28 results on '"[3H]-Guanosine Binding"'
Search Results
2. Specific [3H]-guanosine binding sites in rat brain membranes
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Traversa, Ugo, Bombi, Giulia, Iorio, Patrizia Di, Ciccarelli, Renata, Werstiuk, Eva S, and Rathbone, Michel P
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Male ,Kinetics ,Radioligand Assay ,Binding Sites ,Membranes ,Guanosine ,Papers ,Animals ,Brain ,In Vitro Techniques ,Rats, Wistar ,Binding, Competitive ,Rats - Abstract
1. Extracellular guanosine has diverse effects on many cellular components of the central nervous system, some of which may be related to its uptake into cells and others to its ability to release adenine-based purines from cells. Yet other effects of extracellular guanosine are compatible with an action on G-protein linked cell membrane receptors. 2. Specific binding sites for [(3)H]-guanosine were detected on membrane preparations from rat brain. The kinetics of [(3)H]-guanosine binding to membranes was described by rate constants of association and dissociation of 2.6122 x 10(7) M(-1) min(-1) and 1.69 min(-1), respectively. A single high affinity binding site for [(3)H]-guanosine with a K(D) of 95.4 +/- 11.9 nM and B(max) of 0.57 +/- 0.03 pmol mg(-1) protein was shown. This site was specific for guanosine, and the order of potency in displacing 50 nM [(3)H]-guanosine was: guanosine=6-thio-guanosineinosine6-thio-guanineguanine. Other naturally occurring purines, such as adenosine, hypoxanthine, xanthine caffeine, theophylline, GDP, GMP and ATP were unable to significantly displace the radiolabelled guanosine. Thus, this binding site is distinct from the well-characterized receptors for adenosine and purines. 5. The addition of GTP produced a small concentration-dependent decrease in guanosine binding, suggesting this guanosine binding site was linked to a G-protein. 6. Our results therefore are consistent with the existence of a novel cell membrane receptor site, specific for guanosine.
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- 2002
3. Brain expression and 3H-Guanosine binding analysis of novel G protein-coupled receptor for guanosine (GPR23/LPA4)
- Author
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GRILLO, Maria, DI LIBERTO, Valentina, MUDO', Giuseppa, BELLUARDO, Natale, Garozzo,R, Caciagli,F, Condorelli,DF, Grillo,M, Di Liberto,V, Garozzo,R, Mudò,G, Caciagli,F, Condorelli,DF, and Belluardo,N.
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Guanine-based purines receptor ,Brain ,[3H]-Guanosine Binding - Abstract
Several studies have shown that guanine-based purines exert biological effects on the central nervous system, possibly through membrane receptor. In a parallel work, we have identified the first guanosine G protein-coupled receptor GPR23, known as LPA4 receptor, involved in the modulation of guanosine-mediated antiproliferative effects in human glioma cell lines. Here, we performed in different brain areas the following studies: by PCR, the expression levels of GPR23; by [3H]-Guanosine radioligand binding assay, the binding properties of GPR23; by [35S] GTPγS binding assay, the receptor activation properties of guanosine. Among the examined areas, the cerebral cortex showed the highest GPR23 expression levels and affinity binding site for [3H]-Guanosine (KD 143.8 nM and Bmax 3713 nM) as compared to other brain regions with the following rank order: cerebral cortex>hippocampus>striatum>spinal cord. T! he activation of a G protein-coupled receptor in response to guanosine showed in the cerebral cortex an EC50 92 nM. The binding site for [3H]-guanosine was highly specific and both lysophosphatidic acid and guanine agonists were 10 times less effective than guanosine in displacing 50 nM [3H]-guanosine binding. Overall these data demonstrate the existence of different levels of GPR23 mRNAs and of guanosine binding in the brain areas examined. Nevertheless at this stage of study the guanosine binding observed could include, in addition to GPR23, other unidentified receptors.
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- 2012
4. Specific [[sup3]H]-guanosine binding sites in rat brain membranes.
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Traversa, Ugo, Bombi, Giulia, Di Iorio, Patrizia, Ciccarelli, Renata, Werstiuk, Eva S., and Rathbone, Michel P.
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PURINES ,LABORATORY rats ,BINDING sites - Abstract
Extracellular guanosine has diverse effects on many cellular components of the central nervous system, some of which may be related to its uptake into cells and others to its ability to release adenine-based purines from cells. Yet other effects of extracellular guanosine are compatible with an action on G-protein linked cell membrane receptors. 2 Specific binding sites for [³H]-guanosine were detected on membrane preparations from rat brain. The kinetics of [³H]-guanosine binding to membranes was described by rate constants of association and dissociation of 2.6122 × 10[sup 7] M[sup -1] min[sup -1] and 1.69 min[sup -1], respectively. 3 A single high affinity binding site for [³H]-guanosine with a K[sub D] of 95.4+ 11.9 nM and B[sub max] of 0.57 ± 0.03 pmol mg[sup -1] protein was shown. 4 This site was specific for guanosine, and the order of potency in displacing 50 nm [³H]-guanosine was: guanosine = 6-thio-guanosine >inosine > 6-thio-guanine > guanine. Other naturally occurring purines, such as adenosine, hypoxanthine, xanthine caffeine, theophylline, GDP, GMP and ATP were unable to significantly displace the radiolabelled guanosine. Thus, this binding site is distinct from the well-characterized receptors for adenosine and purines. 5 The addition of GTP produced a small concentration-dependent decrease in guanosine binding, suggesting this guanosine binding site was linked to a G-protein. 6 Our results therefore are consistent with the existence of a novel cell membrane receptor site, specific for guanosine. [ABSTRACT FROM AUTHOR]
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- 2002
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5. The antidepressant-like effect of guanosine involves the modulation of adenosine A1 and A2A receptors.
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Camargo, Anderson, Bettio, Luis E. B., Rosa, Priscila B., Rosa, Julia M., Altê, Glorister A., and Rodrigues, Ana Lúcia S.
