Search Results (1,032)

Cardiovascular disease (CVD) is the leading cause of death worldwide, with pathophysiological mechanisms often involving platelet activation and chronic inflammation. While antiplatelet agents targeting adenosine diphosphate (ADP)-mediated pathways are well established in CVD management, less is known about drug interactions with the platelet-activating factor (PAF) pathway, a key mediator of inflammation. This study aimed to evaluate the effects of several commonly used cardiovascular and anti-inflammatory drug classes—including clopidogrel, non-steroidal anti-inflammatory drugs (NSAIDs), angiotensin II receptor blockers (ARBs), β-blockers, and analgesics—on platelet function via both the ADP and PAF pathways. Using human platelet-rich plasma (hPRP) from healthy donors, we assessed platelet aggregation in response to these two agonists in the absence and presence of graded concentrations of each of these drugs or of their usually prescribed combinations. The study identified differential drug effects on platelet aggregation, with some agents showing pathway-specific activity. Clopidogrel and NSAIDs demonstrated expected antiplatelet effects, while some (not all) antihypertensives exhibited additional anti-inflammatory potential. These findings highlight the relevance of evaluating pharmacological activity beyond traditional targets, particularly in relation to PAF-mediated inflammation and thrombosis. This dual-pathway analysis may contribute to a broader understanding of drug mechanisms and inform the development of more comprehensive therapeutic strategies for the prevention and treatment of cardiovascular, hypertension, and inflammation-driven diseases. Full article

Background: Heat therapy (HT) and electroacupuncture (EA) are widely utilized pain relief methods, but the analgesic mechanisms of their combined application remain unclear. Methods: In acetic acid (AA)-induced writhing test and complete Freund’s adjuvant (CFA)-induced inflammatory pain tests, mice received one of three treatments: EA at bilateral ST36, HT via a 45 °C heating pad, or the combination (EA + HT). To probe underlying pathways, separate groups were pretreated with caffeine, DPCPX (a selective adenosine A₁ receptor antagonist), or naloxone (an opioid receptor antagonist). Spinal expression of glial fibrillary acidic protein (GFAP) and phosphorylated p38 (p-p38) was examined by Western blot and immunofluorescence. Results: Both EA and HT individually reduced AA-induced writhing, with the combination (EA + HT) exhibiting the greatest analgesic effect. EA’s analgesic effect was reversed by caffeine and DPCPX and partially by naloxone, while HT’s effect was reversed by caffeine and DPCPX but was unaffected by naloxone. AA injection elevated spinal p-p38 and GFAP expression, which were attenuated by either EA or HT, with the most substantial suppression observed in the EA + HT group. In the CFA model, both treatments alleviated mechanical allodynia, while the combined treatment resulted in significantly greater analgesia compared to either treatment alone. Conclusions: EA combined with HT synergistically enhances analgesia in both AA and CFA pain models, accompanied by reduced spinal inflammation and astrocyte activation. EA’s analgesic effects appear to involve adenosine A₁ receptor pathways and, to a lesser extent, opioid receptor mechanisms, whereas HT’s effects involve adenosine A₁ receptor pathways. Full article

Nephronophthisis (NPH) is the leading genetic cause of end-stage renal disease in children and young adults, but no effective disease-modifying therapies are currently available. Here, we identify glucagon-like peptide-1 (GLP-1) signaling as a novel therapeutic target for NPH through a systematic drug repurposing screen in zebrafish. By simultaneously depleting nphp1 and nphp4, we developed a robust zebrafish model that reproduces key features of human NPH, including glomerular cyst formation. Our screen revealed that dipeptidyl peptidase-4 (DPP4) inhibitors (Omarigliptin and Linagliptin) and GLP-1 receptor agonists (Semaglutide) significantly reduce cystogenesis in a dose-dependent manner. Genetic analysis demonstrated that GLP-1 receptor signaling is important for maintaining pronephros integrity, with gcgra and gcgrb (GLP-1 receptor genes) playing a particularly important role. Transcriptomic profiling identified adenosine receptor A2ab (adora2ab) as a key downstream effector of GLP-1 signaling, which regulates ciliary morphology and prevents cyst formation. Notably, nphp1/nphp4 double mutant zebrafish exhibited the upregulation of gcgra as a compensatory mechanism, which might explain their resistance to cystogenesis. This compensation was disrupted by the targeted depletion of GLP-1 receptors or the inhibition of adenylate cyclase, resulting in enhanced cyst formation, specifically in the mutant background. Our findings establish a signaling cascade from GLP-1 receptors to adora2ab in terms of regulating ciliary organization and preventing cystogenesis, offering new therapeutic opportunities for NPH through the repurposing of FDA-approved medications with established safety profiles. Full article

