锌对生长期大鼠海马Uch-L1表达的调控作用

目的探讨锌对生长期大鼠海马Uch-L1表达水平的调控作用。方法雄性断乳Wistar大鼠36只,按体重随机分为对照组(ZA)、缺锌组(ZD)和缺锌对喂组(PF),ZD组喂饲含锌量1.5mg/kg的缺锌饲料,PF组和ZA组喂饲含锌量30mg/kg的足锌饲料,PF组摄食量与ZD组一致。喂饲4周后,测定血浆锌含量和碱性磷酸酶活性以评价机体锌状况,用避暗试验测定各组大鼠的学习记忆能力,采用Western blot和RT-PCR方法检测各组大鼠海马Uch-L1蛋白及其mRNA的表达水平。结果ZD组血浆锌含量及碱性磷酸酶活性均显著低于PF组和ZA组;ZD组大鼠在避暗试验中的进洞潜伏期显著低于PF组和ZA组;与PF组和ZA组相比,ZD组大鼠海马Uch-L1及其mRNA表达水平明显降低。结论缺锌可下调大鼠海马Uch-L1表达水平。     

缺锌对大鼠海马和皮层cAMP/PKA-CREB-BDNF信号转导通路的影响

目的观察缺锌对生长期大鼠海马和皮层cAMP/PKA-CREB-BDNF信号转导通路的影响。方法将Wistar大鼠随机分为足锌组(ZA)、对喂组(PF)和缺锌组(ZD),ZA组和PF组喂饲足锌饲料(30mg/kg),ZD组喂饲缺锌饲料(1.5mg/kg)。饲养一个月后处死动物,取海马和皮层,放免法测定cAMP含量;应用PepTag检测系统测定PKA活性;RT-PCR法检测CREB、BDNFmRNA的表达水平。结果ZD组大鼠海马和皮层中cAMP含量明显高于ZA组,同时皮层cAMP含量还显著高于PF组;与ZA组、PF组比较,ZD组大鼠海马和皮层PKA活性均明显降低,同时CREB、BDNFmRNA表达水平下调。结论大鼠海马和皮层cAMP/PKA-CREB-BDNF通路中多种信号分子的表达异常,可能是缺锌导致认知损伤的重要机制之一。     

重度缺锌对生长期大鼠海马超微结构及神经递质和抗氧化能力的影响

目的观察重度缺锌对生长期大鼠海马超微结构、神经递质含量及抗氧化能力的影响。方法将Wistar大鼠30只随机分为足锌组(ZA)、对喂组(PF)和缺锌组(ZD),每组10只。ZA组和PF组喂饲足锌饲料(30 mg/kg),ZD组喂饲重度缺锌饲料(1.5 mg/kg)。饲养28d后,观察海马超微结构变化;测定海马和皮层去甲肾上腺素(NE)、5-羟色胺(5-HT)、多巴胺(DA)含量;检测全血、海马及皮层Ach含量;硫代巴比妥法检测血清、海马及皮层丙二醛(MDA)含量及超氧化物歧化酶(SOD)活性及总抗氧化能力(T-AOC)。结果 ZD组大鼠海马CA3区超微结构严重受损;脑组织单胺类神经递质—NE、5-HT和DA含量不同程度升高;全血Ach含量显著升高,皮层Ach含量显著降低,海马Ach含量有下降趋势,但无显著性差异;血清、海马和皮层组织中MDA含量明显升高,而SOD活性、T-AOC水平显著下降。结论重度缺锌可导致大鼠海马CA3区超微结构严重受损,胆碱能及单胺类神经递质含量异常改变,抗氧化防御系统功能降低,这可能是缺锌导致认知损伤的作用机制之一。     

