RESUMO
It has been suggested that low intensity laser therapy (LILT) acts on pulmonary inflammation. Thus, we investigate in this work if LILT (650nm, 2.5mW, 31.2mW/cm(2), 1.3J/cm(2), laser spot size of 0.08cm(2) and irradiation time of 42s) can attenuate edema, neutrophil recruitment and inflammatory mediators in acute lung inflammation. Thirty-five male Wistar rats (n=7 per group) were distributed in the following experimental groups: control, laser, LPS, LPS+laser and dexamethasone+LPS. Airway inflammation was measured 4h post-LPS challenge. Pulmonary microvascular leakage was used for measuring pulmonary edema. Bronchoalveolar lavage fluid (BALF) cellularity and myeloperoxidase (MPO) were used for measuring neutrophil recruitment and activation. RT-PCR was performed in lung tissue to assess mRNA expression of tumor necrosis factor-α (TNF-α), interleukin-1ß (IL-1ß), interleukin (IL-10), cytokine-induced neutrophil chemoattractant-1 (CINC-1), macrophage inflammatory protein-2 (MIP-2) and intercellular adhesion molecule-1 (ICAM-1). Protein levels in both BALF and lung were determined by ELISA. LILT inhibited pulmonary edema and endothelial cytoskeleton damage, as well as neutrophil influx and activation. Similarly, the LILT reduced the TNF-α and IL-1ß, in lung and BALF. LILT prevented lung ICAM-1 up-regulation. The rise of CINC-1 and MIP-2 protein levels in both lung and BALF, and the lung mRNA expressions for IL-10, were unaffected. Data suggest that the LILT effect is due to the inhibition of ICAM-1 via the inhibition of TNF-α and IL-1ß.
Assuntos
Quimiocinas/metabolismo , Citocinas/metabolismo , Terapia com Luz de Baixa Intensidade , Neutrófilos/efeitos da radiação , Pneumonia/radioterapia , Doença Aguda , Aerossóis/química , Animais , Anti-Inflamatórios/farmacologia , Líquido da Lavagem Broncoalveolar , Quimiocina CXCL1/genética , Quimiocina CXCL1/metabolismo , Quimiocina CXCL2/genética , Quimiocina CXCL2/metabolismo , Quimiocinas/genética , Citocinas/genética , Dexametasona/farmacologia , Modelos Animais de Doenças , Escherichia coli/metabolismo , Molécula 1 de Adesão Intercelular/genética , Molécula 1 de Adesão Intercelular/metabolismo , Interleucina-10/genética , Interleucina-10/metabolismo , Interleucina-1beta/genética , Interleucina-1beta/metabolismo , Lipopolissacarídeos/toxicidade , Pulmão/imunologia , Pulmão/metabolismo , Pulmão/patologia , Masculino , Neutrófilos/metabolismo , Peroxidase/metabolismo , Ratos , Ratos Wistar , Fator de Necrose Tumoral alfa/genética , Fator de Necrose Tumoral alfa/metabolismoRESUMO
BACKGROUND AND OBJECTIVE: Low-level laser therapy (LLLT) is a known modulator of inflammatory process. Herein we studied the effect of 660 nm diode laser on mRNA levels of neutrophils anti-apoptotic factors in lipopolysaccharide (LPS)-induced lung inflammation. STUDY DESIGN/METHODOLOGY: Mice were divided into 8 groups (n=7 for each group) and irradiated with energy dosage of 7.5 J/cm(2). The Bcl-xL and A1 mRNA levels in neutrophils were evaluated by Real Time-PCR (RT-PCR). The animals were irradiated after exposure time of LPS. RESULTS: LLLT and an inhibitor of NF-kappaB nuclear translocation (BMS 205820) attenuated the mRNA levels of Bcl-xL and A1 mRNA in lung neutrophils obtained from mice subjected to LPS-induced inflammation. CONCLUSION: LLLT reduced the levels of anti-apoptotic factors in LPS inflamed mice lung neutrophils by an action mechanism in which the NF-kappaB seems to be involved.
