Search Results (182)

Background: Cerebral aneurysm (CA) is a focal or diffuse pathological dilation of the cerebral arterial wall that arises due to various etiological factors. It represents a serious vascular condition, particularly affecting the elderly, and carries a high risk of rupture and neurological morbidity. Clonidine (CL), an α2-adrenergic receptor agonist, has been reported to suppress aneurysm progression; however, its underlying molecular mechanisms, especially in relation to cerebral endothelial dysfunction, remain unclear. This study aimed to investigate the potential of CL to mitigate CA development by modulating apoptosis, inflammation, and oxidative stress in an Angiotensin II (Ang II)-induced endothelial injury model. Methods: Human brain microvascular endothelial cells (HBMECs) were used to establish an in vitro model of endothelial dysfunction by treating cells with 1 µM Ang II for 48 h. CL was administered 2 h prior to Ang II exposure at concentrations of 0.1, 1, and 10 µM. Cell viability was assessed using the MTT assay. Oxidative stress markers, including reactive oxygen species (ROS) and Nitric Oxide (NO), were measured using 2′,7′–dichlorofluorescin diacetate (DCFDA). Gene expression levels of vascular endothelial growth factor (VEGF), matrix metalloproteinases (MMP-2 and MMP-9), high mobility group box 1 (HMGB1), and nuclear factor kappa B (NF-κB) were quantified using RT-qPCR. Levels of proinflammatory cytokines; tumor necrosis factor-alpha (TNF-α), Interleukin-6 (IL-6), and interferon-gamma (IFN-γ); were measured using commercial ELISA kits. Results: Ang II significantly increased ROS production and reduced NO levels, accompanied by heightened proinflammatory cytokine release and endothelial dysfunction. MTT assay revealed a marked decrease in cell viability following Ang II treatment (34.18%), whereas CL preserved cell viability in a concentration-dependent manner: 44.24% at 0.1 µM, 66.56% at 1 µM, and 81.74% at 10 µM. CL treatment also significantly attenuated ROS generation and inflammatory cytokine levels (p < 0.05). Furthermore, the expression of VEGF, HMGB1, NF-κB, MMP-2, and MMP-9 was significantly downregulated in response to CL. Conclusions: CL exerts a protective effect on endothelial cells by reducing oxidative stress and suppressing proinflammatory signaling pathways in Ang II-induced injury. These results support the potential of CL to mitigate endothelial injury in vitro, though further in vivo studies are required to confirm its translational relevance. Full article

Objectives: Recently, increased attention has been given to pumpkin due to its proved nutritional components, which include antioxidant, antifatigue, and anti-inflammatory effects. The aim of the present work was to assess the impact of Cucurbita pepo L. (CP) on chronic unpredictable mild stress (CUMS)-induced changes in lymphoid organs through evaluating its effect on the histological structure of spleen, thymus gland, and lymph nodes compared to the antidepressant fluoxetine (FLU). Materials and Methods: Fifty male albino rats equally distributed into five groups that included control, control + CP, CUMS-exposed, FLU-treated, and CP-treated groups were used in this study. Rats were exposed to CUMS for 4 weeks, and treatment (either with FLU or CP) was started after 14 days of exposure. Behavior of the rats, serum corticosterone, oxidants/antioxidants profile, proinflammatory cytokines, and gene expression of glucocorticoid receptor (GR) and β-adrenergic receptor (β2-AR) were assessed after 28 days. Spleen, thymus gland, and lymph nodes were histopathologically assessed. Results: CP administration significantly reduced the CUMS-induced behavioural changes evident by the significant reduction in immobility time (p = 0.02) and corticosterone level (p < 0.001). Biochemically, CP reduced TNF-α and IL-6 (p < 0.001) and markedly alleviated the changes in oxidants/antioxidants in the serum and lymphoid organs compared to fluoxetine. CP significantly (p < 0.001) reduced CUMS-induced changes in GR and (β2-AR). Histopathologically, CP alleviated changes observed in the spleen, lymph nodes, and thymus gland. It significantly reduced the number of CD4, CD8, CD68, CD20, and caspase-3 immunopositive cells in the studied organs. Conclusions: This study proved the potential efficacy of CP in alleviating depression-associated immunodysregulation either alone or in combination with antidepressant therapy. Full article