缺锌对生长期大鼠肾脏维生素D受体及钙结合蛋白基因表达的影响

【目的】研究锌缺乏对生长期大鼠肾脏维生素D受体(vitamin Dreceptor,VDR)和钙结合蛋白(CaBP)基因表达水平的影响。【方法】新生大鼠随机分为缺锌组(ZD)、配饲组(PF)、对照组(ZA)3窝,每窝10只;21 d断奶后每只分笼饲养,喂养至第60 d处死;取肾脏,用试剂盒抽提组织RNA,用实时荧光定量PCR检测肾脏组织VDR mRNA及CaBP mRNA的表达。【结果】大鼠肾脏VDR基因表达ZD组较PF组下调34.78%,PF组较ZA组下调25.81%,ZD组较ZA组下调51.61%;CaBP基因表达ZD组较PF组下调23.19%,PF组较ZA组下调13.75%,ZD组较ZA组下调33.75%。【结论】锌缺乏通过改变生长期大鼠肾脏VDR的活性而影响VDR mRNA,从而影响靶基因CaBP转录,进而影响肾脏钙重吸收,可能是导致骨生成障碍的机制之一。     

缺锌对大鼠小肠粘膜维生素D受体及钙结合蛋白基因表达的影响

目的:研究锌缺乏对生长期大鼠小肠粘膜维生素D受体(VDR)和钙结合蛋白(CaBP)基因表达水平的影响。方法:刚断奶的雄性大鼠随机分为缺锌(ZD)、配饲(PF)、对照(ZA)三组,每组10只。喂养15d后处死,取小肠粘膜,用试剂盒抽提组织RNA,用实时荧光定量PCR检测小肠粘膜VDRmRNA及CaBPmRNA的表达。结果:ZD组大鼠小肠粘膜VDR基因表达较PF组下调88.89%,PF组较ZA组VDR基因表达下调50.00%,ZD组较ZA组VDR基因表达下调94.5%。ZD组CaBP基因表达较PF组下调80.16%,PF组较ZA组CaBP基因表达下调39.76%,ZD组较ZA组CaBP基因表达下调88.50%。结论:锌缺乏通过改变VDR的活性而影响VDRmRNA,从而影响靶基因CaBP转录,进而影响钙吸收,导致骨生成障碍。     

生长期大鼠缺锌时股骨病理形态学的改变

目的　通过建立生长期缺锌大鼠模型以阐明锌缺乏对生长期儿童骨骼发育的影响 ,为儿童生长发育迟缓的防治提供理论依据。方法　刚断奶的雄性大鼠随机分为对照组 (ZA)、缺锌组 (ZD)、配饲组 (PF) 3组 ,每组 10只。喂养 15天后处死 ,取股骨称量重量及测量长度、直径 ,并做病理组织切片 ,观察股骨病理改变。结果　ZD组股骨长度 [(2 4 . 80± 0 . 4 2 )mm]明显低于PF组 [(2 6 . 70± 0 . 4 8)mm]及ZA组 [(2 7. 90± 0 . 32 )mm](P <0 . 0 1) ;ZD组股骨直径 [(2 . 0 9± 0 .0 9)mm]明显低于PF组 [(2 . 70± 0 . 0 8)mm]及ZA组 [(2 . 80± 0 . 0 8)mm](P <0 . 0 1) ;ZD组股骨重量 [(0 .5 1± 0 . 0 5 )g]明显低于PF组 [(0 . 6 5± 0 . 0 8) ]及ZA组 [(0 . 76± 0 . 10 )g](P<0 . 0 1)。缺锌组大鼠股骨骺生长板软骨细胞畸形、数量减少 ,骺端骨小梁纤细、疏松、排列紊乱、髓腔相对扩大 ,骨小梁体积显著减少 ,骨小梁板密度降低 ,骨小梁间隙增大。结论　生长期动物缺锌可导致骨骼的形态及病理发生改变而影响骨骼的生长发育。     

