Characteristics of the New Insulin-Resistant Zebrafish Model

Abstract

Insulin resistance, which occurs when insulin levels are sufficiently high over a prolonged period, causing the cells to fail to respond normally to the hormone. As a system for insulin resistance and diabetes drug development, insulin-resistant rodent models have been clearly established, but there is a limitation to high-throughput drug screening. Recently, zebrafish have been identified as an excellent system for drug discovery and identification of therapeutic targets, but studies on insulin resistance models have not been extensively performed. Therefore, we aimed to make a rapid insulin-resistant zebrafish model that complements the existing rodent models. To establish this model, zebrafish were treated with 10 μM insulin for 48 h. This model showed characteristics of insulin-resistant disease such as damaged pancreatic islets. Then we confirmed the recovery of the pancreatic islets after pioglitazone treatment. In addition, it was found that insulin-resistant drugs have as significant an effect in zebrafish as in humans, and these results proved the value of the zebrafish insulin resistance model for drug selection. In addition, RNA sequencing was performed to elucidate the mechanism involved. KEGG pathway enrichment analysis of differentially expressed genes showed that insulin resistance altered gene expression due to the MAPK signaling and calcium signaling pathways. This model demonstrates the utility of the zebrafish model for drug testing and drug discovery in insulin resistance and diabetes.

An Association between Insulin Resistance and Neurodegeneration in Zebrafish Larval Model (Danio rerio)

“…Quantitative PCR analysis was used in this study, showing the time point group designation as shown in the references from previous studies [ 25 , 27 ]. The study is important in terms of glucose dynamic study at different time points to validate that hyperinsulinemia induction can induce hyperglycemia and the transposition of insulin signaling genes ( pepck and akt ) affecting two genes involved in neurodegeneration ( zglut3 and claudin-5a ).…”

“…Coinciding with the loss of insulin sensitivity, perturbation of glucose homeostasis was observed due to the downregulation of phosphoenolpyruvate carboxykinase ( pepck ) and the dephosphorylation of the Akt pathway upon microinjection of insulin (250 nM and 100 nM) into the caudal aorta at 4 days post fertilization (dpf) in larvae [ 25 ]. Similarly, Rocha et al, (2013) and Nam et al, (2021) studies indicate that glucose acts on the physiological changes in zebrafish larvae by glucose and insulin immersion, respectively [ 26 , 27 ]. Nam et al, (2021) focused on the characterization of insulin resistance in a T2DM model in MAPK signaling pathways encoded by the map2k6 -gene-activated inflammatory cytokines [ 27 ].…”

“…Similarly, Rocha et al, (2013) and Nam et al, (2021) studies indicate that glucose acts on the physiological changes in zebrafish larvae by glucose and insulin immersion, respectively [ 26 , 27 ]. Nam et al, (2021) focused on the characterization of insulin resistance in a T2DM model in MAPK signaling pathways encoded by the map2k6 -gene-activated inflammatory cytokines [ 27 ]. However, the association with T2DM-targeted neurodegeneration pathways has yet to be proven.…”

“…Orthologue genes in the insulin signaling pathway are expressed in zebrafish such as glucose transporter (Glut) genes Glut-1 , 2 , 3 , 10 and 12 [ 25 , 26 , 27 , 28 , 29 , 30 ]. The expression of Glut-3 has been widely established in mice and rats’ brain region such as the hippocampus, cerebral cortex, striatum and cerebellum [ 31 ].…”

Establishment of Zebrafish Models for Diabetes Mellitus and Its Microvascular Complications

“…Thus, incubating zebrafish with MG solutions can be a more straightforward way to establish diabetic model [24]. In addition, treating zebrafish embryos with high insulin concentration in a short-term (no more than 120 min) can lead to a hyperinsulinemia condition and a long-term (48 h) treatment causes insulin-resistant in zebrafish that mimics human type 2 DM [25]. Because obesity is usually a major factor for developing type 2 DM in humans, Zang et al [26] construct the obesity-induced zebrafish diabetic model via overfeeding.…”