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We previously found that chronic adenosine A1 receptor stimulation with N6-Cyclopentyladenosine increased α-synuclein misfolding and neurodegeneration in a novel α-synucleinopathy model, a hallmark of Parkinson's disease. Here, we aimed to synthesize a dimer caffeine-indan linked by a 6-carbon chain to cross the blood-brain barrier and tested its ability to bind α-synuclein, reducing misfolding, behavioral abnormalities, and neurodegeneration in our rodent model. Behavioral tests and histological stains assessed neuroprotective effects of the dimer compound. A rapid synthesis of the 18F-labeled analogue enabled Positron Emission Tomography and Computed Tomography imaging for biodistribution measurement. Molecular docking analysis showed that the dimer binds to α-synuclein N- and C-termini and the non-amyloid-ß-component (NAC) domain, similar to 1-aminoindan, and this binding promotes a neuroprotective α-synuclein "loop" conformation. The dimer also binds to the orthosteric binding site for adenosine within the adenosine A1 receptor. Immunohistochemistry and confocal imaging showed the dimer abolished α-synuclein upregulation and aggregation in the substantia nigra and hippocampus, and the dimer mitigated cognitive deficits, anxiety, despair, and motor abnormalities. The 18F-labeled dimer remained stable post-injection and distributed in various organs, notably in the brain, suggesting its potential as a Positron Emission Tomography tracer for α-synuclein and adenosine A1 receptor in Parkinson's disease therapy.
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Cafeína , Receptor de Adenosina A1 , alfa-Sinucleína , alfa-Sinucleína/metabolismo , Animales , Receptor de Adenosina A1/metabolismo , Cafeína/farmacología , Pliegue de Proteína/efectos de los fármacos , Masculino , Ratas , Fármacos Neuroprotectores/farmacología , Simulación del Acoplamiento Molecular , Enfermedad de Parkinson/metabolismo , Enfermedad de Parkinson/tratamiento farmacológico , Enfermedad de Parkinson/patología , Tomografía de Emisión de Positrones/métodos , Conducta Animal/efectos de los fármacosRESUMEN
BACKGROUND AND PURPOSE: Adenosine, through the A1 receptor (A1R), is an endogenous anticonvulsant. The development of adenosine receptor agonists as antiseizure medications has been hampered by their cardiac side effects. A moderately A1R-selective agonist, MRS5474, has been reported to suppress seizures without considerable cardiac action. Hypothesizing that this drug could act through other than A1R and/or through a disease-specific mechanism, we assessed the effect of MRS5474 on the hippocampus. EXPERIMENTAL APPROACH: Excitatory synaptic currents, field potentials, spontaneous activity, [3H]GABA uptake and GABAergic currents were recorded from rodent or human hippocampal tissue. Alterations in adenosine A3 receptor (A3R) density in human tissue were assessed by Western blot. KEY RESULTS: MRS5474 (50-500 nM) was devoid of effect upon rodent excitatory synaptic signals in hippocampal slices, except when hyperexcitability was previously induced in vivo or ex vivo. MRS5474 inhibited GABA transporter type 1 (GAT-1)-mediated γ-aminobutyric acid (GABA) uptake, an action not blocked by an A1R antagonist but blocked by an A3R antagonist and mimicked by an A3R agonist. A3R was overexpressed in human hippocampal tissue samples from patients with epilepsy that had focal resection from surgery. MRS5474 induced a concentration-dependent potentiation of GABA-evoked currents in oocytes micro-transplanted with human hippocampal membranes prepared from epileptic hippocampal tissue but not from non-epileptic tissue, an action blocked by an A3R antagonist. CONCLUSION AND IMPLICATIONS: We identified a drug that activates A3R and has selective actions on epileptic hippocampal tissue. This underscores A3R as a promising target for the development of antiseizure medications.
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The potential role of adenosine, a natural neuroprotective agent, and its receptors in the pathogenesis of Alzheimer's disease has been proposed. The present study aims to examine the effect of administering both an A1 receptor agonist and an A2A adenosine receptor antagonist simultaneously on memory, inflammatory factors, and PSD-95 in an LPS-induced Alzheimer's disease model in rats. Fifty-six male Wistar rats were randomly divided into seven groups: Saline, LPS, Saline + Vehicle, LPS + Vehicle, LPS + SCH58261 (A2A receptor antagonist), LPS + CPA (A1 receptor agonist), LPS + SCH58261+CPA. LPS (3â¯mg/kg/ip) was used to cause memory impairment. Treatment was performed by intraventricular injection of CPA at a dose of 700⯵g and SCH-58261 at 40⯵g for ten days. Passive avoidance and Y-maze tests were performed to examine animals' memories. IL-10, TNF-α, and PSD-95 levels were measured in the brain using ELISA and western blot, respectively. Compared to the groups receiving each medication separately, the simultaneous administration of CPA and SCH58261 improved memory (P<0.05). Additionally, compared to the single medication groups, there was a significant increase in IL-10, PSD-95, and a significant decrease in TNF-α in the brain tissue (P<0.05). These findings suggest that the activation of A1 receptors along with A2A receptor inhibition could be a potential therapeutic strategy for Alzheimer's disease. These findings suggest that A1 receptor activation combined with A2A receptor inhibition may be a promising therapeutic approach for Alzheimer's disease.