- Abstract
Guanosine has been considered a promising candidate for antidepressant responses, but if this nucleoside could modulate adenosine A
1 (A1 R) and A2A (A2A R) receptors to exert antidepressant-like actions remains to be elucidated. This study investigated the role of A1 R and A2A R in the antidepressant-like response of guanosine in the mouse tail suspension test and molecular interactions between guanosine and A1 R and A2 AR by docking analysis. The acute (60 min) administration of guanosine (0.05 mg/kg, p.o.) significantly decreased the immobility time in the tail suspension test, without affecting the locomotor performance in the open-field test, suggesting an antidepressant-like effect. This behavioral response was paralleled with increased A1 R and reduced A2A R immunocontent in the hippocampus, but not in the prefrontal cortex, of mice. Guanosine-mediated antidepressant-like effect was not altered by the pretreatment with caffeine (3 mg/kg, i.p., a non-selective adenosine A1 R/A2A R antagonist), 8-cyclopentyl-1,3-dipropylxanthine (DPCPX — 2 mg/kg, i.p., a selective adenosine A1 R antagonist), or 4-(2-[7-amino-2-{2-furyl}{1,2,4}triazolo-{2,3-a}{1,3,5}triazin-5-yl-amino]ethyl)-phenol (ZM241385 — 1 mg/kg, i.p., a selective adenosine A2A R antagonist). However, the antidepressant-like response of guanosine was completely abolished by adenosine (0.5 mg/kg, i.p., a non-selective adenosine A1 R/A2A R agonist), N-6-cyclohexyladenosine (CHA — 0.05 mg/kg, i.p., a selective adenosine A1 receptor agonist), and N-6-[2-(3,5-dimethoxyphenyl)-2-(methylphenyl)ethyl]adenosine (DPMA — 0.1 mg/kg, i.p., a selective adenosine A2A receptor agonist). Finally, docking analysis also indicated that guanosine might interact with A1 R and A2A R at the adenosine binding site. Overall, this study reinforces the antidepressant-like of guanosine and unveils a previously unexplored modulation of the modulation of A1 R and A2A R in its antidepressant-like effect. [ABSTRACT FROM AUTHOR]- Published
- 2023
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6. Guanine inhibits the growth of human glioma and melanoma cell lines by interacting with GPR23.
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Garozzo, Roberta, Zuccarini, Mariachiara, Giuliani, Patricia, Di Liberto, Valentina, Mudò, Giuseppa, Caciagli, Francesco, Ciccarelli, Renata, Ciruela, Francisco, Di Iorio, Patrizia, and Condorelli, Daniele F.
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CELL lines ,GUANINE ,HUMAN growth ,GLIOMAS ,LYSOPHOSPHOLIPIDS - Abstract
Guanine-based purines (GBPs) exert numerous biological effects at the central nervous system through putative membrane receptors, the existence of which is still elusive. To shed light on this question, we screened orphan and poorly characterized G protein-coupled receptors (GPRs), selecting those that showed a high purinoreceptor similarity and were expressed in glioma cells, where GBPs exerted a powerful antiproliferative effect. Of the GPRs chosen, only the silencing of GPR23, also known as lysophosphatidic acid (LPA) 4 receptor, counteracted GBP-induced growth inhibition in U87 cells. Guanine (GUA) was the most potent compound behind the GPR23-mediated effect, acting as the endpoint effector of GBP antiproliferative effects. Accordingly, cells stably expressing GPR23 showed increased sensitivity to GUA. Furthermore, while GPR23 expression was low in a hypoxanthine-guanine phosphoribosyl-transferase (HGPRT)-mutated melanoma cell line showing poor sensitivity to GBPs, and in HGPRT-silenced glioma cells, GPR23-induced expression in both cell types rescued GUA-mediated cell growth inhibition. Finally, binding experiments using [³H]-GUA and U87 cell membranes revealed the existence of a selective GUA binding (K
D = 29.44 ± 4.07 nM; Bmax 1.007 ± 0.035 pmol/mg prot) likely to GPR23. Overall, these data suggest GPR23 involvement in modulating responses to GUA in tumor cell lines, although further research needs to verify whether this receptor mediates other GUA effects. [ABSTRACT FROM AUTHOR]- Published
- 2022
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7. Rat brain guanosine binding site: Biological studies and pseudo-Receptor construction
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Traversa, Ugo, Bombi, Giulia, Camaioni, Emidio, Macchiarulo, Antonio, Costantino, Gabriele, Palmieri, Clara, Caciagli, Francesco, and Pellicciari, Roberto
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PHARMACOLOGY , *STRUCTURE-activity relationships , *BRAIN , *RATS - Abstract
Rat brain guanosine binding sites were studied by (i) a pharmacological approach to confirm the hypothesis of the existence of specific G-coupled receptors for guanosine (1) and, for the first time, delineate a structure–activity relationship for a series of guanosine derivatives; (ii) a molecular modelling approach to design a pseudo-receptor construction. GTP and its non-hydrolysable analogue Gpp[NH]p decreased [3H]-guanosine binding to rat brain membranes. Gpp[NH]p 30 and 100 μM induced a dose-dependent decrease in [3H]-guanosine affinity and PTX pretreatment of rat brain membranes caused a 50% reduction in binding. In slices from rat brain cortex, guanosine induced a dose-dependent increase in intracellular cAMP. This increase is specific for guanosine, since neither the pretreatment with adenosine deaminase nor the A1 and A2 adenosine receptor antagonists were able to modify the guanosine-induced cAMP accumulation. The structure–activity relationship showed that the potency order of the best substances able to displace 50 nM [3H]-guanosine was guanosine (1)=6-thioguanosine (3)>8-bromoguanosine (4)>inosine (10)>7-methylguanosine (6)=3′-deoxyguanosine (9)>2′-deoxyguanosine (8)=guanine (11)=6-thioguanine (12)>>N2-methylguanosine (5). The competition studies confirmed that [3H]-guanosine site was distinct from the well characterized ATP and adenosine binding sites. The present results are rationalized in terms of a putative pseudo-receptor construct which includes all the relevant physicochemical interaction between guanosine analogues and their putative binding sites. This construct will be useful for the in silico screening of compound libraries in search for new potent and structurally diverse pharmacological tools. [Copyright &y& Elsevier]
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- 2003
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8. Apoptotic and anti-proliferative effect of guanosine and guanosine derivatives in HuT-78 T lymphoma cells.
