High glucose induces apoptosis, glycogen accumulation and suppresses protein synthesis in muscle cells of olive flounder Paralichthys olivaceus

Abstract

The effect and the mechanism of high glucose on fish muscle cells are not fully understood. In the present study, muscle cells of olive flounder (Paralichthys olivaceus) were treated with high glucose (33 mM) in vitro. Cells were incubated in three kinds of medium containing 5 mM glucose, 5 mM glucose and 28 mM mannitol (as an isotonic contrast) or 33 mM glucose named the Control group, the Mannitol group and the HG (high glucose) group, respectively. Results showed that high glucose increased the ADP/ATP ratio and the reactive oxygen species (ROS) level, decreased mitochondrial membrane potential (MMP), induced the release of cytochrome C (CytC) and cell apoptosis. High glucose also led to cell glycogen accumulation by increasing the glucose uptake ability and affecting the mRNA expressions of glycogen synthase and glycogen phosphorylase. Meanwhile, it activated AMP-activated protein kinase (AMPK), inhibited the activity of mammalian target of rapamycin (mTOR) signaling pathway and the expressions of myogenic regulatory factors (MRFs). The expressions of myostatin-1 (mstn-1) and E3 ubiquitin ligases including muscle RING-finger protein 1 (murf-1) and muscle atrophy F-box protein (mafbx) were also increased by the high glucose treatment. No difference was found between the Mannitol group and the Control group. These results demonstrate that high glucose has the effects of inducing apoptosis, increasing glycogen accumulation and inhibiting protein synthesis on muscle cells of olive flounder. The mitochondria mediated apoptotic signaling pathway, AMPK and mTOR pathways participated in these biological effects.

Replacing Fish Meal with Hydrolyzed Collagen Derived from Fish By-Products Improved Muscle Quality and Glycolipid Metabolism of Triploid Crucian Carp

“…In the present study, serum GSH-Px activity increased significantly and serum MDA content decreased significantly with hydrolyzed collagen replacement, which coincided with the former research that the GSH-Px and SOD activities in the skin of mice were significantly increased after oral administration of the diet containing collagen hydrolysate [ 46 ]. Excessive ROS would cause the oxidation of subcellular membrane and structural proteins, and ultimately affect muscle texture, water-holding capacity and other quality characteristics, which was harmful to muscle quality [ 47 ]. When common carp ( Cyprinus carpio ) was exposed to oxidative stress, the muscle physicochemical properties decreased significantly [ 48 ].…”

“…The decreased expression levels of GPase and GK in the liver might be attributed to the decreased hepatic glycogen content, resulting in the decreased activities of glycogen decomposition and glycolysis-related enzymes, but the mechanism of hepatic glycogen decrease needs to be further studied. High glucose level may stimulate vascular cells to produce ROS through the activation of NAD(P)H oxidase, which depends on protein kinase C (PKC) pathway, and ultimately affect the quality of fish [ 47 , 56 ]. In the present experiment, the decrease in serum glucose content may be beneficial in improving the muscle quality of fish to some extent.…”

Revisiting cell culture media for immune cells: Has d‐glucose been necessary?

“…In general, RPMI1640 medium contains 11.1 mM glucose (2 g/L), while DMEM is mainly divided into a 5.55 mM (1 g/L) low-glucose medium and 25 mM (4.5 g/L) high-glucose medium. High-dose supplementation with glucose has shown distinct effects on immune cell-mediated responses, [1][2][3][4] and glycaemic asset and insulin resistance play a role in the inflammatory and immune response. 5 Although studies have used either RPMI1640 or DMEM medium to culture immune cells to evaluate immune-cell response, including T-cell proliferation and T-cell secreting cytokines, whether these two mediums with or without glucose have a different impact on immune function remained unknown.…”