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Insomnia is one of the most common sleep disorders, affecting 10-15% of the global population. Because classical remedies used to treat insomnia have various side effects, new therapeutics for insomnia are attracting attention. In the present study, we found that N2-Ethyl-N4-(furan-2-ylmethyl) quinazoline-2,4-diamine (AR-001) has adenosine A1 receptor agonistic activity and exhibits hypnotic efficacy by decreasing sleep onset latency and increasing total sleep time in a pentobarbital-induced sleep model. This hypnotic effect of AR-001 was significantly inhibited by the adenosine A1 receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine (DPCPX). As a result of immunohistochemistry, AR-001 was shown to increase neural activity in the sleep-promoting region, ventrolateral preoptic nucleus (VLPO), and decrease neural activity in the wake-promoting region, basal forebrain (BF), and lateral hypothalamus (LH), and that these effects of AR-001 were significantly inhibited by DPCPX treatment. In addition, AR-001 increased adenosine A1 receptor mRNA levels in the hypothalamus. In conclusion, this study suggests that AR-001 has a hypnotic effect, at least partially, through adenosine A1 receptor and may have therapeutic potential for insomnia.
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Agonistas del Receptor de Adenosina A1 , Hipnóticos y Sedantes , Receptor de Adenosina A1 , Sueño , Animales , Receptor de Adenosina A1/metabolismo , Receptor de Adenosina A1/genética , Masculino , Hipnóticos y Sedantes/farmacología , Sueño/efectos de los fármacos , Agonistas del Receptor de Adenosina A1/farmacología , Quinazolinas/farmacología , Ratas Sprague-Dawley , Ratas , Ratones , Trastornos del Inicio y del Mantenimiento del Sueño/tratamiento farmacológico , Furanos/farmacología , Hipotálamo/efectos de los fármacos , Hipotálamo/metabolismo , Xantinas/farmacología , ARN Mensajero/metabolismo , ARN Mensajero/genética , Antagonistas del Receptor de Adenosina A1/farmacología , Pentobarbital/farmacologíaRESUMEN
N6-clyclohexyladenosine (CHA) is an adenosine A1 receptor agonist that inhibits thermogenesis. Cardiovascular side effects however, limit use of CHA as a therapeutic. We and others have shown that this can be reversed by administering 8-p-(sulfophenyl)theophylline (8-SPT), a nonspecific antagonist that does not cross the BBB. Other evidence shows that CNS actions of CHA may contribute to bradycardia through enhanced vagal tone and other mechanisms. Here we test the hypothesis that 8-SPT pretreatment alone is sufficient to prevent hypotension caused by CHA. To test this hypothesis, we pretreated rats with 8-SPT alone, and in combination with other antagonists to test the hypothesis that direct action of CHA on the heart is the primary mechanism by which CHA induces bradycardia and hypotension. Results show that pretreatment with 8-SPT alone is not sufficient to prevent CHA-induced hypotension. Pretreatment with 8-SPT or atropine alone did not prevent the fall in mean arterial pressure (MAP) and heart rate (HR), however, pretreatment with 8-SPT (25 mg/kg) and atropine (1 mg/kg) 15 min before CHA (1 mg/kg) preserves MAP and HR baseline values after CHA administration. We next asked if blood pressure was managed during the transition into a hypometabolic state, would prolong CHA-mediated inhibition of metabolism after cardiac arrest improve outcome better than anti-shivering medications meperidine and buspirone. We found that CHA-mediated hypotension can be mitigated by pretreatment with atropine and 8-SPT. This combination administered after cardiac arrest facilitated temperature management and metabolic suppression better than meperidine and buspirone, however, did not improve survival.
