Adenosine A1 Receptor Research Articles

Efficacy and safety of Piclidenoson in the treatment of plaque psoriasis: a systematic review and meta-analysis of randomized controlled trials.

Psoriasis, an autoimmune inflammatory disease characterized by hyperproliferation of keratinocytes, affects 0.2-4.8% of the global population. The disease manifests primarily as plaque psoriasis, causing chronic physical and psychological burdens. Although numerous treatments exist, there is ongoing exploration for novel therapies due to concerns about the toxicity, efficacy, and costs of current options. An A3 adenosine receptor (A3AR) agonist called Piclidenoson has been shown to reduce inflammation and could be used to treat moderate to severe psoriasis. This meta-analysis evaluates the safety and efficacy of Piclidenoson in psoriasis treatment. This meta-analysis was conducted accordance with the PRISMA guidelines and has been registered on PROSPERO (CRD42024566459). A comprehensive search on Cochrane CENTRAL, PubMed/MEDLINE, and Google Scholar was conducted up to July 2024. Included studies were randomized controlled trials (RCTs) involving Piclidenoson. Efficacy outcomes included PASI 75 and PGA 0 or 1, while safety outcomes included adverse events. Pooled outcomes were presented as odds ratio (OR) with 95% confidence intervals (CI). Statistical analysis employed the Mantel-Haenszel random-effects model, and heterogeneity was assessed using the I2 and X2index. Three RCTs with 574 patients (313 Piclidenoson, 261 placebo) met the inclusion criteria. The pooled analysis showed no significant difference in achieving PASI 75 between Piclidenoson and placebo (OR: 1.62, 95% CI 0.70-3.75, P = 0.26, I2 = 12%). However, Piclidenoson significantly improved PGA scores (OR: 2.74, 95% CI 1.22-6.16, P = 0.01, I²=0%). Safety assessment revealed no significant differences in adverse events, including nervous system, gastrointestinal, musculoskeletal, renal, and infections, compared to placebo. Piclidenoson demonstrates a significant improvement in PGA scores and a favorable safety profile, suggesting it could be a valuable addition to plaque-like psoriasis treatment. Further research with larger, longer-term RCTs is needed to confirm its efficacy and optimize clinical use.

Effects of Acute Haloperidol Treatment on Dopaminergic Markers, GAD67, and A2A Receptors in Rats with High and Low VCMs.

Vacuous chewing movements (VCM) have been utilized as an experimental model of orofacial dyskinesia (OD) in rodents to study the underlying molecular mechanisms related to tardive dyskinesia (TD). This study aimed to investigate if the acute treatment with haloperidol can alter components of the dopaminergic synapse or its modulators such as glutamic acid decarboxylase (GAD67) and adenosine 2A (A2A) receptor. Furthermore, to evaluate if changes in molecular markers are associated with the number of VCMs induced by haloperidol in rats it is proposing a method to classify the animals into High and Low VCM groups. Here, we treated rats with haloperidol decanoate (single injection, intramuscularly, 28mg/Kg of unconjugated haloperidol) and evaluated the number of VCMs after 4 weeks. Haloperidol-treated rats were divided into three groups (Low, High, and Spontaneous VCM) according to the evaluation of the VCM profile proposed here. After, dopamine (DA) levels, monoamine oxidase (MAO) activity, and the immunoreactivity of tyrosine hydroxylase (TH), dopamine transporter (DAT), D2 receptor, GAD67, and A2A were determined in brain structures. No significant differences were found in DA levels, MAO activity, and immunoreactivity of the TH, DAT, D2 receptor, GAD67, and A2A receptor in brain structures. VCM intensity was correlated with TH immunoreactivity in Sn in the High VCM group while it was inversely correlated with the immunoreactivity of the A2A receptor in the striatum of the Spontaneous VCM group. Other significant correlations were found considering the VCM profile suggesting that High VCM after acute haloperidol treatment seems to be associated with the lack of ability to reorganize the neurotransmission in the nigrostriatal pathway. Further studies could clarify the main targets involved in the motor side effects of antipsychotics. The present study demonstrated an easy way to separate the animals into High and Low VCMs.

