Circadian rhythm dysregulation and brain functional connectivity alterations in stroke patients: an exploratory study of peripheral and central clock interactions

Abstract Background The human circadian rhythm system is governed by a transcriptional-translational feedback loop of clock genes, including Bmal1 , which exhibits a near-24-hour oscillatory period. Emerging evidence highlights the critical contribution of circadian genes to stroke pathogenesis and outcomes, yet mechanistic insights into their regulatory roles remain limited. To bridge this knowledge gap, we aimed to determine whether the serum of stroke patients could affect changes in the molecular clock and whether such changes in the molecular clock were potentially linked to abnormal brain functional connectivity in stroke patients. Methods This prospective case-control study included 17 patients with stroke and 17 age-matched healthy participants. All participants were required to complete a standardized comprehensive questionnaire. Transfected human osteosarcoma cells (U2OS) stably expressing Bmal1-dluc reporters were treated with serum from both groups to monitor changes in the daily oscillation period of Bmal1. We also compared the changes in resting-state hypothalamic intrinsic functional connectivity(FC) between the two groups. Further, we explored the correlation between the differences in FC between the two groups and the daily oscillation period of Bmal1 . Results Compared to the healthy control group, stroke patients exhibited a significantly prolonged peripheral Bmal1 circadian oscillation period (24.32 ± 0.41 h vs. 23.81 ± 0.48 h, t = 3.352, p = 0.002). In FC analysis, the stroke group showed enhanced connectivity from the hypothalamus to the right occipital lobe and the right insular region. Notably, the degree of this connectivity enhancement demonstrated a significant positive correlation with the length of Bmal1 oscillation period ( r = 0.369, p = 0.032; r = 0.393, p = 0.022). Conclusion Our findings suggest that serum from stroke patients lengthens the circadian period in U2OS cells and may be associated with alterations in brain functional connectivity. However, the small sample size limits statistical power, and these exploratory results require replication in larger independent cohorts. Trial registration ChiCTR2000031671(April 4, 2020).