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PURPOSE: Asthma is a heterogeneous disease with a wide range of symptoms. Severe asthma exacerbations (SAEs) are characterized by worsening symptoms and bronchospasm requiring emergency department visits. In addition to conventional strategies for SAEs (inhaled ß-agonists, anticholinergics, and systemic corticosteroids), another pharmacological option is represented by ketamine. We performed a systematic review to explore the role of ketamine in refractory SAEs. METHODS: We performed a systematic search on PubMed and EMBASE up to August 12th, 2021. We selected prospective studies only, and outcomes of interest were oxygenation/respiratory parameters, clinical status, need for invasive ventilation and effects on weaning. RESULTS: We included a total of seven studies, five being randomized controlled trials (RCTs, population range 44-92 patients). The two small prospective studies (n = 10 and n = 11) did not have a control group. Four studies focused on adults, and three enrolled a pediatric population. We found a large heterogeneity regarding sample size, age and gender distribution, inclusion criteria (different severity scores, if any) and ketamine dosing (bolus and/or continuous infusion). Of the five RCTs, three compared ketamine to placebo, while one used fentanyl and the other aminophylline. The outcomes evaluated by the included studies were highly variable. Despite paucity of data and large heterogeneity, an overview of the included studies suggests absence of clear benefit produced by ketamine in patients with refractory SAE, and some signals towards side effects. CONCLUSION: Our systematic review does not support the use of ketamine in refractory SAE. A limited number of prospective studies with large heterogeneity was found. Well-designed multicenter RCTs are desirable.
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Antiasmáticos , Asma , Ketamina , Corticosteroides , Adulto , Aminofilina/efeitos adversos , Asma/tratamento farmacológico , Criança , Antagonistas Colinérgicos/uso terapêutico , Fentanila/uso terapêutico , Humanos , Ketamina/uso terapêutico , Estudos Multicêntricos como Assunto , Estudos ProspectivosRESUMO
BACKGROUND: Extracorporeal membrane oxygenation (ECMO) represents an advanced option for supporting refractory respiratory and/or cardiac failure. Systemic anticoagulation with unfractionated heparin (UFH) is routinely used. However, patients with bleeding risk and/or heparin-related side effects may necessitate alternative strategies: among these, nafamostat mesilate (NM) has been reported. METHODS: We conducted a systematic literature search (PubMed and EMBASE, updated 12/08/2021), including all studies reporting NM anticoagulation for ECMO. We focused on reasons for starting NM, its dose and the anticoagulation monitoring approach, the incidence of bleeding/thrombosis complications, the NM-related side effects, ECMO weaning, and mortality. RESULTS: The search revealed 11 relevant findings, all with retrospective design. Of these, three large studies reported a control group receiving UFH, the other were case series (n = 3) or case reports (n = 5). The main reason reported for NM use was an ongoing or high risk of bleeding. The NM dose varied largely as did the anticoagulation monitoring approach. The average NM dose ranged from 0.46 to 0.67 mg/kg/h, but two groups of authors reported larger doses when monitoring anticoagulation with ACT. Conflicting findings were found on bleeding and thrombosis. The only NM-related side effect was hyperkalemia (n = 2 studies) with an incidence of 15%-18% in patients anticoagulated with NM. Weaning and survival varied across studies. CONCLUSION: Anticoagulation with NM in ECMO has not been prospectively studied. While several centers have experience with this approach in high-risk patients, prospective studies are warranted to establish the optimal space of this approach in ECMO.
