RESUMEN
Psoriasis, a prevalent chronic inflammatory skin ailment affecting approximately 2-3% of the global population, is characterized by persistent symptoms. Dexamethasone, a primary corticosteroid for treating psoriasis, demonstrates notable efficacy; however, its limited skin permeation results in documented adverse effects. To address this, the presented study employed a novel strategy to conjugate gold nanorod and dexamethasone and evaluate their potential for mitigating psoriatic inflammation using an imiquimod-induced mouse model and human skin cells. Our findings revealed enhanced cutaneous penetration of gold nanorod and dexamethasone conjugates compared with that of dexamethasone, owing to superior skin penetration. Gold nanorod and dexamethasone conjugates demonstrated an optimal pharmacological impact at minimal dosages without toxicity during extended use. To further enhance the effectiveness of gold nanorod and dexamethasone conjugates, 808 nm near-infrared laser irradiation, which reacts to gold, was additionally applied to achieve thermal elevation to expedite drug skin penetration. Supplementary laser irradiation at 808 nm significantly ameliorated psoriatic symptoms following deep gold nanorod and dexamethasone conjugates penetration. This corresponded with restored peroxisome proliferator-activated receptor-γ levels and accelerated dexamethasone release from the gold nanorod and dexamethasone conjugates complex. These findings highlight the potential of gold nanorod and dexamethasone conjugates to enhance drug penetration through dermal layers, thereby aiding psoriasis treatment. Moreover, its compatibility with photothermal therapy offers prospects for novel therapeutic interventions across various inflammatory skin disorders.
Asunto(s)
Nanotubos , Psoriasis , Animales , Ratones , Humanos , Terapia Fototérmica , Oro/farmacología , Oro/uso terapéutico , Psoriasis/tratamiento farmacológico , Dexametasona/farmacología , Dexametasona/uso terapéutico , Inflamación/tratamiento farmacológicoAsunto(s)
Dermatitis Atópica , Humanos , Dermatitis Atópica/metabolismo , Interferón gamma , Piel , Células Th2 , Inmunidad , Células TH1RESUMEN
(1) Background: This study aims to elucidate a novel non-transcriptional action of IRF3 in addition to its role as a transcription factor in mast cell activation and associated allergic inflammation; (2) Methods: For in vitro experiments, mouse bone-marrow-derived mast cells (mBMMCs) and a rat basophilic leukemia cell line (RBL-2H3) were used for investigating the underlying mechanism of IRF3 in mast-cell-mediated allergic inflammation. For in vivo experiments, wild-type and Irf3 knockout mice were used for evaluating IgE-mediated local and systemic anaphylaxis; (3) Results: Passive cutaneous anaphylaxis (PCA)-induced tissues showed highly increased IRF3 activity. In addition, the activation of IRF3 was observed in DNP-HSA-treated mast cells. Phosphorylated IRF3 by DNP-HSA was spatially co-localized with tryptase according to the mast cell activation process, and FcεRI-mediated signaling pathways directly regulated that activity. The alteration of IRF3 affected the production of granule contents in the mast cells and the anaphylaxis responses, including PCA- and ovalbumin-induced active systemic anaphylaxis. Furthermore, IRF3 influenced the post-translational processing of histidine decarboxylase (HDC), which is required for granule maturation; and (4) Conclusion: Through this study, we demonstrated the novel function of IRF3 as an important factor inducing mast cell activation and as an upstream molecule for HDC activity.