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Schneider, Erich H., Hofmeister, Olga, Kälble, Solveig, and Seifert, Roland
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T cells ,LYMPHOBLASTIC leukemia ,NUCLEOSIDE transport proteins ,ADJUVANT treatment of cancer ,STRUCTURAL isomers - Abstract
The effects of 100 μM of 3′,5′-cGMP, cAMP, cCMP, and cUMP as well as of the corresponding membrane-permeant acetoxymethyl esters on anti-CD3-antibody (OKT3)-induced IL-2 production of HuT-78 cutaneous T cell lymphoma (Sézary lymphoma) cells were analyzed. Only 3′,5′-cGMP significantly reduced IL-2 production. Flow cytometric analysis of apoptotic (propidium iodide/annexin V staining) and anti-proliferative (CFSE staining) effects revealed that 3′,5′-cGMP concentrations > 50 μM strongly inhibited proliferation and promoted apoptosis of HuT-78 cells (cultured in the presence of αCD3 antibody). Similar effects were observed for the positional isomer 2′,3′-cGMP and for 2′,-GMP, 3′-GMP, 5′-GMP, and guanosine. By contrast, guanosine and guanosine-derived nucleotides had no cytotoxic effect on peripheral blood mononuclear cells (PBMCs) or acute lymphocytic leukemia (ALL) xenograft cells. The anti-proliferative and apoptotic effects of guanosine and guanosine-derived compounds on HuT-78 cells were completely eliminated by the nucleoside transport inhibitor NBMPR (S-(4-Nitrobenzyl)-6-thioinosine). By contrast, the ecto-phosphodiesterase inhibitor DPSPX (1,3-dipropyl-8-sulfophenylxanthine) and the CD73 ecto-5′-nucleotidase inhibitor AMP-CP (adenosine 5′-(α,β-methylene)diphosphate) were not protective. We hypothesize that HuT-78 cells metabolize guanosine-derived nucleotides to guanosine by yet unknown mechanisms. Guanosine then enters the cells by an NBMPR-sensitive nucleoside transporter and exerts cytotoxic effects. This transporter may be ENT1 because NBMPR counteracted guanosine cytotoxicity in HuT-78 cells with nanomolar efficacy (IC
50 of 25–30 nM). Future studies should further clarify the mechanism of the observed effects and address the question, whether guanosine or guanosine-derived nucleotides may serve as adjuvants in the therapy of cancers that express appropriate nucleoside transporters and are sensitive to established nucleoside-derived cytostatic drugs. [ABSTRACT FROM AUTHOR]- Published
- 2020
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9. IDENTIFICATION AND FUNCTIONAL CHARACTERIZATION OF GPCR23/LPA4 AS A CANDIDATE G PROTEIN-COUPLED RECEPTOR FOR GUANOSINE
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GRILLO, Maria, Grillo, ., BELLUARDO, NATALE, and FERRARO, GIUSEPPE
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GPCR ,Guanosine ,GPCR23 ,Settore BIO/09 - Fisiologia ,Guanine-based purine - Abstract
La guanosina esercita diverse funzioni a livello del Sistema Nervoso Centrale, coinvolgendo recettori di membrana accoppiati a proteine G (GPCR) non ancora identificati. Pertanto, l’obiettivo della ricerca è stato quello di individuare e caratterizzare uno specifico recettore funzionale per la Guanosina. I dati ottenuti su linee cellulari hanno dimostrato che il legame della guanosina con le membrane plasmatiche è incrementato dall’over-espressione del GPCR23 e ridotto dal suo silenziamento ed hanno evidenziato l’attivazione di un GPCR in risposta alla guanosina. A livello cerebrale il GPCR23 è risultato essere maggiormente espresso nella regione corticale, dove si è dimostrata anche una notevole interazione funzionale della guanosina con le membrane cellulari rispetto ad altre strutture cerebrali. Presi nel loro complesso questi dati suggeriscono che il GPCR23 possa agire come recettore funzionale di membrana responsivo alla guanosina. Several studies have shown that guanine-based purines exert biological effects on the central nervous system (CNS), possibly through membrane receptors, but at the present there are not reports related to the identification of such specific receptor(s). According to the results shown in this thesis, we have identified the first guanosine G protein-coupled receptor GPCR23, also known as LPA4 receptor. [3H]-Guanosine radioligand binding assay reveals that [3H]-Guanosine binding to membrane fractions is greatly enhanced by GPCR23 overexpression and reduced by GPCR23 silencing. Furthermore, in [35S] GTPγS binding assay experiments, Guanosine causes a functional G-protein coupled receptor activation in U87-GPCR23 overexpressing cells with an EC50= 8,067 nM. The binding site for [3H]-guanosine is highly specific as well as both lysophosphatidic acid (LPA) and guanine agonists are 10 times less effective than guanosine in displacing 50 nM [3H]-guanosine binding. In order to correlate the effects of guanosine in the CNS to a putative interaction with specific binding sites and in particular to GPCR activation, we performed, in different brain areas [3H]-Guanosine radioligand binding assay and [35S]-GTPγS binding assay. Among the examined brain tissues, the cerebral cortex showed the highest maximal number of binding sites for Guanosine as compared to other brain regions. In each tested brain area, the saturation curves indicates the presence of a single high affinity binding site since it is resolved by non-linear regression analysis with a one-site model. In cortical membranes KD value is 143,8 nM and Bmax 3713 fmol/mg protein. The other considered areas show lower Bmax values for [3H]-Guanosine, with the following rank order: cerebral cortex>hippocampus>striatum>spinal cord. The existence of a specific receptor coupled to a G protein for guanosine in cortical membranes, thus compatible with GPCR23, is also validated by [35S] GTPγS binding assay experiments that demonstrate the activation of a G protein-coupled receptor in response to guanosine both in autoradiography sagittal sections and in cerebral cortex membranes. With the purpose of evaluate downstream signaling activated by guanosine interaction with its binding sites; we conducted in vivo and in vitro experiments. According to our Dott.ssa Maria Grillo Pagina 4 results, Guanosine effects in cerebral cortex may be mediated by ERK1/2 and/or PLC pathways activation. In particular, i.p. administration of 7,5 mg/kg in rats induced ERK enhanced phosphorylation in cortical tissue, with a peak effect at 30 minutes after injection . On the other hand, treatment of cortical neurons with guanosine causes at 7,5 minutes both PLCγ and ERK1/2 pathways activation. Taken together, our findings demonstrate that GPCR23 is the first Receptor for Guanosine and suggest an involvement of GPCR23 in the functional response of cerebral cortex to Guanosine. Even if these observations do not exclude a possible involvement of other unidentified receptors, our study lays the foundation for identification of receptors responsive to Guanine-based purines (GBPs), both in nervous system and in other peripheral tissues and may provide new targets for neuroprotection and neuromodulation.