锌缺乏对生长期大鼠免疫细胞凋亡的影响

目的: 观察饲料锌缺乏对生长期大鼠免疫细胞凋亡的影响,并探讨其分子机制。方法: 通过喂食锌含量不同的饲料,构建生长期缺锌大鼠模型;TUNEL方法原位检测胸腺、脾脏组织淋巴细胞凋亡,半定量RT-PCR方法检测一对凋亡调控基因bcl-2/bax mRNA的表达。结果: 与锌充足组(ZA)和配饲组(PF)相比,缺锌组(ZD)大鼠胸腺、脾脏淋巴细胞凋亡增多,促凋亡基因bax mRNA表达增高,补锌后上述改变可得到恢复。结论: 饲料锌缺乏导致发育中和成熟的淋巴细胞凋亡增多,凋亡调控基因bcl-2/bax表达失衡是重要机制之一。     

生长期缺锌对大鼠海马Egr家族基因表达影响

目的 研究锌缺乏对生长期大鼠海马Egr家族(Egr1、Egr2、Egr3、Egr4)基因表达的影响,探讨缺锌影响学习记忆的基因转录调节机制.方法 选取刚出生的Sprague-Dawley大鼠3窝,每窝1只母鼠、10只仔鼠,3窝母鼠与仔鼠体重相近,仔鼠雌雄各半;随机分为3组:缺锌组(ZD)、配饲组(PF)、对照组(ZA),实验期60 d;用实时荧光定量PCR检测大鼠海马Egr家族(Egr1、Egr2、Egr3、Egr4)mRNA的表达.结果 大鼠海马Egr1、Egr3、Egr4基因表达在3组大鼠间差异有统计学意义(F值分别为13.631,24.435,21.825,),ZD组(2.44×10~(-3),8.72×10~(-3),1.88×10~(-2))表达量低于PF组(3.13×10~(-3),1.60×10~(-2),2.68×10~(-2))、ZA组(3.96×10~(-3),1.92×10~(-2),3.53×10~(-2)),且PF组低于ZA组;海马Egr2基因表达在各组间差异无统计学意义.结论 缺锌使海马锌指蛋白Egr1、Egr3、Egr4基因表达下调,是影响海马学习记忆的机制之一.     

缺锌对大鼠脑组织和血液中乙酰胆碱和5—羟色胺含量的影响

目的：研究缺锌对大鼠脑组织和血液中乙酰胆碱（ACh)和5－羟色胺（5－HT）含量的影响。方法：采用85克左右的Wistar大鼠,随机均分为3组;缺锌组（ZD）,饲喂缺锌饲料,对喂组（PF）,饲喂加锌饲料,但饲喂量与ZD组一致;缺锌补锌组（ZS）,先饲喂缺锌饲料,21天以后改为加锌饲料,给料量与ZD组一致。结果：缺锌组血液中ACh明显升高;皮质中ACh与其他组差异无显性。血液中5－HT显升高,大脑皮质中5－HT显升高,结论：提示缺锌可影响脑组织和血液中乙酰胆碱和5－羟色胺的代谢。     