Asunto(s)
Anafilaxia , Receptores de IgE , Ratas , Ratones , Animales , Receptores de IgE/metabolismo , Mastocitos/metabolismo , Línea Celular , Inflamación/metabolismoRESUMEN
Purpose: The protein corona surrounding nanoparticles has attracted considerable attention as it induces subsequent inflammatory responses. Although mesoporous silica nanoparticles (MSN) are commonly used in medicines, cosmetics, and packaging, the inflammatory effects of the MSN protein corona on the cutaneous system have not been investigated till date. Methods: We examined the greater plasma protein adsorption on MSN leads to serious inflammatory reactions in Dermatophagoides farinae extract (DFE)-induced mouse atopic dermatitis (AD)-like skin inflammation because of increased uptake by keratinocytes. Results: We compare the AD lesions induced by MSN and colloidal (non-porous) silica nanoparticles (CSN), which exhibit different pore architectures but similar dimensions and surface chemistry. MSN-corona treatment of severe skin inflammation in a DFE-induced in vivo AD model greatly increases mouse ear epidermal thickness and infiltration of immune cells compared with the CSN-corona treatment. Moreover, MSN-corona significantly increase AD-specific immunoglobulins, serum histamine, and Th1/Th2/Th17 cytokines in the ear and lymph nodes. MSN-corona induce more severe cutaneous inflammation than CSN by significantly decreasing claudin-1 expression. Conclusion: This study demonstrates the novel impact of the MSN protein corona in inducing inflammatory responses through claudin-1 downregulation and suggests useful clinical guidelines for MSN application in cosmetics and drug delivery systems.
Asunto(s)
Dermatitis Atópica , Nanopartículas , Corona de Proteínas , Adsorción , Animales , Claudina-1/uso terapéutico , Citocinas/metabolismo , Dermatitis Atópica/inducido químicamente , Dermatitis Atópica/tratamiento farmacológico , Histamina , Inmunoglobulina E , Inflamación/tratamiento farmacológico , Ratones , Ratones Endogámicos BALB C , Extractos Vegetales/farmacología , Dióxido de Silicio/uso terapéuticoRESUMEN
Although plasma is a promising technology in various fields, its clinical application is restricted by several limitations. A cold atmospheric plasma (CAP) patch is fabricated to help overcome hurdles, especially when treating skin diseases. This patch has surface dielectric barrier discharge, which generates reactive oxygen species (ROS) and reactive nitrogen species (RNS) on a flexible polymer film surface on which the embedded electrode induces a locally strong electric field. The effect of the CAP patch on psoriasis is also evaluated. The distinct characteristics of psoriasis between the lesion and non-lesion area allow the CAP patch to be suitable for only lesion area for its treatment. The CAP patch induces the opening of calcium channels in keratinocytes, thereby restoring abnormal keratinocyte differentiation and the collapse of the tight junction; thus, alleviating psoriatic symptoms. In addition, the favorable effect is due to the induction of ROS/RNS by the CAP patch, not the electric field generated during plasma generation. The findings indicate that the proposed portable CAP patch can help treat inflammatory skin disorders, especially psoriasis. As this can be used easily as a combination therapy with existing drugs, it may help reduce side effects caused by existing drugs.
Asunto(s)
Gases em Plasma , Gases em Plasma/uso terapéutico , AntiinflamatoriosRESUMEN
Psoriasis, a chronic inflammatory skin disease, is characterized by the excessive proliferation and impaired differentiation of epidermal keratinocytes and is accompanied by the increased infiltration of inflammatory cells. The condition requires longterm treatment and has no definitive cure. Hence, supplements and therapeutic agents have been intensely investigated. Gomisin M2 (GM2), a lignan extracted from Schisandra chinensis (Turcz). Baill. (Schisandraceae; S. chinensis), has demonstrated diverse pharmacological properties, including anticancer, antiinflammatory and antiallergic effects. Based on these findings, the present study examined the effects of GM2 on an imiquimod (IMQ)induced psoriasis mouse model and on keratinocytes stimulated by tumor necrosis factor (TNF)α and interferonγ. IMQ was topically applied to the back skin of mice for 7 consecutive days, and the mice were orally administered CD. These results showed that the oral administration of GM2 suppressed the symptoms of psoriasis, as evidenced by reductions in skin thickness, psoriasis area severity index scores for psoriasis lesions, transepidermal water loss and myeloperoxidase (MPO)associated cell infiltration. Furthermore, GM2 reduced the pathologically increased levels of immunoglobulin G2a, MPO and TNFα in the serum and T helper (Th)1 and Th17 cell populations in the spleen. GM2 decreased the gene expression of inflammatoryrelated cytokines and chemokines and inhibited the expression of signal transducer and activator of transcription 1 and nuclear factorκB in the activated keratinocytes. These results suggested that GM2 from S. chinensis is a potential therapeutic candidate to alleviate psoriasislike skin inflammation.