Assuntos
Terapia com Luz de Baixa Intensidade , Pulmão/imunologia , Pulmão/efeitos da radiação , NF-kappa B/metabolismo , Neutrófilos/metabolismo , Proteínas Proto-Oncogênicas c-bcl-2/metabolismo , Proteína bcl-X/metabolismo , Animais , Inflamação , Lipopolissacarídeos/imunologia , Masculino , Camundongos , Antígenos de Histocompatibilidade Menor , Neutrófilos/efeitos da radiação , Peptídeos/farmacologia , RNA Mensageiro/metabolismo , RNA Mensageiro/efeitos da radiaçãoRESUMO
OBJECTIVE: The aim of this study was to investigate if low-level laser therapy (LLLT) can modulate formation of hemorrhagic lesions induced by immune complex. BACKGROUND DATA: There is a lack of information on LLLT effects in hemorrhagic injuries of high perfusion organs, and the relative efficacy of LLLT compared to anti-inflammatory drugs. METHODS: A controlled animal study was undertaken with 49 male Wistar rats randomly divided into seven groups. Bovine serum albumin (BSA) i.v. was injected through the trachea to induce an immune complex lung injury. The study compared the effect of irradiation by a 650-nm Ga-Al-As laser with LLLT doses of 2.6 Joules/cm(2) to celecoxib, dexamethasone, and control groups for hemorrhagic index (HI) and myeloperoxide activity (MPO) at 24 h after injury. RESULTS: The HI for the control group was 4.0 (95% CI, 3.7-4.3). Celecoxib, LLLT, and dexamethasone all induced significantly (p < 0.01) lower HI than control animals at 2.5 (95% CI, 1.9-3.1), 1.8 (95% CI, 1.2-2.4), and 1.5 (95% CI, 0.9-2.1), respectively, for all comparisons to control. Dexamethasone, but not celecoxib, induced a slightly, but significantly lower HI than LLLT (p = 0.04). MPO activity was significantly decreased in groups receiving celecoxib at 0.87 (95% CI, 0.63-1.11), dexamethasone at 0.50 (95% CI, 0.24-0.76), and LLLT at 0.7 (95% CI, 0.44-0.96) when compared to the control group, at 1.6 (95% CI, 1.34-1.96; p < 0.01), but there were no significant differences between any of the active treatments. CONCLUSION: LLLT at a dose of 2.6 Joules/cm(2) induces a reduction of HI levels and MPO activity in hemorrhagic injury that is not significantly different from celecoxib. Dexamethasone is slightly more effective than LLLT in reducing HI, but not MPO activity.
Assuntos
Hemorragia/radioterapia , Doenças do Complexo Imune/complicações , Terapia com Luz de Baixa Intensidade , Pneumopatias/radioterapia , Animais , Anti-Inflamatórios/farmacologia , Celecoxib , Dexametasona/farmacologia , Hemorragia/tratamento farmacológico , Hemorragia/etiologia , Pneumopatias/tratamento farmacológico , Pneumopatias/etiologia , Masculino , Pirazóis/farmacologia , Ratos , Ratos Wistar , Sulfonamidas/farmacologiaRESUMO
Our objective was to investigate if low-level laser therapy (LLLT) could improve respiratory function and inhibit tumor necrosis factor (TNF-alpha) release into the diaphragm muscle of rats after an intravenous injection of lipopolysaccharide (LPS) (5 mg/kg). We randomly divided Wistar rats in a control group without LPS injection, and LPS groups receiving either (a) no therapy, (b) four sessions in 24 h with diode Ga-AsI-Al laser of 650 nm and a total dose of 5.2 J/cm2, or (c) an intravenous injection (1.25 mg/kg) of the TNF-alpha inhibitor chlorpromazine (CPZ). LPS injection reduced maximal force by electrical stimulation of diaphragm muscle from 24.15+/-0.87 N in controls, but the addition of LLLT partly inhibited this reduction (LPS only: 15.01+/-1.1 N vs LPS+LLLT: 18.84+/-0.73 N, P<0.05). In addition, this dose of LLLT and CPZ significantly (P<0.05 and P<0.01, respectively) reduced TNF-alpha concentrations in diaphragm muscle when compared to the untreated control group.
