Glial Receptors Research Articles

Glial receptor PLXNB2 regulates schizophrenia-related stress perception via the amygdala.

Stress is a trigger for the development of psychiatric disorders. However, how stress trait differs in schizophrenia patients is still unclear. Stress also induces and exacerbates immune activation in psychiatric disorders. Plexins (Plxn) and its ligands semaphorins (Sema) are important cellular receptors with plural functions in both the brain and the immune system. Recently, the role of Plxn/Sema in regulation of neuroinflammation was also noticed. Here, when investigating immune mechanisms underlying stress susceptibility in schizophrenia, we discovered the role of Plxnb2 in stress response. Patients of first-episode schizophrenia (FES) with high stress (FES-hs, n=51) and low stress (FES-ls, n=50) perception and healthy controls (HCs) (n=49) were first recruited for neuroimaging and blood bulk RNA sequencing (RNA-seq). A mouse model of chronic unpredictable stress (CUS) and intra-amygdaloid functional blocking of Plxnb2 were further explored to depict target gene functions. Compared to HCs, FES-hs patients had bigger caudate and thalamus (FDR=0.02&0.001, respectively) whereas FES-ls patients had smaller amygdala (FDR=0.002). Blood RNA-seq showed differentially expressed PLXNB2 and its ligands among patient groups and HCs (FDR<0.05~0.01). Amygdaloid size and PLXNB2 level were both negatively correlated with stress perception (p<0.01&0.05, respectively), which fully mediated the amygdaloid positive association with PLXNB2 expression (β=0.9318, 95% CI: 0.058~1.886) in FES-hs patients. In mice, Plxnb2 was enriched in astrocytes and microglia and CUS reduced its expression in astrocytes (p<0.05). Inhibition of amygdaloid Plxnb2 by its functional blocking monoclonal antibody (mAb)-102 induced mice anxiety (p<0.05), amygdaloid enlargement (p<0.05), and microglial ramification (p<0.001) compared to saline. These data suggest that PLXNB2 regulates amygdala-dependent stress responses.

Multiple Receptors Involved in Invasion and Neuropathogenicity of Canine Distemper Virus: A Review.

The canine distemper virus (CDV) is a morbillivirus that infects a broad range of terrestrial carnivores, predominantly canines, and is associated with high mortality. Similar to another morbillivirus, measles virus, which infects humans and nonhuman primates, CDV transmission from an infected host to a naïve host depends on two cellular receptors, namely, the signaling lymphocyte activation molecule (SLAM or CD150) and the adherens junction protein nectin-4 (also known as PVRL4). CDV can also invade the central nervous system by anterograde spread through olfactory nerves or in infected lymphocytes through the circulation, thus causing chronic progressive or relapsing demyelination of the brain. However, the absence of the two receptors in the white matter, primary cultured astrocytes, and neurons in the brain was recently demonstrated. Furthermore, a SLAM/nectin-4-blind recombinant CDV exhibits full cell-to-cell transmission in primary astrocytes. This strongly suggests the existence of a third CDV receptor expressed in neural cells, possibly glial cells. In this review, we summarize the recent progress in the study of CDV receptors, highlighting the unidentified glial receptor and its contribution to pathogenicity in the host nervous system. The reviewed studies focus on CDV neuropathogenesis, and neural receptors may provide promising directions for the treatment of neurological diseases caused by CDV. We also present an overview of other neurotropic viruses to promote further research and identification of CDV neural receptors.

Impaired bidirectional communication between interneurons and oligodendrocyte precursor cells affects social cognitive behavior

Cortical neural circuits are complex but very precise networks of balanced excitation and inhibition. Yet, the molecular and cellular mechanisms that form the balance are just beginning to emerge. Here, using conditional γ-aminobutyric acid receptor B1- deficient mice we identify a γ-aminobutyric acid/tumor necrosis factor superfamily member 12-mediated bidirectional communication pathway between parvalbumin-positive fast spiking interneurons and oligodendrocyte precursor cells that determines the density and function of interneurons in the developing medial prefrontal cortex. Interruption of the GABAergic signaling to oligodendrocyte precursor cells results in reduced myelination and hypoactivity of interneurons, strong changes of cortical network activities and impaired social cognitive behavior. In conclusion, glial transmitter receptors are pivotal elements in finetuning distinct brain functions.