Asunto(s)
Antiinflamatorios/farmacología , Medicamentos Herbarios Chinos/farmacología , Inflamación/tratamiento farmacológico , Inflamación/metabolismo , Lignanos/farmacología , Psoriasis/tratamiento farmacológico , Psoriasis/metabolismo , Animales , Antiinflamatorios/uso terapéutico , Línea Celular , Citocinas/metabolismo , Modelos Animales de Enfermedad , Medicamentos Herbarios Chinos/uso terapéutico , Femenino , Humanos , Imiquimod/toxicidad , Inflamación/inducido químicamente , Inflamación/genética , Interferón gamma/toxicidad , Queratinocitos/efectos de los fármacos , Queratinocitos/metabolismo , Lignanos/uso terapéutico , Ratones Endogámicos C57BL , FN-kappa B/metabolismo , Psoriasis/inducido químicamente , Psoriasis/patología , Factor de Transcripción STAT1/metabolismo , Transducción de Señal/efectos de los fármacos , Células TH1/efectos de los fármacos , Células Th17/efectos de los fármacos , Factor de Necrosis Tumoral alfa/toxicidadRESUMEN
Psoriasis is a chronic inflammatory skin disease accompanied by excessive keratinocyte proliferation. Corticosteroids, vitamin D3 analogs, and calcineurin inhibitors, which are used to treat psoriasis, have diverse adverse effects, whereas natural products are popular due to their high efficiency and relatively low toxicity. The roots of the Cudrania tricuspidata (C. tricuspidata) are known to have diverse pharmacological effects, among which the anti-inflammatory effect is reported as a potential therapeutic agent in skin cells. Nevertheless, its effectiveness against skin diseases, especially psoriasis, is not fully elucidated. Here, we investigated the effect of cudraxanthone D (CD), extracted from the roots the C. tricuspidata Bureau, on psoriasis using an imiquimod (IMQ)-induced mouse model and the tumor necrosis factor (TNF)-α/interferon (IFN)-γ-activated keratinocytes. IMQ was topically applied to the back skin of C57BL/6 mice for seven consecutive days, and the mice were orally administered with CD. This resulted in reduced psoriatic characteristics, such as the skin thickness and Psoriasis Area Severity Index score, and the infiltration of neutrophils in IMQ-induced skin. CD inhibited the serum levels of TNF-α, immunoglobulin G2a, and myeloperoxidase, and the expression of Th1/Th17 cells in splenocytes. In TNF-α/IFN-γ-activated keratinocytes, CD reduced the expressions of CCL17, IL-1ß, IL-6, and IL-8 by inhibiting the phosphorylation of STAT1 and the nuclear translocation of NF-kB. Taken together, these results suggest that CD could be a potential drug candidate for the treatment of psoriasis.
