Assessment of high fat diet-induced fatty liver in medaka

Abstract

Fatty liver, which has been continuously becoming more common in a number of patients, is the most common liver disease. For detailed analysis, a useful model for fatty liver is needed and fish are considered as a potential candidate. We assessed through direct observation of the liver, which is the most conventional method for non-invasive analysis of progression in fatty liver. By using transparent medaka (Oryzias latipes), we were able to observe changes in fat deposition in the liver. An analysis of the progression of fatty liver using ultrasound showed a significant increase in echo intensity, which indicates that this is a useful examination method. In addition, we clarified a metabolite profile in the medaka liver fed a high-fat diet (HFD), which had not previously been shown in detail. This medaka model, allowing non-invasive and repetitive assessment, is a useful model for the analysis of diseases that cause fatty liver in which changes in detailed metabolites are identified.

Japanese medaka as a model for studying the relaxin family genes involved in neuroendocrine regulation: Insights from the expression of fish-specific rln3 and insl5 and rxfp3/4-type receptor paralogues

“…The growing interest in medaka for endocrine disorder investigation (Untergasser et al, 2012;Ichimura et al, 2013;Kirchmaier et al, 2015;Fujisawa et al, 2018), suggests that it is a timely model for dissecting the role of relaxin family peptides involved in neuroendocrine regulation. To this end, we provide the first experimental evidence for the expression of the relaxin family genes that had previously only been identified in-silico in O. latipes (Good-Avila et al, 2009;Yegorov and Good, 2012), characterise gene expression across multiple medaka tissues, and compare these results to the data available in zebrafish (Donizetti et al 2009(Donizetti et al , 2010Good-Avila et al, 2009;Fiengo et al, 2012;Good et al, 2012;Venditti et al, 2018) to further delineate relaxin ligand-receptor relationships in vertebrates.…”

“…transparency of the eggs and embryos (enabling whole-mount in situ hybridization (ISH)), relatively low maintenance costs, as well as the tremendous genomic resource availability (Kirchmaier et al, 2015;Gut et al, 2017). Of particular relevance for the relaxin family, is the proven utility of medaka as a model for endocrine disorders in human especially metabolic diseases, including obesity, non-alcoholic fatty liver disease, and type 2 diabetes (Matsumoto et al, 2010;Ichimura et al, 2013 41;Seth et al, 2013;Gut et al, 2017;Fujisawa et al, 2018). Additionally, medaka is a good model for studying the effect of stress on behaviour, physiology and/or gene regulation since they are highly sensitive to environmental challenges, including novelty stress, exposure to predators, chemicals, and experimental other methods to induce stress.…”

Seasonal variations in photoperiod affect hepatic metabolism of medaka (Oryzias latipes)

“…We previously reported the utility of a medaka model with a high-fat diet (HFD) for tissue analysis and lipid analysis [7]. In addition, we evaluated HFD-induced hepatic steatosis through direct observation and ultrasound of transparent medaka for non-invasive analyses of the progression of HFD-induced fatty liver disease [8]. Further, direct observation and ultrasound examination of transparent medaka allowed for the evaluation of hepatic steatosis induced by the administration of alcohol [5].…”

Establishment of an Adult Medaka Fatty Liver Model by Administration of a Gubra-Amylin-Nonalcoholic Steatohepatitis Diet Containing High Levels of Palmitic Acid and Fructose

“…We previously reported the utility of the medaka model fed a high-fat diet for tissue and lipid analysis [7]. Furthermore, as a noninvasive method of analyzing fatty liver progression due to HFD liver steatosis has been evaluated using direct observation of transparent medaka or using ultrasound [8]. Changes in liver steatosis due to alcohol administration have also been evaluated using direct observation and ultrasound in transparent medaka [9].…”