Celtis iguanaea, widely used in Brazilian folk medicine, is known for its analgesic and anti-inflammatory properties. This study evaluated the in vitro antioxidant capacity and the in vivo antinociceptive and anti-inflammatory mechanisms of the standardized spray-dried Celtis iguanaea hydroethanolic leaf extract (SDCi). Phytochemical analysis showed that SDCi contains 21.78 ± 0.82 mg/g polyphenols, 49.69 ± 0.57 mg/g flavonoids, and 518.81 ± 18.02 mg/g phytosterols. UFLC-DAD-MS identified iridoid glycosides, p-coumaric acid glycosides, flavones, and unsaturated fatty acids. Antioxidant assays revealed an IC₅₀ of 301.6 ± 38.8 µg/mL for DPPH scavenging and an electrochemical index of 6.1 μA/V. In vivo, SDCi (100–1000 mg/kg, p.o) did not impair locomotor function (rotarod test) but significantly reduced acetic acid-induced abdominal writhing and both phases of the formalin test at higher doses (300 and 1000 mg/kg). The antinociceptive effects were independent of α-2 adrenergic receptors. SDCi also increased latency in the hot-plate test and reduced paw edema in the carrageenan model, accompanied by decreased IL-1β and increased IL-10 levels. Histological analysis showed a 50% reduction in inflammatory cell infiltration. These findings support SDCi as an effective anti-inflammatory and antinociceptive phytopharmaceutical intermediate, with potential applications in managing pain and inflammation. Full article

Recent bioassay studies have unexpectedly supported the high (computationally predicted) binding affinities of angiotensin receptor blockers (ARBs) at α-adrenergic receptors (αARs) in isolated smooth muscle. Computational predictions from ligand docking studies are consistent with very low concentrations of ARBs (e.g., sartans or bisartans) that partially reduce (20–50%) the contractile response to phenylephrine, suggesting that some ARBs may function as partial inverse agonists at αARs. Virtual ligand screening (docking) and molecular dynamics (MD) simulations were carried out to explore the binding affinities and stabilities of selected non-peptide ligands (e.g., ARBs and small-molecule opioids) for several G-protein coupled receptor (GPCR) types, including angiotensin II (AngII) type 1 receptor (AT₁R), α1AR, α2AR, and μ-(µOR) and ժ-opioid receptors (ժOR). Results: All ligands docked preferentially to the binding pocket on the cell surface domain of the GPCR types investigated. Drug binding was characterized by weak interactions (hydrophobic, hydrogen bonding, pi-pi) and stronger ionic and salt-bridge interactions (cation-pi and cation-anion interactions). Ligands specific to each GPCR category showed considerable cross-binding with alternative GPCRs, with small-molecule medications appearing less selective than their peptide or ARB functional equivalents. ARBs that exhibit higher affinities for AT₁R also demonstrate higher affinities for µORs and ժORs than opiate ligands, such as fentanyl and naltrexone. Moreover, ARBs had a higher affinity for αARs than either alpha agonists (epinephrine and phenylephrine) or inhibitors (prazosin and doxazosin). MD simulations of membrane-embedded ARB-GPCR complexes proved stable over nanosecond time scales and suggested that some ARBs may behave as agonists or antagonists depending on the GPCR type. Based on the results presented in this and related investigations, we propose that agonists bind to the resting A-site of GPCRs, while inverse agonists occupy the desensitizing D-site, which partial agonists like morphine and fentanyl share, contributing to addiction. ARBs block both AngII and alpha receptors, suggesting that they are more potent antihypertensive drugs than ACE inhibitors. ARBs have the potential to inhibit morphine tolerance and appear to disrupt receptor desensitization processes, potentially by competing at the D-site. Our results suggest the possible therapeutic potential of ARBs in treating methamphetamine and opiate addictions. Full article