Crosstalk between neurons and glia through G-protein coupled receptors: Insights from Caenorhabditis elegans.

The past decades have witnessed a dogmatic shift from glia as supporting cells in the nervous system to their active roles in neurocentric functions. Neurons and glia communicate and show bidirectional responses through tripartite synapses. Studies across species indicate that neurotransmitters released by neurons are perceived by glial receptors, which allow for gliotransmitter release. These gliotransmitters can result in activation of neurons via neuronal GPCR receptors. However, studies of these molecular interactions are in their infancy. Caenorhabditis elegans has a conserved neuron-glia architectural repertoire with molecular and functional resemblance to mammals. Further, glia in C. elegans can be manipulated through ablation and mutations allowing for deciphering of glial dependent processes in vivo at single glial resolutions. Here, we will review recent findings from vertebrate and invertebrate organisms with a focus on how C. elegans can be used to advance our understanding of neuron-glia interactions through GPCRs.

Glia: A major player in glutamate-GABA dysregulation-mediated neurodegeneration.

The imbalance between glutamate and γ-aminobutyric acid (GABA) results in the loss of synaptic strength leading to neurodegeneration. The dogma on the field considered neurons as the main players in this excitation-inhibition (E/I) balance. However, current strategies focusing only on neurons have failed to completely understand this condition, bringing up the importance of glia as an alternative modulator for neuroinflammation as glia alter the activity of neurons and is a source of both neurotrophic and neurotoxic factors. This review's primary goal is to illustrate the role of glia over E/I balance in the central nervous system and its interaction with neurons. Rather than focusing only on the neuronal targets, we take a deeper look at glial receptors and proteins that could also be explored as drug targets, as they are early responders to neurotoxic insults. This review summarizes the neuron-glia interaction concerning GABA and glutamate, possible targets, and its involvement in the E/I imbalance in neurodegenerative diseases like Alzheimer's disease, Parkinson's disease, Huntington's disease, and multiple sclerosis.

Alzheimer’s Disease: A Molecular View of β-Amyloid Induced Morbific Events

Amyloid-β (Aβ) is a dynamic peptide of Alzheimer’s disease (AD) which accelerates the disease progression. At the cell membrane and cell compartments, the amyloid precursor protein (APP) undergoes amyloidogenic cleavage by β- and γ-secretases and engenders the Aβ. In addition, externally produced Aβ gets inside the cells by receptors mediated internalization. An elevated amount of Aβ yields spontaneous aggregation which causes organelles impairment. Aβ stimulates the hyperphosphorylation of tau protein via acceleration by several kinases. Aβ travels to the mitochondria and interacts with its functional complexes, which impairs the mitochondrial function leading to the activation of apoptotic signaling cascade. Aβ disrupts the Ca2+ and protein homeostasis of the endoplasmic reticulum (ER) and Golgi complex (GC) that promotes the organelle stress and inhibits its stress recovery machinery such as unfolded protein response (UPR) and ER-associated degradation (ERAD). At lysosome, Aβ precedes autophagy dysfunction upon interacting with autophagy molecules. Interestingly, Aβ act as a transcription regulator as well as inhibits telomerase activity. Both Aβ and p-tau interaction with neuronal and glial receptors elevate the inflammatory molecules and persuade inflammation. Here, we have expounded the Aβ mediated events in the cells and its cosmopolitan role on neurodegeneration, and the current clinical status of anti-amyloid therapy.

Locus Coeruleus Modulates Neuroinflammation in Parkinsonism and Dementia.