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Oxigenação por Membrana Extracorpórea , Trombose , Humanos , Oxigenação por Membrana Extracorpórea/efeitos adversos , Heparina/efeitos adversos , Anticoagulantes/efeitos adversos , Estudos Retrospectivos , Hemorragia/etiologia , Trombose/etiologia , Trombose/prevenção & controle , Trombose/tratamento farmacológicoRESUMO
BACKGROUND AND AIMS: There is poor knowledge on characteristics, comorbidities and laboratory measures associated with risk for adverse outcomes and in-hospital mortality in European Countries. We aimed at identifying baseline characteristics predisposing COVID-19 patients to in-hospital death. METHODS AND RESULTS: Retrospective observational study on 3894 patients with SARS-CoV-2 infection hospitalized from February 19th to May 23rd, 2020 and recruited in 30 clinical centres distributed throughout Italy. Machine learning (random forest)-based and Cox survival analysis. 61.7% of participants were men (median age 67 years), followed up for a median of 13 days. In-hospital mortality exhibited a geographical gradient, Northern Italian regions featuring more than twofold higher death rates as compared to Central/Southern areas (15.6% vs 6.4%, respectively). Machine learning analysis revealed that the most important features in death classification were impaired renal function, elevated C reactive protein and advanced age. These findings were confirmed by multivariable Cox survival analysis (hazard ratio (HR): 8.2; 95% confidence interval (CI) 4.6-14.7 for age ≥85 vs 18-44 y); HR = 4.7; 2.9-7.7 for estimated glomerular filtration rate levels <15 vs ≥ 90 mL/min/1.73 m2; HR = 2.3; 1.5-3.6 for C-reactive protein levels ≥10 vs ≤ 3 mg/L). No relation was found with obesity, tobacco use, cardiovascular disease and related-comorbidities. The associations between these variables and mortality were substantially homogenous across all sub-groups analyses. CONCLUSIONS: Impaired renal function, elevated C-reactive protein and advanced age were major predictors of in-hospital death in a large cohort of unselected patients with COVID-19, admitted to 30 different clinical centres all over Italy.
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Betacoronavirus , Doenças Cardiovasculares/etiologia , Infecções por Coronavirus/mortalidade , Mortalidade Hospitalar , Aprendizado de Máquina , Pneumonia Viral/mortalidade , Adolescente , Adulto , Fatores Etários , Idoso , Idoso de 80 Anos ou mais , Proteína C-Reativa/análise , COVID-19 , Feminino , Taxa de Filtração Glomerular , Humanos , Masculino , Pessoa de Meia-Idade , Pandemias , Estudos Retrospectivos , Fatores de Risco , SARS-CoV-2 , Análise de Sobrevida , Adulto JovemRESUMO
The study of strial pericytes has gained great interest as they are pivotal for the physiology of stria vascularis. To provide an easily accessible in vitro model, here we described a growth medium-based approach to obtain and cultivate primary bovine cochlear pericytes (BCP) from the stria vascularis of explanted bovine cochleae. We obtained high-quality pericytes in 8-10 days with a > 90% purity after the second passage. Immunocytochemical analysis showed a homogeneous population of cells expressing typical pericyte markers, such as neural/glial antigen 2 (NG2), platelet-derived growth factor receptorß (PDGFRß), α-smooth muscle actin (α-SMA), and negative for the endothelial marker von Willebrand factor. When challenged with tumor necrosis factor or lipopolysaccharide, BCP changed their shape, similarly to human retinal pericytes (HRPC). The sensitivity of BCP to ototoxic drugs was evaluated by challenging with cisplatin or gentamicin for 48 hr. Compared to human retinal endothelial cells and HRPC, cell viability of BCP was significantly lower ( p < 0.05) after the treatment with gentamicin or cisplatin. These data indicate that our protocol provides a simple and reliable method to obtain highly pure strial BCP. Furthermore, BCP are suitable to assess the safety profile of molecules which supposedly exert ototoxic activity, and may represent a valid alternative to in vivo tests.
