-ranging and diverse effects on the central nervous system. It influences intracellular signaling mechanisms, leading to changes in gene expression, chromatin remodeling, and translation. As a result of these molecular alterations, alcohol affects the activity of neuronal circuits. Together, these mechanisms produce long-lasting cellular adaptations in the brain that in turn can drive the development and maintenance of alcohol use disorder (AUD). We provide an update on alcohol research, focusing on multiple levels of alcohol-induced adaptations, from intracellular changes to changes in neural circuits. A better understanding of how alcohol affects these diverse and interlinked mechanisms may lead to the identification of novel therapeutic targets and to the development of much-needed novel and efficacious treatment options.

Genetic inactivation of midkine, not pleiotrophin, facilitates extinction of alcohol-induced conditioned place preference

Pleiotrophin (PTN) and midkine (MK) are growth factors that modulate alcohol consumption and reward. Since both PTN and MK limit the rewarding effects of alcohol, pharmacological potentiation of the PTN and MK signaling pathways has been proposed for the treatment of alcohol use disorders (AUD). Although the use of this therapy in the prevention of alcohol relapse is important, the potential role of these cytokines in extinguishing alcohol-induced seeking behavior is a key question that remains unanswered. To fill this gap, we have now studied the extinction of the conditioned place preference (CPP) induced by different doses of alcohol in Ptn knockout (Ptn^-/-) and Mk knockout (Mk^-/-) mice. The data confirm a higher sensitivity of Ptn^-/- mice to the conditioning effects of a low dose (1 g/kg) and a rewarding dose (2 g/kg) of alcohol, while Mk^-/- mice are only more susceptible to the conditioning effects of the low dose of this drug. More importantly, the percentage of Mk^-/- mice, not Ptn^-/- mice, that efficiently extinguished alcohol-induced CPP was significantly higher than that of Wt mice. Taken together, the data presented here confirm that Ptn and Mk are genetic factors that determine the conditioning effects of alcohol in mice and that Mk is a novel factor that plays an important role in the extinction of alcohol-induced CPP.