Assuntos
Diafragma/química , Lipopolissacarídeos , Terapia com Luz de Baixa Intensidade , Insuficiência Respiratória/induzido quimicamente , Insuficiência Respiratória/terapia , Fator de Necrose Tumoral alfa/análise , Animais , Clorpromazina/farmacologia , Diafragma/efeitos dos fármacos , Masculino , Distribuição Aleatória , Ratos , Ratos Wistar , Fator de Necrose Tumoral alfa/antagonistas & inibidoresRESUMO
BACKGROUND AND OBJECTIVE: It is unknown if the decreased ability to relax airway smooth muscles in asthma and other inflammatory airways disorders can be influenced by low level laser therapy (LLLT) irradiation. To investigate if LLLT could reduce impairment in inflamed trachea smooth muscles (TSM) in rats. STUDY DESIGN/MATERIALS AND METHODS: Controlled rat study where trachea was dissected and mounted in an organ bath apparatus with or without a TNF-alpha solution. RESULTS: Low level laser therapy administered perpendicularly to a point in the middle of the dissected trachea with a wavelength of 655 nm and a dose of 2.6 J/cm(2), partially restored TSM relaxation response to isoproterenol. Tension reduction was 47.0 % (+/-2.85) in the laser-irradiated group compared to 22.0% (+/-2.21) in the control group (P < 0.01). Accumulation of cAMP was almost normalized after LLLT at 22.3 pmol/mg (+/-2.1) compared to 17.6 pmol/mg (+/-2.1) in the non-irradiated control group (P < 0.01). CONCLUSION: Low level laser therapy partially restores the normal relaxation response in inflamed TSM and normalizes accumulation of cAMP in the presence of isoproterenol.
Assuntos
Terapia com Luz de Baixa Intensidade/métodos , Relaxamento Muscular/efeitos da radiação , Músculo Liso/efeitos da radiação , Traqueia/efeitos da radiação , Fator de Necrose Tumoral alfa/farmacologia , Animais , Técnicas In Vitro , Masculino , Ratos , Ratos WistarRESUMO
OBJECTIVE: The aim of this study was to investigate if low-level laser therapy (LLLT) can modulate acute inflammation and tumor necrosis factor (TNFalpha) levels. BACKGROUND DATA: Drug therapy with TNFalpha-inhibitors has become standard treatment for rheumatoid arthritis, but it is unknown if LLLT can reduce or modulate TNFalpha levels in inflammatory disorders. METHODS: Two controlled animal studies were undertaken, with 35 male Wistar rats randomly divided into five groups each. Rabbit antiserum to ovalbumin was instilled intrabronchially in one of the lobes, followed by the intravenous injection of 10 mg of ovalbumin in 0.5 mL to induce acute lung injury. The first study served to define the time profile of TNFalpha activity for the first 4 h, while the second study compared three different LLLT doses to a control group and a chlorpromazine group at a timepoint where TNFalpha activity was increased. The rats in LLLT groups were irradiated within 5 min at the site of injury by a 650-nm Ga-Al-As laser. RESULTS: There was a time-lag before TNFalpha activity increased after BSA injection. TNFalpha levels increased from < or =6.9 (95% confidence interval [CI], 5.6-8.2) units/mL in the first 3 h to 62.1 (95% CI, 60.8-63.4) units/mL (p < 0.001) at 4 h. An LLLT dose of 0.11 Joules administered with a power density of 31.3 mW/cm(2) in 42 sec significantly reduced TNFalpha level to 50.2 (95% CI, 49.4-51.0), p < 0.01 units/mL versus control. Chlorpromazine reduced TNFalpha level to 45.3 (95% CI, 44.0-46.6) units/mL, p < 0.001 versus control. CONCLUSION: LLLT can reduce TNFalpha expression after acute immunocomplex lung injury in rats, but LLLT dose appears to be critical for reducing TNFalpha release.