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- 2014
10. Neuromodulatory Effects of Guanine-Based Purines in Health and Disease.
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Tasca, Carla I., Lanznaster, Débora, Oliveira, Karen A., Fernández-Dueñas, Victor, and Ciruela, Francisco
- Abstract
The function of guanine-based purines (GBPs) is mostly attributed to the intracellular modulation of heteromeric and monomeric G proteins. However, extracellular effects of guanine derivatives have also been recognized. Thus, in the central nervous system (CNS), a guanine-based purinergic system that exerts neuromodulator effects, has been postulated. The thesis that GBPs are neuromodulators emerged from in vivo and in vitro studies, in which neurotrophic and neuroprotective effects of these kinds of molecules (i.e., guanosine) were demonstrated. GBPs induce several important biological effects in rodent models and have been shown to reduce seizures and pain, stabilize mood disorder behavior and protect against gliomas and diseases related with aging, such as ischemia or Parkinson and Alzheimer diseases. In vitro studies to evaluate the protective and trophic effects of guanosine, and of the nitrogenous base guanine, have been fundamental for understanding the mechanisms of action of GBPs, as well as the signaling pathways involved in their biological roles. Conversely, although selective binding sites for guanosine have been identified in the rat brain, GBP receptors have not been still described. In addition, GBP neuromodulation may depend on the capacity of GBPs to interact with well-known membrane proteins in glutamatergic and adenosinergic systems. Overall, in this review article, we present up-to-date GBP biology, focusing mainly on the mechanisms of action that may lead to the neuromodulator role of GBPs observed in neurological disorders. [ABSTRACT FROM AUTHOR]
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- 2018
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11. Identification and functional binding analysis of GPR23/! LPA4 as a candidate G protein-coupled receptor for Guanosine
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GRILLO, Maria, DI LIBERTO, Valentina, MUDO', Giuseppa, BELLUARDO, Natale, GAROZZO, R, CACIAGLI, F, CONDORELLI, DF, GRILLO, M, DI LIBERTO, V, GAROZZO, R, MUDÒ, G, CACIAGLI, F, CONDORELLI, DF, and BELLUARDO, N
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Binding assay ,Guanosine ,Brain ,Gpr23 ,Settore BIO/09 - Fisiologia - Abstract
Several studies have shown that guanine-based purines exert biological effects on the central nervous system (CNS), possibly through membrane receptors, but at the present there are not reports related to the identification of such specific receptor(s). We have identified the first guanosine G protein-coupled receptor GPR23, also known as LPA4 receptor, involved in the modulation of guanosine-mediated antiproliferative effects in human glioma cell line (U87). We report that the silencing of GPR23 reduces significantly the antiproliferative effects of guanosine, while stably transfected cell clones over-expressing GPR23 increase sensitivity to guanosine. [3H] Guanosine radioligand binding assay reveals that [3H]-Guanosine binding to membrane fractions is greatly enhanced by GPR23 overexpression, and inhibited by GPR23 silencing. Furthermore, in [35S] GTPγS binding assay experiments, Guanosine causes a functional G protein coupled receptor activation in U87GPR23 overexp! ressing cells with an EC50= 8,067 nM. The binding site for [3H]-guanosine is highly specific and both lysophosphatidic acid (LPA) and guanine agonists are 10 times less effective than guanosine in displacing 50 nM [3H]-guanosine binding. In order to correlate the effects of guanosine in the CNS to a putative activation of GPR23, we performed, in different brain areas, the following investigations: by PCR, the expression levels of GPR23; by [3H]-Guanosine radioligand binding assay, the binding properties of Guanosine; by [35S] GTPγS binding assay, the receptor activation properties in response to Guanosine. Among the examined brain areas, the cerebral cortex shows the highest GPR23 expression levels which correlate with the highest Bmax values for [3H]-Guanosine as compared to other brain regions, with the following rank order: cerebral cortex>hippocampus>striatum>spinal cord. [35S] GTPγS binding assay experiments confirm an activation of a G protein-cou! pled receptor in response to guanosine in the cerebral cortex (EC50 10 0 nM). Although these observations do not exclude a possible involvement of other unidentified receptors, they can suggest an involvement of GPR23 in the functional response of cerebral cortex to Guanosine. Overall, together these data suggest that GPR23 may act as a functional membrane receptor for Guanosine.
- Published
- 2013
12. Uncovering the Signaling Pathway behind Extracellular Guanine-Induced Activation of NO System: New Perspectives in Memory-Related Disorders.
