Concentração de leptina sérica e sua relação com a composição corporal em lesionados medulares fisicamente ativos e não ativos

Abstract

The life expectancy of individuals with spinal cord injury (SCI) has increased in recent decades, despite an increased risk of developing cardiovascular disease, diabetes mellitus type 2, obesity due to metabolic, hormonal and body composition changes. The SCI individuals have reduced activity of the sympathetic nervous system and have reduced concentrations of catecholamines, which inhibit lipolysis and promote fat mass increased. The accumulation of body fat, especially abdominal, leads to increased serum concentrations of leptin and c-reactive protein (CRP) and may also alter the concentration of thyroid hormones and TSH. In addition, recurrent urinary tract infections and pressure ulcers can also increase concentrations of CRP. Increased serum leptin and CRP are independent predictors of coronary heart disease. Exercises has effects on motor function, muscle and lipid profile in chronic post-injury and plays an important role in reducing body fat and risk of chronic disease and system inflammation. Studies on this topic in spinal cord injured are scarce. The objectives of this study were to compare the serum leptin in spinal cord injured physically active (PA) and non physically active (N-PA), and assess it s relationship with body composition and concentrations of TSH, T3, T4 and CRP, which are factors that directly affect the serum concentration leptin. The study included 22 spinal cord injured with cervical injury (C5-C7) divided in physically active (PA n=13, with physical activity for at least 3 months, 3 times/week or more, for a total minimum of 150 minutes/week) and non physically active (N-PA n=9). Body composition was determined by dual energy absorptiometry X-ray (iDXA). Blood samples were collected after fasting for 12 hours for determination of serum leptin, TSH, T3, T4 and CRP-us. Physically actives individuals had lower total body mass (p=0.02), fat mass (in kg, p≤0,001 and in percentage, p≤0,001) and BMI (p=0.004). The positive relantionship between serum leptin and fat mass (kg) was observed, more strongly, when considered only the whole group (n=22, r=0.78, p≤0,001). This association had reduced when evaluating the non-PA individuals (n=9, r=0.67, p=0.05) and was not observed in the PA group isolated (n=13; r=0,36; p=0,22). Serum TSH and thyroid hormones were similar, but the concentration of leptin was lower in PA group (p≤0,001). The concentration of CRP-us was lower in PA group than in N-PA group (p<0,04). The results suggest that regular exercises confers an improvement in body composition with reduced fat mass, total body mass and BMI, and reduces serum concentrations of CRP and leptin, contributing possibly to reduce the risk for chronic diseases, especially cardiovascular diseases, which are a major cause of mortality among these individuals. Leptin showed a positive relationship with fat mass, only when all groups were tested. When groups were separated, only the non-PA group maintained a relationship, indicating that through a mechanism that is not explained, the spinal cord injured has the same active behavior than able bodies-athletes in relation to disruption the relationship between leptin and fat mass