Dietary zinc improves and calcium depresses growth and zinc uptake in rats fed rice bran

Wistar rats were fed a basal stabilized-rice bran diet (B), and five additional ones, fortified to supply either 50 or 100% of zinc and calcium requirements, and a combination furnishing 100% of both minerals. Another diet supplemented with the complete mineral mix (MM) was also used. Results show that the low feed efficiency of B was maximized either by supplementation with MM, or by supplementing bran with 50% of the zinc requirement. Attempts to compensate for the low calcium content of bran by supplementation with 50 or 100% of the mineral requirement, did not increase either feed efficiency, growth or liver zinc. These data confirm that only about 11% of zinc contained in bran is nutritionally available and that supplementing with calcium is detrimental, indicating that this by-product is not a recommendable source of minerals.     

Bioavailable zinc intake of Korean adults in relation to the phytate content of Korean foods

This study was conducted to create a phytate database for food items and to evaluate the bioavailability of zinc in Korean adults. Eighty-seven food items were analysed. Phytate content was determined by ion exchange method and zinc bioavailability was assessed through a dietary survey of 841 adults. Measured phytate values in various groups were as follows: 191.7–973.3 mg in cereals, 508.5–1371.8 mg in legumes, 0.4–319.9 mg in vegetables, and 1–50 mg in fruits. Mean zinc intakes of Korean adults (9.5 mg for male and 7.5 mg for female subjects) were less than the Korean recommended dietary allowance. Cereals (68.6%) and legumes (19.3%) supplied the most dietary phytate. Mean phytate:zinc ratios were 9.5 for males and 10.5 for females. High zinc bioavailability (phytate:zinc molar ratio below 5) occurred in 9.6% of subjects, whereas 13.2% had low bioavailability (molar ratio over 15). Below-normative zinc intake levels occurred in 54.3% of subjects (61.8% for male and 49.5% for female). Further studies should be directed towards increasing zinc intake and enhancing bioavailability to improve zinc status in Korea.     

Iron, zinc, copper and phytate content of standardized Nigerian dishes

Representative samples of 20 standardized Nigerian dishes were analyzed for Iron, Copper and Zinc using the automated method of flame atomic absorption spectrophotoscopy (AAS) and for phytate using a colorimetric method. Iron contents ranged from 2.28 mg/100 g for cowpeas and yam pottage to 22.10 mg/100 g for Apapafufu with tuwon shinkafa. The zinc contents ranged from 0.43 mg/100 g for stewed beans and fried plantain to 4.20 mg/100 g for Eberipo. Copper contents ranged from 0.38 mg/100 g for Ikokore to 1.88 mg/100 g for Amala and Alapa with ewedu stew. Phytate contents expressed on a dry weight basis ranged from 0.6 mg/100 g in Burabisko to 6.40 mg/100 g in melon seed and vegetable soup. The phytate: zinc molar ratios calculated for all dishes analyzed ranged from 0 in Burabisko to 1.4 for stewed beans and fried plantain.     

Content of zinc, iron, calcium and their absorption inhibitors in foods commonly consumed in Ethiopia

The zinc, iron, calcium, phosphorus, phytate, tannin and moisture content of 36 foods consumed in rural Ethiopia were analysed. The foods analysed included those based on cereals, starchy tubers and roots, and legumes and vegetables as well as some fruits. Although many foods were relatively rich in zinc and iron, many also contained high levels of phytic acid and tannins, which impair bioavailability of zinc and iron. The phytate:zinc molar ratios were >20 for non-fermented cereal foods, >15 for legumes, and <12 for fermented cereals, starchy tubers and roots. Ratios >15 are associated with low bioavailability of zinc. Given the high iron content and the relatively favourable phytate:iron molar ratio, tef enjera was the best source of bioavailable iron of all foods analysed. Foods prepared from tef, enset and kale are rich sources of calcium. The consumption of diets based on cereals and legumes but poor in animal products can lead to deficiencies of zinc and iron. However, since fermentation can decrease the phytate content by a factor of 3–4, traditional household practices such as fermentation need to be encouraged to address the problem of zinc deficiency, which is particularly prevalent in Ethiopia.     