Locus Coeruleus (LC) is the main noradrenergic nucleus of the central nervous system, and its neurons widely innervate the whole brain. LC is severely degenerated both in Alzheimer’s disease (AD) and in Parkinson’s disease (PD), years before the onset of clinical symptoms, through mechanisms that differ among the two disorders. Several experimental studies have shown that noradrenaline modulates neuroinflammation, mainly by acting on microglia/astrocytes function. In the present review, after a brief introduction on the anatomy and physiology of LC, we provide an overview of experimental data supporting a pathogenetic role of LC degeneration in AD and PD. Then, we describe in detail experimental data, obtained in vitro and in vivo in animal models, which support a potential role of neuroinflammation in such a link, and the specific molecules (i.e., released cytokines, glial receptors, including pattern recognition receptors and others) whose expression is altered by LC degeneration and might play a key role in AD/PD pathogenesis. New imaging and biochemical tools have recently been developed in humans to estimate in vivo the integrity of LC, the degree of neuroinflammation, and pathology AD/PD biomarkers; it is auspicable that these will allow in the near future to test the existence of a link between LC-neuroinflammation and neurodegeneration directly in patients.

Abstract 3056: Growth differentiation factor 15 (GDF-15) inhibition attenuates platinum-based chemotherapy-induced emesis, anorexia and weight loss and increases survival

Abstract Platinum-based chemotherapy is associated with nausea/emesis, anorexia and weight loss which reduce patient quality of life and limit treatment adherence potentially leading to poor treatment outcomes. Cisplatin increases circulating growth differentiation factor 15 (GDF-15), a cytokine that induces conditioned taste aversion, anorexia and weight loss in preclinical models. GDF-15 signals through the hindbrain receptor glial cell-derived neurotrophic factor receptor alpha-like (GFRAL). Cisplatin-induced anorexia/weight loss was attenuated in a GFRAL knockout mouse; therefore, we examined whether GDF-15 inhibition can prevent platinum-based chemotherapy-induced emesis, anorexia and weight loss, and also increase survival using mouse and/or nonhuman primate models. In cancer patients, platinum treatment increased circulating GDF-15 in non small cell lung carcinoma, colorectal, and ovarian cancer (~1.5 fold) compared to those receiving a non-platinum-based therapy. Furthermore, cisplatin, oxaliplatin and carboplatin administered individually all increased circulating GDF-15 in wildtype mice (≥ 5 fold) and induced anorexia, skeletal muscle wasting, and weight loss. GDF-15 mRNA was increased in kidney, liver, brain and white adipose tissue. These effects were prevented in GDF-15 knockout mice, however only a partial blockade was observed in the carboplatin group. In nonhuman primates, cisplatin treatment for 5 days (96% of the daily recommended clinical dose) also increased circulating GDF-15 (&amp;gt; 5 fold), and induced anorexia and emesis. Treatment with the anti-GDF-15 monoclonal antibody (mAB1) resulted in no detectable circulating levels of free GDF-15, and attenuated both cisplatin-induced anorexia and emesis. Furthermore, in a mouse cachectic tumor model (subcutaneous implantation of tumor tissue derived from human non-small cell lung carcinoma adenocarcinoma), cisplatin treatment inhibited tumor growth; however, GDF-15 levels were still elevated and additional weight loss occurred compared to vehicle control. When mAB1 was given in combination with cisplatin, weight loss was reversed and tumor growth inhibition was maintained, resulting in greater survival compared to cisplatin alone. Taken together, these data support the notion that GDF-15 inhibition with mAB1 holds the potential as an effective therapeutic approach to alleviate GDF-15 mediated emesis, anorexia and weight loss with the aim to enable optimal cancer treatment as well as to improve patient quality of life and potentially survival. Citation Format: Danna M. Breen, Kevin Beaumont, Donald Bennett, Julia Brosnan, Roberto Calle, Jeffrey R. Chabot, Susie Collins, Teresa Cunio, Ryan M. Esquejo, Stephanie Joaquim, Alison Joyce, Hanna Kim, Laura Lin, Betty Pettersen, Shuxi Qiao, Michelle Rossulek, Brendan Tierney, Karen M. Walters, Gregory Weber, Zhidan Wu, Bei B. Zhang, Morris J. Birnbaum. Growth differentiation factor 15 (GDF-15) inhibition attenuates platinum-based chemotherapy-induced emesis, anorexia and weight loss and increases survival [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 3056.

