Gene expression profiles analysis of the growing rat liver in response to different zinc status by cDNA microarray analysis.

The effects of zinc on growing rats were characterized using the dietary zinc-deficient (ZD) and Zinc-overdose (ZO) models. Zinc deficiency had negative effects on the host final body weight and liver zinc content, whereas zinc overdose had positive effects. In order to identify the molecular changes in the liver responding to dietary zinc status, cDNA microarrays were used to analyze the expression pattern of 9753 genes in the livers of rats fed ZD and ZO diet for 6 wk, compared with zinc-adequate ZA. The mRNA levels for 62 genes were affected significantly by the ZD diet, whereas 66 gene transcriptions were markedly changed in the ZO diet. Those predominant gene products involved in nitrogen metabolism (glutaminase), carbohydrate metabolism (aldolase), lipid metabolism (stearoyl-CoA desaturase), growth (insulin-like growth factor-binding protein), transcription and translation (zinc-finger protein), immune (natural-killer cell), signal transduction (mitogen- activated protein kinase), and ion transportation (ATPase Na+/K+ transporting peptide) were clustered. In conclusion, a number of mammalian genes related to zinc in the liver were identified. The characterization of the genes and their products will allow a more comprehensive analysis of the role of zinc in metabolism. Furthermore, the mRNA identified could be useful in establishing the mechanisms of zinc in the pleiotropic metabolisms in vivo.

Effects of dietary zinc levels on the activities of enzymes, weights of organs, and the concentrations of zinc and copper in growing rats.

Zinc (Zn) is an essential nutrient that is required in humans and animals for many physiological functions, including immune and antioxidant function, growth, and reproduction. The present study was performed to investigate the effects of three Zn levels, including Zn adequate (35.94 mg/kg, as a control), Zn deficiency (3.15 mg/kg), and Zn overload (347.50 mg/kg) in growing male rats for 6 wk. This allowed for evaluation of the effects that these Zn levels might have on body weight, organ weight, enzymes activities, and tissues concentrations of Zn and Cu. The results showed that Zn deficiency has negative effects on growth, organ weight, and biological parameters such as alkaline phosphatase (ALP) and Cu-Zn superoxide dismutase (Cu-Zn SOD) activities, whereas Zn overload played an effective role in promoting growth, improving the developments of organs and enhancing immune system. Hepatic metallothionein (MT) concentration showed an identical increase tendency in rats fed both Zn-deficient and Zn-overload diets. The actual mechanism of reduction of Cu concentration of jejunum in rats fed a Zn-overload diet might involve the modulation or inhibition of a Cu transporter protein by Zn and not by the induction of MT.