Asunto(s)
Antiinflamatorios/administración & dosificación , Imiquimod/efectos adversos , Queratinocitos/citología , Moraceae/química , Psoriasis/tratamiento farmacológico , Xantonas/administración & dosificación , Administración Oral , Animales , Antiinflamatorios/farmacología , Línea Celular , Modelos Animales de Enfermedad , Femenino , Humanos , Interferón gamma/efectos adversos , Queratinocitos/efectos de los fármacos , Queratinocitos/inmunología , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos C57BL , FN-kappa B/farmacología , Extractos Vegetales/química , Raíces de Plantas/química , Psoriasis/inducido químicamente , Psoriasis/inmunología , Resultado del Tratamiento , Factor de Necrosis Tumoral alfa/farmacología , Xantonas/farmacologíaRESUMEN
BACKGROUND: Mast cells are the primary cells that play a crucial role in the allergic diseases via secretion of diverse allergic mediators. Ursolic acid (UA) is a naturally occurring anti-inflammatory triterpenoid possessing various biological properties such as immune regulation, antioxidant, and anti-fibrotic. The aim of this study was to evaluate the effects of UA in FcεRI-mediated mast cell activation and allergic inflammation. METHODS: In this study, mast cells were stimulated with immunoglobulin E (IgE) and the anti-allergic effects of UA were assessed by measuring the levels of allergic mediators. In vivo effects of UA were observed by generating passive cutaneous anaphylaxis (PCA) and active systemic anaphylaxis (ASA) in mouse model. RESULTS: We found that UA inhibited the degranulation of mast cell by suppressing the intracellular calcium level in a concentration-dependent manner. UA inhibited the expression and the release of pro-inflammatory cytokines in mast cells. Anti-allergic effects of UA were demonstrated via suppression of FcεRI-mediated signaling molecules. In addition, UA inhibited the IgE-mediated PCA and ovalbumin-induced ASA reactions in a dose-dependent manner. CONCLUSIONS: Based on these findings, we suggest that UA might have potential as a therapeutic candidate for the treatment of allergic inflammatory diseases via inhibition of FcεRI-mediated mast cell activation.
Asunto(s)
Antiinflamatorios/farmacología , Degranulación de la Célula/efectos de los fármacos , Inflamación/metabolismo , Mastocitos/metabolismo , Triterpenos/farmacología , Anafilaxia/inducido químicamente , Anafilaxia/tratamiento farmacológico , Animales , Calcio/metabolismo , Citocinas/metabolismo , Inflamación/tratamiento farmacológico , Masculino , Trastornos de la Activación de los Mastocitos , Mastocitos/efectos de los fármacos , Ratones , Ratones Endogámicos ICR , Ratas , Ratas Sprague-Dawley , Transducción de Señal/efectos de los fármacos , Ácido UrsólicoRESUMEN
The extracts of Schisandra chinensis (Turcz.) Baill. (Schisandraceae) have various therapeutic effects, including inflammation and allergy. In this study, gomisin M2 (GM2) was isolated from S. chinensis and its beneficial effects were assessed against atopic dermatitis (AD). We evaluated the therapeutic effects of GM2 on 2,4-dinitrochlorobenzene (DNCB) and Dermatophagoides farinae extract (DFE)-induced AD-like skin lesions with BALB/c mice ears and within the tumor necrosis factor (TNF)-α and interferon (IFN)-γ-stimulated keratinocytes. The oral administration of GM2 resulted in reduced epidermal and dermal thickness, infiltration of tissue eosinophils, mast cells, and helper T cells in AD-like lesions. GM2 suppressed the expression of IL-1ß, IL-4, IL-5, IL-6, IL-12a, and TSLP in ear tissue and the expression of IFN-γ, IL-4, and IL-17A in auricular lymph nodes. GM2 also inhibited STAT1 and NF-κB phosphorylation in DNCB/DFE-induced AD-like lesions. The oral administration of GM2 reduced levels of IgE (DFE-specific and total) and IgG2a in the mice sera, as well as protein levels of IL-4, IL-6, and TSLP in ear tissues. In TNF-α/IFN-γ-stimulated keratinocytes, GM2 significantly inhibited IL-1ß, IL-6, CXCL8, and CCL22 through the suppression of STAT1 phosphorylation and the nuclear translocation of NF-κB. Taken together, these results indicate that GM2 is a biologically active compound that exhibits inhibitory effects on skin inflammation and suggests that GM2 might serve as a remedy in inflammatory skin diseases, specifically on AD.
