Efeitos da suplementação crônica com vitamina D associado à natação regular sobre aspectos histomorfométricos renais em roedores obesos

Abstract

The neonatal administration of monosodium glutamate (MSG) in rats induces obesity associated histopathological renal alteration. Vitamin D (VD) seems to modulate the renal inflammation, while physical exercise enhances proteinuria and glomerulosclerosis. The objective of this study was to evaluate the effects of chronic supplementation with VD associated to regular swimming over renal histomorphometric aspects in MSG-obese rats. To this end, Wistar male rats (n=24), in their first 5 days of life, were given subcutaneous injections of monosodium glutamate (MSG; 4g/kg) while Control rats (CON;n=6) were given equimolar salt. On the 21st day of live the MSG-treated rats were randomly distributed among sedentary animals (S) and were exercised (E, swimming; 3x/week), which were subdivided in orally supplemented with VD (12μg/Kg; 3x/semana) or not supplemented (NS), forming 5 experimental groups (n=6 rats/group): MSG; MSG-SVD; MSG-ENS; MSG-EVD and the group CON. On the 90th day of life the animals were euthanized and the obesity was evaluated by the weight of the white adipose tissue deposits (WAT) and the Lee Index calculus. The kidney was removed, weighted and submitted to histological techniques for histomorphometric analysis. The data was expressed as mean+SEM with Anova Two-way (p<0.05) variance analysis. In this study, the animals from the groups MSG present lower corporal weight and smaller nasal-anal length, but they presented high adiposity when compared to group CON (p<0.05). Notable alterations in the renal morphology were found in group MSG, such as, smaller diameter of the glomerular tuft, area of the glomerular tuft, area of Bowman’s capsule, area of Bowman’s space and renal cortical thickness, when compared to the same renal parameters in the group CON (p<0.05). Thus, the kidney of the group MSG was significantly smaller than the group CON (p<0.05), besides presenting intense renal tubular degeneration. In MSG-EVD animals, the weight of the kidney was reduced in relation to group MSG-ENS (p <0.05). In MSG-SVD, MSG-ENS and MSG-EVD animals there was an increase in the cortical thickness in relation to group MSG (p<0.05). In MSG-ENS and MSG-EVD animals there was a reduction of the tubular degeneration in relation to group MSG and the MSG-EVD group also presented reduction of renal tubular degeneration when compared to group MSG-SVD (p<0.05). Jointly, our data showed that MSG-obese rats had intense glomerular and tubular degeneration, similar to the degeneration observed in the progression of chronic renal disease. The exercise and the VD were effective in increasing the thickness of the renal cortex, and when associated, they protected from tubular degeneration having, this way, an important role in the prevention of renal injury.