Backgrounds: Approximately 18 million individuals were diagnosed with cancer in 2018. The rate is predicted to exceed 22 million by 2030. Radiotherapy is an essential part of cancer therapy, with well documented local and systemic side effects, including oxidative stress and apoptosis. Kidney tissues are also exposed to the deleterious effects of radiotherapy, resulting in acute or chronic kidney function impairment. This study compared the effects of the potent selective α2-adrenoreceptor agonist dexmedetomidine and amifostine on oxidative stress and apoptosis in kidney damage induced by x-irradiation in rats. Methods: Forty Sprague Dawley rats were assigned into five groups: control, x-irradiation, x-irradiation + amifostine, x-irradiation + dexmedetomidine 100 µg/kg, and X-ray irradiation + dexmedetomidine 200 µg/kg. Results: Necrotic tubules and degenerative Bowman’s capsules were present in the x-irradiation group. An increase was determined in malondialdehyde (MDA), Cleaved Caspase-3, and 8-OHdG levels compared to the control group (p ≤ 0.05). In contrast, there was a decrease in necrotic tubules, degenerative Bowman’s capsules, and the levels of MDA, Cleaved Caspase-3, and 8-OHdG in the amifostine and dexmedetomidine 100 µg/kg and 200 µg/kg treatment groups (p ≤ 0.05). Conclusions: Alpha 2 adrenergic receptor agonists exhibit protective effects against kidney injury induced in association with x-irradiation by reducing oxidative stress and apoptosis. Full article

The adrenergic system plays an active role in modulating synaptic transmission in hypothalamic neurocircuitry. While α2-adrenergic receptors are widely distributed in various organs and are involved in various physiological functions, their specific role in the regulation of energy metabolism in the brain remains incompletely understood. Herein, we investigated the functions of α2-adrenergic receptors in the hypothalamus on energy metabolism in mice. Our study confirmed the expression of α2-adrenergic receptors in hypothalamic dopaminergic neurons and assessed metabolic phenotypes, including food intake and energy expenditure, after treatment with guanabenz, an α2-adrenergic receptor agonist. Guanabenz treatment significantly increased food intake (0.25 ± 0.03 g vs. 0.98 ± 0.05 g, p < 0.001) and body weight (−0.1 ± 0.04 g vs. 0.33 ± 0.03 g, p < 0.001) within 6 h post-treatment. Furthermore, guanabenz markedly elevated energy expenditure parameters, including respiratory exchange ratio (RER, 1.017 ± 0.007 vs. 1.113 ± 0.03, p < 0.01) and carbon dioxide production (1.512 ± 0.018 mL/min vs. 1.635 ± 0.036 mL/min, p < 0.05), compared to vehicle-treated controls. Furthermore, using chemogenetic techniques, we demonstrated that the altered metabolic phenotypes induced by guanabenz treatment were effectively reversed by inhibiting the activity of dopaminergic neurons in the hypothalamic arcuate nucleus (ARC) using a chemogenetic technique. Our findings suggest functional connectivity between hypothalamic α2-adrenergic receptor signals and dopaminergic neurons in metabolic controls. Full article

Background: Most animals display different defensive behavioral strategies during imminent or potential threats. These responses are relevant for understanding human behavioral disorders. In addition, α1 adrenergic receptors (α1ARs) are blocked by prazosin and regulate a diverse set of behaviors, including alcohol drinking related to anxiety in humans, alcohol intake in rats, responses to strong acute stresses (like restraint), and several forms of cognitive flexibility. However, the role of α1ARs in regulating panic-like escape behavior remains unexplored. Methods: Male and female Wistar rats were chronic alcohol drinkers and age-matched alcohol naïves. Animals received an injection of 0.75 mg/kg of prazosin or vehicle and then were exposed to the elevated T maze (ETM) to evaluate avoidance and escape behavior. One week later, animals underwent the light-dark test (LDT) and open field test. Results: α1AR inhibition with prazosin increased latency for escape in male and female alcohol drinkers, with no significant effects in alcohol-naïve controls. There were also interesting impacts from alcohol drinking, including a decrease in ETM avoidance in female but not male drinkers. In addition, prazosin increased latency to enter the dark in LDT in female drinkers and male naïves. Although prazosin also decreased the number of transitions in males, no differences were found in open-field locomotion. Conclusions: These results suggest that α1ARs mediate escape-like behavior in male and female alcohol drinkers, shedding light on a novel therapy for alcohol problems related to panic and anxiety. Full article

