Polaprezinc, a zinc compound, is distributed to the lingual epithelium and increases its zinc concentration in zinc-deficient rats.
OBJECTIVE
To clarify the mechanism underlying the effect of polaprezinc on hypogeusia, we investigated the uptake of polaprezinc by the tongue in rats.


METHODS
Rats were fed a zinc-sufficient (Zn(+)) or zinc-deficient (Zn(-)) diet. After 4weeks on the Zn(-) diet, polaprezinc (1, 3, or 10mg/kg) or [(65)Zn] polaprezinc (10mg/kg) was administered orally once a day. The zinc concentration or the (65)Zn radioactivity of the tongue was measured by inductively-coupled plasma mass spectrometry or gamma counting, respectively. In addition, the distribution of (65)Zn in the tongue was analyzed by microautoradiography and the proliferative activity of taste bud cells was measured from the uptake of 5-bromo-2'-deoxyuridine.


RESULTS
The zinc concentration of the lingual epithelium, but not the whole tongue, was markedly decreased in Zn(-) rats compared with Zn(+) rats. After administration of polaprezinc to Zn(-) rats at doses of 1, 3, and 10mg/kg, the zinc concentration in the lingual epithelium increased significantly from 85+/-4 to 105+/-7 (p<0.05), 120+/-3 (p<0.001), and 124+/-3 (p<0.001) microg/g, respectively. After administration of [(65)Zn] polaprezinc, the (65)Zn radioactivity of the tongue and serum were higher in Zn(-) rats than in Zn(+) rats. (65)Zn was mainly detected in the epithelium on microautoradiograms of the tongue in Zn(-) rats. In addition, polaprezinc (3 and 10mg/kg) improved the reduced proliferation of taste bud cells due to zinc deficiency.


CONCLUSIONS
Polaprezinc is distributed to the lingual epithelium and restores its zinc concentration in Zn(-) rats resulting in improvement of cellular functions, especially proliferation.
Central Research Laboratories, Zeria Pharmaceutical Co., Ltd., 2512-1 Numagami, Oshikiri, Kumagaya-City, Saitama 360-0111, Japan.
Hiroki
H
Hamano
Koji
K
Yoshinaga
Takao
T
Tanaka
Runa
R
Eta
Takayuki
T
Horii
Yoshihiro
Y
Kawabata
Shigeru
S
Furuta
Mineo
M
Takei
D000818:Animals; D001345:Autoradiography; D002336:Carnosine / Q000031:analogs & derivatives* / Q000493:pharmacokinetics / Q000627:therapeutic use; D002455:Cell Division / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004848:Epithelium / Q000737:chemistry; D008297:Male; D009942:Organometallic Compounds / Q000493:pharmacokinetics* / Q000627:therapeutic use; D051381:Rats; D017207:Rats, Sprague-Dawley; D013650:Taste Buds / Q000187:drug effects; D014059:Tongue / Q000737:chemistry*; D015032:Zinc / Q000032:analysis / Q000172:deficiency*; D017967:Zinc Compounds / Q000493:pharmacokinetics / Q000627:therapeutic use
D009942:Organometallic Compounds; D017967:Zinc Compounds; C061957:polaprezinc; D002336:Carnosine; D015032:Zinc