The Inhibitory Effect of Hedera helix and Coptidis Rhizome Mixture in the Pathogenesis of Laryngopharyngeal Reflux: Cleavage of E-Cadherin in Acid-Exposed Primary Human Pharyngeal Epithelial Cells

Laryngopharyngeal reflux disease (LPRD) is a prevalent upper airway disorder characterized by inflammation and epithelial damage due to the backflow of gastric contents. Current treatments, primarily proton pump inhibitors (PPIs), often show variable efficacy, necessitating the exploration of alternative or adjunctive therapies. This study investigates the therapeutic potential of a mixture of Hedera helix and Coptidis rhizome (HHCR) in mitigating the pathophysiological mechanisms of LPRD. Using an in vitro model of human pharyngeal epithelial cells exposed to acidic conditions, we observed that acid exposure significantly increased the expression of adenosine A3 receptor (adenosine A3) and matrix metalloproteinase-7 (MMP-7), leading to E-cadherin cleavage and compromised epithelial integrity. Treatment with the HHCR mixture effectively suppressed adenosine A3 expression and MMP-7 activity, thereby reducing E-cadherin cleavage and preserving cellular cohesion. These results highlight the HHCR mixture’s ability to modulate the adenosine A3–MMP-7–E-cadherin pathway, suggesting its potential as a valuable adjunctive therapy for LPRD, particularly for patients unresponsive to conventional PPI treatment. This study provides new insights into the molecular interactions involved in LPRD and supports further clinical evaluation of HHCR as a complementary treatment option.

Possible Mechanism for Perception of Auditory-Verbal Hallucinations in Schizophrenia and Approaches to Their Weakening

We put forward a hypothesis that the processing and perception of auditory-verbal hallucinations in schizophrenia — internally generated speech, occurs in the same neural circuits as speech from external sources. These topographically organized cortico—basal ganglia—thalamocortical neural circuits include auditory, language, and frontal neocortical areas. It follows from our proposed mechanism for sound processing, that the increased action on dopamine D2 receptors on striatal neurons, which is considered the cause of hallucinations, should lead to a determined reorganization of activity in these neural circuits. As a result of this reorganization, the inhibition of neurons in the thalamic nuclei, including the internal geniculate body, should decrease synergistically through the direct and indirect pathways in the basal ganglia, and the excitation of connected with them cortical neurons, in the activity of which speech is represented, should increase. From this mechanism it follows that in order to weaken the perception of auditory-verbal hallucinations, it is necessary to increase the inhibition of thalamic neurons. Taking into account the known data on the distribution of receptors of different types on neurons in the striatum, thalamus and neocortex, as well as the previously formulated unified modification rules for the effectiveness of synaptic transmission in different structures, we proposed that agonists of adenosine A1 and muscarinic M4 receptors located on striatonigral spiny cells, giving rise to a direct disinhibitory pathway through the basal ganglia as well as antagonists of delta-opioid and cannabinoid CB1 receptors, located on striatopallidal spiny cells, giving rise to an indirect inhibitory pathway through the basal ganglia may be useful to weaken the perception of hallucinations. In addition, activation of A1 receptors can directly weaken the activity of neurons in the thalamus and neocortex due to the induction of long-term depression in the efficiency of their excitation. Inactivation of cannabinoid CB1 receptors on the projection GABAergic cells of the reticular thalamic nucleus may enhance their inhibitory effect on neurons of different thalamic nuclei. Since the proposed substances only indirectly affect the dopaminergic system, their use should not cause such pronounced side effects as D2 receptor antagonists, antipsychotics that are widely used to suppress auditory-verbal hallucinations.

Short and long-term blockades of adenosine 2A, 5-HT2A, and 5-HT7 receptors induce apoptosis, reduce proliferation, and show differential effects on miR-27b-3p expression in neuroblastoma cell lines.