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Zuccarini, Mariachiara, Giuliani, Patricia, Frinchi, Monica, Mudò, Giuseppa, Serio, Rosa Maria, Belluardo, Natale, Buccella, Silvana, Carluccio, Marzia, Condorelli, Daniele F., Caciagli, Francesco, Ciccarelli, Renata, and Di Iorio, Patrizia
- Subjects
MEMORY disorders ,GUANINE ,NITRIC oxide ,THERAPEUTICS - Abstract
Mounting evidence suggests that the guanine-based purines stand out as key player in cell metabolism and in several models of neurodegenerative disorders, such as Parkinson's and Alzheimer's diseases. Guanosine (GUO) and guanine (GUA) are extracellular signaling molecules derived from the breakdown of the correspondent nucleotide, GTP, and their intracellular and extracellular levels are regulated by the fine-tuned activity of two major enzymes, purine nucleoside phosphorylase (PNP) and guanine deaminase (GDA). Noteworthy, GUO and GUA, seem to play opposite roles in the modulation of cognitive functions, such as learning and memory. Indeed GUO, despite exerting neuroprotective, anti-apoptotic and neurotrophic effects, causes a decay of cognitive activities, whereas GUA administration in rats results in working memory improvement (prevented by L-NAME pre-treatment). This study was designed to investigate, in a model of SH-SY5Y neuroblastoma cell line, the signal transduction pathway activated by extracellular GUA. Altogether, our results showed that: (i) in addition to an enhanced phosphorylation of ASK1, p38 and JNK, likely linked to a non-massive and transient ROS production, the PKB/NO/sGC/cGMP/PKG/ERK cascade seems to be the main signaling pathway elicited by extracellular GUA; (ii) the activation of this pathway occurs in a pertussis-toxin sensitive manner, thus suggesting the involvement of a putative G protein coupled receptor; (iii) the GUA-induced NO production, strongly reduced by cell pre-treatment with L-NAME, is negatively modulated by the EPAC-cAMP-CaMKII pathway, which causes the over-expression of GDA that, in turn, reduces the levels of GUA. These molecular mechanisms activated by GUA may be useful to support our previous observation showing that GUA improves learning and memory functions through the stimulation of NO signaling pathway, and underscore the therapeutic potential of oral administration of guanine for treating memory-related disorders. [ABSTRACT FROM AUTHOR]
- Published
- 2018
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13. Guanosine: a Neuromodulator with Therapeutic Potential in Brain Disorders.
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Lanznaster, Débora, Dal-Cim, Tharine, Piermartiri, Tetsadê C. B., and Tasca, Carla I.
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GUANOSINE ,BRAIN disease treatment ,PHARMACODYNAMICS - Abstract
Guanosine is a purine nucleoside with important functions in cell metabolism and a protective role in response to degenerative diseases or injury. The past decade has seen major advances in identifying the modulatory role of extracellular action of guanosine in the central nervous system (CNS). Evidence from rodent and cell models show a number of neurotrophic and neuroprotective effects of guanosine preventing deleterious consequences of seizures, spinal cord injury, pain, mood disorders and aging-related diseases, such as ischemia, Parkinson's and Alzheimer's diseases. The present review describes the findings of in vivo and in vitro studies and offers an update of guanosine effects in the CNS. We address the protein targets for guanosine action and its interaction with glutamatergic and adenosinergic systems and with calciumactivated potassium channels. We also discuss the intracellular mechanisms modulated by guanosine preventing oxidative damage, mitochondrial dysfunction, inflammatory burden and modulation of glutamate transport. New and exciting avenues for future investigation into the protective effects of guanosine include characterization of a selective guanosine receptor. A better understanding of the neuromodulatory action of guanosine will allow the development of therapeutic approach to brain diseases. [ABSTRACT FROM AUTHOR]
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- 2016
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14. Guanosine protects against reperfusion injury in rat brains after ischemic stroke.
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Connell, Barry J., Di Iorio, Patrizia, Sayeed, Iqbal, Ballerini, Patrizia, Saleh, Monique C., Giuliani, Patricia, Saleh, Tarek M., Rathbone, Michel P., Su, Caixin, and Jiang, Shucui
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- 2013
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15. Origin, utilization, and recycling of nucleosides in the central nervous system.
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Ipata, Piero Luigi
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PYRIMIDINES ,PURINE nucleotides ,NUCLEOTIDES ,CENTRAL nervous system ,NEURONS ,CELL membranes - Abstract
The brain relies on the salvage of preformed purine and pyrimidine rings, mainly in the form of nucleosides, to maintain its nucleotide pool in the proper qualitative and quantitative balance. The transport of nucleosides from blood into neurons and glia is considered to be an essential prerequisite to enter their metabolic utilization in the brain. Recent lines of evidence have also suggested that local extracellular nucleoside triphosphate (NTP) degradation may contribute to brain nucleosides. Plasma membranelocated ectonucleotidases, with their active sites oriented toward the extracellular space, catalyze the successive hydrolysis of NTPs to their respective nucleosides. Apart from the well-established modulation of ATP, ADP, adenosine (the purinergic agonists), UTP, and UDP (the pyrimidinergic agonists) availability at their respective receptors, ectonucleotidases may also serve the local reutilization of nucleosides in the brain. After their production in the extracellular space by the ectonucleotidase system, nucleosides are transported into neurons and glia and converted back to NTPs via a set of purine and pyrimidine salvage enzymes. Finally, nucleotides are transported into brain cell vescicles or granules and released back into the extracellular space. The key teaching concepts to be included in a two-to threelecture block on the molecular mechanisms of the local nucleoside recycling process, based on a cross talk between the brain extracellular space and cytosol, are discussed in this article. [ABSTRACT FROM AUTHOR]
- Published
- 2011
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16. Expression and contribution of satellite glial cells purinoceptors to pain transmission in sensory ganglia: an update.