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Adenosina , Buspirona , Paro Cardíaco , Meperidina , Ratas Sprague-Dawley , Animales , Ratas , Adenosina/análogos & derivados , Adenosina/farmacología , Buspirona/farmacología , Buspirona/uso terapéutico , Masculino , Paro Cardíaco/tratamiento farmacológico , Meperidina/farmacología , Meperidina/análogos & derivados , Meperidina/uso terapéutico , Frecuencia Cardíaca/efectos de los fármacos , Presión Sanguínea/efectos de los fármacos , Teofilina/análogos & derivados , Teofilina/farmacología , Teofilina/uso terapéutico , Resultado del TratamientoRESUMEN
A significant proportion of the world's population suffers from insomnia, a disorder characterized by complications in initiating and maintaining sleep. Many medications used to treat insomnia target the γ-aminobutyric acid (GABA) neurotransmitter system. However, these substances, such as benzodiazepines, induce significant adverse consequences, including dependence and memory impairment, after prolonged use. Thus, current studies are aimed at developing therapeutic hypnotics derived from natural sources that may cause less severe side effects. Heukharang is a variety of lettuce from Korea that was discovered to contain sleep-promoting compounds. Therefore, we investigated the potential effects of sub-chronic administration of Heukharang extract (FSD-LS) on sleep behavior (pentobarbital-induced sleeping test), brain wave activity and sleep architecture (electroencephalography), and physiological behavior (open-field test and rota-rod) in mice, along with radioligand binding assays (GABAA, adenosine A1 and A2A receptors). We found that FSD-LS prolonged the total sleep duration and reduced the onset time of sleep, and enhanced delta wave power and non-rapid eye movement (NREM) sleep duration, all indicating persistent sleep-enhancing effects. FSD-LS lacked adverse effects on the spontaneous locomotor activity and motor coordination of mice, unlike diazepam. Pharmacological blocking using caffeine and bicuculline supported the possible involvement of adenosine receptors in the sleep-promoting effects of FSD-LS, with partial contribution from GABA receptor activity. Overall, our study recommends FSD-LS as a potential source for the development of sleep-aiding therapeutics.
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The mechanisms responsible for glomerular hemodynamic regulation with sodium-glucose co-transporter 2 (SGLT2) inhibitors in kidney disease due to type 2 diabetes remain unclear. Therefore, we investigated changes in glomerular hemodynamic function using an animal model of type 2 diabetes, treated with an SGLT2 inhibitor alone or in combination with a renin-angiotensin-aldosterone system inhibitor using male Zucker lean (ZL) and Zucker diabetic fatty (ZDF) rats. Afferent and efferent arteriolar diameter and single-nephron glomerular filtration rate (SNGFR) were evaluated in ZDF rats measured at 0, 30, 60, 90, and 120 minutes after the administration of a SGLT2 inhibitor (luseogliflozin). Additionally, we assessed these changes under the administration of the adenosine A1 receptor (A1aR) antagonist (8-cyclopentyl-1,3-dipropylxanthine), along with coadministration of luseogliflozin and an angiotensin II receptor blocker (ARB), telmisartan. ZDF rats had significantly increased SNGFR, and afferent and efferent arteriolar diameters compared to ZL rats, indicating glomerular hyperfiltration. Administration of luseogliflozin significantly reduced afferent vasodilatation and glomerular hyperfiltration, with no impact on efferent arteriolar diameter. Urinary adenosine levels were increased significantly in the SGLT2 inhibitor group compared to the vehicle group. A1aR antagonism blocked the effect of luseogliflozin on kidney function. Co-administration of the SGLT2 inhibitor and ARB decreased the abnormal expansion of glomerular afferent arterioles, whereas the efferent arteriolar diameter was not affected. Thus, regulation of afferent arteriolar vascular tone via the A1aR pathway is associated with glomerular hyperfiltration in type 2 diabetic kidney disease.
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Diabetes Mellitus Tipo 2 , Nefropatías Diabéticas , Tasa de Filtración Glomerular , Glomérulos Renales , Inhibidores del Cotransportador de Sodio-Glucosa 2 , Animales , Masculino , Ratas , Antagonistas del Receptor de Adenosina A1/farmacología , Arteriolas/efectos de los fármacos , Arteriolas/fisiopatología , Diabetes Mellitus Experimental/fisiopatología , Diabetes Mellitus Experimental/complicaciones , Diabetes Mellitus Experimental/tratamiento farmacológico , Diabetes Mellitus Tipo 2/complicaciones , Diabetes Mellitus Tipo 2/fisiopatología , Diabetes Mellitus Tipo 2/tratamiento farmacológico , Nefropatías Diabéticas/etiología , Nefropatías Diabéticas/tratamiento farmacológico , Nefropatías Diabéticas/fisiopatología , Tasa de Filtración Glomerular/efectos de los fármacos , Hemodinámica/efectos de los fármacos , Glomérulos Renales/efectos de los fármacos , Glomérulos Renales/fisiopatología , Glomérulos Renales/patología , Glomérulos Renales/irrigación sanguínea , Ratas Zucker , Sistema Renina-Angiotensina/efectos de los fármacos , Transportador 2 de Sodio-Glucosa/metabolismo , Inhibidores del Cotransportador de Sodio-Glucosa 2/farmacología , Sorbitol/análogos & derivados , Xantinas/farmacologíaRESUMEN
We investigated the effects of Lactuca sativa L. extracts (Lactuc) on pentobarbital-induced sleep in mice to elucidate the mechanisms underlying its impact on sleep quality. Mice were randomly assigned to five groups: control, positive control (diazepam 2 mg/kg b.w.), and three groups orally administered with Lactuc (50, 100, and 200 mg/kg b.w.). After 2 weeks of oral administration and intraperitoneal injections, the mice were killed. We found that the Lactuc-administered groups had significantly reduced sleep latency and increased sleep duration compared with the control group. Furthermore, the oral administration of Lactuc induced a significant increase in mRNA expression and protein expression of adenosine A1 receptor in the brains compared with the expressions in the control group. In addition, the Lactuc-administered groups exhibited significantly higher levels of mRNA expressions of GABAA receptors subunits α2, ß2, γ1, and, γ2 in the brain tissue. Therefore, we suggest that Lactuc could be used to develop natural products that effectively improve sleep quality and duration.
