RESUMO
Isoguanine (2-hydroxyadenine), considered to be a non-natural nucleobase has, however, been shown to occur in the croton bean, butterfly wings and a mollusk. For the first time, to the best of our knowledge, we report the identification of isoguanosine (2-hydroxyadenosine), the ribonucleoside, in humans and mouse. Isoguanosine is identified and quantified in RNA from mouse liver samples and in human urine and cerebrospinal fluid. Isoguanine could not be detected as the 2'-deoxyribonucleoside in mouse liver DNA. It could be speculated that the source of isoguanosine was formation from adenosine during oxidative stress in the body. However, the urinary concentrations of isoguanosine and the levels in the liver found here by using isotope dilution liquid chromatography-tandem mass spectrometry are identical to or exceed those of 8-oxo-7,8-dihydro-2'-deoxyguanosine and 8-oxo-7,8-dihydro-guanosine. Guanine is the nucleobase that is oxidized the easiest, so it appears spectacular that the levels of isoguanosine are higher than the levels of 8-oxo-7,8-dihydro-2'-deoxyguanosine and 8-oxo-7,8-dihydro-guanosine. It also appears intriguing that it was only possible to detect the ribonucleoside isoguanosine and not the 2'-deoxyribonucleoside. These observations could indicate that the isoguanosine found is not formed by oxidative stress and could have biological functions.
Assuntos
Guanosina/metabolismo , Adenosina/metabolismo , Animais , DNA/metabolismo , Guanosina/líquido cefalorraquidiano , Guanosina/química , Guanosina/urina , Humanos , Fígado/metabolismo , Camundongos , RNA/metabolismoRESUMO
In addition to its intracellular roles, the nucleoside guanosine (GUO) also has extracellular effects that identify it as a putative neuromodulator signaling molecule in the central nervous system. Indeed, GUO can modulate glutamatergic neurotransmission, and it can promote neuroprotective effects in animal models involving glutamate neurotoxicity, which is the case in brain ischemia. In the present study, we aimed to investigate a new in vivo GUO administration route (intranasal, IN) to determine putative improvement of GUO neuroprotective effects against an experimental model of permanent focal cerebral ischemia. Initially, we demonstrated that IN [(3)H] GUO administration reached the brain in a dose-dependent and saturable pattern in as few as 5 min, presenting a higher cerebrospinal GUO level compared with systemic administration. IN GUO treatment started immediately or even 3 h after ischemia onset prevented behavior impairment. The behavior recovery was not correlated to decreased brain infarct volume, but it was correlated to reduced mitochondrial dysfunction in the penumbra area. Therefore, we showed that the IN route is an efficient way to promptly deliver GUO to the CNS and that IN GUO treatment prevented behavioral and brain impairment caused by ischemia in a therapeutically wide time window.
Assuntos
Isquemia Encefálica/tratamento farmacológico , Guanosina/administração & dosagem , Guanosina/uso terapêutico , Fármacos Neuroprotetores/administração & dosagem , Fármacos Neuroprotetores/uso terapêutico , Acidente Vascular Cerebral/tratamento farmacológico , Administração Intranasal , Animais , Comportamento Animal , Isquemia Encefálica/psicologia , Infarto Cerebral/patologia , Infarto Cerebral/prevenção & controle , Relação Dose-Resposta a Droga , Comportamento Exploratório/efeitos dos fármacos , Guanosina/líquido cefalorraquidiano , Guanosina/farmacocinética , Masculino , Mitocôndrias/efeitos dos fármacos , Fármacos Neuroprotetores/líquido cefalorraquidiano , Fármacos Neuroprotetores/farmacocinética , Ratos , Ratos Wistar , Acidente Vascular Cerebral/psicologiaRESUMO
Labor pain has been reported as a severe pain and can be considered as a model of acute visceral pain. It is well known that extracellular purines have an important role in pain signaling in the central nervous system. This study analyzes the relationship between extracellular purines and pain perception during active labor. A prospective observational study was performed. Cerebrospinal fluid (CSF) levels of the purines and their metabolites were compared between women at term pregnancy with labor pain (n = 49) and without labor pain (Caesarian section; n = 47). Control groups (healthy men and women without chronic or acute pain-n = 40 and 32, respectively) were also investigated. The CSF levels of adenosine were significantly lower in the labor pain group (P = 0.026) and negatively correlated with pain intensity measured by a visual analogue scale (r = -0.48, P = 0.0005). Interestingly, CSF levels of uric acid were significantly higher in healthy men as compared to women. Additionally, pregnant women showed increased CSF levels of ADP, GDP, adenosine and guanosine and reduced CSF levels of AMP, GTP, and uric acid as compared to non-pregnant women (P < 0.05). These findings suggest that purines, in special the nucleoside adenosine, are associated with pregnancy and labor pain.