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Cóclea/citologia , Pericitos/citologia , Estria Vascular/citologia , Actinas/metabolismo , Animais , Antígenos/metabolismo , Biomarcadores/metabolismo , Bovinos , Técnicas de Cultura de Células/métodos , Sobrevivência Celular , Cisplatino/toxicidade , Cóclea/efeitos dos fármacos , Cóclea/metabolismo , Meios de Cultura , Avaliação Pré-Clínica de Medicamentos/métodos , Gentamicinas/toxicidade , Técnicas In Vitro , Modelos Biológicos , Ototoxicidade/etiologia , Ototoxicidade/metabolismo , Ototoxicidade/patologia , Pericitos/efeitos dos fármacos , Pericitos/metabolismo , Proteoglicanas/metabolismo , Receptor beta de Fator de Crescimento Derivado de Plaquetas/metabolismo , Estria Vascular/efeitos dos fármacos , Estria Vascular/metabolismoRESUMO
BACKGROUND: Propofol is the most commonly used hypnotic agent used during sedation and general anesthesia (GA) practice, offering faster recovery compared to benzodiazepines. However, cardiovascular impact of propofol and pain at injection are commonly encountered side effects. Ciprofol is a novel disubstituted phenol derivative, and there is growing evidence regarding its clinical use. METHODS: We conducted a systematic literature search (updated on 23 July 2023) to evaluate safety and efficacy of ciprofol in comparison to propofol in patients undergoing procedures under sedation or GA. We focused on randomized controlled trials (RCTs) only, extrapolating data on onset and offset, and on the side effects and the pain at injection. RESULTS: The search revealed 14 RCTs, all conducted in China. Eight RCTs studied patients undergoing sedation, and six focused on GA. Bolus of ciprofol for sedation or induction of GA varied from 0.2 to 0.5 mg/kg. In four studies using ciprofol for maintenance of GA, it was 0.8-2.4 mg/kg/h. Ciprofol pharmacokinetics seemed characterized by slower onset and offset as compared to propofol. Pain during injection was less frequent in the ciprofol group in all the 13 studies reporting it. Eight studies reported "adverse events" as a pooled outcome, and in five cases, the incidence was higher in the propofol group, not different in the remaining ones. Occurrence of hypotension was the most commonly investigated side effects, and it seemed less frequent with ciprofol. CONCLUSION: Ciprofol for sedation or GA may be safer than propofol, though its pharmacokinetics may be less advantageous.
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After European Medicines Agency (EMA) approval, national pricing and reimbursement procedures are necessary to guarantee access to drugs, based on the willingness to pay and the recognition of therapeutic value. These can result in delays in drug availability for patients, even for those with important unfmet needs for whom it may be necessary and ethical to ensure access. The objective of this study was to evaluate the use of ruxolitinib for patients with graft-versus-host disease (GvHD) after EMA approval at the University Hospital of Catania. We analysed data about the use of ruxolitinib in patients with GvHD, describing their basic characteristics, their outcomes and the cost of the treatment. In the reference period, 24 ruxolitinib treatments were started according to the Summary of Product Characteristic. The average treatment duration was 10 months. Twenty patients showed a response, maintained over time, with no adverse reactions. The total expenditure amounts to EUR 963,424. The use of ruxolitinib in a real population confirms its role in an important therapeutic need. The quantification of costs requires a reflection on the sustainability of early access to medicines authorised by the EMA for serious diseases and in the absence of therapeutic alternatives.
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In accordance with European regulation, medicines containing a new active substance to treat neurodegenerative diseases as well as autoimmune and other immune dysfunctions must be approved by the European Medicines Agency (EMA) through the centralized procedure before they can be marketed. However, after EMA approval, each country is responsible for national market access, following the assessment performed by health technology assessment (HTA) bodies with regard to the therapeutic value. This study aims to provide a comparative analysis of HTA recommendations issued by three EU countries (France, Germany, and Italy) for new drugs for multiple sclerosis (MS) following EMA approval. In the reference period, we identified 11 medicines authorized in Europe for MS, including relapsing forms of MS (RMS; n = 4), relapsing-remitting MS (RRMS; n = 6), secondary progressive MS (SPMS; n = 1), and the primary progressive form (PPMS; n = 1). We found no agreement on the therapeutic value (in particular, the "added value" compared to the standard of care) of the selected drugs. Most evaluations resulted in the lowest score ("additional benefit not proven/no clinical improvement"), underlining the need for new molecules with better efficacy and safety profiles for MS, especially for some forms and clinical settings.
