On the other hand, the removal of insulin from the medium or inhibition of glycolysis with 2-DG did not increase caspase-3 activation in INL and ONL.
While only photoreceptors in the ONL were found to be sensitive to perturbation of intracellular glucose homeostasis via 2-DG treatment, removal of insulin from the culture medium caused a significant increase in cell death in both INL and ONL.
1: Experimental conditions, medium composition, type of diabetes emulated, and group abbreviations used in this study Experimental R16 medium composition Diabetes condition Control 19 mM glucose = 2 [micro]g/ml insulin Osmotic control 19 mM glucose 2 [micro]g/ml insulin 15 mM mannitol (4 days) No insulin 19 mM glucose Type 1 0 [micro]g/ml insulin (4 days) High glucose, 34 mM glucose (4 days) Type 1 no insulin 0 [micro]g/ml insulin (4 days) High glucose 34 mM glucose (4 days) Type 2 2 [micro]g/ml insulin 2-deoxyglucose 19 mM glucose Type 2 2 [micro]g/ml insulin 20 mM 2-deoxyglucose (24 h) Experimental Abbreviation condition Control Control Osmotic control Mannitol No insulin No INS High glucose, HG, No INS no insulin High glucose HG 2-deoxyglucose 2-DG
We determined how 2-DG and/or melatonin affected known regulators of insulin signaling, phosphoinositide 3-kinase (PI3K), Akt/PKB, and mTOR, in rat insulinoma INS-1E cells.
Next, to characterize intracellular and mitochondrial conditions according to antioxidant and prooxidant proteins, we examined how 2-DG and/or melatonin affected superoxide dismutase (SOD), catalase, Bcl-2, and Bax proteins in rat insulinoma INS-1E cells.
Subsequently, we investigated whether 2-DG reduced insulin synthesis which had been increased by melatonin via EDC3 in rat insulinoma INS-1E cells.
These results suggested that melatonin-mediated insulin synthesis during 2-DG treatment involved autophagy-induced ER stress and EDC3 protein in rat insulinoma INS-1E cells, subsequently resulting in a decrease in insulin protein biosynthesis.
The glucose analog 2-DG acts as a glycolytic inhibitor, leading to ER stress and an unfolded protein response [26-28].
Other studies have showed that conditions including glucose deprivation, 2-DG treatment, and hypoxia or increase of intracellular [Ca.
The interaction between 2-DG and the AMPK/mTOR signal pathway has not been reported in pancreatic [beta] cells.
However, our current study demonstrated that HuD under autophagy and ER stress with 2-DG and melatonin could not negatively regulate insulin production (data not shown).
Glucose deprivation by mechanisms including 2-DG induces the production of reactive oxygen species (ROS) to activate AMPK in pancreatic [beta] cells .