Assuntos
Dor do Parto/líquido cefalorraquidiano , Trabalho de Parto/líquido cefalorraquidiano , Purinas/líquido cefalorraquidiano , Adenosina/líquido cefalorraquidiano , Difosfato de Adenosina/líquido cefalorraquidiano , Adulto , Cesárea , Feminino , Guanosina/líquido cefalorraquidiano , Guanosina Difosfato/líquido cefalorraquidiano , Humanos , Masculino , Medição da Dor , Percepção da Dor , Gravidez , Estudos ProspectivosRESUMO
OBJECTIVE: The Glut1 deficiency syndrome (Glut1 DS) phenotype has expanded dramatically since first described in 1991. Hypoglycorrhachia and decreased erythrocyte 3-OMG uptake are confirmatory laboratory biomarkers. The objective is to expand previous observations regarding the diagnostic value of the uptake assay. METHODS: One hundred and nine suspected cases of Glut-1 DS were studied. All cases had a consistent clinical picture and hypoglycorrhachia. The uptake assay was decreased in 74 cases (group 1) and normal in 35 cases (group 2). We identified disease-causing mutations in 70 group 1 patients (95%) and one group 2 patient (3%). RESULTS: The cut-off for an abnormally low uptake value was increased from 60% to 74% with a corresponding sensitivity of 99% and specificity of 100%. The correlation between the uptake values for the time-curve and the kinetic concentration curve were strongly positive (R(2) = 0.85). Significant group differences were found in CSF glucose and lactate values, tone abnormalities, and degree of microcephaly. Group 2 patients were less affected in all domains. We also noted a significant correlation between the mean erythrocyte 3-OMG uptake and clinical severity (R(2) = 0.94). INTERPRETATION: These findings validate the erythrocyte glucose uptake assay as a confirmatory functional test for Glut1 DS and as a surrogate marker for GLUT1 haploinsufficiency.
Assuntos
Glicemia/metabolismo , Eritrócitos/metabolismo , Transportador de Glucose Tipo 1/deficiência , Doenças Metabólicas/sangue , Pré-Escolar , Saúde da Família , Feminino , Transportador de Glucose Tipo 1/genética , Guanosina/análogos & derivados , Guanosina/sangue , Guanosina/líquido cefalorraquidiano , Humanos , Lactente , Masculino , Doenças Metabólicas/líquido cefalorraquidiano , Doenças Metabólicas/complicações , Doenças Metabólicas/genética , Mutação/genética , Curva ROC , Convulsões/etiologia , Índice de Gravidade de Doença , Estatística como AssuntoRESUMO
BACKGROUND: The pathogenesis of Alzheimer's disease (AD) is related to homocysteine (HC), but the details are unknown. OBJECTIVE: We aimed to measure the cerebrospinal fluid (CSF) concentrations of 8-hydroxyguanosine (8-OHG), considering RNA oxidative damage marker, free HC and total HC in the CSF of patients with AD and in normal control subjects. METHOD AND PATIENTS: Subjects were 18 untreated patients with AD (M/F = 7/11) and 15 age-matched controls (M/F = 9/6), with a mean age +/- SD of 67.4 +/- 5.0 years for patients and of 65.7 +/- 9.2 years for controls. The concentrations of free HC, total HC and 8-OHG in the CSF of AD patients were measured by high-performance liquid chromatography using an electrochemical detector. The control subjects were neurologically normal patients who underwent lumbar spinal anesthesia for minor surgery. RESULTS: Total HC and 8-OHG concentrations were significantly increased, and there was a significant positive correlation between total HC and 8-OHG concentrations. However, the concentration of 8-OHG in the CSF showed no correlation with 8-OHG in serum and was not significantly altered in AD patients. CONCLUSION: These results suggest that total HC and 8-OHG are positively correlated and may be related to AD pathogenesis due to RNA-associated oxidative damage linked to total HC.