Asunto(s)
Antiinflamatorios/farmacología , Ciclooctanos/farmacología , Dermatitis Atópica , Dermatophagoides farinae/inmunología , Dermis/inmunología , Dinitroclorobenceno/toxicidad , Epidermis/inmunología , FN-kappa B/inmunología , Factor de Transcripción STAT1/inmunología , Animales , Antiinflamatorios/química , Ciclooctanos/química , Citocinas/inmunología , Dermatitis Atópica/inducido químicamente , Dermatitis Atópica/tratamiento farmacológico , Dermatitis Atópica/inmunología , Ratones , Ratones Endogámicos BALB CRESUMEN
Specialized proresolving mediators are enzymatically oxygenated natural molecules derived from polyunsaturated fatty acids and are considered novel. These novel mediators include lipoxins from arachidonic acid, resolvins and protectins from omega-3 essential fatty acids, and new maresins. These mediators harbor potent dual proresolving and anti-inflammatory properties. Resolvins and protectins are known to be potent when administered to various inflammation-associated animal models of human diseases. Although psoriasis' etiology remains unknown, there is accumulating evidence indicating that cytokines, including tumor necrosis factor (TNF)-α, interleukin (IL)-23, and IL-17, play pivotal roles in its development. Experimentally, resolvins, maresins, and lipoxins downregulate the cytokine expression of the IL-23/IL-17 axis and inhibition of mitogen-activated protein kinases and nuclear factor kappa-light-chain-enhancer of activated B (NF-κB) cell signaling transduction pathways. Here, we assessed the effects of protectin D1 (PD1) on imiquimod (IMQ)-induced psoriasiform skin inflammation and keratinocytes. PD1 showed clinical improvement in skin thickness, redness, and scaling in psoriasis mouse models. Moreover, PD1 decreased IL-1ß, IL-6, IL-17, and CXCL1 mRNA expressions and reduced STAT1 and NF-κB signaling pathway activation in lesions. Serum myeloperoxidase, IgG2a, IL-1ß, IL-6, IL-17, and TNF-α and spleen CD4+IFN-γ+IL-17+ T lymphocytes were reduced after PD1 treatment in IMQ-induced psoriasiform mouse models. In addition, IL-1ß, IL-6, IL-8, and IL-18BP gene expressions were decreased in PD1-treated keratinocytes. Moreover, a decrease in the expression levels of CCL17 and IL-6 and an inhibition of the STAT1 and NF-κB signaling transduction pathways was observed in keratinocytes. These PD1 anti-inflammatory effects suggest that it is a good therapeutic candidate for psoriasis.
Asunto(s)
Antiinflamatorios/farmacología , Ácidos Docosahexaenoicos/farmacología , Psoriasis/tratamiento farmacológico , Animales , Antiinflamatorios/uso terapéutico , Citocinas/metabolismo , Modelos Animales de Enfermedad , Ácidos Docosahexaenoicos/uso terapéutico , Femenino , Células HaCaT , Humanos , Imiquimod/administración & dosificación , Imiquimod/inmunología , Inyecciones Subcutáneas , Queratinocitos/efectos de los fármacos , Queratinocitos/inmunología , Queratinocitos/metabolismo , Ratones , Fosforilación/efectos de los fármacos , Fosforilación/inmunología , Psoriasis/inmunología , Psoriasis/patología , Factor de Transcripción STAT1/metabolismo , Transducción de Señal/efectos de los fármacos , Transducción de Señal/inmunología , Piel/efectos de los fármacos , Piel/inmunología , Piel/patología , Bazo/citología , Bazo/inmunología , Células TH1/efectos de los fármacos , Células TH1/inmunología , Células Th17/efectos de los fármacos , Células Th17/inmunologíaRESUMEN
Atopic dermatitis (AD) is a chronic inflammatory skin disorder that affects 10-20% of the world's population. Therefore, the discovery of drugs for the treatment of AD is important for human health. Hispidulin (HPD; also known as scutellarein 6-methyl ether or dinatin) is a natural flavone that exerts anti-inflammatory effects. In the present study, the effectiveness of HPD on AD-like skin inflammation was investigated. We used a mouse AD model through repeated exposure of mice to 2,4-dinitrochlorobenzene and house dust mite extract (Dermatophagoides farinae extract, DFE) to the ears. In addition, tumor necrosis factor-α and interferon-γ-activated keratinocytes (HaCaT cells) were used to investigate the underlying mechanism of HPD action. Oral administration of HPD alleviated AD-like skin inflammations: it reduced ear thickness; serum immunoglobulin (Ig)E, DFE-specific IgE, and IgG2a levels; and inflammatory cell infiltration. HPD reduced the expression of pro-inflammatory cytokines and chemokines through inhibition of signal transducer and activator of transcription 1 nuclear factor-κB in HaCaT cells. Taken together, these results suggest that HPD could be a potential drug candidate for the treatment of AD.
