Interaction of zinc and vitamin A on the ocular surface.
OBJECTIVE
The purpose of this study was to assess morphologically the interaction between zinc and vitamin A in their effect on the ocular surface.


METHODS
Three-week-old Wistar Kyoto rats were divided into five groups: group A(+) Zn(+) was fed a diet containing both vitamin A and Zn; group A(-) was fed a vitamin A-deficient diet; group A(-) Zn(+) was given a vitamin A-deficient diet and deionized distilled water with Zn; group Zn(-) and group Zn(-) A(+) were fed a Zn-deficient diet, whereby group Zn(-) A(+) received an intraperitoneal injection of vitamin A. Corneas and conjunctivas of each group were examined by electron microscopy.


RESULTS
The corneas and conjunctivas of group A(-) demonstrated a decrease in the number of microvilli in the epithelium. The corneas and conjunctivas of group A(-) Zn(+) had a decrease in microvilli but more microvilli than those of group A(-). The corneas of group A(-) showed keratinization, but those of group A(-) Zn(+) showed no keratinization. In group Zn(-) the microvilli on the conjunctiva and cornea were sparse. Group Zn(-) A(+) had a decrease in microvilli but more microvilli than group Zn(-). The conjunctivas of group Zn(-) A(+) had more goblet cells with granules than did those of group Zn(-).


CONCLUSIONS
These results suggest that a synergistic interaction exists between vitamin A and zinc for the maintenance of the corneal and conjunctival epithelium.
Kanazawa
Suketaka
S
Department of Ophthalmology and Visual Sciences, Graduate School of Biomedical Sciences, Nagasaki University, 1-7-1 Sakamoto, Nagasaki 852-8501, Japan. Suketaka.Kanazawa@mb6.seikyou.ne.jp
Kitaoka
Takashi
T
Ueda
Yoshiko
Y
Gong
Huaqing
H
Amemiya
Tsugio
T
D000818:Animals; D000831:Animals, Newborn; D003228:Conjunctiva / Q000378:metabolism / Q000648:ultrastructure*; D003315:Cornea / Q000378:metabolism / Q000648:ultrastructure*; D004032:Diet; D004847:Epithelial Cells / Q000378:metabolism / Q000648:ultrastructure; D008855:Microscopy, Electron, Scanning; D008871:Microvilli / Q000378:metabolism / Q000648:ultrastructure; D051381:Rats; D011921:Rats, Inbred WKY; D014801:Vitamin A / Q000378:metabolism*; D014802:Vitamin A Deficiency / Q000378:metabolism / Q000473:pathology*; D015032:Zinc / Q000172:deficiency* / Q000378:metabolism*
D014801:Vitamin A; D015032:Zinc