Adenosine receptors (ARs) are G protein-coupled receptors that are widely expressed across tissues, traditionally associated with cardiovascular, neurological, and immune regulation. Recent studies, however, have highlighted their non-canonical functions, revealing critical roles in metabolism, immunometabolism, and epigenetic regulation. AR subtypes, particularly A2A and A2B, modulate glucose and lipid metabolism, mitochondrial activity, and energy homeostasis. In immune cells, AR signaling influences metabolic reprogramming and polarization through key regulators such as mTOR, AMPK, and HIF-1α, contributing to immune tolerance or activation depending on the context. Additionally, ARs have been implicated in epigenetic modulation, affecting DNA methylation, histone acetylation, and non-coding RNA expression via metabolite-sensitive mechanisms. Therapeutically, AR-targeting agents are being explored for cancer and chronic inflammatory diseases. While clinical trials with A2A antagonists in oncology show encouraging results, challenges remain due to receptor redundancy, systemic effects, and the need for tissue-specific selectivity. Future strategies involve biased agonism, allosteric modulators, and combination therapies guided by biomarker-based patient stratification. Overall, ARs are emerging as integrative hubs connecting extracellular signals with cellular metabolic and epigenetic machinery. Understanding these non-canonical roles may unlock novel therapeutic opportunities across diverse disease landscapes. Full article

Spurred by the enormous therapeutic success of glucagon-like peptide-1 receptor (GLP-1R) agonists (GLP1-RAs) against diabetes and obesity, glucagon family receptor pharmacology has garnered a tremendous amount of interest. Glucagon family receptors, e.g., the glucagon receptor itself (GCGR), the GLP-1R, and the glucose-dependent insulinotropic peptide receptor (GIPR), belong to the incretin receptor superfamily, i.e., receptors that increase blood glucose-dependent insulin secretion. All incretin receptors are class B1 G protein-coupled receptors (GPCRs), coupling to the G_s type of heterotrimeric G proteins which activates adenylyl cyclase (AC) to produce cyclic adenosine monophosphate (cAMP). Most GPCRs undergo desensitization, i.e., uncouple from G proteins and internalize, thanks to interactions with the βarrestins (arrestin-2 and -3). Since the βarrestins can also mediate their own G protein-independent signaling, any given GPCR can theoretically signal (predominantly) either via G proteins or βarrestins, i.e., be a G protein- or βarrestin-“biased” receptor, depending on the bound ligand. A plethora of experimental evidence suggests that the GLP-1R does not undergo desensitization in physiologically relevant tissues in vivo, but rather, it produces robust and prolonged cAMP signals. A particular property of constant cycling between the cell membrane and caveolae/lipid rafts of the GLP-1R may underlie its lack of desensitization. In contrast, GIPR signaling is extensively mediated by βarrestins and the GIPR undergoes significant desensitization, internalization, and downregulation, which may explain why both agonists and antagonists of the GIPR exert the same physiological effects. Here, we discuss this evidence and make a case for the GLP-1R being a phenotypically or functionally G_s-selective receptor. We also discuss the implications of this for the development of GLP-1R poly-ligands, which are increasingly pursued for the treatment of obesity and other diseases. Full article

Equine lutropin hormone/choriogonadotropin receptor (LH/CGR) is a G protein-coupled receptor that binds to both luteinizing hormone and choriogonadotropin, with multiple potential N-linked glycosylation sites in the long extracellular domain region. The roles of these glycosylation sites in hormone binding have been widely studied; however, their relationships with cyclic adenosine monophosphate (cAMP) activation, loss of cell surface receptors, and phosphorylated extracellular signal-regulated kinases1/2 (pERK1/2) expression are unknown. We used site-directed mutagenesis with the substitution of Asn for Gln to alter the consensus sequences for N-linked glycosylation, and cAMP signaling was analyzed in the mutants. Specifically, the N174Q and N195Q mutants exhibited markedly reduced expression levels, reaching approximately 15.3% and 2.5%, respectively, of that observed for wild-type equine LH/CGR. Correspondingly, the cAMP EC₅₀ values were decreased by 7.6-fold and 5.6-fold, respectively. Notably, the N195Q mutant displayed an almost complete loss of cAMP activity, even at high concentrations of recombinant eCG, suggesting a critical role for this glycosylation site in receptor function. Despite these alterations, Western blot analysis revealed that pERK1/2 phosphorylation peaked at 5 min following agonist stimulation across all mutants, indicating that the ERK1/2 signaling pathway remains functionally intact. This study demonstrates that the specific N-linked glycosylation site, N195, in equine LH/CGR is indispensable for cAMP activity but is normally processed in pERK1/2 signaling. Thus, we suggest that in equine LH/CGR, agonist treatment induces biased signaling, differentially activating cAMP signaling and the pERK1/2 pathway. Full article

