Targeting Melanocortin 4 Receptor to Treat Sleep-Disordered Breathing

There is no effective pharmacotherapy for sleep-disordered breathing (SDB). A melanocortin receptor 4 (MCR4) agonist, setmelanotide (SET), is used to treat genetic obesity caused by abnormal melanocortin and leptin signaling. We hypothesized that SET can treat SDB in diet-induced obese mice. We performed a proof-of-concept randomized crossover trial of a single dose of SET vs vehicle and a two-week daily SET vs vehicle trial in obese mice. We also examined co-localization of Mcr4 mRNAs with a marker of CO 2 sensing neurons PHOX2b in the brainstem and performed chemogenetic studies expressing Cre-dependent designer receptors exclusively activated by designer drugs (DREADD) in Mcr4-Cre mice. SET increased minute ventilation across sleep/wake states, greatly enhanced the hypercapnic ventilatory response (HCVR), and abolished apneas during sleep. PHOX2b+ neurons in the nucleus of the solitary tract (NTS) and the parafacial region expressed Mc4r. Chemogenetic stimulation of the MC4R+ neurons in the parafacial region, but not in the NTS, augmented the HCVR without any changes in metabolism. Parafacial MC4R neurons projected to the respiratory pre-motor neurons expressing cholera toxin B after C3-C4 spinal cord injections. In conclusion, MC4R agonists enhance the HCVR and treat SDB by acting on the parafacial MC4R+ neurons. NIH (R01 HL128970, R01 HL133100, and R01 HL138932), AHA (#915167). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.