锌对热应激大鼠β-内啡肽的影响

目的：探讨锌对热应激大鼠β－内啡肽的影响。方法：分别以高、中、低锌饲料（锌含量分别为９２．２０、４５．６１、２１．７０ｍｇ／ｋｇ饲料）喂养三组大鼠，并于热暴露５、３０和６０ｍｉｎ时断头处死进行β－内啡肽测定。结果：三组大鼠热暴露后血液中β－内啡肽含量变化的趋势一致：受热５ｍｉｎ后即上升，至３０ｍｉｎ时继续升高，至６０ｍｉｎ时有所下降，但含量仍然比５ｍｉｎ时高。无论哪一个时间点上，高锌、中锌组含量均比低锌组高，统计学上有显著性差异。结论：足够的锌摄入能提高血浆β－内啡肽水平，锌摄入不足导致血浆β－内啡肽含量减少，而在高温反应中，β－内啡肽能减轻热和疼痛刺激所致的生理反应，由此可认为，锌通过提高血浆β－内啡肽水平而发挥体温调节作用，增强机体热耐力。     

生长期缺锌对大鼠血清元素的影响

目的:研究膳食锌缺乏对生长期大鼠血清各种元素的影响。方法:刚断奶的SD大鼠,按体重相近配伍,随机分为3组,每组8只:缺锌组(ZD),配饲组(PF),对照组(ZA)。缺锌饲料、正常饲料含锌量分别为0.4mg/kg3、0 mg/kg,实验期15 d。用等离子电感耦合质谱仪(ICP—MS)测定大鼠血清元素锌、铁、铜、硒、锰、钴、铬、钙、镁、镉的含量。结果:缺锌组大鼠:血清铁(573.86±201.71μg/L)明显低于配饲组(1372.37±118.69μg/L)和正常组(1463.55±331.66μg/L)(P<0.05);血清锰(12.28±5.33μg/L)明显高于配饲组(4.24±0.73μg/L)和正常组(3.10±1.10μg/L)(P<0.05);血清铜(534.71±113.77μg/L)、硒(262.55±38.57μg/L)、镁(25.26±9.29μg/dl)低于正常组(铜725.91±158.27μg/L,硒465.90±132.18μg/L,镁39.84±14.10μg/dl)(P<0.05),与配饲组无明显差异(铜566.86±134.96μg/L,硒336.71±112.30μg/L,镁29.59±6.99μg/dl)(P>0.05);相比于配饲组与正常组,血清钙有下降趋势,但差异无显著性(P>0.05),血清钴、铬、镉有升高趋势,但差异无显著性(P>0.05)。结论:膳食锌缺乏影响生长期大鼠体内的微量元素水平。     

缺锌对大鼠睾丸功能的影响及其实验性治疗研究

利用缺锌大鼠模型，研究缺锌对睾丸功能的影响，并观察不同剂量硫酸锌的治疗价值。结果：缺锌组大鼠血浆及器官锌含量显著降低，体重、血浆蛋白含量、精子计数、血浆及睾丸酮水平、睾丸ＲＮＡ和蛋白质含量等均显著低于自由摄食组和对饲组。给予缺锌大鼠补充硫酸锌４周，剂量为０．１５ｍｇ／ｋｇ时睾丸功能未见恢复，３．７５ｍｇ／ｋｇ时显示一定疗效，７．５０ｍｇ／ｋｇ则能有效提高缺锌大鼠锌储备和改善睾丸功能。提示缺锌损害睾丸功能，及时适量补锌则可使其恢复。     

Accessibility of trace metals,co-precipitated with calcium phytate,to soluble chelating agents

This study was designed to show the extent to which some trace metals, i.e. cadmium, copper, lead, and zinc, when co-precipitated in vitro with calcium phytate, are accessible to soluble chelating agents. Accessibility was found to range from 58% to 92%, depending on the metal, temperature, ratio of trace metal to phytate, and concentration of calcium phytate. Zinc was most sensitive to the conditions under which precipitation occurred. Less cadmium, copper, and zinc were accessible when co-precipitated at 37°C compared with co-precipitation at 20°C, and more cadmium and zinc were accessible at lower ratios of trace metal to phytate, than at higher ratios. At the lower concentration of calcium phytate, co-precipitated zinc was less accessible.     