Growth differentiation factor 15 (GDF-15) as a key regulator of cachexia induced by platinum-based chemotherapy.

e24162 Background: Platinum-based drug use in cancer treatment is restricted by dose-limiting side effects, including nausea/emesis, anorexia and weight loss that reduce patient quality of life and limit treatment adherence. Cisplatin increases GDF-15, a cytokine that induces aversion, anorexia and weight loss in preclinical models. GDF-15 signals through the hindbrain receptor glial cell-derived neurotrophic factor receptor alpha-like (GFRAL) and cisplatin-induced weight loss was attenuated in a GFRAL knockout mouse. Methods: In the current study, using mouse and/or nonhuman primate models, we examined whether GDF-15 inhibition via a potent and selective monoclonal antibody (mAB1) prevents platinum-induced emesis, anorexia, weight loss, with increased survival. Results: Circulating GDF-15 levels in NSCLC and colorectal cancer were higher (~1.5 fold) in patients on platinum therapy compared to non-platinum-based therapy. Higher levels of circulating GDF-15 were also associated with greater weight loss in colorectal cancer patients prior to receiving FOLFOX as part of cancer treatment. In wildtype mice, cisplatin, oxaliplatin and carboplatin each increased circulating GDF-15 (≥ 5-fold) and induced anorexia, skeletal muscle wasting, and weight loss. These effects were prevented in GDF-15 knockout mice, however only a partial blockade of carboplatin was observed. The GDF-15 neutralizing efficacy of mAB1 was confirmed by reversing AAV-GDF-15-induced weight loss in wildtype mice. In nonhuman primates, cisplatin treatment for 5 days (96% of the daily recommended clinical dose) also increased circulating GDF-15 ( &gt; 5-fold), and induced anorexia and emesis. Treatment with mAB1 resulted in no detectable circulating levels of free GDF-15 and attenuated both cisplatin-induced anorexia and emesis. In a mouse cachectic tumor model (subcutaneous; NSCLC patient derived xenograft), cisplatin inhibited tumor growth; however, GDF-15 levels remained elevated and additional weight loss occurred compared to control. When mAB1 was given in combination with cisplatin, weight loss was reversed and tumor growth inhibition was maintained, resulting in greater survival compared to cisplatin alone. Conclusions: Taken together, these data support that GDF-15 inhibition with mAB1 holds the potential as an effective therapeutic approach to alleviate GDF-15 mediated emesis, anorexia and weight loss, with the aim to enable optimal cancer treatment as well as to improve patient quality of life and potentially survival.

Oligodendrocyte Neurofascin Independently Regulates Both Myelin Targeting and Sheath Growth in the CNS.

SummarySelection of the correct targets for myelination and regulation of myelin sheath growth are essential for central nervous system (CNS) formation and function. Through a genetic screen in zebrafish and complementary analyses in mice, we find that loss of oligodendrocyte Neurofascin leads to mistargeting of myelin to cell bodies, without affecting targeting to axons. In addition, loss of Neurofascin reduces CNS myelination by impairing myelin sheath growth. Time-lapse imaging reveals that the distinct myelinating processes of individual oligodendrocytes can engage in target selection and sheath growth at the same time and that Neurofascin concomitantly regulates targeting and growth. Disruption to Caspr, the neuronal binding partner of oligodendrocyte Neurofascin, also impairs myelin sheath growth, likely reflecting its association in an adhesion complex at the axon-glial interface with Neurofascin. Caspr does not, however, affect myelin targeting, further indicating that Neurofascin independently regulates distinct aspects of CNS myelination by individual oligodendrocytes in vivo.