The first of our aims in this study was to investigate the effects of 5-HT2AR, 5-HT7R, and A2AR blockades on miR-27b-3p expression in the short and long-term in neuroblastoma cells. Our second aim was to reduce the expression of pERK and suppress proliferation by blocking the 5-HT2AR with ketanserin. Our third aim was to reduce the expression of pAKT and induce apoptosis by blocking the A2AR and 5-HT7R with MSX3 and SB269970. Thus, we aimed to investigate the therapeutic efficacy of ketanserin, MSX3 and SB269970, individually or in combination, on neuroblastoma cells. We found that short and long-term blockades of A2A, 5-HT2A, and 5-HT7 receptors had different effects on miR-27b-3p expression. Blockade of A2AR and 5-HT7R with MSX3 and SB269970 decreased miR-27b-3p expression in the short term while increasing it in the long term. Ketanserin increased miR-27b-3p expression in both the short and long term. When 5-HT2AR was blocked with ketanserin, no significant difference was observed in pERK expression and proliferation in the short term. In contrast, a substantial decrease in pERK expression and proliferation was detected in the long term. Our findings show that the MSX3 + SB269970 dual combination and ketanserin + MSX3 + SB269970 triple combination are especially critical in suppressing pAKT expression in the long term. These findings showed that pAKT protein expression induced apoptosis due to decreased in neuroblastoma cells. Our study provides the first evidence for the relationships between ketanserin/miR-27b-3p/pERK, MSX3/miR-27b-3p/pAKT, and SB269970/miR-27b-3p/pAKT in neuroblastoma cells. Ketanserin, MSX3, and SB269970 drug combinations may be promising therapeutic agents in neuroblastoma cells.

Abstract 4139169: Treatment with methotrexate associated with LDL-like nanoparticles prevents the development of left ventricular fibrosis in a spontaneously hypertensive rat model

Introduction: Systemic arterial hypertension (SAH) can lead to left ventricle (LV) fibrosis and ventricular dysfunction. Methotrexate (MTX) associated with lipid nanoparticles (LDE) increases the cellular uptake of MTX by ninety-fold, which leads to therapeutic efficacy and reduces drug toxicity. Previously, treatment of rats with myocardial infarction with LDE-MTX decreased LV fibrosis and prevented ventricular dysfunction. The aim was to test LDE-MTX to preclude the development of cardiac damages caused by hypertension in spontaneously hypertensive rats (SHR). Methods: Twenty-four male rats with six-week-old were allocated in 3 groups: Control (CT): Wistar-Kyoto rats injected with saline; SHR: treated with LDE only and SHR-LDE-MTX: treated with LDE-MTX (1mg/Kg/week, I.P.). After 20 weeks of treatment, echocardiography, morphometry and protein expression were performed in the LV. The data were analyzed by ANOVA with Turkey’s post-test or Kruskal-Wallis test with Dunn's post-test. Linear regression was used to evaluate potential relationships. Results: Compared to CT, the two SHR groups showed dilation (increase in systolic and diastolic diameter); hypertrophy (increased thickness of the posterior wall) and systolic dysfunction (decreased ejection and shortening fractions). Furthermore, the SHR group showed increased LV fibrosis in both the interstitial region and the papillary muscle, possibly resulting from increased of type I collagen content. Treatment of SHR with LDE-MTX had no effect on LV dilation, hypertrophy or systolic dysfunction. However, LDE-MTX decreased LV fibrosis of the interstitial region and the papillary muscle. In addition, LDE-MTX increased the expression of MMP-2, and increased the bioavailability of intracellular adenosine, via increased expression of the adenosine A3 receptor. There was a negative correlation between the expression of the adenosine A3 receptor with interstitial fibrosis (r2=-0.31, p=0.03) and papillary muscle (r2=-0.47, p=0.03), indicating that the increased bioavailability of intracellular adenosine also contributed to the decrease in LV fibrosis in SHR. Conclusion: In SHR, treatment with LDE-MTX reduced LV fibrosis, possibly by modulating MMP-2 expression and increasing the bioavailability of intracellular adenosine, via the adenosine A3 receptor. These results suggest a therapeutic role for LDE-MTX in patients with LV fibrosis and heart failure caused by SAH, to be explored in future clinical studies.

METTL14 regulates inflammation in ulcerative colitis via the lncRNA DHRS4-AS1/miR-206/A3AR axis.