Assuntos
Líquido da Lavagem Broncoalveolar/química , Inflamação/metabolismo , Terapia com Luz de Baixa Intensidade , Fator de Necrose Tumoral alfa/análise , Animais , Pulmão/metabolismo , Masculino , Modelos Animais , Dosagem Radioterapêutica , Ratos , Ratos Wistar , Traumatismo por Reperfusão/metabolismoRESUMO
The purpose of this study was to investigate the effect of low level laser therapy (LLLT) on male Wistar rat trachea hyperreactivity (RTHR), bronchoalveolar lavage (BAL) and lung neutrophils influx after Gram-negative bacterial lipopolyssacharide (LPS) intravenous injection. The RTHR, BAL and lung neutrophils influx were measured over different intervals of time (90 min, 6 h, 24 h and 48 h). The energy density (ED) that produced an anti-inflammatory effect was 2.5 J/cm(2), reducing the maximal contractile response and the sensibility of trachea rings to methacholine after LPS. The same ED produced an anti-inflammatory effect on BAL and lung neutrophils influx. The Celecoxib COX-2 inhibitor reduced RTHR and the number of cells in BAL and lung neutrophils influx of rats treated with LPS. Celecoxib and LLLT reduced the PGE(2) and TXA(2) levels in the BAL of LPS-treated rats. Our results demonstrate that LLLT produced anti-inflammatory effects on RTHR, BAL and lung neutrophils influx in association with inhibition of COX-2-derived metabolites.
Assuntos
Hiper-Reatividade Brônquica/radioterapia , Terapia com Luz de Baixa Intensidade/métodos , Pneumonia/radioterapia , Pirazóis/farmacologia , Sulfonamidas/farmacologia , Animais , Líquido da Lavagem Broncoalveolar/citologia , Celecoxib , Quimiotaxia de Leucócito , Dinoprostona/metabolismo , Modelos Animais de Doenças , Mediadores da Inflamação/análise , Lipopolissacarídeos , Masculino , Neutrófilos/citologia , Probabilidade , Distribuição Aleatória , Ratos , Valores de Referência , Sensibilidade e Especificidade , Traqueia/fisiopatologiaRESUMO
Nidularium procerum, a common plant of the Brazilian flora, has not yet been studied for its pharmacological properties. We report here that extracts of N. procerum show both analgesic and anti-inflammatory properties. Oral (p.o.) or intraperitoneal (i.p.) administration of an aqueous crude extract from leaves of N. procerum (LAE) inhibited the writhing reaction induced by acetic acid (ED50 value = 0.2 mg/kg body weight, i.p.) in a dose-dependent manner. This analgesic property was confirmed in rats using two different models of bradykinin-induced hyperalgesia; there was 75% inhibition of pain in the modified Hargreaves assay, and 100% inhibition in the classical Hargreaves assay. This potent analgesic effect was not blocked by naloxone, nor was it observed in the hot plate model, indicating that the analgesic effect is not associated with the activation of opioid receptors in the central nervous system. By contrast, we found that LAE (0.02 microg/ml) selectively inhibited prostaglandin E2 production by cyclooxygenase (COX)-2, but not COX-1, which is a plausible mechanism for the analgesic effect. A crude methanol extract from the leaves also showed similar analgesic activity. An identical extract from the roots of N. procerum did not, however, block acetic acid-induced writhes, indicating that the analgesic compounds are concentrated in the leaves. Finally, we found that LAE inhibited an inflammatory reaction induced by lipopolysaccharide in the pleural cavity of mice.