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Villa, Giovanni, Fumagalli, Marta, Verderio, Claudia, Abbracchio, Maria P., and Ceruti, Stefania
- Abstract
The role of adenosine-5′-triphosphate (ATP) and of the ligand-gated P2X3 receptor in neuronal dorsal root ganglia (DRG) pain transmission is relatively well established. Much less is known about the purinergic system in trigeminal ganglia (TG), which are involved in certain types of untreatable neuropathic and inflammatory pain, as well as in migraine. Emerging data suggest that purinergic metabotropic P2Y receptors on both neurons and satellite glial cells (SGCs) may also participate in both physiological and pathological pain development. Here, we provide an updated literature review on the role of purinergic signaling in sensory ganglia, with special emphasis on P2Y receptors on SGCs. We also provide new original data showing a time-dependent downregulation of P2Y2 and P2Y4 receptor expression and function in purified SGCs cultures from TG, in comparison with primary mixed neuron–SGCs cultures. These data highlight the importance of the neuron–glia cross-talk in determining the SGCs phenotype. Finally, we show that, in mixed TG cultures, both adenine and guanosine induce intracellular calcium transients in neurons but not in SGCs, suggesting that also these purinergic-related molecules can participate in pain signaling. These findings may have relevant implications for the development of new therapeutic strategies for chronic pain treatment. [ABSTRACT FROM PUBLISHER]
- Published
- 2010
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17. Neurotrophic Effects of Extracellular Guanosine.
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Rathbone, Michel, Pilutti, Lara, Caciagli, Francesco, and Jiang, Shucui
- Subjects
CENTRAL nervous system ,MITOSIS ,CELL cycle ,APOPTOSIS ,PURINES ,NUCLEOSIDES - Abstract
Central nervous system (CNS) astrocytes release guanosine extracellularly, that exerts trophic effects. In CNS, extracellular guanosine (GUO) stimulates mitosis, synthesis of trophic factors, and cell differentiation, including neuritogenesis, is neuroprotective, and reduces apoptosis due to several stimuli. Specific receptor-like binding sites for eGUO in the nervous system may mediate its effects through both MAP kinase and PI3-kinase signalling pathways. Extracellular guanine (eGUA) also exerts several effects; the trophic effects of eGUO are likely regulated by conversion of eGUO to eGUA by a membrane located purine nucleoside phosphorylase (ecto-PNP) and by conversion of eGUA to xanthine by guanine deaminase. [ABSTRACT FROM AUTHOR]
- Published
- 2008
- Full Text
- View/download PDF
18. A purine-selective nucleobase/nucleoside transporter in PK15NTD cells.
- Author
-
Hoque, Kazi Mirajul, Linxi Chen, Leung, George P. H., and Chung-Ming Tse
- Subjects
NUCLEOSIDES ,PURINES ,PYRIMIDINES ,CELLS ,ADENOSINES - Abstract
Nucleoside and nucleobase transporters are important for salvage of purines and pyrimidines and for transport of their analog drugs into cells. However, the pathways for nucleobase translocation in mammalian cells are not well characterized. We identified an Na-independent purine-selective nucleobase/nucleoside transport system in the nucleoside transporter-deficient PK15NTD cells. This transport system has 1,000-fold higher affinity for nucleobases than nucleosides with K
m values of 2.5 ± 0.7 µM for [³H]adenine, 6.4 ± 0.5 µM for [³H] guanine, 1.1 ± 0.1 mM for [³H]guanosine, and 4.2 ± 0.5 mM [³H]adenosine. The uptake of [³H]guanine (0.05 µM) was inhibited by other nucleobases and nucleobase analog drugs (at 0.5-1 mM in the order of potency): 6-mercaptopurine = thioguanine = guanine > adenine >>> thymine = fluorouracil = uracil. Cytosine and methylcytosine had no effect. Nucleoside analog drugs with modification at 2′ and/or 5 positions (all at 1 mM) were more potent than adenosine in competing the uptake of [³H]guanine: 2-chloro-2′-deoxyadenosine > 2-chloroadenosine > 2′3′-dideoxyadenosine = 2′-deoxyadenosine> 5-deoxyadenosine > adenosine. 2-Chloro-2′-deoxyadenosine and 2-chloroadenosine inhibited [³H]guanine uptake with IC50 values of 68 ± 5 and 99 ± 10 µM, respectively. The nucleobase/nucleoside transporter was resistant to nitrobenzylthioinosine {6-[(4-nitrobenzyl)thiol]-9-β-D-ribofuranosylpurine}, dipyridamole, and dilazep, but was inhibited by papaverine, the organic cation transporter inhibitor decynium-22 (IC50 of ~1 µM), and by acidic pH (pH = 5.5). In conclusion, we have identified a mammalian purine-selective nucleobase/nucleoside transporter with high affinity for purine nucleobases. This transporter is potentially important for transporting naturally occurring purines and purine analog drugs into cells. [ABSTRACT FROM AUTHOR]- Published
- 2008
- Full Text
- View/download PDF
19. Quinolinic Acid-induced Seizures Stimulate Glutamate Uptake into Synaptic Vesicles from Rat Brain: Effects Prevented by Guanine-based Purines.