Asunto(s)
Antialérgicos/uso terapéutico , Dermatitis Atópica/tratamiento farmacológico , Dinitroclorobenceno , Flavonas/uso terapéutico , Pyroglyphidae/inmunología , Piel/patología , Animales , Antígenos Dermatofagoides , Dermatitis Atópica/inmunología , Dermatitis Atópica/patología , Eosinófilos/efectos de los fármacos , Femenino , Inmunoglobulinas/metabolismo , Queratinocitos/efectos de los fármacos , Mastocitos/efectos de los fármacos , Ratones , Ratones Endogámicos BALB CRESUMEN
Psoriasis is a chronic inflammatory skin disease characterized by hyperproliferation and abnormal differentiation of epidermal keratinocytes accompanied by increased infiltration of immune cells. Previous studies have demonstrated that hispidulin (4',5,7-trihydroxy-6-methoxyflavone, HPD) has various pharmacological benefits such as anti-fungal, anti-inflammation, and anti-allergic effects. This study investigated the effectiveness of HPD to treat psoriasis using an imiquimod (IMQ)-induced mouse model and activated keratinocytes. IMQ was topically applied to the back skin of mice for six consecutive days, and the mice were orally administered HPD. Based on the histological observation and immunological analysis, oral administration of HPD suppressed psoriatic characteristics including skin thickness, psoriasis area severity index, transepidermal water loss, and neutrophil infiltration. HPD alleviated pathologically increased levels of immunoglobulin G2a, myeloperoxidase, and tumor necrosis factor-α. Splenic Th1 and Th17 cell populations were also reduced by HPD in the murine model. In addition, in activated keratinocytes, HPD inhibited gene expression of Th1- and Th17-associated cytokines and chemokines, and phosphorylation of mitogen-activated protein kinases and nuclear factor-κB. In summary, HPD alleviates psoriasis skin inflammation in vivo and in vitro. Therefore, we suggest that HPD would be a potent therapeutic candidate for the treatment of psoriasis.
