锌对热暴露大鼠血浆与肝、肾上腺中锌、铜、铁含量的影响

EFFECT OF ZINC ON CONTENTS OF Zn,Cu AND Fe IN PLASMA, LIVER AND ADRENALS OF HEAT EXPOSED RATS

目的： 测定热暴露大鼠血浆、肝、肾上腺 Ｚｎ 、 Ｃｕ 、 Ｆｅ 含量以探讨锌对热暴露动物某些微量元素的影响。方法： ４８ 只７ ～８ 周龄雄性 Ｓ Ｄ 大鼠随机等分为高锌（ Ｈ Ｚ） 、中锌（ Ｍ Ｚ） 和低锌（ Ｌ Ｚ） 三组。每组大鼠再等分为两部分，一部分用于高温暴露，另一部分用于室温对照。每公斤高、中、低锌饲料锌含量测定值（ ｍ ｇ） 分别为９２ ．２ 、４５ ．６ 、２１ ．７ 。三组大鼠在室温下预饲相应饲料１４ｄ 后，将高温暴露大鼠转入高温室（ Ｔｄ Ｂ４０ ．５ ℃， Ｔｗ ｂ３０ ．８ ℃） 连续暴露３ｈ 后，即刻断头取样。用 Ａ Ａ Ｓ 火焰法测定样品中 Ｚｎ 、 Ｃｕ 、 Ｆｅ 含量。结果： （１） 与室温对照值比，热暴露３ｈ 后，血浆 Ｚｎ 、 Ｆｅ 浓度下降， Ｃｕ 浓度升高，肝 Ｚｎ 和肾上腺 Ｃｕ 含量增加；（２） 在室温对照值之间， Ｈ Ｚ 组血浆锌浓度显著高于 Ｌ Ｚ 组；（３） 在热暴露值之间， Ｈ Ｚ 组肾上腺 Ｃｕ 含量显著或非常显著地高于 Ｍ Ｚ 组与 Ｌ Ｚ 组。结论： （１） 补锌主要影响热应激大鼠体内微量元素 Ｚｎ与 Ｃｕ 的代谢或分布，而对 Ｆｅ 的影响较小；（２） 高锌（９２ ．２ ｍ ｇ／ｋｇ 饲料） 摄入可使热应激大鼠血浆 Ｚｎ 浓度升高。

Objective: In order to probe the effects of Zn on levels of some trace elements in heat exposed animals, we determined contents of Zn,Cu and Fe in heat exposed rat plasma, liver and adrenals. Method: 48 SD rats (6 7 weeks old) were equally divided into 3 groups, i.e, high Zn(HZ) group, middle Zn(MZ) group and low Zn(LZ) group. Rats in each group were also divided into 2 parts which were used for hyperthermal exposure and room temperature control. On the basis of AIN 93M diet composition, high, middle and low Zn diets were prepared by adding or reducing zinc carbonate. Zn contents of high, middle and low Zn diets per kilogram were 92.20 mg, 45.61 mg and 21.70 mg respectively. Rats in 3 groups were fed with corresponding diets for 14 days in room temperature. And then rats for heat exposure in these 3 groups were placed in high temperature room (Tdb40.5℃, Twb30.8℃) for 3 hours. After that, all rats were killed and samples were collected. Contents of Zn,Cu and Fe in the samples were measured by flame method of atomic absorption spectrophotometer. Result: (1)Plasma Zn and Fe concentrations lowered, Cu level rose, liver Zn and adrenal Cu contents increased after 3h heat exposure (compared with room temperature control); (2)In room temperature control, plasma Zn concentration in HZ group was higher than that in LZ group; (3)In heat exposure groups, adrenal Cu content in HZ group was higher than that in MZ group and LZ group respectively. Conclusion: (1)Zn supplementation chiefly influences the metabolism or distribution of Zn and Cu in heat stressed rats, whereas Zn supplementation seldom affects Fe; (2)High Zn(92.2mg/kg diet) intake can raise plasma Zn concentration and increase adrenal Cu content in heat stressed rats obviously.