Relationship between bone mineral density, leptin and insulin concentration in Brazilian obese adolescents.

Despite the epidemic of adolescent obesity, the effect of obesity and hormones on bone mineral accrual during growth is poorly understood. Studies using dual-energy X-ray to examine the effect of obesity on bone mass in children and adolescents have yielded conflicting results. The aim of this study was to explore the combined and independent contributions of body mass index, body composition, leptin, insulin, glucose levels and Homeostasis Model Assessment Insulin Resistance (HOMA-IR) to bone mineral density (BMD) and bone mineral content in a group of Brazilian obese adolescents. This study included 109 post-pubescent obese adolescents. A whole-body dual-energy X-ray absorptiometry scan was performed,using a HOLOGIC QDR4200, to determine whole-body BMD and body composition. Blood samples were collected in the outpatient clinic after an overnight fast, and evaluated for fasting blood glucose and immunoreactive insulin. Leptin levels were assessed with a radioimmunoassay kit. Insulin resistance was assessed by HOMA-IR and the quantitative insulin sensitivity check index. Our results showed that insulin levels and HOMA-IR correlated negatively with BMD and a linear regression analysis showed that serum leptin is inversely associated to BMD adjusted for body mass. In conclusion, our data support the hypothesis that leptin, insulin and HOMA-IR are inversely associated with BMD and play a significant direct role in bone metabolism.

Obesidade e adipocinas inflamatórias: implicações práticas para a prescrição de exercício: [revisão] / Obesity and inflammatory adipokines: practical implications for exercise prescription: [review]

A obesidade é uma doença complexa de etiologia multifacetada, com sua própria fisiopatologia, comorbidades e capacidades desabilitantes. Aceitar a obesidade como uma doença é fundamental para o seu tratamento. Atualmente, o tecido adiposo é um dos principais focos das pesquisas em obesidade, devido a uma revolução no entendimento da função biológica desse tecido desde a última década. Já está muito claro que o tecido adiposo branco secreta múltiplos peptídeos bioativos, denominados adipocinas (proteínas sintetizadas e secretadas pelo tecido adiposo). Dessa forma, o objetivo deste trabalho de revisão foi investigar a relação entre obesidade e adipocinas inflamatórias, buscando discutir o papel do exercício físico no tratamento dessa patologia. Os resultados demonstram que uma das mais importantes descobertas das pesquisas recentes em obesidade é o conceito de que ela é caracterizada por uma inflamação crônica. Dentre todas as adipocinas, sem dúvida, a IL-6, o TNF-α, a leptina (pró-inflamatórias) e a adiponectina (anti-inflamatória) vêm recebendo atenção especial da literatura especializada. O aumento da concentração dessas adipocinas promove grande impacto em diversas funções corporais que estão fortemente correlacionadas com doenças cardiovasculares. Uma vez que a obesidade é considerada uma doença inflamatória e o exercício físico modula de forma direta tais processos, é essencial que tenhamos como um dos objetivos principais de nossos programas de exercícios físicos a melhora da resposta inflamatória de obesos.

Obesity is a complex disease with a multifaceted etiology with its own physiopathology, co-morbidities and disabiliting capacities. It is crucial that obesity is acknowledged as a disease in order to treat it. Nowadays, the adipose tissue is the main focus of obesity research due to the improvement in the last decade on biological function of this tissue. It is now clear that white adipose tissue release a large amount of bioactive peptides called adipokines (which are proteins synthesized and released by adipose tissue). Thus, the aim of this review was to investigate the relationship between obesity and inflammatory adipokines, trying to discuss the role of physical exercise in the treatment of this pathology. The results have shown that one of the most important recent discoveries is the concept that obesity is characterized by a chronic inflammation state. Among all adipokines, IL-6, TNF- α, leptin (pro-inflammatory) and adiponectin (anti-inflammatory), have received special attention from the specialized literature. High concentration of these adipokines promotes impact in several body functions, which is strongly linked with cardiovascular diseases. Since obesity is considered an inflammatory disease, and exercise directly modulates this process, it is essential that one of the main aims of exercise therapies is the improvement of the inflammatory response of obese individuals.