Avaliação dos efeitos induzidos pelo ácido nicotínico e pela nicotinamida sobre a migração de neutrófilos induzida por diferentes estímulos inflamatórios em camundongos

Abstract

During the last decades some sutudies have shown that nicotinic acid (NIA) and nicotinamide (NIC), vitamins of the B3 family, besides the known nutritional functions, have antiinflammatory properties. Therefore, to better understand how these vitamins can interfere with the process of cell migration to inflamed focus, male Balb/c mice, weighing 20-25 g, were challenged with carrageenan (200 g/cavity-0.1ml), zymosan (ZYM 200 g/cavity-0.1 ml), leukotriene B4 (LTB4 500 ng/cavity-0.1 mL) or interleukin-8 (IL-8 60 ng/cavity-0.1 mL) to pleurisy induction. These mice were treated with NIC (250, 500, 1000 mg/Kg-0.2 mL, per os) or NIA (150, 300, 600 mg/Kg-0.2 mL, per os) 30 min before and 1 h after the challenge with the inflammatory agents. Four hours after the challenge, the animals were euthanized in CO2 chamber, the lavage of pleural cavity was collected, centrifuged and the precipitate was used to perform the total and differential counting of leukocytes. The double treatment with NIC (1000 mg/Kg) reduced the migration of neutrophils to pleural cavity of mice challenged with CG, ZYM, LTB4 e IL-8. The double treatment with NIA (600 mg/Kg) also reduced the neutrophil migration in mice challenged with CG, ZYM, LTB4 and IL-8. To assess the profile of the adhesion and rolling of leukocyte, a protocol of intravital microscopy was performed. The mice were treated with NIC (1000 mg/Kg) or NIA (600 mg/Kg), 30 min before and 1 h after the challenge with CG (100 g/0.1 mL) injected directly into the scrotum. Four hours after the challenge with CG, images were collected from microcirculation of cremaster muscle with the aid of a fluorescence microscope. The analysis of images revealed that the double treatment with NIC or NIA reduced the process of rolling and adhesion of leukocytes on microcirculation of the cremaster muscle of mice. In addition, after the capture of images, the mice were euthanized, the cremaster muscle was collected and used for histological analysis. The qualitative analysis of the slides revealed a lower number of leukocytes in the interstitial region of mice treated with NIC and NIA compared to untreated mice. In conclusion, the results demonstrated that the treatment with NIC and NIA reduced the neutrophil migration to pleural cavity of mice challenged with different inflammatory agents. The treatment with B3 vitamins also reduced rolling and adhesion of leukocytes on microcirculation of cremaster muscle, so the inhibition on the neutrophil migration to pleural cavity of the mice could be explained, in part by the reduction of leukocyte rolling and adhesion induced by NIC e NIA.