Cuscutae Semen ameliorates mepanipyrim-induced visual impairment in zebrafish via the phototransduction pathway with identification of potential active constituents

Background: The global rise in visual impairment, driven by population aging, the increasing prevalence of lifestyle-related chronic diseases, and environmental factors, has made it a critical public health concern, highlighting the urgent need for effective preventive strategies and eye health maintenance. Cuscutae Semen (CS), a traditional Chinese herbal medicine long regarded for its vision-enhancing properties, has been widely used to support ocular health. However, its underlying molecular mechanisms and bioactive constituents remain poorly understood, limiting its modernization and broader clinical application. Objective: This study aims to investigate the restorative effects of CS on visual impairment, elucidate its underlying mechanisms, and identify potential active components. Methods: A zebrafish model of visual impairment was established using mepanipyrim to simulate retinal structural damage and visual dysfunction. The therapeutic effects of CS were systematically evaluated through behavioral analyses and histomorphological observations. To elucidate the underlying mechanisms, an integrated approach was employed, combining transcriptome sequencing (RNA-seq), reverse transcription quantitative polymerase chain reaction validation, and immunofluorescence staining to identify critical genes and pathways involved. Furthermore, macroporous resin column chromatography was employed for the fractionation and screening of potential active components. Results: CS treatment significantly alleviated mepanipyrim-induced ocular abnormalities in zebrafish, restoring approximately 82% of the observed morphological defects. Behavioral assessments revealed that CS-treated zebrafish exhibited markedly increased swimming speed and distance, indicating enhanced visual light sensitivity. Histopathological analysis demonstrated that CS effectively repaired the structure of retinal cell layers. RNA-seq revealed that CS broadly reversed mepanipyrim-induced gene expression disturbances, suggesting a restorative effect on transcriptomic homeostasis. Gene Ontology enrichment analysis identified the phototransduction pathway as a key mediator of CS’s therapeutic effects. This was further supported by reverse transcription quantitative polymerase chain reaction validation of critical genes and immunofluorescence staining, which confirmed the restored expression of Pde6a and Gnat2, key proteins involved in photic signal transmission. Active component screening indicated that high-polar constituents, including chlorogenic acid, may constitute one of the major bioactive fractions responsible for the observed therapeutic effects. Conclusion: This study provides evidence of the vision-protective effects of CS in a zebrafish model, demonstrating that its therapeutic mechanism involves modulation of the phototransduction pathway. Chlorogenic acid was identified as one of the key bioactive constituents contributing to this effect. These findings not only provide scientific validation for the traditional use of CS in ocular protection but also present promising therapeutic prospects for the prevention and treatment of visual impairment.