Obstructive sleep apnea is associated with type 2 diabetes. We have previously developed a mouse model of intermittent hypoxia (IH) mimicking oxyhemoglobin desaturations in patients with sleep apnea and have shown that IH increases fasting glucose, hepatic glucose output, and plasma catecholamines. We hypothesize that adrenal medulla modulates glucose responses to IH, and that such responses can be prevented by adrenal medullectomy. We performed adrenal medullectomy or sham surgery in lean C57BL/6J mice, which were exposed to IH or intermittent air (control) for 4 weeks followed by the frequently sampled intravenous glucose tolerance test (FSIVGTT) in unanesthetized unrestrained animals. IH was administered during the 12 hr light phase (9am - 9 pm) by decreasing inspired oxygen from 21% to 6.5% 60 cycles/hr. Insulin sensitivity (SI), insulin independent glucose disposal (glucose effectiveness, SG), and the insulin response to glucose (AIRG) were determined using the Minimal Model method. In contrast to our previous data obtained in restrained mice, IH did not affect fasting blood glucose and plasma insulin levels in sham-operated mice. IH significantly decreased SG, but did not affect SI and AIRG. Adrenal medullectomy decreased fasting blood glucose and plasma insulin levels and increased glycogen synthesis in the liver in hypoxic mice, but did not have a significant effect on the FSIVGTT metrics. We conclude that, in the absence of restraints, IH has no effect on glucose metabolism in lean mice with exception of decreased SG, whereas adrenal medullectomy decreases fasting glucose and insulin levels in the IH environment.
- obstructive sleep apnea
- type 2 diabetes
- glucose effectiveness
- insulin resistance
- Copyright © 2016, Journal of Applied Physiology