Cannabis sativa L. is a phytochemically rich plant with therapeutic potential across various clinical domains, including pain, inflammation, and neurological disorders. Among its constituents, terpenes are gaining recognition for their capacity to modulate the pathophysiological processes underlying chronic pain syndromes. Traditionally valued for their aromatic qualities, terpenes such as myrcene, β-caryophyllene (BCP), limonene, pinene, linalool, and humulene have demonstrated a broad spectrum of biological activities. Beyond their observable analgesic, anti-inflammatory, and anxiolytic outcomes, these compounds exert their actions through distinct molecular mechanisms. These include the activation of cannabinoid receptor type 2 (CB₂), the modulation of transient receptor potential (TRP) and adenosine receptors, and the inhibition of pro-inflammatory signalling pathways such as Nuclear Factor kappa-light-chain-enhancer of activated B cells (NF-κB) and Cyclooxygenase-2 (COX-2). This narrative review synthesizes the current preclinical and emerging clinical data on terpene-mediated analgesia, highlighting both monoterpenes and sesquiterpenes, and discusses their potential for synergistic interaction with cannabinoids, the so-called entourage effect. Although preclinical findings are promising, clinical translation is limited by methodological variability, the lack of standardized formulations, and insufficient pharmacokinetic characterization. Further human studies are essential to clarify their therapeutic potential. Full article

This narrative review examines the effects of caffeine on brain health in older adults, with particular attention to its potential for dependence—an often-overlooked issue in geriatric care. Caffeine acts on central adenosine, dopamine, and glutamate systems, producing both stimulating and rewarding effects that can foster tolerance and habitual use. Age-related pharmacokinetic and pharmacodynamic changes prolong caffeine’s half-life and increase physiological sensitivity in the elderly. While moderate consumption may enhance alertness, attention, and possibly offer neuroprotective effects—especially in Parkinson’s disease and Lewy body dementia—excessive or prolonged use may lead to anxiety, sleep disturbances, and cognitive or motor impairment. Chronic exposure induces neuroadaptive changes, such as adenosine receptor down-regulation, resulting in tolerance and withdrawal symptoms, including headache, irritability, and fatigue. These symptoms, often mistaken for typical aging complaints, may reflect a substance use disorder yet remain under-recognized due to caffeine’s cultural acceptance. The review explores caffeine’s mixed role in neurological disorders, being beneficial in some and potentially harmful in others, such as restless legs syndrome and frontotemporal dementia. Given the variability in individual responses and the underestimated risk of dependence, personalized caffeine intake guidelines are warranted. Future research should focus on the long-term cognitive effects and the clinical significance of caffeine use disorder in older populations. Full article

The blood–brain barrier (BBB) is a highly selective interface between the bloodstream and the brain that prevents systemically administered therapeutics from effectively reaching tumor cells. As tumors progress, this barrier undergoes structural and functional alterations, giving rise to the blood–tumor barrier (BTB)—a pathologically modified structure that, despite increased permeability, often exhibits heterogeneous and clinically insufficient drug transport. Although a new generation of therapies is promising, their therapeutic potential cannot be realized unless the challenges posed by these barriers are effectively addressed. Various pharmacological strategies were explored to enhance brain tumor drug delivery. These include receptor-mediated disruption, inhibition of efflux transporters, and the engineering of delivery platforms that leverage endogenous transport pathways—such as carrier-mediated, adsorptive-mediated, and receptor-mediated mechanisms—as well as cell-mediated drug delivery. This review synthesizes (1) the BBB and BTB’s structural characteristics; (2) the influence of the tumor microenvironment (TME) on drug delivery; (3) pharmacological strategies to enhance drug accumulation within brain tumors; (4) the integration of pharmacological methods with neurosurgical techniques to enhance drug delivery. As efforts to improve drug delivery across the BBB and BTB accelerate, this review aims to map the current landscape of pharmacological approaches for enhancing drug penetration into brain tumors. Full article