MGluR2 versus mGluR3 Metabotropic Glutamate Receptors in Primate Dorsolateral Prefrontal Cortex: Postsynaptic mGluR3 Strengthen Working Memory Networks.

The newly evolved circuits in layer III of primate dorsolateral prefrontal cortex (dlPFC) generate the neural representations that subserve working memory. These circuits are weakened by increased cAMP-K+ channel signaling, and are a focus of pathology in schizophrenia, aging, and Alzheimer's disease. Cognitive deficits in these disorders are increasingly associated with insults to mGluR3 metabotropic glutamate receptors, while reductions in mGluR2 appear protective. This has been perplexing, as mGluR3 has been considered glial receptors, and mGluR2 and mGluR3 have been thought to have similar functions, reducing glutamate transmission. We have discovered that, in addition to their astrocytic expression, mGluR3 is concentrated postsynaptically in spine synapses of layer III dlPFC, positioned to strengthen connectivity by inhibiting postsynaptic cAMP-K+ channel actions. In contrast, mGluR2 is principally presynaptic as expected, with only a minor postsynaptic component. Functionally, increase in the endogenous mGluR3 agonist, N-acetylaspartylglutamate, markedly enhanced dlPFC Delay cell firing during a working memory task via inhibition of cAMP signaling, while the mGluR2 positive allosteric modulator, BINA, produced an inverted-U dose-response on dlPFC Delay cell firing and working memory performance. These data illuminate why insults to mGluR3 would erode cognitive abilities, and support mGluR3 as a novel therapeutic target for higher cognitive disorders.

Bone mesenchymal stem cell-conditioned medium induces the upregulation of Smad6, which inhibits the BMP-4/Smad1/5/8 signaling pathway

Objectives: In this study, we aimed to investigate the effect of bone mesenchymal stem cells (BMSCs) conditioned medium on BMP4-induced activation of the Smad signaling pathway during the process of neural stem cells differentiation.Methods: We designed four experimental groups: (A) control group, (B) BMP-4 treatment group, (C) BMSC-CM group, and (D) BMSC-CM (BMSC-conditioned medium) combined with BMP-4 group. The expression of microtube-associated protein-2 (MAP-2) detected by immunocytochemical staining and western blot. The expression of glial fibrillary acidic protein (GFAP) and BMP receptors (BMPRII and BMPRIa) was determined by western blot, while SMAD1/5/8 and SMAD6 mRNA expression was detected by quantitative real-time polymerase chain reaction (Q-RT-PCR).Results: We found that the expression of microtube-associated protein-2 (MAP-2) increased in group B compared to group A. In group C, the expression of GFAP was increased and the expression of MAP-2 was decreased compared to group A. This phenomenon was weaker in group D. We also demonstrated that BMSC-CM could inhibit the activation of BMP signaling by downregulating the expression of BMPRII and BMPRIa proteins. Moreover, BMSC-CM could upregulate the expression of Smad6 mRNA and inhibit the activation of Smad1/5/8 mRNA.Conclusion: These observations suggest that BMSC-CM could neutralize the effect of BMP-4 on the differentiation of NSCs by upregulating the expression of Smad6 and decrease the expression of GFAP by inhibiting the BMP-4-SMAD1/5/8 signaling pathway, conversely increasing the generation of neurons.