Assuntos
Doença de Alzheimer/patologia , Encéfalo/metabolismo , Homocisteína/metabolismo , RNA/metabolismo , Idoso , Doença de Alzheimer/líquido cefalorraquidiano , Estudos de Casos e Controles , Feminino , Guanosina/análogos & derivados , Guanosina/líquido cefalorraquidiano , Humanos , Masculino , Pessoa de Meia-Idade , Estatística como AssuntoRESUMO
Bipolar disorder (BD) is a mental disorder characterized by recurrent relapses of affective episodes, cognitive impairment, illness progression, and reduced life expectancy. Increased systemic oxidatively generated nucleoside damage have been found in some neurodegenerative disorders and in BD. As the first, this naturalistic prospective, longitudinal follow-up case-control study investigated cerebrospinal fluid (CSF) oxidative stress markers 8-oxo-7,8-dihydroguanosine (8-oxoGuo) and 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) that relate to RNA and DNA damage, respectively. Patients with BD (n = 86, 51% female) and gender-and-age-matched healthy control individuals (HC; n = 44, 44% female) were evaluated at baseline (T0), during (T1) and after a new affective episode (T2), if it occurred, and after a year (T3). Cerebrospinal and urine oxidative stress markers were analyzed using ultra-performance liquid chromatography-tandem mass spectrometry. CSF-8-oxoGuo was statistically significantly higher by 18% (p = 0.003) in BD versus HC at T0, and by 22% (p = 0) at T3. CSF-8-oxoGuo had increased by 15% (p = 0.042) from T0 to T3, and by 14% (p = 0.021) from T2 to T3 in patients, who experienced an episode during follow-up. CSF-8-oxodG had increased by 26% (p = 0.054) from T0 to T2 and decreased by 19% (p = 0.041) from T2 to T3 in patients, who experienced an episode during follow-up. CSF-8-oxoGuo did not show a statistically significant change in HC during the one-year follow-up. CSF and urine-8-oxoGuo levels correlated moderately. In conclusion, CSF oxidative stress marker of RNA damage 8-oxoGuo showed both state and trait dependence in BD and stability in HC. Central RNA damage may be a potential biomarker for BD.
Assuntos
8-Hidroxi-2'-Desoxiguanosina/líquido cefalorraquidiano , Transtorno Bipolar/líquido cefalorraquidiano , Guanosina/análogos & derivados , Estresse Oxidativo/fisiologia , Adulto , Biomarcadores/líquido cefalorraquidiano , Estudos de Casos e Controles , Feminino , Guanosina/líquido cefalorraquidiano , Humanos , Estudos Longitudinais , Masculino , Adulto JovemRESUMO
It is well known that adenine-based purines exert multiple effects on pain transmission. However, less attention has been given to the potential effects of guanine-based purines (GBPs) on pain transmission. The aim of this study was to investigate the effects of intracerebroventricular (i.c.v.) guanosine and GMP on mice pain models. Mice received an i.c.v. injection of vehicle (saline or 10 muM NaOH), guanosine (5 to 400 nmol), or GMP (240 to 960 nmol). Additional groups were also pre-treated with i.c.v. injection of the A(1)/A(2A) antagonist caffeine (15 nmol), the non-selective opioid antagonist naloxone (12.5 nmol), or the 5'-nucleotidase inhibitor AOPCP (1 nmol). Measurements of CSF purine levels and cortical glutamate uptake were performed after treatments. Guanosine and GMP produced dose-dependent antinociceptive effects. Neither caffeine nor naloxone affected guanosine antinociception. Pre-treatment with AOPCP completely prevented GMP antinociception, indicating that conversion of GMP to guanosine is required for its antinociceptive effects. Intracerebroventricular administration of guanosine and GMP induced, respectively, a 180- and 1800-fold increase on CSF guanosine levels. Guanosine was able to prevent the decrease on cortical glutamate uptake induced by intraplantar capsaicin. This study provides new evidence on the mechanism of action of GBPs, with guanosine and GMP presenting antinociceptive effects in mice. This effect seems to be independent of adenosine and opioid receptors; it is, however, at least partially associated with modulation of the glutamatergic system by guanosine.
Assuntos
Analgésicos , Guanosina Monofosfato/farmacologia , Guanosina/farmacologia , Animais , Química Encefálica/efeitos dos fármacos , Capsaicina , Cromatografia Líquida de Alta Pressão , Ácido Glutâmico/metabolismo , Guanosina/administração & dosagem , Guanosina/líquido cefalorraquidiano , Guanosina Monofosfato/administração & dosagem , Guanosina Monofosfato/líquido cefalorraquidiano , Temperatura Alta , Injeções Intraventriculares , Masculino , Camundongos , Atividade Motora/efeitos dos fármacos , Naloxona/farmacologia , Antagonistas de Entorpecentes/farmacologia , Medição da Dor/efeitos dos fármacos , Equilíbrio Postural/efeitos dos fármacos , Desempenho Psicomotor/efeitos dos fármacos , Tempo de Reação/efeitos dos fármacosRESUMO
Increased levels of nucleosides modified by oxidation in human cerebrospinal fluid (CSF) have several times been reported in Alzheimer patients and patients suffering from Parkinson's disease. The focus has especially been on nucleosides containing the 8-hydroxylation of guanine. Only few reports on quantification of the ribonucleoside 8-oxo-7,8-dihydro-guanosine (8oxoGuo) in CSF have been published, whereas more have been published on the quantification of the deoxy-ribonucleoside 8-oxo-7,8-dihydro-2'-deoxyguanosine (8oxodGuo). The reports on the quantification of 8oxodGuo concentrations in CSF report absolute concentrations varying by a factor >105 in healthy humans. This could indicate that there is a serious specificity problem in some of the methods. In this paper an isotope-dilution UPLC-MS/MS method with high specificity and sensitivity for the quantification of 8oxoGuo and 8oxodGuo in CSF is presented. LLOQ for the two analytes is determined to 4pM and 2pM, respectively. The calibration curves has been tested to be linear in the range from 4 to 3,000pM for 8oxoGuo and between 2 and 3,000pM for 8oxodGuo. Using a weighting factor of 1/x the correlation coefficient "r" for both analytes is >0.999.
Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Desoxiguanosina/análogos & derivados , Guanosina/análogos & derivados , Espectrometria de Massas em Tandem/métodos , 8-Hidroxi-2'-Desoxiguanosina , Idoso , Criança , Desoxiguanosina/líquido cefalorraquidiano , Guanosina/líquido cefalorraquidiano , Humanos , Modelos Lineares , Pessoa de Meia-Idade , Estresse Oxidativo , Reprodutibilidade dos Testes , Sensibilidade e EspecificidadeRESUMO
BACKROUND: 8-hydroxy-2 deoxyguanosine (8-OHdG) and the 8-hydroxyguanosine (8-OHG) are the most widely used biomarkers of nucleoside oxidation affecting DNA and RNA and are considered reliable markers of oxidative stress. Increased levels of these markers are found in the various biological fluids of patients with neurodegenerative disorders. OBJECTIVE: The primary aim of our study was to assess the differences of investigated markers between patient groups and subsequently study the influence of clinical factors that might modify the levels of investigated markers during the disease progression. METHODS: In this study, we analysed the 8-OHdG and 8-OHG levels in the cerebrospinal fluid (CSF) and serum from 44 patients with Parkinson's disease (PD) and 32 controls using an ELISA. RESULTS: There were significantly higher CSF levels of both investigated markers in Parkinson's disease patients as compared to controls (p=0.02 and p=0.04). Significantly higher CSF values of 8-OHdG were found in PD patients without dementia (p=0.05), whereas patients with dementia recorded lower 8-OHG CSF levels compared to controls (p=0.04). The disease duration and age influenced the levels of both markers within investigated groups. CONCLUSION: Oxidative DNA damage plays an important role in the early stages of PD, whereas during the progression of the disease the process is more complex, and other mechanisms are in the foreground. The measurement of 8-OHdG might be used as an "early-stage marker", whereas the decrease of 8-OHG in CSF might reflect the degree of neurodegeneration during the disease progression, suggesting its utility as a prognostic marker of advanced PD stages.
Assuntos
DNA/líquido cefalorraquidiano , Doença de Parkinson/líquido cefalorraquidiano , 8-Hidroxi-2'-Desoxiguanosina , Adulto , Idoso , Idoso de 80 Anos ou mais , Biomarcadores/líquido cefalorraquidiano , Estudos de Casos e Controles , Dano ao DNA , Desoxiguanosina/análogos & derivados , Desoxiguanosina/líquido cefalorraquidiano , Feminino , Guanosina/análogos & derivados , Guanosina/líquido cefalorraquidiano , Humanos , Masculino , Pessoa de Meia-Idade , Oxirredução , RNA/líquido cefalorraquidianoRESUMO
Elevated systemic oxidative stress levels of 8-oxoGuo and 8-oxodG have been reported in individuals with severe mental illness (SMI). As no previous studies have addressed the link between local levels of 8-oxoGuo and 8-oxodG in the central nervous system (CNS), measured in cerebrospinal fluid (CSF), and urinary systemic levels, we employed autopsy-based material to elucidate this aspect. Additionally, we investigated the impact of 8-oxoGuo and 8-oxodG levels on the prevalence of somatic co-morbidities. Based on post mortem samples from deceased individuals with SMI (Nâ¯=â¯107), we found significantly elevated urinary levels of both 8-oxoGuo and 8-oxodG compared to mentally healthy living controls. While we found an association between urinary and CSF 8-oxodG levels (râ¯=â¯0.50, Pâ¯<â¯0.001), a similar correlation was not evident for 8-oxoGuo (râ¯=â¯0.15, Pâ¯=â¯0.16). Additionally, the two r-values were significantly different (Pâ¯<â¯0.001). Neither marker in urine or CSF was associated with obesity-related variables, metabolic syndrome or type 2 diabetes. The post mortem interval did not affect the results, but the agonal phase seemingly introduced bias. This study provided novel insights into the cellular oxidative stress levels in individuals with SMI. We demonstrated that increased oxidative stress locally and systemically is correlated and is a clear phenomenon in SMI. Although post mortem measurements contain some weaknesses, our study indicates DNA as the main site of oxidative stress modifications in the CNS in SMI. This may provide novel opportunities for treatment modalities. Additionally, our study demonstrated the applicability of post mortem material investigating systemic and local 8-oxoGuo and 8-oxodG levels.
