Lectina da alga marinha vermelha Solieria filiformis (Kützing) P.W. Gabrielson: caracterização parcial e efeito antidepressivo em modelos experimentais de depressão

Abstract

Lectins are proteins that bind to specific mono or oligosaccharides. This interaction with carbohydrates makes of the lectins valuable tools for biotechnological applicattions. The aim of this study was, therefore, to partially characterize the red alga marine Solieria filiformis lectin (SfL) and investigate its effect in depression experimental models. The SfL was isolated by extraction with Tris-HCl buffer 25 mM (pH 7,5), precipitation with ammonium sulfate (70%) and chromatographies in DEAE-cellulose and Sephadex G-100 matrices. Subsequently, was characterized by circular dichroism (CD) spectroscopy, followed by evaluation of its effect in the central nervous system, using behavioral tests for screening of anxiolytic and antidepressant agents, such as the open field, elevated plus maze, hole-board, tail suspension and forced swimming tests. For these tests, male Swiss mice (n = 6-10) were pretreated with SfL (1, 3 or 9 mg/kg; iv.). Since the SfL showed significant antidepressant effect, it was evaluated the monoaminergic system involvement in this effect, and, for this, forced swimming tests were performed, using specific antagonists. Posteriorly, it was analyzed the SfL effect (9 mg/kg; iv.) in depression model induced by administration of the Escherichia coli lipopolysaccharide (LPS – 0,5 mg/kg; i.p.), through prevention and reversion protocols. Finally, the SfL antioxidant capacity was evaluated, through lipid peroxidation, reduced glutathione (GSH) and nitrite dosages in the prefrontal cortex, hippocampus and striatum of the mice. As experiments positive controls, imipramine (10 or 30 mg/kg; ip.), bupropion (30 mg/kg) and fluoxetine (35 mg/kg) were used. As result, the CD analysis revealed that the SfL is composed, predominantly, by β-sheet, and the behavioral screening showed that the SfL has antidepressant-like effect, without psychostimulant and anxiolytic effects. Its action mechanism in the depression seems to involve the dopaminergic system and its ability to contain the oxidative stress in the analyzed brain areas. Additionally, the SfL was able to prevent and reverse the behavioral and neurochemical changes induced by LPS, confirming, thus, its potential antidepressant. Like this, this study suggests that, in depression experimental models, the SfL has antidepressant-like effect, and may, therefore, to represent a potential therapeutic agent for the depression treatment.