Screening effects of HCN channel blockers on sleep/wake behavior in zebrafish

Abstract

Hyperpolarization-activated cyclic nucleotide-gated (HCN) ion channels generate electrical rhythmicity in various tissues although primarily heart, retina and brain. The HCN channel blocker compound, Ivabradine (Corlanor), is approved by the US Food and Drug Administration (FDA) as a medication to lower heart rate by blocking hyperpolarization activated inward current in the sinoatrial node. In addition, a growing body of evidence suggests a role for HCN channels in regulation of sleep/wake behavior. Zebrafish larvae are ideal model organisms for high throughput drug screening, drug repurposing and behavioral phenotyping studies. We leveraged this model system to investigate effects of three HCN channel blockers (Ivabradine, Zatebradine Hydrochloride and ZD7288) at multiple doses on sleep/wake behavior in wild type zebrafish. Results of interest included shorter latency to day time sleep at 0.1 M dose of Ivabradine (ANOVA, p:0.02), moderate reductions in average activity at 30 M dose of Zatebradine Hydrochloride (ANOVA, p:0.024) in daytime, and increased nighttime sleep at 4.5 M dose of ZD7288 (ANOVA, p:0.036). These differences support the hypothesis that compounds blocking HCN channels decreases wakefulness. HighlightsO_LIA drug screening study in which effects of HCN channel blocker compounds were tested displayed decreased wakefulwness in zebrafish. C_LIO_LIThere was modest evidence of these drugs on sleep and wake phenotypes including shorter latency to sleep, moderate reductions in average activity and increased sleep at different doses of three compounds compared to DMSO. C_LIO_LIWhile several specific doses of Ivabradine, Zatebradine hydrochloride or ZD7288 demonstrated some differences compared to DMSO, effects of these compounds was smaller than the effect of melatonin, a positive control. C_LI