Glia and glial polyamines. Role in brain function in health and disease

The roles of glia and polyamines (PA) in brain function and dysfunction are highlighted in this review. We emphasize that PA accumulation preferentially in glia, but not in neurons, is clearly evolutionarily determined; it is found throughout the brain, retina, peripheral nervous system, and in glial-neuronal co-cultures of multiple species, including man. This phenomenon raises key questions: (i) What are the mechanisms that underlie such uneven distribution, accumulation and release from glia? (ii) What are the consequences of PA fluxes within the brain on neuronal function? (iii) What are the roles of PAs in brain disorders and diseases? This review includes suggestions on the roles of PAs, such as putrescine (PT), spermidine (SPD), spermine (SPM) and their derivatives as novel glio-transmitters in brain since PA affect many neuronal and glial receptors, channels and transporters. Polyamines hitherto have been neglected, although it is evident that these molecules are key elements for normal brain function and their metabolic disorders, apparently, cause the development of many pathological syndromes and diseases. The study of endogenous PA allows one to put forward the basic principles of scientific research on glio-neuronal interactions and clinical therapies, which are based on the exclusivity of glial cells in terms of accumulation of PA and PA-dependent functions.

Consequences of hepatic damage after traumatic brain injury: current outlook and potential therapeutic targets.

Consequences of hepatic damage after traumatic brain injury: current outlook and potential therapeutic targets.

Abstract 5084: A multifaceted role of the Hedgehog pathway in modulating pancreatic ductal adenocarcinoma biology

Abstract The Hedgehog (Hh) developmental pathway is reactivated in pancreatic ductal adenocarcinoma (PDA) and forms a paracrine axis from the tumor cells to the supporting stromal cells. Previous work from this laboratory found that, in established tumors, inhibition of the Hedgehog (Hh) pathway caused a loss of tumor stroma implicating this axis in the development of the profuse desmoplastic stroma observed in PDA. However, the mechanisms by which Hh signaling modulates the stroma in PDA remain unknown. In this study we have attempted to identify the target genes of the Hh pathway in the stroma of pancreatic tumors. Using a novel tumor biopsy procedure coupled with RNA-SEQ analysis we have identified genes acutely sensitive to Hh pathway inhibition in the KPC mouse model of PDA. The gene signature of down-regulated genes following Hh inhibition implicated the Hh pathway in the proliferation of its target stromal cells as well as a possible indirect effect on the proliferation of tumor cells. Interestingly, a significant number of genes were also up-regulated following inhibition of the Hh pathway. This gene signature was consistent with the migration and infiltration of leukocytes. Taken together these data suggest that the Hh pathway can drive proliferation of both the stromal and epithelial compartments as well as actively suppress leukocyte infiltration into pancreatic tumors. In addition we have utilized a Gli1-GFP reporter mouse to study the Hh target cells in the stroma of KPC mice. Previous work has suggested that Hh target cells in pancreatic tumors are myofibroblasts and thus α-Smooth muscle actin (α-SMA) positive. However, we observed that while some Gli1 positive stromal cells are α-SMA positive a significant proportion are α-SMA negative. In addition, costaining KPC-Gli1-GFP tumors for other stromal markers, including Fibroblast specific protein-1 (FSP-1), Glial Fibrillary Acidic Protein (GFAP), Desmin, Vimentin and Platelet-derived growth factor receptor β (PDGFRβ) reveals subsets of Hh target cells in the tumor stroma. These data suggest the Hh pathway targets a complex set of stromal fibroblasts to mediate its effects. Taken together, these data suggest that the Hh pathway regulates multiple facets of pancreatic tumor biology both in negative and positive manner and does so through targeting a complex array of stromal cells. Citation Format: Dafydd Huw Thomas, Albert Lee, Carmine Palermo, Stephen Sastra, Raul Rabadan, Kenneth Olive. A multifaceted role of the Hedgehog pathway in modulating pancreatic ductal adenocarcinoma biology. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 5084. doi:10.1158/1538-7445.AM2015-5084

The lack of CD131 and the inhibition of Neuro-2a growth by carbamylated erythropoietin.