As a chronic inflammatory bowel disease, the pathogenesis of ulcerative colitis (UC) has not been fully elucidated. N6-methyladenosine (m6A) modification, observed in various RNAs, is implicated in inflammatory bowel diseases. Methyltransferase-like 14 (METTL14) is the major subunit of the methyltransferase complex catalyzing m6A modifications. Here, we designated to examine the regulatory effects and mechanisms of METTL14 on long non-coding RNA (lncRNA) during UC progression. METTL14 knockdown decreased cell viability, promoted apoptosis, increased cleaved PARP and cleaved Caspase-3 levels, while reducing Bcl-2 levels. METTL14 knockdown also led to a significant increase in NF-κB pathway activation and inflammatory cytokine production in the Caco-2 cells treated with TNF-α. Moreover, the suppression of METTL14 aggravated colonic damage and inflammation in our dextran sulfate sodium (DSS)-induced murine colitis model. METTL14 silencing suppressed DHRS4-AS1 expression by reducing the m6A modification of DHRS4-AS1 transcripts. Furthermore, DHRS4-AS1 mitigated inflammatory injury by targeting the miR-206/adenosine A3 receptor (A3AR) axis. DHRS4-AS1 overexpression counteracted the enhancing impact of METTL14 knockdown on TNF-α-induced inflammatory injury in Caco-2 cells. In conclusion, our findings suggest that METTL14 protects against colonic inflammatory injury in UC via regulating the DHRS4-AS1/miR-206/A3AR axis, thus representing a potential therapeutic target for UC.

Structural insights into the agonist selectivity of the adenosine A3 receptor

Adenosine receptors play pivotal roles in physiological processes. Adenosine A3 receptor (A3R), the most recently identified adenosine receptor, is expressed in various tissues, exhibiting important roles in neuron, heart, and immune cells, and is often overexpressed in tumors, highlighting the therapeutic potential of A3R-selective agents. Recently, we identified RNA-derived N6-methyladenosine (m6A) as an endogenous agonist for A3R, suggesting the relationship between RNA-derived modified adenosine and A3R. Despite extensive studies on the other adenosine receptors, the selectivity mechanism of A3R, especially for A3R-selective agonists such as m6A and namodenoson, remained elusive. Here, we identify tRNA-derived N6-isopentenyl adenosine (i6A) as an A3R-selective ligand via screening of modified nucleosides against the adenosine receptors. Like m6A, i6A is found in the human body and may be an endogenous A3R ligand. Our cryo-EM analyses elucidate the A3R-Gi complexes bound to adenosine, 5’-N-ethylcarboxamidoadenosine (NECA), m6A, i6A, and namodenoson at overall resolutions of 3.27 Å (adenosine), 2.86 Å (NECA), 3.19 Å (m6A), 3.28 Å (i6A), and 3.20 Å (namodenoson), suggesting the selectivity and activation mechanism of A3R. We further conduct structure-guided engineering of m6A-insensitive A3R, which may aid future research targeting m6A and A3R, providing a molecular basis for future drug discovery.

Synthesis and biological evaluation of sugar-modified truncated carbanucleosides as A2A and A3 adenosine receptor ligands to explore conformational effect to the receptors

Synthesis and biological evaluation of sugar-modified truncated carbanucleosides as A2A and A3 adenosine receptor ligands to explore conformational effect to the receptors

Uncovering the therapeutic potential of green pea waste in breast cancer: a multi-target approach utilizing LC-MS/MS metabolomics, molecular networking, and network pharmacology

Background Pisum sativum(PS) is a universal legume plant utilized for both human and animal consumption, particularly its seeds, known as green peas. The processing of PS in food industries and households produces a significant amount of waste that needs to be valorized.MethodsIn this study, the metabolite profiles of the 70% ethanolic extracts of PS wastes, namely peels (PSP) and a combination of leaves and stems (PSLS), were investigated by liquid chromatography-electrospray ionization-quadrupole time-of-flight tandem mass spectrometry (LC-ESI-QTOF-MS/MS) followed by molecular networking.ResultsDifferent classes of metabolites were identified, being flavonoids and their derivatives, along with phenolic acids, the most abundant categories. Additionally, a comprehensive network pharmacology strategy was applied to elucidate potentially active metabolites, key targets, and the pathways involved in cytotoxic activity against breast cancer. This cytotoxic activity was investigated in MCF-7 and MCF-10a cell lines. Results revealed that PSLS extract exhibited a potent cytotoxic activity with a good selectivity index (IC50 = 17.67 and selectivity index of 3.51), compared to the reference drug doxorubicin (IC50 = 2.69 µg/mL and selectivity index of 5.28). Whereas PSP extract appeared to be less potent and selective (IC50 = 32.92 µg/mL and selectivity index of 1.62). A similar performance was also observed for several polyphenolics isolated from the PSLS extract, including methyl cis p-coumarate, trans p-coumaric acid, and liquiritigenin/ 7-methyl liquiritigenin mixture. Methyl cis p-coumarate showed the most potent cytotoxic activity against MCF-7 cell line and the highest selectivity (IC50 = 1.18 µg/mL (6.91 µM) and selectivity index of 27.42). The network pharmacology study revealed that the isolated compounds could interact with several breast cancer-associated protein targets including carbonic anhydrases 1, 2, 4, 9, and 12, as well as aldo-keto reductase family 1 member B1, adenosine A3 receptor, protein tyrosine phosphatase non-receptor type 1, and estrogen receptor 2.ConclusionThe uncovered therapeutic potential of PSLS and its metabolite constituents pave the way for an efficient and mindful PS waste valorization, calling for further in-vitro and in-vivo research.Graphical