Assuntos
Analgésicos/farmacologia , Anti-Inflamatórios não Esteroides/farmacologia , Bromeliaceae , Dor/prevenção & controle , Fitoterapia , Extratos Vegetais/farmacologia , Ácido Acético , Administração Oral , Analgésicos/administração & dosagem , Analgésicos/uso terapêutico , Animais , Anti-Inflamatórios não Esteroides/administração & dosagem , Anti-Inflamatórios não Esteroides/uso terapêutico , Bradicinina , Brasil , Relação Dose-Resposta a Droga , Edema/induzido quimicamente , Edema/prevenção & controle , Temperatura Alta , Injeções Intraperitoneais , Lipopolissacarídeos , Masculino , Dor/induzido quimicamente , Extratos Vegetais/administração & dosagem , Extratos Vegetais/uso terapêutico , Folhas de Planta , Raízes de Plantas , Pleurisia/induzido quimicamente , Pleurisia/prevenção & controle , Ratos , Ratos Wistar , ÁrvoresRESUMO
The purpose of the present study was to investigate the effect of the low power laser therapy on the acute inflammatory process. Male Wistar rats were used. The rat paw oedema was induced by sub-plantar injection of carrageenan, the paw volume was measured before and 1, 2, 3 and 4 h after the injection using a hydroplethysmometer. To investigate the mechanism action of the Ga-Al-As laser on inflammatory oedema, parallel studies were performed using adrenallectomized rats or rats treated with sodium diclofenac. Different laser irradiation protocols were employed for specific energy densities (EDs), exposure times and repetition rates. The rats were irradiated with the Ga-Al-As laser during 80 s each hour. The ED that produced an anti-inflammatory effect were 1 and 2.5 J/cm(2), reducing the oedema by 27% (P<0.05) and 45.4% (P<0.01), respectively. The ED of 2.5 J/cm(2) produced anti-inflammatory effects similar to those produced by the cyclooxigenase inhibitor sodium diclofenac at a dose of 1 mg/kg. In adrenalectomized animals, the laser irradiation failed to inhibit the oedema. Our results suggest that low power laser irradiation possibly exerts its anti-inflammatory effects by stimulating the release of adrenal corticosteroid hormones.
Assuntos
Alumínio , Arseniatos , Carragenina/farmacologia , Edema/induzido quimicamente , Edema/radioterapia , Extremidades/efeitos da radiação , Gálio , Terapia com Luz de Baixa Intensidade , Adrenalectomia , Animais , Diclofenaco/farmacologia , Edema/tratamento farmacológico , Edema/patologia , Extremidades/patologia , Inflamação/induzido quimicamente , Inflamação/patologia , Inflamação/radioterapia , Masculino , Ratos , Ratos Wistar , Fatores de TempoRESUMO
O objetivo do presente estudo foi investigar o efeito do laser de baixa potência (LLLT) na hiper-reatividade da traquéia de ratos Wistar macho(RTHR) depois da administração de lipopolissacarídeo (LPS)
Assuntos
Animais , Masculino , Ratos , Lipopolissacarídeos , Terapia com Luz de Baixa Intensidade , Pneumopatias , Cloreto de Metacolina , Pneumonia , Ratos Wistar , TraqueiaRESUMO
The aqueous fraction of the ethanolic extract (AFL) of Cissampelos sympodialis Eichl (Menispermaceae), popularly known as milona, has been shown to have both immunosuppressive and anti-inflammatory effects. In the present study we investigated the modulation of macrophage antimicrobicidal activity by in vitro treatment with the extract from C. sympodialis. Normal and thioglycolate-elicited mouse peritoneal macrophages were infected in vitro with the protozoan Trypanosoma cruzi DM28c clone. We observed that the AFL (used at doses ranging from 13 to 100 microg/ml) increased T. cruzi growth and induced a 75% reduction in nitric oxide production. This inhibition could be mediated by the stimulation of macrophage interleukin-10 (IL-10) secretion since the in vitro treatment with the AFL stimulated IL-10 production by T. cruzi-infected macrophages. These results suggest that the anti-inflammatory effect of the AFL from C. sympodialis could be, at least in part, mediated by the inhibition of macrophage functions and that the inhibition of macrophage microbicidal activity induced by the C. sympodialis extract may be mediated by the decrease in macrophage function mediated by interleukin-10 production.