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Gilteritinib has been approved as monotherapy in adults with acute myeloid leukemia (AML) FLT3 mutated with relapsed or refractory disease, in light of its advantages in terms of survival and the favorable safety profile. Hepatobiliary disorders and musculoskeletal and connective tissue disorders represent the most frequent adverse reactions associated with gilteritinib, whereas the most frequent serious adverse reaction is acute kidney injury. In the summary of product characteristics, gastrointestinal (GI) events are indicated as very common, in particular diarrhea, nausea and stypsis. Furthermore, serious GI disorders have been observed with gilteritinib in clinical trials, including GI hemorrhage, GI perforation and GI obstruction. However, the association with the FLT3 inhibitor has not been confirmed. Nevertheless, serious GI AEs have been recognized as an important potential risk to be monitored in postmarketing surveillance. We present three cases of serious self-limiting GI events observed in patients on gilteritinib treatment for AML, and an analysis of relevant available postmarketing surveillance data.
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Despite the availability of a lot of effective disease-modifying drugs, multiple sclerosis (MS) (in particular the progressive forms) still represents an important unmet medical need, because of issues in terms of effectiveness, duration of response, safety, and patient compliance. An increasing body of evidence from randomized clinical trials and real-world data suggest that rituximab is a highly effective alternative in both relapsing and progressive MS, with a low discontinuation rate, related to a good benefit/risk profile, and a good compliance. To date, the use of rituximab in patients with multiple sclerosis is not in accordance with the authorized product information (off-label use). However, the use of this medicine is widespread in several countries, and in some cases, it is the most commonly used disease-modifying drug for MS subtypes. This use could be officially recognized by national regulatory authorities, according to specific procedures, to ensure equal access for patients to a safe and effective option.
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Aprovação de Drogas , Esclerose Múltipla/tratamento farmacológico , Rituximab/uso terapêutico , Humanos , Esclerose Múltipla/classificação , Esclerose Múltipla Crônica Progressiva/tratamento farmacológico , Esclerose Múltipla Recidivante-Remitente/tratamento farmacológico , Ensaios Clínicos Controlados Aleatórios como Assunto , RecidivaRESUMO
Fertility preservation represents one important goal of cancer patients' management due to the high impact on health and quality of life of survivors. The available preventive measures cannot be performed in all patients and are not feasible in all health-care facilities. Therefore, the pharmacological treatment with GnRHa has become a valuable non-invasive and well-tolerated alternative, especially in those who cannot access to cryopreservation options due to clinical and/or logistic issues. Supporting data demonstrate a significant advantage for the survivors who received GnRHa in the long-term maintenance of ovarian function and preservation of fertility. The prevention of the risk of ovarian failure with GnRHa is a typical off-label use, defined as the administration of a medicinal product not in accordance with the authorized product information. Italy has officially recognized the off-label use of GnRHa in adult women at risk of premature and permanent menopause following chemotherapy. However, fertility preservation still represents an unmet medical need in adolescents who cannot access to other treatment options.
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Even for centrally approved products, each European country is responsible for the effective national market access. This step can result in inequalities in terms of access, due to different opinions about the therapeutic value assessed by health technology assessment (HTA) bodies. Advanced therapy medicinal products (ATMPs) represent a major issue with regard to the HTA in order to make them available at a national level. These products are based on genes, tissues, or cells, commonly developed as one-shot treatment for rare or ultrarare diseases and mandatorily authorized by the EMA with a central procedure. This study aims to provide a comparative analysis of HTA recommendations issued by European countries (France, Germany, and Italy) following EMA approval of ATMPs. We found a low rate of agreement on the therapeutic value (in particular the "added value" compared to the standard of care) of ATMPs. Despite the differences in terms of clinical assessment, the access has been usually guaranteed, even with different timing and limitations. In view of the importance of ATMPs as innovative therapies for unmet needs, it is crucial to understand and act on the causes of disagreement among the HTA. In addition, the adoption of the new EU regulation on HTA would be useful to reduce disparities of medicine's assessment among European countries.
