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Impact of interrupted leptin pathways on ventilatory control
Vsevolod Y Polotsky1, Marc C Smaldone, Matthew T Scharf
1Department of Medicine, Division of Pulmonary and Critical Care Medicine, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD 21224, USA. vpolots1@jhmi.edu
Journal of Applied Physiology (Bethesda, Md. : 1985)
|October 28, 2003
Summary
Leptin deficiency does not alter hypoxic ventilatory response in mice. However, blocking melanocortin 4 pathways significantly depresses hypercapnic sensitivity during non-rapid eye movement sleep.
Area of Science:
- Physiology
- Neuroscience
- Respiratory Regulation
Background:
- Leptin deficiency in ob/ob mice impairs hypercapnic ventilatory response, especially during sleep.
- The role of leptin in hypoxic sensitivity and the impact of downstream pathway modulation remain unclear.
Purpose of the Study:
- To investigate if leptin deficiency affects hypoxic ventilatory response.
- To determine the impact of blocking leptin's downstream melanocortin 4 (MCR4) or neuropeptide Y (NPY) pathways on hypercapnic and hypoxic sensitivity.
Main Methods:
- Comparison of hypoxic ventilatory response in leptin-deficient (ob/ob) mice and weight-matched controls.
- Assessment of hypercapnic and hypoxic sensitivity in mice with blocked MCR4 (agouti yellow) or NPY pathways.
- Measurements conducted during both wakefulness and non-rapid eye movement sleep.
Main Results:
- Leptin deficiency did not alter hypoxic ventilatory response in ob/ob mice compared to controls.
- Agouti yellow mice (MCR4 blockade) showed significantly reduced hypercapnic sensitivity during non-rapid eye movement sleep.
- NPY-deficient mice exhibited a minor increase in hypercapnic response during wakefulness only.
Conclusions:
- Leptin pathways do not influence hypoxic sensitivity during sleep or wakefulness.
- Melanocortin 4 receptor blockade is linked to decreased hypercapnic sensitivity during non-rapid eye movement sleep.