Cancer remains a leading cause of mortality worldwide, necessitating innovative therapeutic strategies. Drug repurposing offers a cost-effective approach to cancer treatment by identifying new anticancer applications for existing drugs. Terbutaline, a β2-adrenergic receptor agonist, and Milrinone, a phosphodiesterase-3 inhibitor, are traditionally used as positive inotropic agents but have shown potential anticancer effects. This review explores their mechanisms of action in cancer, focusing on their roles in modulating cyclic adenosine monophosphate (cAMP) levels, oxidative stress, and the tumor microenvironment. Terbutaline influences β2-adrenergic signaling, impacting cell proliferation, angiogenesis, and immune evasion. Milrinone, through PDE3 inhibition, elevates cAMP, promoting apoptosis and reducing tumor growth. Both agents exhibit anti-inflammatory and anti-angiogenic properties, suggesting their potential as adjuvant therapies in oncology. Despite promising preclinical data, clinical validation is required to confirm their efficacy and safety in cancer patients. This review highlights the therapeutic promise of repurposing Terbutaline and Milrinone, emphasizing the need for further research to optimize their application in cancer therapy. Full article

Hyperbaric oxygenation (HBO₂) can modify gene and protein expression, signaling pathways, and vascular function, leading to altered vasomotor responses. Adenosine receptors (ARs) may mediate these effects by modulating vasoactivity. This study investigated flow-induced dilation (FID) and hypoxia-induced dilation (HID) in the presence or absence of A1R/A2aR agonists (CCPA and CGS-21680, respectively) and antagonists (DPCPX and SCH-58261, respectively) in isolated middle cerebral arteries (MCAs) from Sprague Dawley rats of both sexes and the direct dose-dependent effects of A1R and A2aR agonists on the vascular reactivity of MCAs. Rats were exposed to either acute HBO₂ (Ac-HBO₂) or intermittent HBO₂ over four days (In-HBO₂). Ac-HBO₂ impaired vascular responses to A1R and A2aR agonists and significantly decreased FID and HID. In both Ac-HBO₂ and In-HBO₂, A1R modulation did not significantly affect FID or HID. A2aR stimulation reduced FID in the In-HBO₂ group, while A2aR antagonism had no significant effect on HID. However, the A2aR agonist’s presence enhanced HID in In-HBO₂-exposed rats. Protein expression of A1R and A2aR decreased after Ac-HBO₂, while gene expression increased following In-HBO₂. These findings suggest that ARs play a role in HBO₂-induced vasoreactivity, which possibly changes in MCA, potentially via the modulation of ARs gene and protein expression. Full article

Over the past decades, bile acids have been recognized as important signaling molecules with significant roles in metabolic health and disease. Many of their beneficial effects are mediated through the activation of the Takeda G protein-coupled receptor 5 (TGR5), a G protein-coupled receptor ubiquitously expressed in both humans and animals. Upon activation, TGR5 stimulates adenylate cyclase, leading to increased cyclic adenosine monophosphate (cAMP) levels and subsequent activation of protein kinase A (PKA). PKA then phosphorylates and activates several downstream signaling pathways, including exchange protein directly activated by cAMP (EPAC), extracellular signal-regulated kinase 1/2 (ERK1/2), and protein kinase B (AKT). Through these pathways, TGR5 acts as a key molecular link between bile acid signaling and the regulation of energy metabolism. TGR5 activation has been associated with body weight loss in obese models, primarily by reducing food intake, enhancing thermogenesis in adipose tissue and muscle to increase energy expenditure, and improving insulin secretion. This review highlights recent advances in our understanding of TGR5 biology and critically examines its therapeutic potential, limitations, and controversies in the context of energy metabolism, offering new perspectives and opportunities for treating metabolic disorders. Full article