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Lactuca , Pentobarbital , Extractos Vegetales , Receptor de Adenosina A1 , Receptores de GABA-A , Sueño , Regulación hacia Arriba , Animales , Extractos Vegetales/farmacología , Extractos Vegetales/administración & dosificación , Pentobarbital/farmacología , Ratones , Receptores de GABA-A/metabolismo , Receptores de GABA-A/genética , Sueño/efectos de los fármacos , Masculino , Receptor de Adenosina A1/metabolismo , Receptor de Adenosina A1/genética , Regulación hacia Arriba/efectos de los fármacos , Lactuca/química , Lactuca/metabolismo , Encéfalo/metabolismo , Encéfalo/efectos de los fármacos , Humanos , Ratones Endogámicos ICR , Duración del SueñoRESUMEN
Organophosphorus nerve agents, such as soman (GD), produce excitotoxic effects resulting in sustained status epilepticus (SSE) and brain damage. Previous work shows that neuronal inhibitory effects of A1 adenosine receptor (A1AR) agonists, such as N6- Bicyclo (2.2.1)-hept-2-yl-5'-chloro-5'-deoxyadenosine (Cl-ENBA), suppresses GD-induced SSE and improves neuropathology. Some other physiologic effects of these agonists are hypothermia, hypotension, and sedation. Hypothermia may also shield the brain from injury by slowing down chemical insults, lessening inflammation, and contributing to improved neurological outcomes. Therefore, we attempted to isolate the hypothermic effect from ENBA by assessing the neuroprotective efficacy of direct surface body cooling in a rat GD-induced SSE model, and comparing the effects on seizure termination, neuropathology, and survival. Male rats implanted with a body temperature (Tb) transponder and electroencephalographic (EEG) electrodes were primed with asoxime (HI-6), exposed to GD 30 min later, and then treated with Cl-ENBA or had Tb lowered directly via body cooling at 30 min after the onset of seizure activity. Afterwards, they were either allowed to develop hypothermia as expected, or received thermal support to maintain normothermic Tb for a period of 6-h. Neuropathology was assessed at 24 h. Regardless of Cl-ENBA or surface cooling, all hypothermic GD-exposed groups had significantly improved 24-h survival compared to rats with normothermic Tb (81% vs. 39%, p < 0.001). Cl-ENBA offered neuroprotection independently of hypothermic Tb. While hypothermia enhanced the overall efficacy of Cl-ENBA by improving survival outcomes, body cooling didn't reduce seizure activity or neuropathology following GD-induced SSE.