Assuntos
Desoxiguanosina/análogos & derivados , Guanosina/análogos & derivados , Transtornos Mentais/líquido cefalorraquidiano , Estresse Oxidativo/genética , 8-Hidroxi-2'-Desoxiguanosina , Idoso , Autopsia , Transtorno Bipolar/líquido cefalorraquidiano , Transtorno Bipolar/fisiopatologia , Transtorno Bipolar/urina , Sistema Nervoso Central/metabolismo , Sistema Nervoso Central/fisiopatologia , Desoxiguanosina/líquido cefalorraquidiano , Desoxiguanosina/urina , Depressão/líquido cefalorraquidiano , Depressão/fisiopatologia , Depressão/urina , Feminino , Guanosina/líquido cefalorraquidiano , Guanosina/urina , Humanos , Masculino , Transtornos Mentais/fisiopatologia , Transtornos Mentais/urina , Pessoa de Meia-Idade , Estresse Oxidativo/fisiologia , Esquizofrenia/líquido cefalorraquidiano , Esquizofrenia/fisiopatologia , Esquizofrenia/urinaRESUMO
Studies on the purinergic system normally deal with adenine-based purines, namely, adenine nucleotides and adenosine. However, a guanine-based purinergic system may also have important neuromodulatory roles. Guanine-based purines exert trophic effects on neural cells, protect brain slices in a model of hypoxia and stimulate glutamate uptake. In vivo, both guanosine 5'-monophosphate (GMP) and guanosine (GUO) protected against seizures. In this study, we investigated if the anticonvulsant effect of GMP is mediated by guanosine and if guanosine or GMP treatments were able to increase adenosine levels. Intraperitoneal (i.p.) treatments with 7.5 mg/kg GMP or guanosine prevented 50% of seizures by quinolinic acid (QA) and increased guanosine cerebrospinal fluid (CSF) levels around twofold and threefold, respectively; GMP and adenosine levels remained unchanged. Intracerebroventricular treatment with 960 nmol GMP prevented 80% of seizures and the 5'-nucleotidase inhibitor alpha-beta-methyleneadenosine 5'-diphosphate (AOPCP), when injected 3 min before, reduced this anticonvulsant effect to 30% protection as well as significantly decreased the conversion of GMP into guanosine measured in the CSF. This study shows that the previously reported effect of GMP as an anticonvulsant seems to be related to its ability to generate guanosine through the action of ecto-5'-nucleotidase.
Assuntos
Difosfato de Adenosina/análogos & derivados , Anticonvulsivantes/uso terapêutico , GMP Cíclico/uso terapêutico , Guanosina/metabolismo , Guanosina/farmacologia , Convulsões/tratamento farmacológico , Difosfato de Adenosina/farmacologia , Animais , Anticonvulsivantes/metabolismo , GMP Cíclico/antagonistas & inibidores , GMP Cíclico/metabolismo , Relação Dose-Resposta a Droga , Guanosina/antagonistas & inibidores , Guanosina/líquido cefalorraquidiano , Masculino , Ratos , Ratos Wistar , Convulsões/líquido cefalorraquidianoRESUMO
In order to investigate the possible role of oxidative RNA damage in the pathogenesis of Parkinson's disease (PD), the concentrations of the oxidative stress marker 8-hydroxyguanosine (8-OHG) were measured in the cerebrospinal fluid (CSF) and the serum of patients with PD and control subjects. The concentration of 8-OHG in CSF in PD patients was approximately three-fold that in controls (P < 0.001). The concentration of 8-OHG in CSF decreased significantly with the duration of disease (r(s) = -0.46, P < 0.05). However, the concentration of 8-OHG in serum was not significantly altered in PD patients compared to that in controls. In addition, the concentration of 8-OHG in CSF showed no correlation with that in serum in both the controls and PD patients suggesting that the 8-OHG concentrations in the CSF do not reflect those in serum and may be probably reflect those in brain tissue. These in vivo findings suggest a possible role of 8-OHG and increased oxidative RNA damage in the early stage of the development of PD.
Assuntos
Guanosina/análogos & derivados , Guanosina/sangue , Guanosina/líquido cefalorraquidiano , Doença de Parkinson/sangue , Doença de Parkinson/líquido cefalorraquidiano , Biomarcadores/sangue , Biomarcadores/líquido cefalorraquidiano , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estresse Oxidativo , RNA/metabolismo , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Estatística como AssuntoRESUMO
The efflux of purine nucleobases and their nucleosides from the rat brain was investigated using the brain efflux index (BEI) method. Calculated BEI values showed that purine nucleobases had very rapid initial efflux after the intracerebral injection, which was followed by the slower efflux due to the intracellular trapping of labelled molecules and confirmed by the capillary depletion technique. The efflux of ribonucleosides was much slower than the efflux of nucleobases and the structure of the sugar moiety seemed to be important, since a significant difference in the efflux velocity between ribo- and deoxyribonucleosides was observed. The results of self- and cross-inhibition studies suggested that the efflux of test molecules was saturable and that purines shared the same transport system on the abluminal side of the blood-brain barrier.