Background: Alterations in the adrenergic system have been associated with the pathophysiology of Alzheimer’s disease (AD). A novel α_1A-adrenergic receptor (AR)-positive allosteric modulator (PAM), CCF219B, has been shown to outperform donepezil with rescue of AD cognition/memory deficits with a reduction in amyloid biomarkers and without cardiovascular side effects. Initial pharmacological analysis in transfected cell lines revealed a signal bias with increased efficacy (but not potency) of cAMP signaling and ligand selectivity for norepinephrine (NE). As most GPCR allosteric modulators change the potency of agonists, we hypothesized and now report that CCF219B induced additional aspects of its allosteric interactions with NE that may provide mechanistic insight. Methods: Using Rat-1 fibroblasts stably transfected with α_1A-AR, we determined the activation profile of pERK and p38 messengers by CCF219B in the presence of NE. Using membranes prepared from the stably transfected fibroblasts or from the brain of WT mice or the AD mouse model, hAPP(lon), equilibrium or kinetic radioligand-binding analyses were performed. Results: We identified p-ERK1/2 but not p38 as an additional signal pathway that is potentiated by CCF219B in the presence of NE. An analysis of binding studies of CCF219B in membranes derived from the brains of WT or hAPP(lon) mice revealed profiles that were time-dependent and resulted in an increase in α_1A-AR expression that was unaltered in the presence of cycloheximide or when performed at 37 °C. hAPP(lon) mice displayed a reduction in α_1A-AR-binding sites that were rescued upon prolonged incubation with CCF219B but also displayed a compensatory increase in α_1B/D-AR subtype expression. Binding kinetics reveal that CCF219B can decrease the association rate of ³H-NE but only in the presence of GTP. The association rate increased for the radiolabeled antagonist, ¹²⁵I-HEAT. There were no changes in the dissociation rate of either radiolabel. Conclusions: CCF219B affects the association but not the dissociation rate of NE and explains its ability to increase the active state of the receptor by promoting a pre-coupled conformation, consistent with increasing efficacy but not potency. Potentiation of pERK may contribute to CCF219B’s ability to confer neuroprotection and be pro-cognitive in AD. CCF219B’s ability to increase the expression of α_1A-AR provides a positive feedback loop and strengthens the hypothesis that α₁-AR subtypes may be involved in AD etiology and/or progression. Full article

This study evaluated the effects of α2-adrenergic agonist, prostaglandin F2α analog, and EP2 receptor agonist on tunicamycin-induced endoplasmic reticulum (ER) stress and fibrosis in human trabecular meshwork (TM) cells. Human TM cells were treated with tunicamycin for 24 h, followed by cotreatment with brimonidine (BRI), latanoprost (LAT), or omidenepag (OMD). Immunocytochemistry was used to assess expressions of collagen type I alpha 1 chain (COL1A1), fibronectin, F-actin, and alpha-smooth muscle actin (α-SMA). Western blotting was performed to evaluate levels of C/EBP homologous protein (CHOP), 78-kDa glucose-regulated protein (GRP78), and splicing X-box binding protein-1 (sXBP-1). Real-time qPCR was used to examine the mRNA expressions of COL1A1, connective tissue growth factor (CTGF), fibronectin, α-SMA, CHOP, GRP78, and sXBP-1. Expressions of COL1A1, CTGF, F-actin, fibronectin, α-SMA, CHOP, GRP78, and sXBP-1 significantly increased after tunicamycin treatment. BRI cotreatment significantly downregulated the mRNA and protein expressions of GRP78, and LAT or OMD cotreatment significantly reduced the CHOP and sXBP-1 expressions compared to the tunicamycin-treated group. BRI, LAT, or OMD cotreatment significantly attenuated cellular cytoskeletal changes and the increase of fibrosis markers such as COL1A1, CTGF, fibronectin, and α-SMA. In addition, COL1A1 mRNA expression was significantly lowered with LAT or OMD cotreatment compared to the BRI-cotreated group. Cotreatment with α2-adrenergic agonist, prostaglandin F2α analog, or EP2 receptor agonist alleviates tunicamycin-induced ER stress in human TM cells. Full article