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Agonistas del Receptor de Adenosina A1 , Hipotermia Inducida , Ratas Sprague-Dawley , Convulsiones , Soman , Animales , Masculino , Agonistas del Receptor de Adenosina A1/farmacología , Soman/toxicidad , Hipotermia Inducida/métodos , Convulsiones/inducido químicamente , Convulsiones/tratamiento farmacológico , Convulsiones/prevención & control , Ratas , Adenosina/análogos & derivados , Adenosina/farmacología , Temperatura Corporal/efectos de los fármacos , Encéfalo/efectos de los fármacos , Encéfalo/patología , Electroencefalografía , Modelos Animales de EnfermedadRESUMEN
Imaging of the A1 adenosine receptor (A1R) by positron emission tomography (PET) with 8-cyclopentyl-3-(3-[18F]fluoropropyl)-1-propyl-xanthine ([18F]CPFPX) has been widely used in preclinical and clinical studies. However, this radioligand suffers from rapid peripheral metabolism and subsequent accumulation of radiometabolites in the vascular compartment. In the present work, we prepared four derivatives of CPFPX by replacement of the cyclopentyl group with norbornane moieties. These derivatives were evaluated by competition binding studies, microsomal stability assays and LC-MS analysis of microsomal metabolites. In addition, the 18F-labeled isotopologue of 8-(1-norbornyl)-3-(3-fluoropropyl)-1-propylxanthine (1-NBX) as the most promising candidate was prepared by radiofluorination of the corresponding tosylate precursor and the resulting radioligand ([18F]1-NBX) was evaluated by permeability assays with Caco-2 cells and in vitro autoradiography in rat brain slices. Our results demonstrate that 1-NBX exhibits significantly improved A1R affinity and selectivity when compared to CPFPX and that it does not give rise to lipophilic metabolites expected to cross the blood-brain-barrier in microsomal assays. Furthermore, [18F]1-NBX showed a high passive permeability (Pc = 6.9 ± 2.9 × 10-5 cm/s) and in vitro autoradiography with this radioligand resulted in a distribution pattern matching A1R expression in the brain. Moreover, a low degree of non-specific binding (5%) was observed. Taken together, these findings identify [18F]1-NBX as a promising candidate for further preclinical evaluation as potential PET tracer for A1R imaging.
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Tomografía de Emisión de Positrones , Receptor de Adenosina A1 , Xantinas , Receptor de Adenosina A1/metabolismo , Humanos , Animales , Xantinas/química , Xantinas/síntesis química , Ratas , Células CACO-2 , Masculino , Estructura Molecular , Relación Estructura-Actividad , Radiofármacos/química , Radiofármacos/síntesis química , Relación Dosis-Respuesta a Droga , Radioisótopos de Flúor/químicaRESUMEN
Metabolic (dysfunction)-associated steatohepatitis (MASH) is the advanced stage of metabolic (dysfunction)-associated fatty liver disease (MAFLD) lacking approved clinical drugs. Adenosine A1 receptor (A1R), belonging to the G-protein-coupled receptors (GPCRs) superfamily, is mainly distributed in the central nervous system and major peripheral organs with wide-ranging physiological functions; however, the exact role of hepatic A1R in MAFLD remains unclear. Here, we report that liver-specific depletion of A1R aggravates while overexpression attenuates diet-induced metabolic-associated fatty liver (MAFL)/MASH in mice. Mechanistically, activation of hepatic A1R promotes the competitive binding of sterol-regulatory element binding protein (SREBP) cleavage-activating protein (SCAP) to sequestosome 1 (SQSTM1), rather than protein kinase A (PKA) leading to SCAP degradation in lysosomes. Reduced SCAP hinders SREBP1c/2 maturation and thus suppresses de novo lipogenesis and inflammation. Higher hepatic A1R expression is observed in patients with MAFL/MASH and high-fat diet (HFD)-fed mice, which is supposed to be a physiologically adaptive response because A1R agonists attenuate MAFL/MASH in an A1R-dependent manner. These results highlight that hepatic A1R is a potential target for MAFL/MASH therapy.
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Hígado Graso , Receptor de Adenosina A1 , Humanos , Ratones , Animales , Receptor de Adenosina A1/genética , Receptor de Adenosina A1/metabolismo , Hígado Graso/tratamiento farmacológico , Lipogénesis/genética , Dieta Alta en Grasa/efectos adversosRESUMEN
Acute alcoholic hepatitis (AAH) from binge drinking is a serious disease. It is associated with a high mortality rate, especially among young adults. Apoptosis is known to be a primary cause of liver damage, and it can be induced by either intrinsic signaling pathways or by reactive oxygen species (ROS). Adenosine A1 receptors (ADORA1) are known to be involved in ethanol metabolism; however, underlying mechanism is not well understood. For investigating how the intrinsic ADORA1 function in ethanol metabolism in normal human hepatocytes without interference by extrinsic molecules, primary hepatocytes pose a challenge, due to unavoidable contamination by other kinds of cells in the liver. Also, they are difficult to culture stably. As a novel alternative, hepatocytes derived from human-induced pluripotent stem cells were employed because they display similar function to primary hepatocytes and they can be stably cultured. The dynamics and integrity of signal transduction mechanisms were investigated by following chronological changes in gene expression. This shed light on how and when the ADORA1 function and on causal relationships between the pathways and clinical symptoms. The findings of the present study shows that ADORA1 are most activated soon after exposure to ethanol, and transfection of small interfering RNA targeting ADORA1-messenger-RNA (ADORA1-siRNA) into the hepatocytes significantly suppresses production of actin protein and ROS. It suggests that ADORA1 in the liver contribute to apoptosis in acute alcoholism through both intrinsic pathway and ROS activity. Also, actin that is abundant in the cells could be an appropriate biomarker evaluating hepatic function status.