Assuntos
Barreira Hematoencefálica/efeitos dos fármacos , Encéfalo/efeitos dos fármacos , Proteínas de Transporte/efeitos dos fármacos , Nucleosídeos de Purina/metabolismo , Purinas/metabolismo , Adenosina/sangue , Adenosina/líquido cefalorraquidiano , Animais , Barreira Hematoencefálica/fisiologia , Encéfalo/metabolismo , Radioisótopos de Carbono/metabolismo , Proteínas de Transporte/fisiologia , Desoxirribonucleosídeos/sangue , Desoxirribonucleosídeos/líquido cefalorraquidiano , Espaço Extracelular/efeitos dos fármacos , Espaço Extracelular/metabolismo , Guanosina/sangue , Guanosina/líquido cefalorraquidiano , Hipoxantina/sangue , Hipoxantina/líquido cefalorraquidiano , Injeções Intraventriculares , Inosina/sangue , Inosina/líquido cefalorraquidiano , Nucleosídeos de Purina/sangue , Nucleosídeos de Purina/líquido cefalorraquidiano , Ratos , Ratos WistarRESUMO
UNLABELLED: It is well known that adenine-based purines exert multiple effects on pain transmission. Less attention has been given, however, to the antinociceptive effects of guanine-based purines. The aim of this study was to investigate the effects of intraperitoneal administration of guanosine on a rat model of peripheral mononeuropathy. Additionally, investigation of the mechanism of action of guanosine, its general toxicity and measurements of central nervous system purine levels were performed. Rats received an intraperitoneal administration of vehicle (0.1 mM NaOH) or guanosine (up to 120 mg.kg(-1)) in an acute or chronic regimen. Guanosine significantly reduced thermal hyperalgesia on the ipsilateral side of the sciatic nerve ligation. Additionally, guanosine prevented locomotor deficits and body weight loss induced by the mononeuropathy. Acute systemic administration of guanosine caused an approximately 11-fold increase on central nervous system guanosine levels, but this effect was not observed after chronic treatment. Chronic guanosine administration prevented the increase on cortical glutamate uptake but not the decrease in spinal cord glutamate uptake induced by the mononeuropathy. No significant general toxicity was observed after chronic exposure to guanosine. This study provides new evidence on the mechanism of action of guanine-based purines, with guanosine presenting antinociceptive effects against a chronic pain model. PERSPECTIVE: This study provides a new role for guanosine: chronic pain modulation. Guanosine presents as a new target for future drug development and might be useful for treatment of neuropathic pain.
Assuntos
Analgésicos/uso terapêutico , Guanosina/uso terapêutico , Hiperalgesia/etiologia , Hiperalgesia/prevenção & controle , Ciática/complicações , Analgésicos/líquido cefalorraquidiano , Analgésicos/farmacologia , Animais , Sistema Nervoso Central/efeitos dos fármacos , Sistema Nervoso Central/metabolismo , Cromatografia Líquida de Alta Pressão/métodos , Modelos Animais de Doenças , Relação Dose-Resposta a Droga , Vias de Administração de Medicamentos , Comportamento Exploratório/efeitos dos fármacos , Ácido Glutâmico/metabolismo , Guanosina/líquido cefalorraquidiano , Guanosina/farmacologia , Hiperalgesia/patologia , Masculino , Transtornos dos Movimentos/etiologia , Transtornos dos Movimentos/prevenção & controle , Medição da Dor , Limiar da Dor/efeitos dos fármacos , Ratos , Ratos Wistar , Ciática/tratamento farmacológico , Estatísticas não Paramétricas , Fatores de TempoRESUMO
BACKGROUND AND PURPOSE: It is well known that adenine-based purines exert multiple effects on pain transmission. However, less attention has been given to the potential effects of guanine-based purines on pain transmission. The aim of this study was to investigate the effects of intraperitoneal (i.p.) and oral (p.o.) administration of guanosine on mice pain models. Additionally, investigation into the mechanisms of action of guanosine, its potential toxicity and cerebrospinal fluid (CSF) purine levels were also assessed. EXPERIMENTAL APPROACH: Mice received an i.p. or p.o. administration of vehicle (0.1 mM NaOH) or guanosine (up to 240 mg x kg(-1)) and were evaluated in several pain models. KEY RESULTS: Guanosine produced dose-dependent antinociceptive effects in the hot-plate, glutamate, capsaicin, formalin and acetic acid models, but it was ineffective in the tail-flick test. Additionally, guanosine produced a significant inhibition of biting behaviour induced by i.t. injection of glutamate, AMPA, kainate and trans-ACPD, but not against NMDA, substance P or capsaicin. The antinociceptive effects of guanosine were prevented by selective and non-selective adenosine receptor antagonists. Systemic administration of guanosine (120 mg x kg(-1)) induced an approximately sevenfold increase on CSF guanosine levels. Guanosine prevented the increase on spinal cord glutamate uptake induced by intraplantar capsaicin. CONCLUSIONS AND IMPLICATIONS: This study provides new evidence on the mechanism of action of the antinociceptive effects after systemic administration of guanosine. These effects seem to be related to the modulation of adenosine A(1) and A(2A) receptors and non-NMDA glutamate receptors.