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Even for products centrally approved, each European country is responsible for national market access after European Medicines Agency (EMA) approval. This step can result in inequalities in terms of access, due to different opinions about the therapeutic value assessed by Health Technology Assessment (HTA) bodies. This study aims to provide a comparative analysis of HTA recommendations issued by EU countries (France, Germany, and Italy) for new neurological drugs following EMA approval. In the reference period, we identified 11 innovative medicines authorized in Europe for five neurological diseases (cerebral adrenoleukodystrophy, spinal muscular atrophy, metachromatic leukodystrophy, migraine, and polyneuropathy in patients with hereditary transthyretin amyloidosis), including eight drugs for genetic rare diseases. We found no agreement on the therapeutic value (in particular the "added value" compared to the standard of care) of the selected drugs. Despite the differences in terms of assessment, the access has been usually guaranteed even if with various types of limitations. The heterogeneity of the HTA assessment of clinical data among countries is probably related to the uncertainties about clinical value at the time of EMA approval and the lack of long-term data and of direct comparison with available alternatives. Given the importance of new medicines especially for rare diseases, it is crucial to understand and act on the causes of inconsistency among the HTA assessments, in order to ensure rapid and uniform access to innovation for patients who can benefit.
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Despite the progress in the development of new therapeutic strategies, relapsed/refractory (R/R) acute myeloid leukemia (AML) still represents a high unmet medical need. Treatment options in this setting include enrollment into clinical trials, allogeneic stem cell transplantation and/or targeted therapy. Nevertheless, it is associated with poor outcomes. Thus, the development of new treatments, which could ameliorate the prognosis of these patients with a good safety profile are highly demanded. Recently, venetoclax (VEN) has been approved for naïve AML patients unfit for intensive chemotherapy. In this regard, regimens including VEN could represent a valuable treatment option even in those with R/R disease and several studies have been conducted to demonstrate its role in this clinical setting. This review aims to summarize the current evidence on the use of VEN regimens in the treatment of R/R AML.
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The potent oral inhibitor of BCL2, venetoclax (VEN), used to treat adults with chronic lymphocytic leukaemia, has been approved in US for the treatment of naïve patients with acute myeloid leukemia (AML) unfit for intensive chemotherapy and recently in Europe, too. However, the drug has been used for years in combination with hypomethylating agents (HMAs) in patients not eligible to other treatment option, according to the so-called off-label use. We collected real-world data about patients treated with VEN + HMAs in the context of a pharmacovigilance project focused on the evaluation of the safety and effectiveness of drugs used for unapproved indication in Italian hospitals. From March to December 2020, 24 patients started treatment with VEN combined with HMAs. 21 patients have been assessed for response. Eleven (52%) patients reached complete remission (CR), and three patients (14%) CR with partial hematological recovery (CRh), with a median duration of response of 4.5 months (range 0.5-12.5). 19 patients experienced at least 1 adverse drug reaction (ADR), mostly serious, including 3 deaths (9% of ADRs; 12.5% of patients) in febrile neutropenia. Hematological toxicities and infections (cytopenia, neutropenia, febrile neutropenia, sepsis), were the most reported ADRs (84.4%). In general, neutropenic fever occurred more frequently in patients treated with decitabine (7 out of 9, 78%) compared to azacitidine (5 out of 15, 33%; p = 0.03), whereas response assessment did not differ based on used HMA (p = 0.1). These results confirm the benefit-risk profile of VEN in a real-world setting of patients with no adequate therapeutic options.