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Alcoholismo , Células Madre Pluripotentes Inducidas , Humanos , Receptor de Adenosina A1/genética , Alcoholismo/genética , Alcoholismo/metabolismo , Especies Reactivas de Oxígeno/metabolismo , Actinas/metabolismo , Células Madre Pluripotentes Inducidas/metabolismo , Hepatocitos/metabolismo , Etanol/farmacologíaRESUMEN
Glutamate is a neurotransmitter that can cause excitatory neurotoxicity when its extracellular concentration is too high, leading to disrupted calcium balance and increased production of reactive oxygen species (ROS). Cordycepin, a nucleoside adenosine derivative, has been shown to protect against excitatory neurotoxicity induced by glutamate. To investigate its potential neuroprotective effects, the present study employed fluorescence detection and spectrophotometry techniques to analyze primary hippocampal-cultured neurons. The results showed that glutamate toxicity reduced hippocampal neuron viability, increased ROS production, and increased intracellular calcium levels. Additionally, glutamate-induced cytotoxicity activated acetylcholinesterase and decreased glutathione levels. However, cordycepin inhibited glutamate-induced cell death, improved cell viability, reduced ROS production, and lowered Ca2+ levels. It also inhibited acetylcholinesterase activation and increased glutathione levels. This study suggests that cordycepin can protect against glutamate-induced neuronal injury in cell models, and this effect was inhibited by adenosine A1 receptor blockers, indicating that its neuroprotective effect is achieved through activation of the adenosine A1 receptor.
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Fármacos Neuroprotectores , Fármacos Neuroprotectores/farmacología , Ácido Glutámico/toxicidad , Ácido Glutámico/metabolismo , Acetilcolinesterasa/metabolismo , Acetilcolinesterasa/farmacología , Especies Reactivas de Oxígeno/metabolismo , Calcio/metabolismo , Apoptosis , Desoxiadenosinas/farmacología , Desoxiadenosinas/metabolismo , Hipocampo/metabolismo , Neuronas/metabolismo , Glutatión/metabolismoRESUMEN
Ethanol is one of the most commonly used and abused substances in the world. While the behavioral effects of ethanol are well characterized, mechanisms of its action on neurons and synapses remain elusive. Prior research suggested that ethanol could affect neurons by interfering with metabolism of biologically active molecules, such as adenosine. Here, we explored the involvement of adenosine A1 receptors (A1R) in mediating ethanol's effects on synaptic transmission to layer 2/3 pyramidal neurons of visual cortex using wild type (WT) and A1R knock-out (KO) mice. Ethanol differentially affected excitatory and inhibitory transmission in WT and KO mice. In slices from WT mice ethanol had heterogeneous effects on excitatory transmission (facilitation, suppression or no change), with no net change. Ethanol's effects remained heterogeneous during acute blockade of A1Rs with a selective antagonist DPCPX. However, in A1RKO mice ethanol consistently suppressed excitatory transmission, with no cases of enhancement observed. Inhibitory transmission was suppressed by ethanol in both WT and A1RKO mice. At both excitatory and inhibitory synapses, changes of response amplitude correlated with changes of paired-pulse ratio, suggesting involvement of presynaptic mechanisms. We conclude that A1Rs are not involved in mediating effects of ethanol on synaptic transmission in mouse visual cortex. However, A1Rs are necessary for development of mechanisms mediating facilitation at some excitatory synapses. Our results add evidence for the diversity of ethanol's effects and mechanisms of action on synaptic transmission in different brain structures, and even in the same brain area (visual cortex) in different species, rats vs mice.
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Etanol , Corteza Visual , Ratas , Ratones , Animales , Etanol/farmacología , Adenosina/metabolismo , Ratones Noqueados , Transmisión Sináptica/fisiología , Sinapsis/metabolismo , Receptores Purinérgicos P1/metabolismo , Corteza Visual/fisiologíaRESUMEN
L-Glutamate (L-Glu) is an amino acid present in the diet that plays a fundamental role in the central nervous system, as the main excitatory neurotransmitter participating in learning and memory processes. In addition, the nucleoside adenosine has a crucial role in L-Glu metabolism, by regulating the liberation of this neurotransmitter through four different receptors: A1, A2A, A2B and A3, which activate (A2A and A2B) or inhibit (A1 and A3) adenylate cyclase pathway. L-Glu at high concentrations can act as a neurotoxin and induce oxidative stress. The study of the oxidative stress correlated with an excess of L-Glu consumption during maternity is key to understand its effects on foetuses and neonates. Previous studies have shown that there is a change in the receptor levels in the brain of pregnant rats and their foetuses when mothers are administered L-Glu during gestation; however, its effect on the cerebellum is unknown. Cerebellum is known to be responsible for motor, cognitive and emotional functions, so its possible involvement after L-Glu consumption is an important issue to study. Therefore, the aim of the present work was to study the effect of L-Glu exposure during gestation and lactation on oxidative stress biomarkers and neurotransmitter receptors from the cerebellum of foetuses and neonates. After maternal L-Glu intake during gestation, oxidative stress was increased, as the ionotropic L-Glu receptors, and GluR1 AMPA subunit levels were altered in foetuses. A1 adenosine receptor suffered changes after L-Glu treatment during gestation, lactation or both, in lactating neonate cerebellum, while adenylate cyclase activity remain unaltered. Further studies will be necessary to elucidate the importance of L-Glu intake and its possible excitotoxicity in the cerebellum of Wistar rats during the pregnancy period and their involvement in long-term neurodegeneration.