Recombinant human erythropoietin (EPO), a glycohormone, is one of the leading biopharmaceutical products, while carbamylated erythropoietin (CEPO), an EPO derivative, is attracting widespread interest due to its neuroprotective effects without erythropoiesis in several cells and animal models. However, exogenous EPO promotes an angiogenic response from tumor cells and is associated with tumor growth, but knowledge of CEPO on tumor growth is lacking. Here we show that CEPO, but not EPO, inhibited Neuro-2a growth and viability. As expected, CEPO--unlike EPO--did not activate JAK-2 either in primary neurons or in Neuro-2a cells. Interestingly, CEPO did not induce GDNF expression and subsequent AKT activation in Neuro-2a cells. Before CEPO/EPO treatment, glial cell line-derived neurotrophic factor (GDNF) neutralization and GFR receptor blocking decreased the viability of EPO-treated Neuro-2a cells but did not influence CEPO-treated Neuro-2a cells. As compared to primary neurons, the expression of CD131, as a receptor complex binding to CEPO, is almost lacking in Neuro-2a cells. In BABL/C-nu mice, CEPO did not promote the growth of Neuro-2a cells nor extended the survival time compared to mice treated with EPO. The results indicate that CEPO did not promote tumor growth because of lower expression of CD131 and subsequent dysfunction of CD131/GDNF/AKT pathway in Neuro-2a cells, revealing its therapeutic potential in future clinical application.

Neurotransmitter signaling in white matter.

White matter (WM) tracts are bundles of myelinated axons that provide for rapid communication throughout the CNS and integration in grey matter (GM). The main cells in myelinated tracts are oligodendrocytes and astrocytes, with small populations of microglia and oligodendrocyte precursor cells. The prominence of neurotransmitter signaling in WM, which largely exclude neuronal cell bodies, indicates it must have physiological functions other than neuron-to-neuron communication. A surprising aspect is the diversity of neurotransmitter signaling in WM, with evidence for glutamatergic, purinergic (ATP and adenosine), GABAergic, glycinergic, adrenergic, cholinergic, dopaminergic and serotonergic signaling, acting via a wide range of ionotropic and metabotropic receptors. Both axons and glia are potential sources of neurotransmitters and may express the respective receptors. The physiological functions of neurotransmitter signaling in WM are subject to debate, but glutamate and ATP-mediated signaling have been shown to evoke Ca(2+) signals in glia and modulate axonal conduction. Experimental findings support a model of neurotransmitters being released from axons during action potential propagation acting on glial receptors to regulate the homeostatic functions of astrocytes and myelination by oligodendrocytes. Astrocytes also release neurotransmitters, which act on axonal receptors to strengthen action potential propagation, maintaining signaling along potentially long axon tracts. The co-existence of multiple neurotransmitters in WM tracts suggests they may have diverse functions that are important for information processing. Furthermore, the neurotransmitter signaling phenomena described in WM most likely apply to myelinated axons of the cerebral cortex and GM areas, where they are doubtless important for higher cognitive function.

Actions and Interactions of Alcohol and Transforming Growth Factor β1 on Prepubertal Hypothalamic Gonadotropin‐Releasing Hormone

Alcohol (ALC) diminishes gonadotropin-releasing hormone (GnRH) secretion and delays puberty. Glial transforming growth factor β1 (TGFβ1) plays a role in glial-neuronal communications facilitating prepubertal GnRH secretion. We assessed the effects of acute ALC administration on TGFβ1-induced GnRH gene expression in the brain preoptic area (POA) and release of the peptide from the medial basal hypothalamus (MBH). Furthermore, we assessed actions and interactions of TGFβ1 and ALC on an adhesion/signaling gene family involved in glial-neuronal communications. Prepubertal female rats were administered ALC or water via gastric gavage at 7:30 am. At 9:00 am, saline or TGFβ1 (100 ng/3 μl) was administered into the third ventricle. At 3:00 pm, the POA was removed and frozen for gene expression analysis and repeated for protein assessments. In another experiment, the MBH was removed from ALC-free rats. After equilibration, tissues were incubated in Locke's medium only or medium containing TGFβ1 with or without 50 mM ALC for measurement of GnRH peptide released in vitro. TGFβ1 induced GnRH gene expression in the POA, and this effect was blocked by ALC. We also described the presence and responsiveness of the TGFβ1 receptor in the POA and showed that acute ALC exposure not only altered the TGFβ1-induced increase in TGFβ-R1 protein expression but also the activation of receptor-associated proteins, Smad2 and Smad3, key downstream components of the TGFβ1 signaling pathway. Assessment of an adhesion/signaling family consisting of glial receptor protein tyrosine phosphatase beta and neuronal contactin-associated protein-1 (Caspr1) and contactin showed that the neuronal components were induced by TGFβ1 and that ALC blocked these effects. Finally, TGFβ1 was shown to induce release of the GnRH peptide in vitro, an action that was blocked by ALC. We have demonstrated glial-derived TGFβ1 induces GnRH gene expression in the POA and stimulates release of the peptide from the MBH, actions necessary for driving the pubertal process. Importantly, ALC acted at both brain regions to block stimulatory effects of TGFβ1. Furthermore, ALC altered neuronal components of an adhesion/signaling family previously shown to be expressed on GnRH neurons and implicated in glial-GnRH neuronal communications. These results further demonstrate detrimental effects of ALC at puberty.