- Author
-
Rejane Tavares, André Schmidt, Carla Tasca, and Diogo Souza
- Subjects
URIC acid ,NEURAL transmission ,DEVELOPMENTAL disabilities ,EPILEPSY - Abstract
Abstract  Glutamate uptake into synaptic vesicles is a vital step for glutamatergic neurotransmission. Quinolinic acid (QA) is an endogenous glutamate analog that may be involved in the etiology of epilepsy and is related to disturbances on glutamate release and uptake. Guanine-based purines (GBPs) guanosine 5â²-monophosphate (GMP and guanosine) have been shown to exert anticonvulsant effects against QA-induced seizures. The aims of this study were to investigate the effects of in vivo administration of several convulsant agents on glutamate uptake into synaptic vesicles and investigate the role of MK-801, guanosine or GMP (anticonvulsants) on glutamate uptake into synaptic vesicles from rats presenting QA-induced seizures. Animals were treated with vehicle (saline 0.9%), QA 239.2 nmoles, kainate 30 mg/kg, picrotoxin 6 mg/kg, PTZ (pentylenetetrazole) 60 mg/kg, caffeine 150 mg/kg or MES (maximal transcorneal electroshock) 80 mA. All convulsant agents induced seizures in 80â100% of animals, but only QA stimulated glutamate uptake into synaptic vesicle. Guanosine or GMP prevented seizures induced by QA (up to 52% of protection), an effect similar to the NMDA antagonist MK-801 (60% of protection). Both GBPs and MK-801 prevented QA-induced glutamate uptake stimulation. This study provided additional evidence on the role of QA and GBPs on glutamatergic system in rat brain, and point to new perspectives on seizures treatment. [ABSTRACT FROM AUTHOR]
- Published
- 2008
- Full Text
- View/download PDF
20. Guanosine promotes the up-regulation of inward rectifier potassium current mediated by Kir4.1 in cultured rat cortical astrocytes.
- Author
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Benfenati, Valentina, Caprini, Marco, Nobile, Mario, Rapisarda, Carmela, and Ferroni, Stefano
- Subjects
GUANOSINE triphosphate ,ASTROCYTES ,ION channels ,PATHOLOGICAL physiology ,NEUROGLIA ,PURINE nucleotides - Abstract
Guanosine (Guo) is an endogenous neuroprotective molecule of the CNS, which has various acute and long-term effects on both neurones and astroglial cells. Whether Guo also modulates the activity/expression of ion channels involved in homeostatic control of extracellular potassium by the astrocytic syncytium is still unknown. Here we provide electrophysiological evidence that chronic exposure (48 h) to Guo (500 μm) promotes the functional expression of an inward rectifier K
+ (Kir) conductance in primary cultured rat cortical astrocytes. Molecular screening indicated that Guo promotes the up-regulation of the Kir4.1 channel, the major component of the Kir current in astroglia in vivo. Furthermore, the properties of astrocytic Kir current overlapped those of the recombinant Kir4.1 channel expressed in a heterologous system, strongly suggesting that the Guo-induced Kir conductance is mainly gated by Kir4.1. In contrast, the expression levels of two other Kir channel proteins were either unchanged (Kir2.1) or decreased (Kir5.1). Finally, we showed that inhibition of translational process, but not depression of transcription, prevents the Guo-induced up-regulation of Kir4.1, indicating that this nucleoside acts through de novo protein synthesis. Because accumulating data indicate that down-regulation of astroglial Kir current contributes to the pathogenesis of neurodegenerative diseases associated with dysregulation of extracellular K+ homeostasis, these results support the notion that Guo might be a molecule of therapeutic interest for counteracting the detrimental effect of K+ -buffering impairment of the astroglial syncytium that occurs in pathological conditions. [ABSTRACT FROM AUTHOR]- Published
- 2006
- Full Text
- View/download PDF
21. Neurotoxicity Induced by Glutamate in Glucose-Deprived Rat Hippocampal Slices is Prevented by GMP.
- Author
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Simone Molz, Helena Decker, Ivaldo J. L. Oliveira, Diogo O. Souza, and Carla I. Tasca
- Subjects
GLUCOSE ,PROPIONIC acid ,CELL membranes ,DEHYDROGENASES - Abstract
Abstract Guanosine-5'-monophosphate (GMP) was evaluated as a neuroprotective agent against the damage induced by glutamate in rat hippocampal slices submitted to glucose deprivation. In slices maintained under physiological conditions, glutamate (0.01 to 10 mM), Kainate, alpha-amino-3-hydroxi-5-methylisoxazole-propionic acid (AMPA), N-methyl-D-aspartate (NMDA), 1S,3R-aminocyclopentane-1,3-dicarboxylic acid (1S,3R-ACPD), or L-2-amino-4-phosphonobutanoic acid (L-AP4) (100 µM) did not alter cell membrane permeability, as evaluated by lactate dehydrogenase (LDH) release assay. In slices submitted to glucose deprivation, GMP (from 0.5 mM) prevented LDH leakage and the loss of cell viability induced by 10 mM glutamate. LDH leakage induced by Kainate, AMPA, NMDA or 1S,3R-ACPD was fully prevented by 1 mM GMP. However, glutamate uptake was not altered in slices submitted to glucose deprivation and glutamate analogues. Glucose deprivation induced a significant decrease in ATP levels which was unchanged by addition of glutamate or GMP. Our results show that glucose deprivation decreases the energetic charge of cells, making hippocampal slices more susceptible to excitotoxicity and point to GMP as a neuroprotective agent acting as a glutamatergic antagonist. [ABSTRACT FROM AUTHOR]
- Published
- 2005
22. Intracerebroventricular Guanine-Based Purines Protect Against Seizures Induced by Quinolinic Acid in Mice.
- Author
-
André P. Schmidt, Thiago T. Ávila, and Diogo O. Souza
- Subjects
RODENTS ,URIC acid ,PYRIDINE ,NUCLEIC acids - Abstract
Abstract Acute and chronic administration of the nucleoside guanosine have been shown to prevent quinolinic acid (QA) and a-dendrotoxin-induced seizures, as well as to impair memory and anxiety in rats and mice. In this study, we investigated the effect of i.c.v. administration of guanine-based purines (GTP, GDP, GMP, and guanosine) against seizures induced by the NMDA agonist and glutamate releaser quinolinic acid in mice. We also aimed to study the effects of the poorly hydrolysable analogs of GTP (GppNHp and GTP?S) and GDP (GDPßS) in this seizure model. QA produced seizures in 100% of mice, an effect partially prevented by guanine-based purines. In contrast to GTP (480 nmol), GDP (320–640 nmol), GMP (320–480 nmol) and guanosine (300–400 nmol), the poorly hydrolysable analogs of GTP and GDP did not affect QA-induced seizures. Thus, the protective effects of guanine nucleotides seem to be due to their conversion to guanosine. Altogether, these findings suggest a potential role of guanine-based purines for treating diseases involving glutamatergic excitotoxicity. [ABSTRACT FROM AUTHOR]