Placenta and maternal effects of marginal zinc deficiency during gestation in rats

Effects of a marginally zinc deficient diet (6 μg Zn/g diet) were investigated in the pregnant rat. In comparison to the control group (50 μg Zn/g diet), serum zinc concentration was significantly lower (P<0.01) in the marginal group on day 18 of gestation; serum decreased by about 45 μg/dl between days 18 and 22 of gestation in both groups, however. Dam cumulative weight gain increased 25% during the last four days of gestation in the marginal group, but it nearly doubled in the control group. Average fetal weight in the marginal group was 16% lower than controls, but placental weight, placental DNA, and protein concentration were not reduced. The total activity of the zinc metalloenzyme, leucine aminopeptidase (LAP) (E.C.3.4.11.3.) in the placenta and maternal serum was not affected by the marginal zinc diet. Apparent K_m and relative V_max of placental LAP were also unaffected. It appears that maternal zinc status and weight gain are reduced in a marginal zinc deficiency to support placental function and fetal growth.     

Some behavioural effects of prenatal marginal zinc deficiency in young rats

During pregnancy rats were fed either a marginally zinc deficient (18.33 ppm zinc) or a control diet (about 100 ppm). At birth control offspring were fostered to other control dams or cross-fostered to zinc deficient dams. All deficient pups were cross-fostered to control dams. Neonatal mortality was higher in zinc deficient pups. At 14–15 days of age, deficient pups opened their eyes earlier and control pups cross-fostered to deficient dams were heavier and emitted more ultrasonic distress calls than pups from the other groups. They also spontaneously alternated the most at 28–31 days and, along with deficient rats ambulated more than control rats fostered to control dams. At 56–64 days rats in this latter group were lighter than all other rats. For males only, 56–64 day old deficient rats achieved the highest ambulation counts. Control females of this age fostered to control dams showed the lowest female preference for novelty. The results were discussed in the light of complex relationships between prenatal marginal zinc deficiency, postnatal maternal influences, sex of the rats and possible zinc toxicity in control animals.     

锌对热应激大鼠热休克蛋白70mRNA表达的影响

目的：锌对热应激大鼠热休克蛋白７０ ｍ Ｒ Ｎ Ａ 表达的影响。方法：分别以高、中、低锌饲料（锌含量分别为９２２０、４５６１、２１７０ ｍ ｇ／ｋｇ 饲料）喂养３ 组大鼠,热暴露（干球４１５ ° Ｃ、湿球３２ ° Ｃ）３０ ｍ ｉｎ 时断头处死,应用 Ｎｏｒｔｈｅｒｎ 印迹杂交和斑点杂交检测热应激大鼠肝脏热休克蛋白７０ ｍ Ｒ Ｎ Ａ 的表达情况。结果：不经受热暴露的３ 组动物仅高锌组能检测到热休克蛋白７０ ｍ Ｒ Ｎ Ａ,而热暴露３０ ｍ ｉｎ 的３ 组动物均有热休克蛋白７０ ｍ Ｒ Ｎ Ａ 条带,且依锌水平不同,其表达强弱依次为高锌组强于中锌组,中锌组强于低锌组。结论：热应激时热休克蛋白７０ 基因的转录水平提高;锌通过活化热休克蛋白７０ 基因的转录而诱发热应激大鼠热休克蛋白７０ 的合成,从而使机体对热暴露产生更强的耐受力。     

锌缺乏对大鼠骨骼矿化的影响

目的　探讨缺锌对大鼠骨骼矿化的影响。方法　将 30只Wistar大鼠按体重随机分为缺锌组、对照组和对喂组 ,每组 10只。缺锌组饲料锌含量为 3 9mg/kg ,对照组饲料锌含量为 2 4 7mg/kg,对喂组饲对照组饲料 ,饲料摄入量与缺锌组相同。运用骨组织形态计量学方法测量骨骼矿化相关指标、测定股骨矿物质含量、骨密度、骨中锌、钙、磷、镁、锰、铜元素和骨骼羟脯氨酸含量及血中甲状旁腺激素、降钙素和骨钙素含量。结果　缺锌组大鼠与对照组和对喂组相比 ,骨矿化沉积速率、股骨磷、锌、骨羟脯氨酸及血清降钙素、骨钙素含量显著降低 ,缺锌组相应指标分别为 :( 3 2 6± 0 34) μm/d、( 6 4 5 4± 2 34)g/kg、( 5 4 4± 9 5 )mg/kg、( 9 2 8± 1 6 2 )g/kg、( 41 2± 13 5 ) μg/L、( 82± 30 ) μg/L ;对照组分别为 :( 5 37± 0 5 3) μm/d、( 6 9 0 1± 4 0 5 )g/kg、( 117 4± 8 0 )mg/kg、( 11 31± 1 30 )g/kg、( 6 8 3± 14 4)μg/L、( 131± 46 ) μg/L ;对喂组分别为 :( 5 45± 0 30 ) μm/d、( 6 7 81± 3 5 6 )g/kg、( 10 6 7± 8 4)mg/kg、( 10 88± 1 47)g/kg、( 6 3 7± 12 0 ) μg/L、( 12 0± 5 2 ) μg/L。骨矿化延迟时间和骨基质成熟时间显著增加 ,缺锌组相应指标分别为 :( 1 0 8± 0 19)     