Assuntos
Anti-Inflamatórios/farmacologia , Cissampelos/química , Interleucina-10/biossíntese , Macrófagos Peritoneais/efeitos dos fármacos , Extratos Vegetais/farmacologia , Trypanosoma cruzi/efeitos dos fármacos , Animais , Células Cultivadas , Feminino , Ativação de Macrófagos/efeitos dos fármacos , Macrófagos Peritoneais/parasitologia , Macrófagos Peritoneais/fisiologia , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Óxido Nítrico/biossíntese , Folhas de Planta , Trypanosoma cruzi/crescimento & desenvolvimentoRESUMO
The aqueous fraction of the ethanolic extract (AFL) of Cissampelos sympodialis Eichl (Menispermaceae), popularly known as milona, has been shown to have both immunosuppressive and anti-inflammatory effects. In the present study we investigated the modulation of macrophage antimicrobicidal activity by in vitro treatment with the extract from C. sympodialis. Normal and thioglycolate-elicited mouse peritoneal macrophages were infected in vitro with the protozoan Trypanosoma cruzi DM28c clone. We observed that the AFL (used at doses ranging from 13 to 100 æg/ml) increased T. cruzi growth and induced a 75 percent reduction in nitric oxide production. This inhibition could be mediated by the stimulation of macrophage interleukin-10 (IL-10) secretion since the in vitro treatment with the AFL stimulated IL-10 production by T. cruzi-infected macrophages. These results suggest that the anti-inflammatory effect of the AFL from C. sympodialis could be, at least in part, mediated by the inhibition of macrophage functions and that the inhibition of macrophage microbicidal activity induced by the C. sympodialis extract may be mediated by the decrease in macrophage function mediated by interleukin-10 production
Assuntos
Animais , Masculino , Feminino , Camundongos , Anti-Inflamatórios , Cissampelos/química , Interleucina-10 , Macrófagos Peritoneais , Extratos Vegetais , Trypanosoma cruzi , Células Cultivadas , Ativação de Macrófagos , Macrófagos Peritoneais , Camundongos Endogâmicos BALB C , Óxido Nítrico , Folhas de Planta , Trypanosoma cruziRESUMO
We investigated the presence of PAF receptor subtypes in the tissues of the gastrointestinal tract, airways, blood vessels and in murine macrophages. For this purpose we have used a competitive PAF receptor antagonist, yangambin (YAN), extracted from the Brazilian plant "louro de cheiro" (Ocotea duckei Vattimo). Rat duodenum, jejunum, ileum, colon, stomach fundus, trachea and bronchia were removed and 1.5-2 cm muscle segments from those regions were mounted in a 10 ml organ bath with aerated physiological solution at 37 degrees C. PAF evoked a contraction of the rat jejunum, ileum, colon and stomach fundus. The contraction was slow and resistant to wash and was followed by desensitization to further doses of PAF. Contractions induced by PAF (10(-6) M) were inhibited by YAN (10(-7) to M-2 x 10(-5) M) and WEB 2086 (10(-6) m to M-5 M) in rat jejunum, ileum and colon but not in the stomach fundus. In the rat stomach fundus only WEB 2086 (5 x 10(-6) M) was able to block PAF-induced contraction. The contractions induced by acetylcholine, histamine, 5-hydroxytryptamine and vasopressin were not inhibited by prior administration of YAN. Yangambin also significantly inhibited PAF-induced vascular permeability in rat duodenum, jejunum, ileum, colon, and mesentery. Yangambin significantly inhibited PAF-induced lipid body formation in mice peritoneal macrophages. We suggest that YAN is a selective PAF antagonist which is able to discriminate putative PAF receptors subtypes present in the stomach fundus.