Assuntos
Analgésicos/uso terapêutico , Guanosina/uso terapêutico , Dor/tratamento farmacológico , Administração Oral , Analgésicos/administração & dosagem , Analgésicos/líquido cefalorraquidiano , Analgésicos/farmacologia , Analgésicos/toxicidade , Animais , Comportamento Animal/efeitos dos fármacos , Córtex Cerebral/efeitos dos fármacos , Córtex Cerebral/metabolismo , Cromatografia Líquida de Alta Pressão , Modelos Animais de Doenças , Relação Dose-Resposta a Droga , Edema/tratamento farmacológico , Guanosina/administração & dosagem , Guanosina/líquido cefalorraquidiano , Guanosina/farmacologia , Guanosina/toxicidade , Injeções Intraperitoneais , Dose Letal Mediana , Masculino , Camundongos , Atividade Motora/efeitos dos fármacos , Dor/líquido cefalorraquidiano , Dor/fisiopatologia , Limiar da Dor/efeitos dos fármacos , Medula Espinal/efeitos dos fármacos , Medula Espinal/metabolismoRESUMO
BACKGROUND: Insufficient cerebral O2 supply leads to cellular energy failure and loss of brain cell function. The relationship between the severity of cellular energy failure due to hemorrhagic hypotension and the loss of electrocortical brain activity (ECBA), as a measure of brain cell function, is not yet fully elucidated in near-term born lambs. OBJECTIVES: To study the relationship between cerebral purine and pyrimidine metabolism, as a measure of brain cell energy failure, and brain cell function after hemorrhagic hypotension in near-term born lambs. METHODS: Eight near-term lambs (term 147 days) were delivered at 131 days of gestation. After a stabilization period, mean arterial blood pressure was reduced till 30% of baseline by withdrawal of blood. Cerebrospinal fluid (CSF) was obtained at the end of the hypotensive period (2.5 h). CSF from 8 siblings was used for comparison. HPLC was used to determine purine and pyrimidine metabolites in CSF, as a measure of cellular energy failure. ECBA was calculated as the root mean square value of a band-filtered (2-16 Hz) one-channel EEG. RESULTS: Values of guanosine, inosine, hypoxanthine, xanthine and uridine were significantly higher, while ECBA was significantly lower after hemorrhagic hypotension than control values. The concentrations of inosine, hypoxanthine, xanthine and uridine were significantly negatively linearly related to ECBA. CONCLUSIONS: Brain cell function is negatively related to concentrations of inosine, hypoxanthine, xanthine and uridine in the CSF after hemorrhagic hypotension in near-term born lambs.
Assuntos
Animais Recém-Nascidos , Encéfalo/fisiopatologia , Hipotensão/veterinária , Purinas/líquido cefalorraquidiano , Pirimidinas/líquido cefalorraquidiano , Doenças dos Ovinos/fisiopatologia , Animais , Eletroencefalografia , Guanosina/líquido cefalorraquidiano , Hemorragia , Hipotensão/etiologia , Hipotensão/fisiopatologia , Hipoxantina/líquido cefalorraquidiano , Inosina/líquido cefalorraquidiano , Consumo de Oxigênio , Uridina/líquido cefalorraquidiano , Xantina/líquido cefalorraquidianoRESUMO
Adenosine monophosphate, inosine monophosphate, inosine, adenosine, guanosine, adenine, guanine, hypoxanthine, xanthine, uric acid and pyrimidine bases were determined in the CSF of 18 children after simple febrile seizures and in a control group. There was no statistically significant difference between the two groups for any of these metabolites. This suggests that simple febrile seizures neither significantly disturb the metabolism of nucleotides, nucleosides or bases, nor significantly deplete neuron adenosine triphosphate ATP levels.