Asunto(s)
Antiinflamatorios/uso terapéutico , Flavonas/uso terapéutico , Psoriasis/tratamiento farmacológico , Animales , Antiinflamatorios/farmacología , Línea Celular , Citocinas/inmunología , Femenino , Flavonas/farmacología , Humanos , Imiquimod , Queratinocitos/efectos de los fármacos , Ratones Endogámicos C57BL , Proteínas Quinasas Activadas por Mitógenos/inmunología , FN-kappa B/inmunología , Neutrófilos/efectos de los fármacos , Neutrófilos/inmunología , Psoriasis/inducido químicamente , Psoriasis/inmunología , Bazo/efectos de los fármacos , Bazo/inmunología , Células TH1/efectos de los fármacos , Células TH1/inmunología , Células Th17/efectos de los fármacos , Células Th17/inmunologíaRESUMEN
High-salt intake and high-fructose intake are risk factors for hypertension via oxidative stress and inflammation. T helper (Th)17 lymphocytes play an important role in the development of hypertension. Here, we tested the hypothesis that activation of pathogenic Th17 lymphocytes induces hypertension after high-fructose intake in Dahl salt-sensitive (SS) but not Dahl salt-resistant (SR) rats. Eight-week-old male SS and SR rats were offered 20% fructose solution or tap water only for 4â weeks. Systolic blood pressure was measured by the tail-cuff method. T lymphocyte [Th17 and T regulatory (Treg)] profiling was determined via flow cytometry. The expression of Th17-related (IL-17A, IL-17RA, IL-23R and RORγt) and Treg-related (IL-10, CD25, FOXP3 and TGFß) factors were measured via ELISA or qRT-PCR. Th17 lymphocytes isolated from high-fructose-fed SS rats were intraperitoneally injected into recipient SS and SR rats, and recombinant IL-23 protein was subcutaneously injected into SS and SR rats to induce hypertension.High-fructose intake induced hypertension via the activation of pathogenic Th17 lymphocytes in SS but not SR rats. Injection of activated Th17 lymphocytes isolated from fructose-fed SS rats induced hypertension via increase of serum IL-17A only in recipient SS rats. In addition, injection of IL-23 induced hypertension via activation of pathogenic Th17 lymphocytes only in SS rats.Thus, activation of pathogenic Th17 lymphocytes induces hypertension after high-fructose intake in SS but not SR rats. These results indicate that immunologic tolerance plays an important role in protection against hypertension in SR rats.
Asunto(s)
Hipertensión/inmunología , Activación de Linfocitos/inmunología , Células Th17/inmunología , Animales , Presión Sanguínea , Peso Corporal , Citocinas/sangre , Citocinas/metabolismo , Factores de Transcripción Forkhead/metabolismo , Fructosa , Intolerancia a la Glucosa/sangre , Intolerancia a la Glucosa/complicaciones , Intolerancia a la Glucosa/inmunología , Hipertensión/sangre , Hipertensión/complicaciones , Proteínas Inmediatas-Precoces/metabolismo , Interleucina-23/metabolismo , Masculino , Modelos Biológicos , Fosforilación , Proteínas Serina-Treonina Quinasas/metabolismo , Ratas Endogámicas Dahl , Transducción de Señal , Sístole , Linfocitos T Reguladores/inmunologíaRESUMEN
The N-methyl-D-aspartate receptor (NMDAR) exhibits strong voltage-dependent block by extracellular Mg(2+) , which is relieved by sustained depolarization and glutamate binding, and which is central to the function of the NMDAR in synaptic plasticity. Rapid membrane depolarization during agonist application reveals a slow unblock of NMDARs, which has important functional implications, for example in the generation of NMDAR spikes, and in determining the narrow time window for spike-timing-dependent plasticity. However, its mechanism is still unclear. Here, we study unblock of divalent cations in native NMDARs in nucleated patches isolated from mouse cortical layer 2/3 pyramidal neurons. Comparing unblock kinetics of NMDARs in the presence of extracellular Mg(2+) or in nominally zero Mg(2+) , and with Mn(2+) or Co(2+) substituting for Mg(2+) , we found that the properties of slow unblock were determined by the identity of the blocking metal ion at the binding site, presumably by affecting the operation of a structural link to channel gating. The time course of slow unblock was not affected by zinc, or the zinc chelator TPEN [N,N,N',N'-tetrakis-(2-pyridylmethyl)-ethylenediamine], while the slower fraction of unblock was reduced by ifenprodil, an NR2B-selective antagonist. Slow unblock was only weakly temperature dependent, speeding up with rise in temperature with a Q(10) of ≈1.5. Finally, using action potential waveform voltage-clamp, we show that this slow relief from divalent cation block is a prominent feature in physiologically realistic patterns of changing membrane potential.