The impact of bilberry extract combined with docosahexaenoic acid on the expression of Chrnb4 gene in the sclera of myopic guinea pigs.

Abstract

Objective: This study aimed to investigate the therapeutic potential of bilberry extract combined with docosahexaenoic acid (DHA) in myopia management by examining their effects on Chrnb4 gene expression in the sclera of lens-induced myopic guinea pigs and elucidating the underlying regulatory mechanisms, thereby providing a theoretical foundation for the development of natural active component-based myopia prevention and treatment strategies.

Methods: One hundred twenty guinea pigs were systematically allocated into five experimental groups: normal control (NC), lens-induced myopia (LIM), LIM+DHA, LIM+bilberry extract (LIM+BE), and LIM+DHA+BE. Myopia was experimentally induced through the application of -6.0D lenses. The intervention groups received daily administrations of DHA (100 mg/kg), bilberry extract (16.5 mg/kg), or their combination for a duration of 12 weeks. Ocular parameters including refractive status and axial length were quantified using a handheld refractometer and A-scan ultrasound, respectively. Choroidal thickness (ChT) and choroidal vascularity index (CVI) were evaluated through swept-source OCT imaging. Molecular analyses encompassing Chrnb4 expression, dopamine concentrations, and TGF-β/MMP-2/TIMP-1 pathway components were conducted using immunofluorescence, ELISA, and Western blot techniques.

Results: Following 4 weeks of myopia induction, the LIM group demonstrated significant myopic changes, including reduced refraction (-3.75 ± 1.35 D), decreased ChT (89.00 ± 10.37 μm), increased axial length (11.33 ± 1.67 mm), and diminished CVI (22.64 ± 4.91%) compared to NC group (all P < 0.001). After 12 weeks of therapeutic intervention, the combined treatment group showed marked improvements in ocular parameters, with refraction measuring -2.46 ± 0.92 D and axial length reduced to 9.94 ± 1.10 mm. Notably, ChT and CVI increased by 8.7 and 15.6%, respectively, compared to the LIM group (P < 0.05). Molecular analysis revealed significant upregulation of Chrnb4 protein expression, elevation of dopamine levels to 41.13 ± 1.58 nmol/g, suppression of TGF-β and MMP-2 expression, and enhancement of TIMP-1 levels (all P < 0.05).

Conclusion: The combination of bilberry extract and DHA demonstrates significant efficacy in controlling myopia progression through multiple mechanisms, including upregulation of Chrnb4 gene expression, modulation of the TGF-β/MMP-2/TIMP-1 signaling pathway, and enhancement of dopamine levels. These findings collectively contribute to the inhibition of scleral remodeling and axial elongation. This study provides valuable insights for the development of novel, multi-targeted natural therapeutic approaches for myopia prevention and treatment.