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Janus kinase inhibitors (JAKi) belong to a new class of oral targeted disease-modifying drugs which have recently revolutionized the therapeutic panorama of rheumatoid arthritis (RA) and other immune-mediated diseases, placing alongside or even replacing conventional and biological drugs. JAKi are characterized by a novel mechanism of action, consisting of the intracellular interruption of the JAK-STAT pathway crucially involved in the immune response. The aim of this narrative review is to globally report the most relevant pharmacological features and clinical outcomes of the developed and incoming JAKi for RA, based on the available preclinical and clinical evidence. A total of 219 papers, including narrative and systematic reviews, randomized controlled trials (RCTs), observational studies, case reports, guidelines, and drug factsheets, were selected. The efficacy and safety profile of both the first generation JAKi (baricitinib and tofacitinib) and the second generation JAKi (upadacitinib, filgotinib, peficitinib, decernotinib and itacitinib) were compared and discussed. Results from RCTs and real-life data are encouraging and outline a rapid onset of the pharmacologic effects, which are maintained during the time. Their efficacy and safety profile are comparable or superior to those of biologic agents and JAKi proved to be efficacious when given as monotherapy. Finally, the manufacturing of JAKi is relatively easier and cheaper than that of biologics, thus increasing the number of compounds being formulated and tested for clinical use.
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Artrite Reumatoide/tratamento farmacológico , Inibidores de Janus Quinases/uso terapêutico , Artrite Reumatoide/metabolismo , Ensaios Clínicos como Assunto , Regulação da Expressão Gênica/efeitos dos fármacos , Humanos , Inibidores de Janus Quinases/farmacologia , Fatores de Transcrição STAT/metabolismo , Transdução de Sinais/efeitos dos fármacosRESUMO
The aim of the present study was to analyze the potential role of substance P (SP) in gastric mucosal defense and to clarify the receptors and mechanisms that may be involved in it. Gastric ulceration was induced by oral administration of acidified ethanol in male Wistar rats. Mucosal levels of calcitonin gene-related peptide (CGRP) and somatostatin were determined by radioimmunoassay. For analysis of gastric motor activity the rubber balloon method was used. We found that central (intracerebroventricular) injection of SP (9.3-74 pmol) dose-dependently inhibited the formation of ethanol-induced ulcers, while intravenously injected SP (0.37-7.4 nmol/kg) had no effect. The mucosal protective effect of SP was inhibited by pretreatment with neurokinin 1-, neurokinin 2-, neurokinin 3- and µ-opioid receptor antagonists, while δ- and κ-opioid receptor antagonists had no effect. Endomorphin-2 antiserum also antagonized the SP-induced mucosal protection. In the gastroprotective dose range SP failed to influence the gastric motor activity. Inhibition of muscarinic cholinergic receptors, or the synthesis of nitric oxide or prostaglandins significantly reduced the effect of SP. In addition, centrally injected SP reversed the ethanol-induced reduction of gastric mucosal CGRP content. It can be concluded, that SP may induce gastric mucosal protection initiated centrally. Its protective effect is likely to be mediated by endomorphin-2, and vagal nerve may convey the centrally initiated protection to the periphery, where both prostaglandins, nitric oxide and CGRP are involved in mediating this effect.
