Anat Cell Biol.  2021 Sep;54(3):375-386. 10.5115/acb.21.077.

Topical onion juice mitigates the morphological alterations of the cornea in the aged male rats

• Abdel Fattah IO
• Madani GA
• Nasr El-Din WA

• KMID: 2521050
• DOI: http://doi.org/10.5115/acb.21.077

Abstract

Aging is associated with structural and functional changes of the cornea. Fresh onion juice contains phenolic compounds and flavonoids that may provide an anti-aging effect. The aim of this study was to assess the ability of the onion juice to ameliorate these aging changes. Rats were grouped as adult and aged groups. Rats of both groups received eye drops of diluted onion juice in their right eyes every 8 hours for 12 weeks, while the left ones were served as control eyes. The corneas of both eyes underwent histopathological, immunohistochemical and morphometric assessments, in addition to measuring their intraocular pressure (IOP). The aged group exhibited a significantly elevated IOP, decreased tear secretion, degenerated corneal epithelium and endothelium, surface erosions and stromal edema with irregular collagen fibers. Administration of onion juice led to lowering of IOP, significant increase in tearing, restoration of most of epithelial, endothelial and stromal integrity, and increased epithelial, keratocystic and endothelial cell densities. Immunohistochemically, the epithelium and endothelium revealed positive immune reactions for both epidermal growth factor receptor (EGFR) and paired box protein-6 (PAX6) in the control and onion-treated corneas of the adult group, while these immune reactions were negative in the untreated aged ones. Onion drops in aged corneas showed a positive immune reaction for EFGR and PAX6 involving the epithelial and endothelial layers. In conclusion, topical onion juice improves corneal aging changes through its direct effect, and indirectly through lowering IOP and enhancing tear secretion.

Keyword

Aging; Cornea; Epidermal growth factor receptor; Paired box protein-6; Onion juice

Figure

• 

  Fig. 1 Changes of IOP of study groups (n=15). Values are presented as means. IOP, intraocular pressure. aP<0.05 vs. control and treated eyes of adult group; bP<0.05 vs. control eye of aged group as determined by a one-way ANOVA followed by Tukey’s post-hoc test.

• 

  Fig. 2 Modified Schirmer test results of study groups (n=15). Values are presented as means. aP<0.05 vs. control eye of adult group; bP<0.05 vs. treated eye of adult group, cP<0.05 vs. control eye of aged group as determined by a one-way ANOVA followed by Tukey’s post-hoc test.

• 

  Fig. 3 Photomicrographs of sections of corneas of different study groups. (A, B) Control and treated corneas of the adult group respectively showing normally arranged 5 layers; stratified nonkeratinized epithelium (Ep), Bowman’s layer (B), stroma (S) with keratocytes (K), Descemet’s membrane (D) and endothelial layer (En). (C) Control cornea of the aged group showing irregular eroded surface (s), thin epithelial layer with flat epithelial cells and degenerated nuclei (n) specially in the deep regions and absent nuclei in the superficial ones (a), thickened stroma with irregular collagenous fibers (c) and wide spaces in between (Sp), areas of edema (e), and areas of degenerated endothelial cells (l). (D) Treated cornea of the aged group showing regular surface (s), restoration of most of the epithelial cell nuclei (n), stroma with regular collagenous fibers (c) and relatively narrow spaces in-between (Sp), markedly thickened Descemet’s membrane (D) and a continuous layer of endothelium (En) (H&E, ×400; scale bar=50 μm).

• 

  Fig. 4 Photomicrographs of sections of corneas of different study groups. (A) Control corneas of the adult group showing well distinct basal lamina of the epithelium (arrowheads) in most of areas and normally appearing Descemet’s membrane (arrows). (B) Treated corneas of the adult group showing well distinct basal lamina of the epithelium (arrowheads) in most of areas and slightly thickened Descemet’s membrane (arrows). (C) Control cornea of the aged group showing disappeared basal lamina of the epithelium and normal thickness of Descemet’s membrane (arrows). (D) Treated cornea of the aged group showing apparent basal lamina of the epithelium (arrowheads) and markedly thickened Descemet’s membrane (arrows) (periodic acid–Schiff stain, ×400; Scale bar=50 μm).

• 

  Fig. 5 Photomicrographs of epidermal growth factor receptor (EGFR) immuno-stained sections of cornea of study groups. (A) Control cornea of the adult group showing an endothelial (arrow) and basal epithelial (black arrowhead) extensive cytoplasmic immune reactions. The superficial layers of the epithelium show a minimal cytoplasmic expression (white arrowhead). (B) Treated cornea of the adult group showing moderate cytoplasmic immune reaction in the superficial epithelial layers (white arrowhead) with a membranous minimal basal epithelial (black arrowhead) and cytoplasmic endothelial (arrow) immune reactions. (C) Control cornea of the aged group showing a negative immune reaction in its all layers. (D) Treated cornea of the aged group showing an extensive cytoplasmic endothelial (arrow) and superficial epithelial (white arrowhead) immune reactions, and a minimal cytoplasmic basal epithelial reaction (black arrowhead) (EGFR immuno-stain, ×400; scale bar=50 μm).

• 

  Fig. 6 Photomicrographs of paired box protein-6 (PAX6) immuno-stained sections of cornea of study groups. (A) Control cornea of the adult group showing minimal cytoplasmic basal epithelial (arrowhead) and endothelial (arrow) immune reactions. (B) Treated cornea of the adult group showing a negative immune reaction. (C) Control cornea of the aged group showing a negative immune reaction in all layers. (D) Treated cornea of the aged group showing a minimal cytoplasmic superficial epithelial (arrowhead) and endothelial (arrow) immune reactions (PAX6 immuno-stain, ×400; scale bar=50 μm).

Reference

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