RESUMO
Possible central nervous system effects of the gymnosperm lectin from Araucaria angustifolia seeds were studied in seizure and open field tests. Male Swiss mice were administered saline (control), lectin (0.1, 1, and 10 mg/kg), flumazenil (1 mg/kg), or diazepam (1 mg/kg) intraperitoneally. Lectin at the highest dose increased time to death in the pentylenetetrazole- and strychnine-induced seizure models as compared with control, but not in the pilocarpine model. In the open field test, lectin reduced locomotor activity at all doses tested, as did diazepam, when compared with control. These locomotor effects were reversed by flumazenil pretreatment. In conclusion, A. angustifolia lectin had a protective effect in the pentylenetetrazole- and strychnine-induced seizure models, suggestive of activity in the GABAergic and glycinergic systems, respectively, and also caused a reduction in animal movements, which was reversed by flumazenil, pointing to a depressant action mediated by a GABAergic mechanism.
Assuntos
Lectinas/farmacologia , Lectinas/uso terapêutico , Sementes/química , Convulsões/tratamento farmacológico , Análise de Variância , Animais , Anticonvulsivantes/farmacologia , Anticonvulsivantes/uso terapêutico , Diazepam/farmacologia , Diazepam/uso terapêutico , Modelos Animais de Doenças , Relação Dose-Resposta a Droga , Comportamento Exploratório/efeitos dos fármacos , Flumazenil/farmacologia , Flumazenil/uso terapêutico , Locomoção/efeitos dos fármacos , Masculino , Camundongos , Pentilenotetrazol , Fitoterapia/métodos , Extratos Vegetais/uso terapêutico , Tempo de Reação/efeitos dos fármacos , Convulsões/induzido quimicamente , EstricninaRESUMO
This work evaluated the antinociceptive effect of proteins from the Calotropis procera (Asclepiadaceae) latex using three different experimental models of nociception in mice. The latex protein fraction administered intraperitoneally in male mice at the doses of 12.5, 25 and 50 mg/kg showed the antinociceptive effect in a dose dependent manner compared to the respective controls in all assays. Inhibitions of the acetic acid-induced abdominal constrictions were observed at the doses of 12.5 (67.9%), 25 (85%) and 50 (99.5%) mg/kg compared to controls. Latex protein at the doses of 25 (39.8%; 42%) and 50 mg/kg (66.6%; 99.3%) reduced the nociception produced by formalin in the 1st and 2nd phases, respectively, and this effect was not reversed by pretreatment with naloxone (1 mg/kg). In the hot plate test, an increase of the reaction time was observed only at 60 min after the treatment with latex at the doses of 25 (79.5%) and 50 (76.9%) mg/kg, compared to controls and naloxone was ineffective to reverse the effect. It was concluded that the protein fraction derived from the whole latex of Calotropis procera possesses antinociceptive activity, which is independent of the opioid system.