Purple sweet potato (PSP) powder with anthocyanins possesses the ability to reduce oxidative stress and inflammation. Studies have presumed a positive correlation between body fat and dry eye disease (DED) in adults. The regulation of oxidative stress and inflammation has been proposed as the mechanism underlying DED. This study developed an animal model of high fat diet (HFD)-induced DED. We added 5% PSP powder to the HFD to evaluate the effects and underlying mechanisms in mitigating HFD-induced DED. A statin drug, atorvastatin, was also added to the diet separately to assess its effect. The HFD altered the structure of lacrimal gland (LG) tissue, reduced LG secretory function, and eliminated the expression of proteins related to DED development, including α-smooth muscle actin and aquaporin-5. Although PSP treatment could not significantly reduce body weight or body fat, it ameliorated the effects of DED by preserving LG secretory function, preventing ocular surface erosion, and preserving LG structure. PSP treatment increased superoxide dismutase levels but reduced hypoxia-inducible factor 1-α levels, indicating that PSP treatment reduced oxidative stress. PSP treatment increased ATP-binding cassette transporter 1 and acetyl-CoA carboxylase 1 levels in LG tissue, signifying that PSP treatment regulated lipid homeostasis maintenance to reduce the effects of DED. In conclusion, PSP treatment ameliorated the effects of HFD-induced DED through the regulation of oxidative stress and lipid homeostasis in the LG.

Light-evoked retinal photodamage is considered an important factor contributing to functional vision deterioration and can even lead to light maculopathy or dry age-related macular degeneration. Loss of visual acuity (VA) and visual contrast sensitivity function (VCSF) are the major symptoms of retinal degenerative diseases. Cordyceps militaris is a carotenoid-rich Chinese medicinal fungus with antioxidant, anti-inflammatory, and immunomodulatory functions. C. militaris extract is a natural substance, and its bioactive constituents have been shown to confer health benefits, but their application in retinal tissue and functional vision protection in vivo remain incompletely understood. In the present study, we evaluated the influence of water-soluble, carotenoid-rich C. militaris extracts on the visual performance of light-damaged mouse retinas in vivo, using adult female CD-1^® (ICR) albino mice. We showed that oral administration of this C. militaris extract (10 mg/kg, twice daily) protected the neural retina tissue against light-evoked photoreceptor cell death, reduced Müller cell hypertrophic gliosis, and elevated GSH levels and promoted the recovery of VA- and VCSF-thresholds, especially for high spatial frequency-characterized vision. These results suggest that, probably because of its water-soluble carotenoids, C. militaris extract has the potential to prevent or treat light-induced visual dysfunction.

Abnormal dislocation of cone opsin protein affects the sensitivity function of photoreceptors and results in depressed central vision. Nutraceutical therapy is needed to restore the residual function of photoreceptors. Crocin is a natural substance for retinal health. However, its effect on the restoration of functional vision and its underlying mechanisms have not been fully studied. This study analyzed the restorative effect of crocin on residual functional vision in vivo in a mouse model. High-energy light-evoked photoreceptor dysfunction was confirmed by M opsin dislocation in the retina accompanied by a loss of functional vision. Crocin treatment significantly increased brain-derived neurotrophic factor (BDNF) protein in retinas, thus contributing to the re-localization of the M opsin protein, restoration of the visual acuity (VA), and high spatial frequency-characterized visual contrast sensitivity function (VCSF). In contrast, such effects were significantly reversed after the washout period. Additionally, the restorative effect of crocin on functional vision and M opsin re-localization can be reversed and blocked by synchronous injection of a tropomyosin receptor kinase B (TrkB) receptor antagonist (ANA-12). This study demonstrated the major functional vision-rescuing or restoring effect of crocin in vivo by modulating M opsin location plasticity and increasing the capacity of the residual photoreceptor function through the BDNF–TrkB receptor pathway.