👤 Junia L de Deus

The primary cause of death associated with opioids is opioid-induced respiratory depression (OIRD). Naloxone is used to reverse OIRD, but this drug is a competitive antagonist of µ-opioid receptor (MOR) and reverses analgesia, which limits its therapeutic use. Alternative non-opioid receptor antagonist-based approaches to OIRD treatment and prevention are needed. The aim of this study was to evaluate if setmelanotide (SET) is capable of reversing OIRD in a mouse model. C57BL/6J male and female mice and Sprague-Dawley rats were given IP morphine or fentanyl and then treated 15 min later with either SET or vehicle VEH (IP) in a random order. Breathing was recorded by barometric plethysmography, and pain sensitivity was measured by the tail-flick test. In mice with OIRD, SET induced a 3-fold reduction of the apnea index, and decreased apnea duration as compared to the VEH treatment. SET increased respiratory rate and did not affect opioid-induced analgesia. Photostimulation of MC4R+ ChR2-expressing fibers in the parafacial region of MC4R-Cre mice elicited short-latency excitatory postsynaptic current in rostral ventral respiratory group (rVRG) pre-motoneurons projecting to the phrenic nucleus in the C3-C4 ventral horns of the spinal cord. Fentanyl inhibited the activity of rVRG neurons and SET reversed this effect. SET effectively treated OIRD by increasing respiratory rate and inducing a significant decrease in the number of apneas without decreasing analgesia. Show less

Alzheimer's disease (AD) is the most prevalent cause of dementia and has been closely linked to βSupplemental data for this article can be accessed online at ht tps://doi.org/-amyloid accumulation. However, the efficacy and safety of anti-β-amyloid monoclonal antibodies remain debated. We systematically searched PubMed, Embase, and Cochrane databases for RCTs comparing anti-β-amyloid monoclonal antibodies with placebo in early-stage AD. Eligible trials enrolled participants with biomarker-supported AD and reported global, cognitive, or safety outcomes, including the CDR-SB, ADAS-Cog 13/14, ARIA, and brain volumetric measures. Six RCTs including 7837 participants were analyzed. Mean age ranged from 69.8 to 75.4 years, and 57.4% were APOE ε4 carriers. Anti-β-amyloid therapy was associated with small differences in global and cognitive outcomes, best described as a modest slowing of decline on the CDR-SB and ADAS-Cog scales. Treatment was associated with increased risks of ARIA-E (RR, 9.40; 95% CI, 6.98-12.66) and ARIA-H (RR, 2.40; 95% CI, 2.08-2.78), as well as greater ventricular enlargement and hippocampal atrophy. In early AD, anti-β-amyloid monoclonal antibodies are associated with modest slowing of decline accompanied by increased ARIA risk and unfavorable structural brain changes, limiting clinical applicability. www.crd.york.ac.uk/prospero identifier is CRD420251071393. Show less

Weight loss medications are emerging candidates for pharmacotherapy of sleep-disordered breathing (SDB). A melanocortin 4 receptor (MC4R) agonist, setmelanotide (Set), is used to treat obesity caused by abnormal melanocortin and leptin signaling. We hypothesized that Set can treat SDB in mice with diet-induced obesity. We performed a proof-of-concept randomized crossover trial of a single dose of Set versus vehicle and a 2-week daily Set versus vehicle trial, examined colocalization of Mc4r mRNAs with the markers of CO2-sensing neurons Phox2b and neuromedin B in the brainstem, and expressed Cre-dependent designer receptors exclusively activated by designer drugs (DREADDs) or caspase in obese Mc4r-Cre mice. Set increased minute ventilation across sleep/wake states, 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 HCVR without any changes in metabolism. Caspase elimination of the parafacial MC4R+ neurons abolished effects of Set on HCVR. Parafacial MC4R+ neurons projected to the respiratory premotor neurons retrogradely labeled from C3-C4. In conclusion, MC4R agonists enhance the HCVR and treat SDB by acting on the parafacial MC4R+ neurons. Show less