饲料锌过量对幼鼠脑发育及学习记忆的影响及其机理探讨

目的观察锌过量对幼鼠脑发育和学习记忆行为的影响。方法从哺乳期开始建立过量锌幼鼠模型,采用电镜观察、神经生化和神经行为观察等方法。结果随饲料锌含量的增加幼鼠大脑及海马重量减少,血清及海马锌增高。过量锌１、２组（ＺＥ１、ＺＥ２组）幼鼠主动回避反应（ＡＡＲ）习得率及活动明显低于自由喂养组（ＡＬ组）及ＺＥ２组的配对组（ＰＦ组）,ＺＥ２组的恢复组（ＺＥ２Ｒ组）ＡＡＲ习得率也明显低于ＡＬ和ＰＦ组,但明显高于ＺＥ２组。ＰＦ组与ＡＬ组ＡＡＲ习得率差异无显著性,但活动较ＡＬ组多。ＺＥ２组海马一氧化氮含量增加而生长抑素含量减少,脑组织兴奋性氨基酸和抑制性氨基酸总量增高,尤其是谷氨酸增高更为明显。ＺＥ２组海马ＣＡ１区神经元、胶质细胞及细胞器均有不同程度变性、坏死,突触小泡破裂。结论过量锌饲料明显影响幼鼠脑发育和功能,其机理是多方面的     

Changes in plasma zinc following the ingestion of a zinc multivitamin-mineral supplement with and without breakfast

The change in concentration of plasma zinc after the oral administration of zinc was used as an index of zinc absorption. The source of zinc was a multivitamin mineral supplement, which contained 25 mg of elemental zinc as zinc oxide. Taking the supplement without breakfast caused a significant increase (P<.01) in plasma zinc over the baseline concentration. Eating breakfast prior to taking the supplement prevented a rise in plasma zinc for at least three hours after taking the supplement. This suggests that a meal either inhibits the absorption of zinc from the supplement or reduces the rate of absorption, or increases turnover and/or excretion.     

补锌对缺锌烫伤大鼠肠粘膜营养状态的影响

目的 :研究补锌对缺锌烫伤大鼠肠粘膜营养状态的影响。　方法 :1月龄大鼠进食低锌饲料 (含锌量为 1.6μg/g) 1周 ,造成缺锌模型 ,2 0 %深二度烫伤后分别改饲三种不同含锌量饲料 (各为 1.6 μg/g、2 4 .7μg/g和 2 86 .9μg/g) ,同时设一组大鼠烫伤前后均进食正常含锌饲料 (2 4 .7μg/g)作对照组。伤后第 8天处死并留取标本。动物处死前注射长春新碱 ,以肠腺细胞增生率 (CCPR)、粘膜湿重、空肠与回肠的DNA、蛋白质含量反映肠粘膜的营养状态。　结果 :各补锌组空肠DNA含量及CCPR均显著高于缺锌组 ,回肠也存在类似的趋势。　结论 :缺锌大鼠烫伤后补锌有利于肠粘膜营养状态的改善和损伤的修复     

Effects of zinc deficiency upon pituitary function in sexually mature and immature male rats.

