Effects of polaprezinc on morphological change of the tongue in zinc-deficient rats.
OBJECTIVE
To examine the effects of polaprezinc on morphologic change of the tongue epithelium and on cell cycle regulation of taste bud cells by using zinc-deficient rats, an animal model of taste disturbance.


METHODS
After 28 days of feeding with zinc-sufficient or -deficient diet, the rats fed a zinc-deficient diet were divided into four groups in which 0, 1, 3 and 10 mg/kg of polaprezinc were administered for 28 days with continuation of diet. Histopathological and morphological examinations of the tongue were carried out.


RESULTS
Parakeratosis was observed in all rats receiving the zinc-deficient diet and 1 mg/kg polaprezinc but not in rats receiving 3 and 10 mg/kg polaprezinc. The ratio of keratinizing epithelium in the outer and inner circumference were significantly increased from 9.6% and 11.3%, respectively, in zinc-sufficient rats to 36.9% and 32.9%, respectively, in zinc-deficient rats (P<0.001 and <0.01). This increase was reversed to 13.7% and 12.3% in rats that received 3 and 10 mg/kg polaprezinc in the outer circumference, respectively. Same phenomenon was seen in the inner circumference part, 13.0% and 10.8% (P<0.01), respectively. In addition, proliferating cell nuclear antigen-positive cells in the taste bud were significantly decreased from 75.5% in zinc-sufficient rats to 32.2% in zinc-deficient rats (P<0.001). This decrease was reversed to 70.3%, 83.1% and 81.2% in rats that received 1, 3 and 10 mg/kg polaprezinc, respectively.


CONCLUSIONS
Polaprezinc improves parakeratosis and decreases taste bud cell proliferation caused by zinc deficiency. These effects may be involved in mechanisms underlying improvement of taste disorders in animal models.
Central Research Laboratories, Zeria Pharmaceutical Co., Ltd., Saitama, Japan.
Toshiko
T
Kinomoto
Miwa
M
Sawada
Yu
Y
Ohnishi
Takashi
T
Yamaguchi
Shinji
S
Tsuge
Shuji
S
Ogawa
Masataka
M
Washizuka
Jun
J
Minaguchi
Yukinori
Y
Mera
Kazushige
K
Takehana
D000818:Animals; D002336:Carnosine / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000627:therapeutic use; D002452:Cell Count; D002453:Cell Cycle / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D004195:Disease Models, Animal; D004848:Epithelium / Q000187:drug effects / Q000473:pathology; D007972:Leukoplakia, Oral / Q000188:drug therapy / Q000209:etiology; D008297:Male; D008855:Microscopy, Electron, Scanning; D008871:Microvilli / Q000648:ultrastructure; D009942:Organometallic Compounds / Q000008:administration & dosage / Q000627:therapeutic use*; D018809:Proliferating Cell Nuclear Antigen / Q000032:analysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D013650:Taste Buds / Q000187:drug effects / Q000473:pathology; D013651:Taste Disorders / Q000188:drug therapy; D013997:Time Factors; D014059:Tongue / Q000187:drug effects* / Q000473:pathology; D014131:Trace Elements / Q000172:deficiency*; D015032:Zinc / Q000172:deficiency*; D017967:Zinc Compounds / Q000008:administration & dosage / Q000627:therapeutic use*
D009942:Organometallic Compounds; D018809:Proliferating Cell Nuclear Antigen; D014131:Trace Elements; D017967:Zinc Compounds; C061957:polaprezinc; D002336:Carnosine; D015032:Zinc