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Mucosa Gástrica/metabolismo , Neurotransmissores/metabolismo , Oligopeptídeos/biossíntese , Substância P/metabolismo , Álcoois/toxicidade , Animais , Peptídeo Relacionado com Gene de Calcitonina/biossíntese , Modelos Animais de Doenças , Etanol/toxicidade , Mucosa Gástrica/efeitos dos fármacos , Mucosa Gástrica/patologia , Injeções Intraventriculares , Masculino , Neurotransmissores/administração & dosagem , Radioimunoensaio , Ratos , Ratos Wistar , Úlcera Gástrica/induzido quimicamente , Úlcera Gástrica/metabolismo , Úlcera Gástrica/patologia , Substância P/administração & dosagemRESUMO
Several lines of evidence suggest that imidazoline receptors mediate various physiological processes. It is rather difficult, however, to distinguish the imidazoline receptor-mediated effects from the alpha2-adrenoceptor-mediated ones due to the reasonable affinity of most imidazoline ligands for the alpha2-adrenoceptors. In the present study the effects of different imidazoline ligands were tested on the electrical field stimulation (EFS)-induced gastric contractions in wild-type (WT), alpha2A-, alpha2B- and alpha2C-adrenoceptor knockout (KO) mice in order to analyze, whether imidazoline I1 and I2 receptors take part in the regulation of gastric motor activity. Clonidine, moxonidine and rilmenidine inhibited the EFS-induced gastric contractions in a concentration dependent manner in WT, alpha2B- and alpha2C-adrenoceptor KO mice, whereas they had no or only weak effect in alpha2A-adrenoceptor KO mice. Their effects in WT mice were inhibited by idazoxan and BRL 44408, but not by ARC 239, AGN 192403 and BU 224. The endogenous imidazoline receptor ligand agmatine failed to affect the EFS-induced contractions, while harmane (an other endogenous imidazoline receptor ligand) and 2-BFI (a selective imidazoline I2 receptor agonist) exerted a slight effect in both WT and alpha2A-adrenoceptor KO mice, but this was not reversible by idazoxan, AGN 192403 and BU 224. It can be concluded, that the inhibitory effect of the tested imidazoline compounds on cholinergic gastric contractions is mediated mainly by alpha2A-adrenoceptors. Although at higher concentrations other receptors may also contribute to their effects, the lack of inhibition by AGN 192403 and BU 224 suggests that these are not imidazoline I1 and I2 receptors.
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Esvaziamento Gástrico/fisiologia , Receptores de Imidazolinas/fisiologia , Receptores Adrenérgicos alfa 2/fisiologia , Agmatina/farmacologia , Animais , Estimulação Elétrica , Feminino , Esvaziamento Gástrico/efeitos dos fármacos , Harmina/análogos & derivados , Harmina/farmacologia , Imidazóis/farmacologia , Receptores de Imidazolinas/antagonistas & inibidores , Técnicas In Vitro , Isoquinolinas/farmacologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Oxazóis/farmacologia , Piperazinas/farmacologia , Rilmenidina , Estômago/efeitos dos fármacos , Estômago/fisiologiaRESUMO
α(2)-adrenoceptors are known to mediate gastroprotective effect in both acid-dependent and acid-independent ulcer models. The aim of the present study was to determine, which of the three α(2)-adrenoceptor subtypes (α(2A), α(2B) or α(2C)) is responsible for this protection. Various α(2)-adrenoceptor agonists and antagonists were administered intracerebroventricularly (i.c.v.) to C57BL/6 mice with deletion of genes encoding the different subtypes. The gastric mucosal damage was induced by orally injected acidified ethanol. Both the non-selective α(2)-adrenoceptor agonist clonidine (0.3-2.8 nmol) and the α(2B/C)-adrenoceptor subtype preferring agonist ST-91 (0.5-11.5 nmol) induced dose-dependent gastroprotective effect in wild type, α(2A)-, α(2B)- and α(2C)-KO mice. In contrast, the α(2A)-adrenoceptor subtype agonist oxymetazoline (0.07-84 nmol i.c.v.) reduced only slightly the development of ethanol-induced ulcers. The effect of clonidine was antagonized by the non-selective antagonist yohimbine (25 nmol) and the α(2B/C)-adrenoceptor antagonist ARC 239 (10.4 nmol), but not by the α(2A)-adrenoceptor antagonist BRL 44408 (7.5 nmol). ARC 239 also reversed the effect of clonidine in α(2A)-, α(2B)- and α(2C)-KO mice, while the selective α(2C)-adrenoceptor antagonist JP 1302 (52 nmol) antagonized that only in α(2B)-KO, but not in α(2A)- and α(2C)-KO mice. These results suggest that α(2B)- and α(2C)-adrenoceptor subtypes can equally contribute to the mediation of gastroprotective effect induced by α(2)-adrenoceptor agonists in mice.