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Obesity is related to several organs, but the liver is particularly affected. Adenosine monophosphate-activated protein kinase (AMPK) is a cellular energy sensor and regulator of liver lipid dysfunction and glucose metabolism. The mechanistic target of rapamycin (mTOR) is a protein kinase regulating cell growth, survival, metabolism, and immunity. Together, these pathways are involved in obesity, insulin resistance, non-alcoholic fatty liver disease (NAFLD) and its progression, and autophagy. During energy demand, liver kinase B (LKB) phosphorylation helps activate the AMPK/mTOR pathways. Likewise, the protein forkhead box O family (FOXO) negatively regulates adipogenesis by binding to the promoter sites of peroxisome proliferator-activated receptor-gamma coactivator 1-alpha, initiating adipogenesis. In addition, acetyl-CoA carboxylase, which regulates de novo lipogenesis, is linked to LKB and FOXO in developing NAFLD. The kinase complex, consisting of Unc-51-like autophagy-activating kinase 1 or 2 (ULK1, ULK2) by stimulating autophagy, and eliminating fat droplets in NAFLD, is regulated by mTORC1 and negatively regulated by AMPK that suppresses liver lipogenesis and increases fatty acid oxidation. Also, ULK1 is essential for initiating phagophore formation, establishing macrophagy, and generating autophagosomes. The selective breakdown of lipid droplets through macroautophagy, or macrolipophagy, occurs on a cellular energy level using free fatty acids. In addition, mTORC1 promotes lipogenesis by activating sterol regulatory element-binding protein. Finding new components and novel regulatory modes in signaling is significant for a better understanding of the AMPK/mTOR pathways, potentially facilitating the development of future diagnostic and therapeutic strategies for NAFLD and its progression to non-alcoholic steatohepatitis, cirrhosis, and hepatocellular carcinoma.IA Marcondes-de-Castro et al.

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Mitochondria (m) are responsible for the energy availability of cells, and their analysis is indicated for example, in studies related to metabolism and oxidative stress. The direct measurement of mitochondria (morphometry) is biased because of the section obliquity and position relative to the mitochondria length (non-equatorial cut). Therefore, stereology is an appropriate technique to evaluate mitochondria. However, before beginning the study, it is necessary to consider the premises to obtain random and uniform samples to be analyzed stereology. Mitochondria must have the chance to appear in all the possibilities of cut and orientation in the micrographs. The number of micrographs to be analyzed will depend on the distribution and occupation of mitochondria in the cell. After this is resolved, a proposal is the estimation of the following stereological data: volume density (Vv), surface density (Sv), and mean cross-sectional area (A). Overlapping a known test area at each micrograph, the density by area of mitochondria is estimated (N AT). Vv [m] can easily be estimated by point-counting (Vv = Pp/P T ; Pp are the points hitting the structure, P T are the number of points of the test system). Sv is estimated overlaying a test-line (L T) on the micrographs and counting the intersections of the lines (I) with the outer membrane (om), inner membrane (im), and crests (c), thus, Sv [om], Sv [im], Sv [c] (Sv = 2I / L T). A [m] is obtained as the ratio: A = Vv / 2N AT .

No abstract