Assuntos
Sistema Digestório/efeitos dos fármacos , Furanos/farmacologia , Lauraceae/química , Lignanas/farmacologia , Inibidores da Agregação Plaquetária/farmacologia , Glicoproteínas da Membrana de Plaquetas/efeitos dos fármacos , Receptores de Superfície Celular , Receptores Acoplados a Proteínas G , Animais , Azepinas/farmacologia , Sistema Digestório/metabolismo , Feminino , Furanos/metabolismo , Técnicas In Vitro , Lignanas/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C3H , Inibidores da Agregação Plaquetária/metabolismo , Glicoproteínas da Membrana de Plaquetas/classificação , Ratos , Ratos Wistar , Triazóis/farmacologiaRESUMO
The effects of the furofuran lignan yangambin on rabbit platelet aggregation and binding of [3H]-PAF to rabbit platelet plasma membranes were studied. Log concentration-response curves to PAF were obtained in the presence or absence of increasing concentrations of yangambin. This lignan dose-dependently inhibited PAF-induced platelet aggregation in platelet-rich plasma (PRP) and shifted PAF curves to the right without decreasing the maximal response. The Schild plot constructed from these data showed a slope of 1.17 and a pA2 of 6.45. Moreover, yangambin at 10(-5) M did not inhibit the platelet aggregation induced by ADP (5 x 10(-7) M), collagen (0.1 microgram ml-1), or thrombin (0.05 U ml-1). Biochemical studies showed that [3H]-PAF labelled in a saturable manner a single class of binding sites on platelet membranes with a Kd of 1.25 +/- 0.24 nM and a maximal binding capacity (Bmax) of 14.9 +/- 2.4 pmol mg protein-1. Both unlabelled PAF and yangambin competitively displaced [3H]-PAF binding with an IC50 of 1.54 +/- 0.37 nM and 1.93 +/- 0.53 microM, respectively. The incubation of rabbit blood neutrophils with yangambin at 10(-5) M did not prevent PAF-induced in vitro chemotaxis in conditions where the PAF antagonist SR 27417 at 10(-5) M abolished the phenomenon. These results indicate that yangambin is an antagonist that selectively blocks PAF receptors on platelets.
Assuntos
Furanos/farmacologia , Lignanas/farmacologia , Plantas/química , Glicoproteínas da Membrana de Plaquetas/antagonistas & inibidores , Receptores de Superfície Celular , Receptores Acoplados a Proteínas G , Animais , Quimiotaxia de Leucócito/efeitos dos fármacos , Furanos/metabolismo , Lignanas/metabolismo , Neutrófilos/citologia , Neutrófilos/efeitos dos fármacos , Fator de Ativação de Plaquetas/farmacologia , Agregação Plaquetária/efeitos dos fármacos , Inibidores da Agregação Plaquetária/metabolismo , Inibidores da Agregação Plaquetária/farmacologia , CoelhosRESUMO
The pharmacological profile of a novel specific platelet-activating factor (PAF) receptor antagonist-yangambin-isolated from the Brazilian plant Ocotea duckei Vattimo (Lauraceae), was investigated in the pentobarbitone-anaesthetized rabbit. The i.v. administration of PAF (0.03-3.0 microgram kg-1) induced marked but reversible hypotensive effects and mild reductions in the heart rate. Both effects are independent of the respiratory conditions imposed on the animals. Moreover, PAF (3.0 microgram kg-1, i.v.) induced a reversible decrease of the circulating levels of platelets and of polymorphonuclear leukocytes. Pretreatment with yangambin (10 and 20 mg kg-1, i.v.) dose-dependently attenuated PAF-induced cardiovascular changes and thrombocytopaenia. Nevertheless, the neutropenic leukopaenia elicited by PAF (3.0 microgram kg-1, i.v.) was not prevented by yangambin whereas the reference PAF antagonists WEB 2086 (2 mg kg-1, i.v.) and SR 27417 (1 mg kg-1, i.v.) significantly inhibited the phenomenon. The hypotensive effects of acetylcholine, histamine, and 5-hydroxytryptamine were not affected by prior administration of yangambin. It is concluded that yangambin is a selective antagonist of the cardiovascular effects of PAF which could be useful in pathological states characterized by abnormal PAF release, such as anaphylactic and septic shocks. Furthermore, yangambin might discriminate a PAF receptor subtype present in the cardiovascular system and platelets from the one existing in polymorphonuclear leukocytes in the rabbit.