Styrylchromones: Biological Activities and Structure-Activity Relationship.

Styrylchromones (SC) are a group of oxygen-containing heterocyclic compounds, which are characterized by the attachment of a styryl group to the chromone core. SC can be found in nature or can be chemically synthesized in the laboratory. As their presence in nature is scarce, the synthetic origin is the most common. Two types of SC are known: 2-styrylchromones and 3-styrylchromones. However, 2-styrylchromones are the most common, being more commonly found in nature and which chemical synthesis is more commonly described. A wide variety of SC has been described in the literature, with different substituents in different positions, the majority of which are distributed on the A- and/or B-rings. Over the years, several biological activities have been attributed to SC. This work presents a comprehensive review of the biological activities attributed to SC and their structure-activity relationship, based in a published literature search, since 1989. The following biological activities are thoroughly revised and discussed in this review: antioxidant, antiallergic, antiviral, antibacterial, antifungal, anti-inflammatory and antitumoral, affinity and selectivity for A3 adenosine receptors, neuroprotective, and α-glucosidase inhibition. In general, SC are composed by a promising scaffold with great potential for the development of new drugs.

Exploring C2 and N6 Substituent Effects on Truncated 4'-Thioadenosine Derivatives as Dual A2A and A3 Adenosine Receptor Ligands.

Based on high binding affinity of truncated 2-hexynyl-4'-thioadenosine (3a) at both A2A adenosine receptor (AR) and A3 AR, we explored structure-activity relationship (SAR) of the C2-substitution by altering chain length of the 2-hexynyl moiety, thereby evaluating the hydrophobic pocket size. A series of truncated N6-substituted 4'-thioadenosine derivatives with C2-alkynyl substitution were successfully synthesized from D-mannose, using a palladium-catalyzed Sonogashira coupling reaction as the key step, whose structures were confirmed by the X-ray crystal structure of 4h. As the size of the alkynyl group at the C2-position increased, the binding affinity improved; however, when the substituted group was larger than hexynyl, the binding affinity decreased. The introduction of a bulky hydrophobic group such as 3-halobenzyl group at the free N6-amino group decreased the binding affinity at hA2AAR. These results confirm our previous findings that a free amino group at N6-position and longer hydrophobic chain at C2-position are essential for hA2A AR binding affinity. The introduction of a bulky hydrophobic group at free N6-amino group maintained the binding affinity at hA3 AR. The binding mode of truncated 2-substituted-4'-thioadenosine derivatives to hA2A and hA3 AR were predicted by a molecular docking study.

Introduction of asingle-nucleotide variant, rs16851030, into the ADORA1 gene increased cellular susceptibility to hypoxia.

Aim: Rs16851030, a single-nucleotide variant located in the 3'-untranslated region of the ADORA1 gene, has been proposed as a potential marker of caffeine sensitivity in apnea of prematurity. Besides, it is associated with aspirin-induced asthma and the development of acute chest syndrome. However, its functional significance is still unconfirmed. This study aimed to elucidate the functional impact of rs16851030 by using CRISPR/Cas9 approach to induce the DNA variant and attendant physiological changes.Methods: Rs16851030 was introduced into HEK293 cells via homology-directed repair (HDR). Edited cells were fluorescence-enriched, sorted, isolated, and expanded into single-cell-derived clones. The edit was confirmed by Sanger sequencing. RNA sequencing was used to analyze affected pathways.Results: Rs16851030-mutant cells showed increased susceptibility to hypoxia, a condition related to apnea of prematurity. After 24h of hypoxia, the viability of mutant clones 1 and 2 was low compared with wild-type cells (75.45% and 74.47% vs. 96.34%). RNA sequencing revealed transcriptomic changes linked to this increased vulnerability.Conclusion: Rs16851030 impairs cellular resistance to hypoxia, suggesting its role in conditions like apnea of prematurity. Further research should investigate the molecular mechanisms and transcriptomic alterations caused by rs16851030 under hypoxic conditions.