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Ácido Glutámico , Efectos Tardíos de la Exposición Prenatal , Humanos , Animales , Ratas , Femenino , Embarazo , Ácido Glutámico/metabolismo , Lactancia , Ácido alfa-Amino-3-hidroxi-5-metil-4-isoxazol Propiónico/metabolismo , Ácido alfa-Amino-3-hidroxi-5-metil-4-isoxazol Propiónico/farmacología , Ratas Wistar , Adenosina/metabolismo , Receptores AMPA , Adenilil Ciclasas/metabolismo , Adenilil Ciclasas/farmacología , Cerebelo/metabolismo , Feto/metabolismo , Estrés Oxidativo , Neurotransmisores/metabolismo , Neurotransmisores/farmacologíaRESUMEN
AIM:To observe the effect of acupuncture on adenosine A1 receptor(A1R)in the caudate puta-men(CPu)of complete Freund's adjuvant(CFA)rats,and to explore the potential mechanism of acupuncture in treat-ment of inflammatory pain.METHODS:Sixty-four 6～8-week-old male Wistar rats were randomly divided into saline group,model group(CFA group),CFA+manual acupuncture(MA)group,CFA+solvent dimethyl sulfoxide(DMSO)group,CFA+A1R agonist 2-chloro-N6-cyclopentyladenosine(CCPA)group,CFA+A1R antagonist 8-cyclopentyl-1,3-di-propylxanthine(DPCPX)group,CFA+MA+DMSO group and CFA+MA+DPCPX group.In MA groups,on the 2nd day af-ter modeling,the rats were needled at Zusanli points on both sides,30 min at a time,once per day,for 7 d.Pain threshold of plantar thermal radiation was used to observe the pain response of the rats.The content of cyclic adenosine monophos-phate(cAMP)in the CPu was detected by ELISA.The protein expression and phosphorylation levels of protein kinase A(PKA)and cAMP response element-binding protein(CREB)were detected by Western blot.The expression of A1R in the CPu was detected by immunofluorescence staining.RESULTS:Compared with saline group,CFA modeling signifi-cantly lowered the thermal pain threshold of the rats(P<0.01).Compared with CFA group,the thermal pain threshold of the rats in CFA+MA group and CFA+CCPA group was significantly increased(P<0.05 or P<0.01).Compared with CFA+ MA+DMSO group,the thermal pain threshold of the rats in CFA+MA+DPCPX group was decreased(P<0.05).Compared with CFA group,A1R protein relative expression level and positive cells in the CPu of the rats in CFA+MA group were in-creased(P<0.05 or P<0.01).Compared with saline group,cAMP content and p-CREB protein level in the CPu of the rats in CFA+MA group were decreased(P<0.05).Compared with CFA+DMSO group,cAMP content and p-CREB pro-tein level in CFA+MA+DMSO and CFA+CCPA groups were significantly decreased(P<0.01).Compared with CFA+MA+ DMSO group,the levels of cAMP,p-PKA and p-CREB in CFA+MA+DPCPX group were significantly increased(P<0.05 or P<0.01).CONCLUSION:Acupuncture on bilateral Zusanli can relieve inflammatory pain in CFA rats,and its mech-anism may be related to A1R/cAMP/p-CREB signaling pathway.