Background/Objectives: To analyze the genotype that predicts the phenotypic characteristics of a cohort of patients with glaucoma and ocular hypertension (OHT) and explore their influence on the response to ocular hypotensive treatment. Methods: This was a prospective study that included 193 eyes of 109 patients with glaucoma or OHT under monotherapy with beta-blockers, prostaglandin, or prostamide analogues (BBs, PGAs, PDs). Eight single-nucleotide polymorphisms were genotyped using real-time PCR assays: prostaglandin-F2α receptor (PTGFR) (rs3766355, rs3753380); beta-2-adrenergic receptor (ADRB2) (rs1042714); and cytochrome P450 2D6 (CYP2D6) (*2 rs16947; *35 rs769258; *4 rs3892097; *9 rs5030656, and *41 rs28371725). The main variables studied were baseline (bIOP), treated (tIOP), and rate of variation in intraocular pressure (vIOP), and mean deviation of the visual field (MD). The metabolizer phenotype and the CYP2D6 copy number variation were also evaluated. Results: In total, 112 eyes were treated with PGAs (58.0%), 59 with BBs (30.6%), and 22 with PDs (11.4%). For PTGFR (rs3753380), statistically significant differences were observed in vIOP in the PGA group (p = 0.032). Differences were also observed for ADRB2 (rs1042714) in MD (p < 0.001) and vIOP (p = 0.017). For CYP2D6, ultrarapid metabolizers exhibited higher tIOP (p = 0.010) and lower vIOP (p = 0.046) compared to the intermediate and poor metabolizers of the BB group. Additionally, systemic treatment metabolized by CYP2D6 showed a significant influence on vIOP (p = 0.019) in this group. Conclusions: These preliminary findings suggest the future potential of pharmacogenetic-based treatments in glaucoma to achieve personalized treatment for each patient, and thus optimal clinical management. Full article

Diabetic retinopathy (DR) is a microvascular complication of diabetes mellitus and a leading cause of blindness in the working-age population. Current pharmacological treatments counteract DR’s later stages without targeting the earlier disease phases. Using computational approaches, our group previously identified the α1D and α2C adrenoceptors (α1DR and α2CR) as new putative drug targets for DR. Therefore, the aim of this work was to validate the role of these receptors in an in vitro model of DR, i.e., retinal pigmented epithelial cells (ARPE-19) challenged with high glucose (HG, 50 mM). We examined the effects of selective α1DR and α2CR agonists and antagonists on hyperglycemia-induced mitochondrial dysfunction and blood retinal barrier breakdown. Seahorse XFe was employed to assess the oxygen consumption rate and extracellular acidification rate. The integrity of the ARPE-19 barrier was evaluated through transepithelial electrical resistance measurements and a sodium fluorescein permeability test. α1DR pharmacological modulation through the α1DR antagonist BMY 7378 (0.1–1 µM, 24 h), but not α2CR, significantly attenuated HG-induced mitochondrial dysfunction. BMY 7378 (0.1–1 µM, 48 h) also prevented HG-mediated damage to retinal epithelial integrity. In contrast, the α1DR agonist phenylephrine (1–10 μM, 24 h) further reduced ARPE-19 mitochondrial activity compared to HG, indicating that α1D activation is directly implicated in DR-mediated mitochondrial dysfunction. In conclusion, the current in vitro study validated α1DR as a pharmacological target for DR. Full article

Astrocytes from different brain regions respond with Ca²⁺ elevations to the catecholamine norepinephrine (NE). However, whether this noradrenergic-mediated signaling is present in astrocytes from the ventral tegmental area (VTA), a dopaminergic circuit receiving noradrenergic inputs, has not yet been investigated. To fill in this gap, we applied a pharmacological approach along with two-photon microscopy and an AAV strategy to express a genetically encoded calcium indicator in VTA astrocytes. We found that VTA astrocytes from both female and male young adult mice showed a strong Ca²⁺ response to NE at both soma and processes. Our results revealed that Gq-coupled α1 adrenergic receptors, which elicit the production of IP3, are the main mediators of the astrocyte response. In mice lacking the IP3 receptor type-2 (IP3R2^−/− mice), we found that the astrocyte response to NE, even if reduced, is still present. We also found that in IP3R2^−/− astrocytes, the residual Ca²⁺ elevations elicited by NE depend on the release of Ca²⁺ from the endoplasmic reticulum, through IP3Rs different from IP3R2. In conclusion, our results reveal VTA astrocytes as novel targets of the noradrenergic signaling, opening to new interpretations of the cellular and molecular mechanisms that mediate the NE effects in the VTA. Full article