Stereochemical influence of 4ʹ-methyl substitutions on truncated 4ʹ-thioadenosine derivatives: Impact on A3 adenosine receptor binding and antagonism

Herein, we investigated the stereochemical effects of 4ʹ-methyl substitution on A3 adenosine receptor (A3AR) ligands by synthesizing and evaluating a series of truncated 4ʹ-thioadenosine derivatives featuring 4ʹ-α-methyl, 4ʹ-β-methyl, and 4ʹ,4ʹ-dimethyl substitutions. We successfully synthesized these derivatives, using the stereoselective addition of an organometallic reagent, KSAc-mediated sulfur cyclization, and Vorbrüggen condensation. Binding assays demonstrated that the 4ʹ-β-methyl substitution conferred the highest affinity for A3AR, with compound 1 h exhibiting a Ki = 3.5 nM, followed by the 4ʹ,4ʹ-dimethyl and 4ʹ-α-methyl substitutions. Notably, despite the absence of the 5ʹ-OH group, compound 1 h unexpectedly displayed partial agonism. Computational docking studies indicated that compound 1 h, the β-methyl derivative, adopted a South conformation and maintained strong interactions within the receptor, including a critical interaction with Thr94, a residue known to be notable for agonistic effects. Conversely, compound 2 h, the α-methyl derivative, also adopted a South conformation but resulted in a flattened structure that hindered interactions with Thr94 and Asn250. The dimethyl derivative 3 h exhibited steric clashes with Thr94, contributing to a reduction in binding affinity. However, the docking results for 3 h indicated a North conformation, suggesting that the change in sugar conformation due to the additional 4ʹ-methyl group altered the angle between the α-methyl group and the sugar plane, enabling binding despite the increased steric bulk. These findings suggest that not only do the substituents and their stereochemistry influence receptor–ligand interactions, but the conformation and the resulting spatial orientation of the substituents also play a crucial role in modulating receptor–ligand interaction. This stereochemical insight offers a valuable framework for the design of new, selective, and potent A3AR ligands, potentially facilitating the development of novel therapeutics for A3AR-related diseases such as glaucoma, inflammation, and cancer.

Interaction of Purine and its Derivatives with A1, A2-Adenosine Receptors and Vascular Endothelial Growth Factor Receptor-1 (Vegf-R1) as a Therapeutic Alternative to Treat Cancer.

There are several studies that indicate that cancer development may be conditioned by the activation of some biological systems that involve the interaction of different biomolecules, such as adenosine and vascular endothelial growth factor. These biomolecules have been targeted of some drugs for treat of cancer; however, there is little information on the interaction of purine derivatives with adenosine and vascular endothelial growth factor receptor (VEGF-R1). The aim of this research was to determine the possible interaction of purine (1: ) and their derivatives (2-31: ) with A1, A2-adenosine receptors, and VEGF-R1. Theoretical interaction of purine and their derivatives with A1, A2-adenosine receptors and VEGF-R1 was carried out using the 5uen, 5mzj and 3hng proteins as theoretical tools. Besides, adenosine, cgs-15943, rolofylline, cvt-124, wrc-0571, luf-5834, cvt-6883, AZD-4635, cabozantinib, pazopanib, regorafenib, and sorafenib drugs were used as controls. The results showed differences in the number of aminoacid residues involved in the interaction of purine and their derivatives with 5uen, 5mzj and 3hng proteins compared with the controls. Besides, the inhibition constants (Ki) values for purine and their derivatives 5: , 9: , 10: , 14: , 15: , 16: , and 20: were lower compared with the controls CONCLUSIONS: Theoretical data suggest that purine and their derivatives 5: , 9: , 10: , 14: , 15: , 16: , and 20: could produce changes in cancer cell growth through inhibition of A1, A2-adenosine receptors and VEGFR-1 inhibition. These data indicate that these purine derivatives could be a therapeutic alternative to treat some types of cancer.

