Sleep need driven oscillation of glutamate synaptic phenotype

Melanin concentrating hormone-sleep pressure loop regulates melanin degradation through both autophagic degradation and lysosomal hydrolysis in zebrafish

Melanin-concentrating hormone (MCH) is a cyclic peptide initially isolated from salmon and later found to be conserved in mammals. It plays a role in regulating melanin changes and rhythmic behaviors such as sleep and feeding, though its relationship with these processes is not fully understood. Our preliminary research revealed significant differences in melanin degradation in zebrafish under varying light conditions, suggesting a link to MCH. This study aims to explore MCH's role in lighting-induced changes in rhythmic behavior patterns and melanin of zebrafish. Using the zebrafish model, we evaluated MCH expression under different lighting conditions and analyzed the effects of arousal-promoting and sleep-inducing agents. We also investigated the impact of exogenous MCH and its inhibitors on melanin degradation, behavioral changes, and differences in MCH expression to uncover potential regulatory relationships between MCH, sleep pressure, and melanin. In-depth research using flow cytometry, acridine orange staining, LysoTracker Red staining, and quantitative real-time PCR analysis of autophagy- and apoptosis-related genes showed that melanin degradation regulation depends on MCH expression levels. Sleep pressure can intervene in MCH's effects, forming a regulatory loop to jointly regulate melanin degradation. The influence of the MCH-sleep pressure loop on melanin degradation is closely tied to autophagic and lysosomal pathways. Our findings reveal a mutually regulatory loop in zebrafish between MCH and sleep pressure, affecting melanin degradation through these pathways.

Per-and polyfluoroalkyl substances and disrupted sleep: mediating roles of proteins

Background

Per-and polyfluoroalkyl substances (PFAS) contamination may disrupt sleep through disrupted metabolic and immune functions. The study aims to investigate the association and potential mechanism between PFAS and sleep.

Methods

We included 136 young adults recruited between 2014-2018 and 76 were re-assessed between 2020-2022. Additional 8 participants only had complete data between 2020-2022. Plasma PFAS (PFOS, PFOA, PFHxS, PFHpS, PFPeS, PFNA, PFDA) were measured at both visits using liquid-chromatography high-resolution mass spectrometry. Plasma proteins were measured by Olink® Explore 384 Cardiometabolic and Inflammation Panel I. Sleep duration was self-reported at both visits along with follow-up sleep disturbance and sleep-related impairment using validated instruments. We utilized multiple linear regression to explore the association between individual PFAS (in tertile) and these sleep outcomes. PFAS associated with sleep outcomes were subjected to computational toxicology analysis using the Comparative Toxicogenomics Database and Toxicology in the 21st Century database to identify potential genetic links between them. Mediation analysis using proteomic data was then performed to confirm the findings from computational toxicology analysis.

Results

At baseline, one tertile increase in PFDA was associated with 0.39 (95 % CI: 0.05, 0.73) hours of shorter nightly sleep duration, and, at follow-up, PFHxS and PFOA were associated with 0.39 (95 % CI: 0.05, 0.72) and 0.32 (95 % CI: 0.01, 0.63) hours shorter sleep duration, respectively. One tertile increase in PFOS exposure was associated with a 2.99-point increase in sleep disturbance scores (95 % CI: 0.67, 5.31) and a 3.35-point increase in sleep-related impairment scores (95 % CI: 0.51, 6.20). Computational toxicology and mediation analyses identified potential mediating roles for several proteins in the PFAS-sleep associations, including 11-beta-dehydrogenase isozyme 1 (HSD11B1), cathepsin B (CTSB) and several immune system-related proteins.

Conclusion

Future large scale epidemiological and mechanistic studies should confirm our findings and test effect measure modification of the associations by age.