- Published
- 2005
23. Guanosine Enhances Glutamate Uptake in Brain Cortical Slices at Normal and Excitotoxic Conditions.
- Author
-
dos Santos Frizzo, Marcos, Lara, Diogo, Prokopiuk, Alexandre, Vargas, Carmen, Salbego, Christianne, Wajner, Moacir, and Souza, Diogo
- Abstract
1. The effect of guanosine on L-[2,3-
3 H]glutamate uptake was investigated in brain cortical slices under normal or oxygen–glucose deprivation (OGD) conditions. 2. In slices exposed to physiological conditions, guanosine (1–100 μM) stimulated glutamate uptake (up to 100%) in a concentration-dependent manner when a high (100 μM) but not a low (1 μM) concentration of glutamate was used. 3. In slices submitted to OGD, guanosine 1 and 100 μM also increased 100 μM glutamate uptake (38 and 70%, respectively). 4. The increasing of glutamate and taurine released to the incubation medium in cortical slices submitted to OGD were significantly attenuated by the presence of guanosine in the incubation medium. 5. Guanosine prevented the increase in propidium iodide incorporation into cortical slices induced by OGD, indicating a protective role against ischemic injury. 6. These results support the hypothesis of a protective role for guanosine during brain ischemia, possibly by activating glutamate uptake into neural cells. [ABSTRACT FROM AUTHOR]- Published
- 2002
- Full Text
- View/download PDF
24. Neuroprotective Effects of Guanosine in Ischemic Stroke—Small Steps towards Effective Therapy.
- Author
-
Chojnowski, Karol, Opielka, Mikolaj, Nazar, Wojciech, Kowianski, Przemyslaw, and Smolenski, Ryszard T.
- Subjects
ISCHEMIC stroke ,GUANOSINE ,EXCITATORY amino acids ,CEREBRAL ischemia ,NEUROPROTECTIVE agents ,ATP-binding cassette transporters - Abstract
Guanosine (Guo) is a nucleotide metabolite that acts as a potent neuromodulator with neurotrophic and regenerative properties in neurological disorders. Under brain ischemia or trauma, Guo is released to the extracellular milieu and its concentration substantially raises. In vitro studies on brain tissue slices or cell lines subjected to ischemic conditions demonstrated that Guo counteracts destructive events that occur during ischemic conditions, e.g., glutaminergic excitotoxicity, reactive oxygen and nitrogen species production. Moreover, Guo mitigates neuroinflammation and regulates post-translational processing. Guo asserts its neuroprotective effects via interplay with adenosine receptors, potassium channels, and excitatory amino acid transporters. Subsequently, guanosine activates several prosurvival molecular pathways including PI3K/Akt (PI3K) and MEK/ERK. Due to systemic degradation, the half-life of exogenous Guo is relatively low, thus creating difficulty regarding adequate exogenous Guo distribution. Nevertheless, in vivo studies performed on ischemic stroke rodent models provide promising results presenting a sustained decrease in infarct volume, improved neurological outcome, decrease in proinflammatory events, and stimulation of neuroregeneration through the release of neurotrophic factors. In this comprehensive review, we discuss molecular signaling related to Guo protection against brain ischemia. We present recent advances, limitations, and prospects in exogenous guanosine therapy in the context of ischemic stroke. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
25. Astrocyte dysfunction following molybdenum-associated purine loading could initiate Parkinson's disease with dementia.
- Author
-
Bourke, Christopher A.
- Published
- 2018
- Full Text
- View/download PDF
26. Purinergic Signaling in Neurodevelopment, Neuroinflammation and Neurodegeneration
- Author
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Henning Ulrich, Peter Illes, Talita Glaser, Henning Ulrich, Peter Illes, and Talita Glaser
- Subjects
- Neurosciences, Neurochemistry, Medicine—Research, Biology—Research, Regenerative medicine
- Abstract
This volume explores the quickly evolving field of Purinergic signaling, and examines how receptors for ATP and other nucleotides, and receptors for adenosine, act in neuronal transmission, control of synaptic activity, proliferation, differentiation and cell death regulation in the CNS. This book focuses on the participation of purinergic receptors and ectonucleotidases, degrading ATP into adenosine, in embryonic and adult neurogenesis in vitro and in vivo as well as in synaptic transmission and pathophysiology. Further, the chapters discuss varying brain diseases, including Parkinson's, and Alzheimer's disease, autism, mood disorders and epilepsy, as well as brain tumors, in the context of purinergic signaling and its clinical aspects. The development of purinergic receptor agonists is also an important issue of this book. This book provides a critical review of the current state of science and will be useful for both scientists and students who are or would like to get involved in this area. Furthermore, this book addresses neuroscientists, physician and professionals from the industry, who would like to update themselves in this exciting and rapidly growing field of neuroscience.
- Published
- 2023
27. The antidepressant-like effect of guanosine involves the modulation of adenosine A1 and A2A receptors
- Author
-
Camargo, Anderson, Bettio, Luis E. B., Rosa, Priscila B., Rosa, Julia M., Altê, Glorister A., and Rodrigues, Ana Lúcia S.
- Published
- 2022
- Full Text
- View/download PDF
28. Handbook of Venoms and Toxins of Reptiles
- Author
-
Stephen P. Mackessy and Stephen P. Mackessy
- Subjects
- Toxins, Dangerous reptiles, Venom--Physiological effect, Poisonous snakes--Venom, Reptiles--Venom, Reptiles
- Abstract
The Handbook of Venoms and Toxins of Reptiles offers'one-stop shopping'to all biologists, biochemists, toxicologists, physicians, clinicians, and epidemiologists, and informed laypersons interested in the biology of venomous reptiles, the biochemistry and molecular biology of venoms, and the effects and treatment of human envenomation. This book
- Published
- 2010
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