A1 adenosine receptor evoked Ca2+ signals in astrocytes

Abstract In addition to neurons, glial cells make up the nervous system. These glial cells are divided into macroglial cells - including astrocytes - and microglial cells. Astrocytes have several important functions in the central nervous system, such as synthesizing transmitters and releasing them, thereby activating the surrounding neurons and astrocytes. Astrocytes do not generate action potentials, but they can transmit information to neighboring cells and react to external stimuli by employing Ca2+ dynamics. Increased neuronal activity can lead to an increased extracellular level of adenosine, reflected by a change in the metabolic state. Adenosine is a naturally occurring nucleoside distributed throughout the body as a metabolic intermediary. Its action is mediated by binding to adenosine receptors, such as the G-protein coupled receptors (GPCRs) A1 adenosine receptor. The binding of adenosine to the specific receptor type activates different signaling pathways in astrocytes. In our work, we studied Ca2+ signals generated upon adenosine A1 receptor activation by adding the pathway to the computational astrocyte model by Oschmann et.al (2017). We investigated the influence of the high-affinity A1 adenosine receptor in various astrocyte domains on the regulated Ca2+ release from the endoplasmic reticulum (ER) of astrocytes and concluded that the receptor-dependent pathway contributes to Ca2+ signals mainly in the soma.

Adenosine 2A Receptors Link Astrocytic Alpha-1 Adrenergic Signaling to Wake-Promoting Dopamine Neurons

BACKGROUNDSleep and arousal disorders are common, but the underlying physiology of wakefulness is not fully understood. The locus coeruleus promotes arousal via alpha-1 adrenergic receptor (α1AR) driven recruitment of wake-promoting dopamine (DA) neurons in the ventral periaqueductal gray (vPAGDA neurons). α1AR expression is enriched on vPAG astrocytes, and chemogenetic activation of astrocytic Gq signaling promotes wakefulness. Astrocytes can release extracellular "gliotransmitters," such as ATP and adenosine, but the mechanism underlying how vPAG astrocytic α1ARs influence sleep/wake behavior and vPAGDA neuron physiology is unknown. METHODSIn this study, we utilized genetic manipulations with ex vivo calcium imaging in vPAGDA neurons and astrocytes, patch-clamp electrophysiology, and behavioral experiments in mice to probe our hypothesis that astrocytic α1ARs mediate noradrenergic modulation of wake-promoting vPAGDA neurons via adenosine signaling. RESULTSActivation of α1ARs with phenylephrine increased calcium transients in vPAGDA neurons and vPAG astrocytes, and increased vPAGDA neuron excitability ex vivo. Chemogenetic Gq-DREADD activation of vPAG astrocytes similarly increased vPAGDA neuron calcium activity and intrinsic excitability. Conversely, shRNA knockdown of vPAG astrocytic α1ARs reduced the excitatory effect of phenylephrine on vPAGDA neurons and blunted arousal during the wake phase. Pharmacological blockade of adenosine 2A (A2A) receptors precludes the α1AR-induced increase in vPAGDA calcium activity and excitability in brain slices, as well as the wake-promoting effects of vPAG α1AR activation in vivo. CONCLUSIONSWe have identified a crucial role for vPAG astrocytic α1AR receptors in sustaining arousal through heightened excitability and activity of vPAGDA neurons mediated by local A2A receptors.

Putative Role of Adenosine A1 Receptors in Exogenous Ketone Supplements-Evoked Anti-Epileptic Effect.

