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Metabolic syndrome is a cluster of metabolic risk factors such as obesity, diabetes and cardiovascular diseases. Mitochondria is the main site of ATP production and its dysfunction leads to decreased oxidative phosphorylation, resulting in lipid accumulation and insulin resistance. Our group has demonstrated that kinins can modulate glucose and lipid metabolism as well as skeletal muscle mass. By using B2 receptor knockout mice (B2R-/-) we investigated whether kinin action affects weight gain and physical performance of the animals. Our results show that B2R-/- mice are resistant to high fat diet-induced obesity, have higher glucose tolerance as well as increased mitochondrial mass. These features are accompanied by higher energy expenditure and a lower feed efficiency associated with an increase in the proportion of type I fibers and intermediary fibers characterized by higher mitochondrial content and increased expression of genes related to oxidative metabolism. Additionally, the increased percentage of oxidative skeletal muscle fibers and mitochondrial apparatus in B2R-/- mice is coupled with a higher aerobic exercise performance. Taken together, our data give support to the involvement of kinins in skeletal muscle fiber type distribution and muscle metabolism, which ultimately protects against fat-induced obesity and improves aerobic exercise performance.

Mitochondrial diseases are complex disorders caused by nuclear or mitochondrial DNA mutations, leading to oxidative phosphorylation deficiency and excessive production of reactive oxygen species (ROS). While ROS have been well established in the pathogenesis of these diseases, the role of reactive nitrogen species (RNS) remains unclear. In this study, we performed a quantitative analysis of muscle fibers to investigate the relationship between protein nitration and mitochondrial abnormalities (mitochondrial proliferation and cytochrome-c oxidase (COX) deficiency) and factors like genotype, muscle damage, and age. A total of 1961 muscle fibers (303 from 4 controls and 1658 from 29 patients with mitochondrial diseases) were analyzed by immunostaining for nitro-tyrosine. Contrary to previous findings, which identified nitro-tyrosine only in small muscle vessels, we observed a broader distribution affecting the sarcolemma and sarcoplasm. Using multivariate techniques, we identified a significant correlation between protein nitration and mitochondrial proliferation but found no associations with COX deficiency, age, muscle damage, or genotype. These findings suggest that nitrative stress may contribute to mitochondrial dysfunction or play a role in signaling processes that induce mitochondrial biogenesis. Our results provide new insights into the molecular mechanisms of mitochondrial diseases and highlight the potential relevance of protein nitration.

Foram individualizados 17 pacientes com distrofia muscular congênita (DMC) por critérios clínico-laboratoriais e biópsia muscular com estudo histoquímico do músculo deltóide superficial. São descritas e ilustradas, com detalhes, as alterações histológicas observadas nas respectivas biópsias e que compõem seu substrato anátomo-patológico: proliferação conjuntiva, alteração na arquitetura interna, necrose, involução gordurosa, macrofagia, regeneração, segmentação, centralizações nucleares e predominância de fibras tipo I. Destacamos a intensa proliferação conjuntiva endomisial ,que tende a isolar cada fibra muscular separadamente, e as importantes alterações na arquitetura, interna, com formação de fibras bizarras, que constituem dois importantes sinais que devem ser ressaltados tendo em vista um diagnóstico histológico diferencial com a distrofia muscular de Duchenne e Becker (DMD/ B) e com a distrofia forma cintura-membros. A importância de se individualizar a DMC das outras formas de distrofias musculares reside principalmente em seu prognóstico que, na maioria das vezes, é mais favorável que na DMD.