Paraneoplastic internal jugular vein thrombosis leading to diagnosis of bilateral ovarian ependymoma.

Ovarian ependymomas are extremely rare tumors of the ovary. We present a case of a 67-year-old lady presented to us with swelling in the right side of neck for 2 months followed by pelvic pain, lower abdominal distention, and weight loss for 1 month. Her coagulation profile, blood chemistry, lipid profile, and tumor markers were within normal limits. Neck Doppler ultrasonography revealed thrombus in the right internal jugular vein and CT scan of the abdomen showed bilateral ovarian masses. Patient was subjected to debulking surgery for suspected ovarian cancer and microscopy revealed a highly cellular tumor composed of small cells with hyperchromatic, round-to-oval nuclei with scanty cytoplasm, and perivascular pseudorosettes. Diagnosis was confirmed by immunophenotype showing strong positivity to glial fibrillary acidic protein, estrogen receptors, and progesterone receptors. Patient was successfully managed with anticoagulants, adjuvant chemotherapy with BEP regimen, and letrozole. After ruling out other common conditions for thrombosis in this age group, this seems to be a paraneoplastic presentation of ovarian malignancy that preceded the diagnosis of ependymoma by 2 months. To the best of our knowledge this is the first case report in the world literature as “paraneoplastic internal jugular vein thrombosis leading to diagnosis of bilateral ovarian ependymoma.”

Antibodies to Gliomedin Cause Peripheral Demyelinating Neuropathy and the Dismantling of the Nodes of Ranvier

Guillain-Barré syndrome (GBS) and chronic inflammatory demyelinating polyneuropathy (CIDP) are conditions that affect peripheral nerves. The mechanisms that underlie demyelination in these neuropathies are unknown. Recently, we demonstrated that the node of Ranvier is the primary site of the immune attack in patients with GBS and CIDP. In particular, GBS patients have antibodies against gliomedin and neurofascin, two adhesion molecules that play a crucial role in the formation of nodes of Ranvier. We demonstrate that immunity toward gliomedin, but not neurofascin, induced a progressive neuropathy in Lewis rats characterized by conduction defects and demyelination in spinal nerves. The clinical symptoms closely followed the titers of anti-gliomedin IgG and were associated with an important deposition of IgG at nodes. Furthermore, passive transfer of antigliomedin IgG induced a severe demyelinating condition and conduction loss. In both active and passive models, the immune attack at nodes occasioned the loss of the nodal clusters for gliomedin, neurofascin-186, and voltage-gated sodium channels. These results indicate that primary immune reaction against gliomedin, a peripheral nervous system adhesion molecule, can be responsible for the initiation or progression of the demyelinating form of GBS. Furthermore, these autoantibodies affect saltatory propagation by dismantling nodal organization and sodium channel clusters. Antibodies reactive against nodal adhesion molecules thus likely participate in the pathologic process of GBS and CIDP.