Background: Paclitaxel is a widely used anticancer drug for ovarian, lung, breast, and stomach cancers; however, its clinical use is often limited by the side effects of peripheral neuropathy. This study evaluated the effects of Cyperus rotundus (C. rotundus) extract and its active metabolite, α-cyperone, on paclitaxel-induced neuropathic pain. Methods: The oral administration of C. rotundus extract at doses of 500 mg/kg and intraperitoneal administration of α-cyperone at doses of 480 and 800 μg/kg prevented both the development of cold and mechanical pain. Results: The gene and protein expressions of tyrosine hydroxylase and noradrenergic receptors (α1- and α2-adrenergic), which were upregulated by paclitaxel, were significantly downregulated in the C. rotundus extract-treated group. In the locus coeruleus region of the mouse brain, C. rotundus extract administration also reduced the elevated expression of tyrosine hydroxylase induced by paclitaxel. The concentration of α-cyperone in C. rotundus extract was quantified using high-performance liquid chromatography (HPLC). In the group treated with α-cyperone, at levels corresponding to its content in C. rotundus, both cold and mechanical allodynia were effectively prevented. Conclusions: This study suggests that α-cyperone shows potential as a preventive agent for paclitaxel-induced neuropathic pain. Full article

The purpose of this review is to compile and discuss available evidence in humans on the efficacy of YHM supplementation on performance in different exercise modalities. Yohimbine (YHM) is a naturally occurring alkaloid that induces increases in sympathetic nervous system (SNS) activation effectively initiating “fight or flight” responses. In supplement form, YHM is commonly sold as an isolated product or combined into multi-ingredient exercise supplements and is widely consumed in fitness settings despite the lack of empirical support until recently. YHM primarily acts as an α2-adrenergic receptor antagonist effectively increasing norepinephrine release from sympathetic neurons. YHM has been implicated in improving or altering cardiovascular function, blood flow, lactate metabolism, and muscle function. Emerging evidence has suggested that YHM may have the potential to improve performance in a wide range of exercise modes including endurance, sprint, and resistance exercise. Performance enhancement with YHM is mediated by mechanistic underpinnings of physiological and psychological alterations to exercise responses including increased sympathetic activation, adaptive hemodynamic changes, increased alertness, and decreased fatigue. However, YHM use is not without risk as it has high interindividual variability in bioavailability, can be deceptively potent, lacks widely accepted dosing recommendations, and, when taken in large doses, has been empirically documented to result in serious side effects. Despite this, the evidence presented in this review suggests low doses of YHM are tolerable and may serve as an ideal exercise training aid due to acute enhancement of physical performance. However, safety concerns remain outstanding and temperance should be used when using YHM and similar sympathomimetics. Full article

Background/Objectives: The aim of this study is to investigate the effect on choroidal parameters of drug withdrawal in patients taking α1 adrenergic receptor antagonist (ARA) inhibitors. Methods: In total, 32 eyes of 32 patients under alpha-lytic therapy, and 32 eyes of 32 control subjects, both scheduled for cataract surgery in the fellow eye, were included. EDI-OCT was performed in all patients and subfoveal choroidal thickness (SFCT), luminal choroidal area (LCA), stromal choroidal area (SCA), total choroidal area (TCA), and choroidal vascularity index (CVI) during the preoperative visit were compared with data approximately 1 month after alpha-lytic withdrawal. The same assessments were performed in the control group. Results: SFCT and LCA were significantly reduced in the patients 1 month after alfa-lytic therapy withdrawal (p < 0.05), whereas in the control group, no changes in choroidal parameters were observed. Conclusions: The data proved that α1ARA inhibitors affected choroidal vessels, whereas no modification of choroidal stroma was observed. Full article