Effects of zinc deficiency on the vallate papillae and taste buds in rats

Background and Purpose: Zinc deficiency is associated with multiple clinica l complications, including taste disturbance, anorexia, growth retardation. skill changes, and hypogonadism. We investigated the zinc-deficiency-induc ed morphologic changes in the vallate taste buds of weanling and young adul t male Wistar rats. Methods: A total of 24 weanling and 30 young adult rats were used. Each age glc,up was further divided into a control group fed a zinc-adequate (50 pp m) diet, a zinc-deficient (< 1 ppm) diet group, and a zinc-adequate pair-fe d group. Weanling rats the same amount of food as that taken by the zinc-de ficient group. Weanling rats were fed for 4 weeks and young adult rats were fed for 6 weeks. The morphometry and morphologic changes of vallate taste buds were analyzed using light and transmission electron microscopy. Results: Light microscopy revealed no significant difference in papilla siz e and morphology among the various groups. In both weanling and young adult rats in the zinc-deficient diet and pair-fed groups, the number of taste b uds per papilla (per animal) and the average profile area of the taste bud were significantly smaller than those of the corresponding controls (P < 0. 05). Ultrastructural changes were seen only in the taste buds of weanling r ats fed the zinc-deficient diet, with derangement of the architecture of th e taste bud and widening of the intercellular space between taste bud cells . The proportion of type I taste bud cells in the taste buds of weanling ra ts fed the zinc-deficient diet decreased fr om 59% to 39%, and that of type II taste bud cells decreased from 25% to 12%. No obvious changes in the ul trastructure of type III taste bud cells were observed. Conclusions: The main effects of zinc deficiency in weanling and young adul t rats and in adequate diet pair-fed rats were changes in the number and si ze of taste buds, and fine structure changes in the taste bud cells, especi ally during the accelerated growth stage after weaning.