Assuntos
Purinas/líquido cefalorraquidiano , Nucleosídeos de Pirimidina/líquido cefalorraquidiano , Convulsões Febris/líquido cefalorraquidiano , Adenina/líquido cefalorraquidiano , Adenosina/líquido cefalorraquidiano , Monofosfato de Adenosina/líquido cefalorraquidiano , Pré-Escolar , Citosina/líquido cefalorraquidiano , Feminino , Guanina/líquido cefalorraquidiano , Guanosina/líquido cefalorraquidiano , Humanos , Hipoxantina , Hipoxantinas/líquido cefalorraquidiano , Lactente , Inosina/líquido cefalorraquidiano , Inosina Monofosfato/líquido cefalorraquidiano , Masculino , Timina/líquido cefalorraquidiano , Uracila/líquido cefalorraquidiano , Ácido Úrico/líquido cefalorraquidiano , Xantina , Xantinas/líquido cefalorraquidianoRESUMO
(-)-beta-D-2-Aminopurine dioxolane (APD) and (-)-beta-D-2-amino-6-chloropurine dioxolane (ACPD) are recently synthesized dioxolanylpurine nucleoside derivatives being developed as potential prodrugs for the antiviral nucleoside analog (-)-beta-D-dioxolane guanine (DXG). In vitro, APD and ACPD are converted to DXG by xanthine oxidase and adenosine deaminase, respectively. The purpose of this study was to evaluate the preclinical pharmacokinetics of APD and ACPD and their potential for generating sustained levels of the parent nucleoside, DXG, in rhesus monkeys following oral administration. Both nucleoside derivatives were rapidly absorbed, with similar peak concentrations achieved within 1 h after administration. However, concentrations of APD were more markedly sustained than those of ACPD. Both prodrugs yielded DXG, but significantly higher serum concentrations of DXG and area under the concentration-time curve values were observed following administration of APD. In addition, APD produced higher concentrations of prodrug and DXG in cerebrospinal fluid than did ACPD. Thus, the results of this pharmacokinetic study suggest that APD is likely to serve as a better prodrug of DXG and should be considered for clinical trials for antiviral therapy against human immunodeficiency virus and hepatitis B virus.
Assuntos
Antivirais/farmacocinética , Dioxolanos/farmacologia , Dioxolanos/farmacocinética , Guanosina/análogos & derivados , Purinas/farmacologia , Purinas/farmacocinética , Animais , Antivirais/líquido cefalorraquidiano , Contagem de Células Sanguíneas , Dioxolanos/líquido cefalorraquidiano , Guanosina/líquido cefalorraquidiano , Guanosina/farmacocinética , Humanos , Macaca mulatta , Masculino , Purinas/líquido cefalorraquidianoRESUMO
To investigate the possible role of oxidative RNA damage in the pathogenesis of Alzheimer's disease (AD), the concentrations of the oxidative stress marker 8-hydroxyguanosine (8-OHG) were measured in the cerebrospinal fluid (CSF) and the serum of patients with AD and control subjects. The concentration of 8-OHG in CSF in AD patients was approximately fivefold that in controls (P < 0.001). The concentration of 8-OHG in CSF decreased significantly with the duration of illness (r(s) = -0.48, P < 0.05) and the progression of cognitive dysfunctions (r(s) = 0.67, P < 0.01). However, the concentration of 8-OHG in CSF showed no correlation with that in serum in both the controls and AD patients. In addition, the concentration of 8-OHG in serum was not significantly altered in AD patients compared to that in controls, suggesting that the 8-OHG concentrations in the CSF do not reflect those in serum and may be probably reflect those in brain tissue. These in vivo findings suggest a possible role of 8-OHG and increased oxidative RNA damage in the early stage of the development of AD.
Assuntos
Doença de Alzheimer/líquido cefalorraquidiano , Guanosina/análogos & derivados , Guanosina/líquido cefalorraquidiano , Estresse Oxidativo/genética , RNA/metabolismo , Regulação para Cima/genética , Idoso , Doença de Alzheimer/sangue , Doença de Alzheimer/genética , Encéfalo/metabolismo , Encéfalo/fisiopatologia , Feminino , Guanosina/sangue , Humanos , Masculino , Pessoa de Meia-Idade , Neurônios/metabolismoRESUMO
(-)-beta-D-2-Aminopurine dioxolane (APD), (-)-beta-D-2-amino-6-chloropurine dioxolane (ACPD) and dioxolane guanine (DXG) are nucleoside analogues possessing potent activity against human immunodeficiency virus (HIV) and hepatitis B virus (HBV) in vitro. APD and ACPD are metabolized in vivo to yield DXG. Reversed-phase HPLC analytical methodologies were developed for the simultaneous determination of APD and DXG, and for ACPD and DXG in monkey serum, urine and cerebrospinal fluid (CSF). 2-Fluoro-2',3'-dideoxyinosine (FDDI) served as the internal standard. The extraction recoveries of the nucleoside analogues from serum samples were similar, averaging approximately 90%. The limit of quantitation of the analytical method for serum samples was 0.1 microg/ml for DXG, and 0.25 microg/ml for APD and ACPD. The intra- and inter-day relative standard deviations for each compound at low, medium and high nucleoside concentrations were less than 9.0%. The accuracy of the assay methods was greater than 90% for prodrugs and parent compound. Similar results were observed with urine and CSF samples. Thus, these methods provide sensitive, accurate and reproducible determination of the prodrugs and parent nucleoside in biological samples.