Serum pituitary levels of growth hormone (GH), thyrotropin (TSH), prolactin (PRL), luteinizing hormone (LH) and follicle stimulating hormone (FSH) were measured in sexually mature (adult) and sexually immature (juvenile) male rats who had been deprived of dietary zinc for 15 and 7 weeks, respectively. When compared to pair-fed control rats receiving a zinc supplemented diet, both the adult and juvenile zinc deficient rats had significantly lower body weights, tail lengths and ventral prostate weights. The testes of the sexually immature rats were also smaller than those of the pair-fed animals. In sexually mature, zinc deficient rats serum concentrations of GH and testosterone were significantly lower and serum LH levels significantly higher than in ad libitum fed control rats. Pituitary and hypothalamic levels of other hormones did not differ from values recorded in control animals. In sexually immature zinc deficient rats serum concentrations of GH were also significantly depressed; pituitary content and concentration of LH and pituitary and serum levels of FSH were significantly increased over control values. No discernible effects of zinc deficiency upon hyplthalamic content of LH-releasing hormone or serum concentrations of PRL or TSH were recorded in juvenile rats. Zinc deficiency has minimal effects upon the hypothalamic-pituitary axis of sexually mature rats. In sexually immature males, zinc deprivation leads to impairment of gonadal growth and increased synthesis and/or secretion of the pituitary gonadotropins.     

铅暴露对雄性仔鼠海马锌离子转运体3表达的影响

目的探讨铅暴露对雄性仔鼠海马锌离子转运体3(zinc transporter 3,ZNT3)表达的影响。方法将12只健康SPF级雌性SD大鼠随机分为3组,分别为对照(去离子水)组和低(0.5 g/L乙酸铅)、高(2.0 g/L乙酸铅)剂量铅染毒组,每组4只。采取自由饮水方式进行染毒,自妊娠前10 d至仔鼠断乳(出生后21 d)。采用等离子体发射光谱(ICP-AES)法检测雄性仔鼠全血及海马组织中铅、锌的含量;采用RT-PCR法检测其海马组织中ZNT3 m RNA的表达水平;采用Western blot法检测其海马组织中ZNT3蛋白的表达。结果与对照组比较,各剂量铅染毒组雄性仔鼠全血与海马组织中的铅含量均较高,锌含量均较低,差异有统计学意义(P0.05);且随着铅染毒剂量的升高,雄性仔鼠全血和海马组织中铅的含量呈上升趋势,锌含量呈下降趋势。与对照组比较,各剂量铅染毒组雄性仔鼠海马组织中ZNT3 m RNA及蛋白的表达水平均较高,差异有统计学意义(P0.05);但高、低剂量铅染毒组雄性仔鼠海马组织中ZNT3 m RNA及蛋白的表达水平间比较,差异无统计学意义(P0.05)。结论铅暴露上调了大鼠海马组织中ZNT3的表达水平,这可能与铅暴露使海马锌含量的降低有关。     

糖尿病足溃疡大鼠血锌水平及金属硫蛋白的表达意义

目的 探讨糖尿病足溃疡大鼠血锌水平及金属硫蛋白（ metallothionein,MT）的表达对清除自由基及抗氧化作用的意义.方法 将60只雄性Wistar大鼠随机分为对照组（20只）和造模组（40只）,其中造模组链脲佐菌素尾静脉注射诱导糖尿病,对照组注射等量柠檬酸-柠檬酸钠缓冲液.将两组大鼠足背部一矩形全层皮肤组织切除,建立糖尿病足溃疡大鼠模型,监测两组大鼠血锌水平变化,应用免疫组化技术检测MT的表达.结果 造模组大鼠血锌水平（1.17 ±0.09）较对照组（ 1.48±0.07）明显减低,差异有统计学意义（t=12.94,P＜0.01）.免疫组化研究发现在对照组大鼠有少量MT表达,而造模组大鼠MT的表达明显增高,差异有统计学意义（x2=12.78,P＜0.01）.结论 糖尿病足溃疡大鼠的血锌水平及MT的表达情况可能与清除自由基、抗氧化作用有关,MT的表达增高对防止糖尿病足溃疡病变进一步发展可能具有重要作用.     

硫酸锌对孕鼠子宫平滑肌的作用效果观察

目的:观察硫酸锌对已孕小鼠离体子宫平滑肌收缩的影响,从而探讨硫酸锌孕期用药的安全性。方法:以正常组和缩宫素组作为对照组,通过灌胃法和直接滴加法两种给药途径,给予不同浓度的硫酸锌溶液,分别观察内源性和外源性硫酸锌对离体小鼠子宫平滑肌收缩的影响。结果:内源性和外源性硫酸锌对小鼠子宫平滑肌收缩的幅度和频率均无显著影响。结论:孕期在安全剂量下可以放心补锌,不会引起子宫强烈收缩而影响妊娠。