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Rationale: Obstructive sleep apnea is recurrent upper airway obstruction caused by a loss of upper airway muscle tone during sleep. The main goal of our study was to determine if designer receptors exclusively activated by designer drugs (DREADD) could be used to activate the genioglossus muscle as a potential novel treatment strategy for sleep apnea. We have previously shown that the prototypical DREADD ligand clozapine-N-oxide increased pharyngeal diameter in mice expressing DREADD in the hypoglossal nucleus. However, the need for direct brainstem viral injections and clozapine-N-oxide toxicity diminished translational potential of this approach, and breathing during sleep was not examined.Objectives: Here, we took advantage of our model of sleep-disordered breathing in diet-induced obese mice, retrograde properties of the adeno-associated virus serotype 9 (AAV9) viral vector, and the novel DREADD ligand J60.Methods: We administered AAV9-hSyn-hM3(Gq)-mCherry or control AAV9 into the genioglossus muscle of diet-induced obese mice and examined the effect of J60 on genioglossus activity, pharyngeal patency, and breathing during sleep.Measurements and Main Results: Compared with control, J60 increased genioglossus tonic activity by greater than sixfold and tongue uptake of 2-deoxy-2-[18F]fluoro-d-glucose by 1.5-fold. J60 increased pharyngeal patency and relieved upper airway obstruction during non-REM sleep.Conclusions: We conclude that following intralingual administration of AAV9-DREADD, J60 can activate the genioglossus muscle and improve pharyngeal patency and breathing during sleep.

Rationale: North America is currently facing an opioid epidemics. Over 130 Americans die every day from an opioid overdose and the COVID-19 pandemic has increased opioid usage and opioid-related deaths. Respiratory depression is the main cause of morbidity and mortality from opioids. We have previously shown that leptin acts as respiratory stimulant and prevents opioid-induced respiratory depression and upper airway obstruction without reducing analgesia. In this study, we aimed to examine if intranasal (IN) administration of leptin effectively delivers leptin to the brain and prevents opioid-related deaths. Methods: To determine leptin delivery to the brain male C57BL/6J mice, were treated with IN leptin at 1.2 mg/kg in 1% BSA (n=5) or 1% BSA (n=5) and sacrificed 20 min later. Brains were harvested, the olfactory bulbs, medullas and hypotalami were isolated, quick frozen and stored at-80°C. For leptin level measurements, brain tissue was homogenized, protease inhibitors and protein concentrations were determined and ELISA was performed. To determine the survival probability, male C57BL/6J mice, 12 weeks of age, received IN leptin (n=26) or vehicle (n=25) at 1.2 mg/kg and 30 minutes later received a bolus of intraperitoneal (IP) morphine at 400mg/kg. Mice were video monitored for 24 hours and survival time after morphine injection was recorded Results: IN leptin significantly increased leptin levels in the olfactory bulb (from 0 ng/mL to 7.53 ng/mL, p = 0.004) and medulla (from 0.008 ng/mL to 0.107 ng/mL) and presented a trend in the hypothalamus (from 0.018 ng/mL to 0.291 ng/mL, p = 0.1). Mice that received IN leptin had a higher survival rate when compared to mice that received vehicle (69% vs 92%, p = 0.044, Figure). Conclusion: We demonstrated that the intranasal route is effective for the delivery of leptin to the brain and that leptin reduced opioid-induced mortality. (Table Presented).