Caffeine, one of the most widely consumed bioactive compounds worldwide, is gaining recognition for its potential anticancer properties beyond its well-known neurological and metabolic effects. Mechanistically, caffeine exerts anti-tumor activity by modulating key cellular pathways involved in carcinogenesis, including the inhibition of phosphodiesterases, antagonism of adenosine A2A receptors, and disruption of the DNA damage response through ATR-Chk1 pathway inhibition. These actions collectively promote apoptosis, suppress tumor cell proliferation, and impair metastatic spread. In vitro and in vivo studies have demonstrated that caffeine can enhance the cytotoxic effects of chemotherapeutic agents and radiation therapy, suggesting a synergistic role in conventional cancer treatments. Epidemiological data further supports an inverse association between habitual caffeine consumption and the incidence of several cancers, notably liver, colorectal, breast, and prostate cancers. Among these, the most consistent experimental and clinical evidence exists for liver and colorectal cancer, where caffeine’s modulatory effects on inflammation and cell proliferation have been repeatedly observed. Additionally, caffeine’s anti-oxidant and anti-inflammatory properties may contribute to a microenvironment less conducive to tumor initiation and progression. While promising, the anticancer effects of caffeine are influenced by factors such as dosage, individual genetic variability, and cancer type, underscoring the need for further clinical investigation. This review explores the emerging role of caffeine as a potential chemopreventive and adjuvant therapeutic agent in oncology. Full article

Adenylyl cyclases (ACs) are key regulators of cyclic adenosine monophosphate (cAMP) signaling—a pathway critical for neuroregeneration, synaptic plasticity, and neuronal survival. In both the central and peripheral nervous systems, injury-induced activation of ACs promotes axonal outgrowth and functional recovery through the stimulation of protein kinase A (PKA), exchange proteins directly activated by cAMP (Epac), and cAMP-response element-binding protein (CREB). Among the various AC isoforms, calcium-sensitive AC1, AC8, and AC5, as well as bicarbonate-responsive soluble AC (sAC), have emerged as crucial mediators of neuroplasticity and axon regeneration. These isoforms coordinate diverse cellular responses—including gene transcription, cytoskeletal remodeling, and neurotransmitter release—to metabolic, synaptic, and injury-related signals. Dysregulation of AC activity has been implicated in the pathophysiology of neurodegenerative diseases such as Parkinson’s disease, Alzheimer’s disease, and amyotrophic lateral sclerosis, as well as in chronic pain syndromes. Pharmacological modulation of cAMP levels through AC activation, phosphodiesterase (PDE) inhibition, or pituitary adenylyl cyclase-activating polypeptide (PACAP) receptor signaling has shown therapeutic promise in preclinical models by enhancing neurogenesis, remyelination, and synaptic repair. Conversely, targeted inhibition of specific AC isoforms, particularly AC1, has demonstrated efficacy in reducing maladaptive plasticity and neuropathic pain. This review highlights the diverse roles of ACs in neuronal function and injury response and discusses emerging strategies for their therapeutic targeting. Full article

Background/Objectives: Chronic inflammation and inappropriate NLRP3 inflammasome regulation are related to many brain diseases. Purinergic mediators may play an important role in inflammation regulation and could be targeted for effective therapies for these illnesses. We evaluated resveratrol’s anti-neuroinflammatory potential in BV-2 microglia cells using an innovative in vitro method of NLRP3 inflammasome activation, correlating with the P2X7 purinergic receptor. Methods: In silico analyses were used to estimate resveratrol’s interaction with NLRP3, and its cytotoxicity was measured for 24, 48, and 72 h. Moreover, microglia were exposed to lipopolysaccharide and nigericin to activate the NLRP3 inflammasome and treated with resveratrol between these inflammatory agents. Results: It was found that resveratrol has binding compatible with modulating NLRP3. Specifically, 0.1–25 µM of resveratrol presented a favorable safety profile in BV-2 cells. Microglia exposed to the inflammatory agents had increased levels of oxidative species, the P2X7 receptor, and pro-inflammatory cytokines. However, resveratrol decreased the NLRP3, caspase-1, IL-1β, IL-6, and TNF-α mRNA levels and protein density; on the other hand, IL-10 was increased, acting as a protector, preventing exacerbated inflammation. Under resveratrol exposure, P2X7 was negatively expressed, regulating inflammation to establish homeostasis and microglial proliferation. Additionally, resveratrol activates the A1 adenosine receptor, possibly correlated with neuroprotective effects. Conclusions: We confirmed the anti-neuroinflammatory action of resveratrol via the P2X7 receptor and NLRP3’s combined modulation, regulating the cell cycle and reducing pro-inflammatory and oxidant agents. Considering this pathway, resveratrol could be a candidate for further investigations as a potential treatment against neuroinflammatory diseases. Full article