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OBJECTIVES: The goal of the research is to investigate the protocatechuic acid (PCA) potential action, a phenolic acid derivative, on pain induced by neuropathy and to determine its efficacy on activation of KATP type channels and A1 receptors. MATERIALS AND METHODS: Neuropathic pain by cause of sciatic nerve damage was induced in Sprague-Dawley rats. Anti-allodynic and anti-hyperalgesic effects were evaluated with von Frey apparatus and Hargreave's plantar test apparatus, respectively. The effects of PCA at the doses of 75, 150 and 300 mg/kg, carbamazepine at the doses of 50 and 100 mg/kg, combination of low effective doses of PCA and carbamazepine were tested. Pretreatments 3 µg/kg DPCPX as adenosine A1 receptor antagonist and 60.7 nmol glibenclamide as KATP channel blocker were applied for mechanistic studies. RESULTS: PCA showed anti-allodynic and anti-hyperalgesic effects without impairing locomotor activity. In addition, the combination treatment was found to be more effective than the separate individual treatments of drugs. KATP channel activation related with A1 receptor stimulation makes a significant contribution to the anti-allodynia and anti-hyperalgesia induced by PCA. CONCLUSIONS: It can be said that PCA has similar effects with carbamazepine, which is used in clinical practice, and that PCA can take place as an adjuvant drug in neuropathic pain with the combination group. In addition, it is seen that the undesirable effects that drugs can cause alone can be avoided and a more effective treatment potential can be created with multiple mechanisms.
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Neuralgia , Ratas , Animales , Ratas Sprague-Dawley , Neuralgia/tratamiento farmacológico , Hiperalgesia/tratamiento farmacológico , Carbamazepina/uso terapéutico , Adenosina Trifosfato/uso terapéuticoRESUMEN
Chronic inflammation plays an important role in the development of neurodegenerative diseases, such as Parkinson's disease (PD). In the present study, we synthesized 25 novel xanthine derivatives with variable substituents at the N1-, N3- and C8-position as adenosine receptor antagonists with potential anti-inflammatory activity. The compounds were investigated in radioligand binding studies at all four human adenosine receptor subtypes, A1, A2A, A2B and A3. Compounds showing nanomolar A2A and dual A1/A2A affinities were obtained. Three compounds, 19, 22 and 24, were selected for further studies. Docking and molecular dynamics simulation studies indicated binding poses and interactions within the orthosteric site of adenosine A1 and A2A receptors. In vitro studies confirmed the high metabolic stability of the compounds, and the absence of toxicity at concentrations of up to 12.5 µM in various cell lines (SH-SY5Y, HepG2 and BV2). Compounds 19 and 22 showed anti-inflammatory activity in vitro. In vivo studies in mice investigating carrageenan- and formalin-induced inflammation identified compound 24 as the most potent anti-inflammatory derivative. Future studies are warranted to further optimize the compounds and to explore their therapeutic potential in neurodegenerative diseases.
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Neuroblastoma , Animales , Humanos , Ratones , Antiinflamatorios/farmacología , Inflamación , Adenosina , CarrageninaRESUMEN
G-protein coupled receptors (GPCRs) present specific activation pathways and signaling among receptor subtypes. Hence, an extensive knowledge of the structural dynamics of the receptor is critical for the development of therapeutics. Here, we target the adenosine A1 receptor (A1R), for which a negligible number of drugs have been approved. We combine molecular dynamics simulations, enhanced sampling techniques, network theory and pocket detection to decipher the activation pathway of A1R, decode the allosteric networks and identify transient pockets. The A1R activation pathway reveal hidden intermediate and pre-active states together with the inactive and fully-active states observed experimentally. The protein energy networks computed throughout these conformational states successfully unravel the extra and intracellular allosteric centers and the communication pathways that couples them. We observe that the allosteric networks are dynamic, being increased along activation and fine-tuned in presence of the trimeric G-proteins. Overlap of transient pockets and energy networks uncover how the allosteric coupling between pockets and distinct functional regions of the receptor is altered along activation. By an in-depth analysis of the bridge between activation pathway, energy networks and transient pockets, we provide a further understanding of A1R. This information can be useful to ease the design of allosteric modulators for A1R.
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Proteínas de Unión al GTP , Transducción de Señal , Adenosina , Comunicación , ConocimientoRESUMEN
OBJECTIVE: To ensure reproducibility in biomedical research, the biological variable sex must be reported; yet a reason for using male (instead of female) rodents is seldom given. In our search for novel adenosine receptor ligands, our research group routinely determines a test compound's binding affinities at male Sprague-Dawley rat (r) adenosine A1 and A2A receptors via in vitro radioligand binding studies. This pilot study compared the binding affinities of four adenosine receptor ligands (frequently used as reference standards) at male and female adenosine rA1 and rA2A receptors. RESULTS: The inhibition constant (Ki) values determined using female rats correspond well to the values obtained using male rats and no markable difference could be observed in affinity and selectivity of reference standards. For example, DPCPX the selective adenosine A1 receptor antagonist: male rA1Ki: 0.5 ± 0.1 nM versus female rA1Ki: 0.5 ± 0.03 nM; male rA2AKi: 149 ± 23 nM versus female rA2AKi: 135 ± 29 nM. From the limited data at hand, we conclude that even when using female rats for in vitro studies without regard for the oestrous cycle, the obtained data did not vary much from their male counterparts.