Obesity is associated with hyperlipidemia resulting in an increased delivery of fatty acid to most tissues including the pancreas. Excess fatty acid oxidation in β-cells of the pancreas results in increased reactive oxygen species (ROS) production. The increased ROS production ultimately contributes to β-cell apoptosis and the need for exogenous insulin in poorly controlled Type 2 diabetes. The deleterious effects of ROS within the pancreas are amplified due to limited expression of which of the following?
A) caspase 9
B) catalase
C) glutathione peroxidase
D) peroxiredoxin
E) superoxide dismutase

Question

Quizplus · Accepted Answer

The pancreas has limited expression of catalase, an enzyme that helps in breaking down hydrogen peroxide, a reactive oxygen species, into water and oxygen, thus reducing oxidative stress. The oxidation of fatty acids results in the generation of ROS both via mitochondrial and peroxisomal pathways. When fatty acid levels rise significantly, as in obesity, peroxisomal oxidation of fatty acids increases. The initial enzyme in peroxisomal fatty acid oxidation generates H₂O₂. The primary antioxidant enzyme tasked with removal of H₂O₂ is catalase. Pancreatic β-cells are highly susceptible to the damaging effects of H₂O₂ due to a significantly reduced level of expression of catalase compared to other tissue.

Obesity Is Associated with Hyperlipidemia Resulting in an Increased Delivery