Adiponectin ameliorated pancreatic islet mitochondrial injury induced by chronic intermittent hypoxia

Objective To explore the effect of adiponectin (APN) on islet injury induced by chronic intermittent hypoxia (CIH). Methods Thirty-six SD rats were randomly divided into three groups: Normal control (NC), CIH, and CIH + APN groups. The rats in the CIH and CIH+APN groups received an intermittent hypoxia exposure while the rats in NC group received the room air only. The rats in CIH+APN group received the intravenous injection of APN. The intermittent hypoxia events persisted 8 hours a day and last for 35 days. The fasting blood glucose and fasting insulin were detected at the time of 0, 7, 14, 21, 28, and 35 day. After 35 days, the level of serum adiponectin, and adenosine triphosphate (ATP) level, superoxide dismutase (SOD), malondialdehyde (MDA), the mRNA levels of mitochondrial oxidative phosphorylation function and mitochondrial synthesis gene, and the protein level of mitochondrial and cytoplasmic cytochrome C of pancreatic islet were detected. Results The glucose and insulin level had no statistically differences among three groups at different time points (all P>0.05). However, compared with NC and CIH+APN groups, CIH reduced the serum adiponectin [(7 265±2 209) ng/ml, (6 536±1 678) ng/ml vs (4 923±1 742) ng/ml, both P<0.05], ATP levels [(30.92±1.12) nmol/mg, (26.55±0.72) nmol/mg vs (20.22±1.47) nmol/mg, both P<0.05], mRNA levels of mitochondria oxidative phosphorylation function and mitochondrial synthesis gene, the activity of SOD, and the rate of mitochondrial/cytoplasmic cytochrome C protein level while increased the MDA level in pancreatic islet. Compared with NC group, the MDA level increased (P<0.05) and the APN level had no statistically difference, while the level of other indicators decreased in CIH+APN group (all P<0.05). Conclusion APN ameliorates the pancreatic islet injury induced by CIH through inhibition of oxidative stress. Key words: Sleep apnea, obstructive; Adiponectin; Mitochondria; Oxidative stress; Chronic intermittent hypoxia