Effect of zinc on biochemical parameters and changes in related gene expression assessed by cDNA microarrays in pituitary of growing rats.
OBJECTIVE
The present study simultaneously investigated the effects of different zinc (Zn) levels on the growth performance and relative biochemical parameters in growing rats and analyzed the molecular mechanism of zinc influencing food intake.


METHODS
Three diets with different Zn levels--Zn adequate (ZA; 35.94 mg/kg, control), Zn deficient (ZD; 3.15 mg/kg), and Zn overdose (ZO; 347.50 mg/kg)--were fed to rats for 6 wk. Dietary Zn was supplemented with ZnSO4. The relation between zinc and food intake was studied by pituitary cDNA microarrays.


RESULTS
Compared with ZA group, rats fed the ZD diet showed decreases in body weight (P < 0.01), food intake (P < 0.05), tissue zinc concentrations (P < 0.01), and specific activities of alkaline phosphatase (P < 0.01) and copper/Zn superoxide dismutase (P < 0.05), whereas the ZO diet had positive effects on body weight (P < 0.05), zinc concentrations (P < 0.01), and alkaline phosphatase activity (P < 0.05). The villi of the jejunum became shorter (P < 0.01), shriveled, and flattened. This change in morphology decreased absorption surface area, and there was a substantial decrease (P < 0.01) in villi number per unit area in ZD rats. Metallothionein concentration was increased in livers of rats fed ZD (P < 0.01) and ZO (P < 0.05) diets. Moreover, ZD and ZO influenced normal growth and development of organs. The results from pituitary cDNA arrays indicated that different Zn levels affect gene expression of appetite-related peptides, including neuropeptide-Y, melanin-concentrating hormone, ghrelin, calcitonin gene-related product, and serotonin.


CONCLUSIONS
The present results showed that zinc deficiency has a negative effect on the growth performance and biochemical parameters of rats. The ZO diet increased body weight (P < 0.05) but had no effect (P > 0.05) on food intake, copper/Zn superoxide dismutase activity, and intestinal morphology. The ZD diet decreased rat food intake by regulating appetite-related gene expression in the pituitary gland.
Sun
Jian-Yi
JY
The Key Laboratory of Molecular Animal Nutrition, Ministry of Education and Institute of Feed Science, Zhejiang University, Hangzhou, China. jysun@zju.edu.cn
Jing
Ming-Yan
MY
Wang
Jian-Feng
JF
Zi
Nai-Tao
NT
Fu
Liang-Jian
LJ
Lu
Ming-Qi
MQ
Pan
Lin
L
D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D001835:Body Weight / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D004435:Eating / Q000187:drug effects*; D005786:Gene Expression Regulation / Q000187:drug effects*; D007408:Intestinal Absorption / Q000187:drug effects; D008297:Male; D020411:Oligonucleotide Array Sequence Analysis; D009929:Organ Size / Q000187:drug effects; D010902:Pituitary Gland / Q000187:drug effects / Q000378:metabolism*; D051381:Rats / Q000254:growth & development*; D017207:Rats, Sprague-Dawley; D013482:Superoxide Dismutase / Q000378:metabolism; D015032:Zinc / Q000172:deficiency / Q000378:metabolism / Q000494:pharmacology*
D013482:Superoxide Dismutase; D000469:Alkaline Phosphatase; D015032:Zinc