Approximately 30% of patients with epilepsy are drug-refractory. There is an urgent need to elucidate the exact pathophysiology of different types of epilepsies and the mechanisms of action of both antiseizure medication and metabolic therapies to treat patients more effectively and safely. For example, it has been demonstrated that exogenous ketone supplement (EKS)-generated therapeutic ketosis, as a metabolic therapy, may decrease epileptic activity in both animal models and humans, but its exact mechanism of action is unknown. However, it was demonstrated that therapeutic ketosis, among others, can increase adenosine level, which may enhance activity of A1 adenosine receptors (A1Rs) in the brain. It has also been demonstrated previously that adenosine has anti-epileptic effect through A1Rs in different models of epilepsies. Thus, it is possible that (i) therapeutic ketosis generated by the administration of EKSs may exert its anti-epileptic effect through, among other mechanisms, increased adenosine level and A1R activity and that (ii) the enhanced activity of A1Rs may be a necessary anti-epileptic mechanism evoked by EKS administration-generated ketosis. Moreover, EKSs can evoke and maintain ketosis without severe side effects. These results also suggest that the therapeutic application of EKS-generated ketosis may be a promising opportunity to treat different types of epilepsies. In this literature review, we specifically focus on the putative role of A1Rs in the anti-epileptic effect of EKS-induced ketosis.

Pharmacology of Adenosine A1 Receptor Agonist in a Humanized Esterase Mouse Seizure Model Following Soman Intoxication

Recently a novel genetically modified mouse strain with serum carboxylesterase knocked-out and the human acetylcholinesterase gene knocked-in (KIKO) was created to simulate human responses to nerve agent (NA) exposure and its standard medical treatment. A1 adenosine receptor (A1AR) agonist N-bicyclo-(2.2.1)-hept-2-yl-5'-chloro-5'-deoxyadenosine (ENBA) alone is a potent anticonvulsant and neuroprotectant (A/N) in both rat and KIKO mouse soman (GD) seizure models. In this study we utilized the KIKO mouse to evaluate further the basic pharmacologic A/N effects of ENBA as an adjunct to standard NA medical treatments (i.e., atropine sulfate, pralidoxime chloride [2-PAM], and midazolam). Male mice, implanted with cortical electroencephalographic (EEG) electrodes, were pretreated with asoxime (HI-6) and exposed to an epileptogenic dose of GD (33 µg/kg, s.c.) or saline (sham exposure) and then treated 15 min after seizure onset with ENBA at 15 mg/kg, i.p. (a minimum efficacy dose in suppressing NA-induced seizure) alone or as an adjunct to standard medical treatments. We collected EEG activity, seizure suppression outcomes, daily body temperature and weight, heart rate, toxic signs, neuropathology, and lethality data for up to 14 days. Without ENBA, death from NA exposure was 45%, while with ENBA, either alone or in combination with midazolam, the survival improved to 80% and 90%, respectively. Additionally, seizure was suppressed quickly and permanently, toxic signs, hypothermia, and bradycardia recovered by 48 h, and no neuropathology was evident. Our findings confirmed that ENBA is a potent A/N adjunct for delayed medical treatments of NA exposure.

Impact of Coffee Intake on Measures of Wellbeing in Mice.

Coffee intake is increasingly recognized as a life-style factor associated with the preservation of health, but there is still a debate on the relative effects of caffeinated and decaffeinated coffee. We now tested how the regular drinking of caffeinated and decaffeinated coffee for 3 weeks impacted on the behavior of male and female adult mice. Males drinking caffeinated coffee displayed statistically significant lower weight gain, increased sensorimotor coordination, greater motivation in the splash test, more struggling in the forced swimming test, faster onset of nest building, more marble burying and greater sociability. Females drinking caffeinated coffee displayed statistically significant increased hierarchy fighting, greater self-care and motivation in the splash test and faster onset of nest building. A post-hoc two-way ANOVA revealed sex-differences in the effects of caffeinated coffee (p values for interaction between the effect of caffeinated coffee and sex) on the hierarchy in the tube test (p = 0.044; dominance), in the time socializing (p = 0.044) and in the latency to grooming (p = 0.048; selfcare), but not in the marble burying test (p = 0.089). Intake of decaffeinated coffee was devoid of effects in males and females. Since caffeine targets adenosine receptors, we verified that caffeinated but not decaffeinated coffee intake increased the density of adenosine A1 receptors (A1R) and increased A1R-mediated tonic inhibition of synaptic transmission in the dorsolateral striatum and ventral but not dorsal hippocampus, the effects being more evident in the ventral hippocampus of females and striatum of males. In contrast, caffeinated and decaffeinated coffee both ameliorated the antioxidant status in the frontal cortex. It is concluded that caffeinated coffee increases A1R-mediated inhibition in mood-related areas bolstering wellbeing of both males and females, with increased sociability in males and hierarchy struggling and self-care in females.