不同剂量锌缺乏对小鼠及其胚胎发育的影响

目的 :　用昆明种雌性小鼠建立成不同程度缺锌动物模型 ,研究不同程度锌缺乏和孕早期补锌对小鼠及其胚胎发育的影响 ,并探求其发育毒性作用的阈剂量。方法 :　实验分两阶段进行。实验一用 36只初断乳 1 4～ 1 8g小鼠 ,分为低锌 (ZD)、中锌 (ZM)、常锌 (ZN)三组 ,喂饲含锌分别为 3.0± 0 .5、1 5、30 mg/kg的饲料 ,经 50 d喂养平均体重达 30 g后交配。实验二选用 80只 ,2 5～ 30 g成熟小鼠 ,随机分为低锌组 [ZD,饲料含锌 (3.0± 0 .5) mg/kg];低锌补锌组 (ZS,于孕第 7d将低锌饲料换为含锌 30 mg/kg的常锌饲料 ) ;边缘缺锌组 (MD,饲料含锌 9mg/kg) ;常锌组(ZN,饲料含锌 30 mg/kg)。 2 5d锌耗竭性喂养后交配。所有孕鼠于妊第 1 8d活杀。结果 :　实验一 :低锌组小鼠锌水平显著低于常锌组 (P<0 .0 5) ,有典型缺锌症状 ,几乎全部出现生长抑制 ,58.33%的小鼠衰竭死亡 ,存活小鼠亦不能正常交配妊娠。 1 5mg/kg剂量组小鼠则生长发育良好 ,各项指标与常锌组间无异 (P>0 .0 5)。实验二 :ZD组小鼠血清碱性磷酸酶 (AKP)活性 ,股骨锌含量显著低于 ZN组 (P<0 .0 1 ) ;该组小鼠胚胎有明显发育不良 ,畸胎及死胎出现率显著高于 ZN组 (P<0 .0 1 )。ZS组小鼠在孕第 7d补锌后活胎仔大小已趋正常 (P>0 .0 5) ,畸胎出现率与 ZD?     

Reevaluation of zinc deficiency on concanavalin-A-induced rat spleen lymphocyte proliferation

Zinc concentrations of serum, nonlymphoid and lymphoid tissues, and the responsiveness of concanavalin-A (Con-A)-stimulated spleen lymphocytes (SL) and cervical lymph node cells ( CLNC ) from ad libitum-fed zinc-deficient (ZD), pair-fed (PF) and ad libitum-fed zinc-adequate rats (AL) were determined. In vitro effects of serum from ZD, PF and AL rats on responsiveness of Con-A-stimulated SL and CLNC were determined. Weanling male Long-Evans rats were fed ad libitum zinc-deficient (less than 1.0 microgram Zn/g diet) and zinc-adequate (20 micrograms Zn/g diet) diets for 7-42 days. Effects of undernutrition on test parameters were determined on PF rats, which received a restricted zinc-adequate diet (restricted in amount to that consumed by ZD rats). Growth, food intake and zinc concentrations in serum, liver and pancreas were significantly depressed in ZD and PF rats. Zinc per gram of thymus tissue and per number of SL was elevated in ZD and PF rats. Spleen lymphocytes from ZD and PF rats displayed equivalent to significantly increased levels of proliferation following stimulation with Con-A. [3H]Thymidine incorporation by Con-A-stimulated SL and CLNC from ZD, PF and AL rats was not significantly different when cultured in medium containing serum from ZD, PF and AL rats. The present study shows that zinc deficiency causes major changes in total-body and organ growth but minor changes in zinc content and mitogen-induced proliferation of lymphocytes.     

Zinc status affects neurotransmitter activity in the paraventricular nucleus of rats

Alterations in neurochemical activity in the paraventricular nucleus (PVN) of the hypothalamus may account for decreased intake of zinc-deficient diets. Male Sprague-Dawley rats were fed zinc-deficient (ZD) or zinc-adequate (ZA) diet for 14 d before samples of extracellular fluid in the PVN were collected by microdialysis or push-pull perfusion. A third set of rats was pair-fed (PF) an amount of ZA diet equal to the intake of ZD rats. Samples were collected over a 2-h period spanning the transition from light to dark. All rats then consumed the zinc adequate diet ad libitum for 3 d before a second set of samples was collected. The increase in extracellular norepineprhrine (NE) during h 1 of the dark period to 147 +/- 13% of baseline (P < 0.05) was apparent only in ZA rats at d 14. After the 3-d repletion period, the increase in NE at dark onset occurred in all three groups. An increase in extracellular neuropeptide Y (NPY) at dark onset to 174 +/- 32% of baseline in rats fed ZA (P < 0.01) was measured in all three groups at both d 14 and 17. Basal NPY concentrations were significantly elevated in PF rats on d 14 (7.45 +/- 2.01 vs. 0.58 +/- 0.23 pmol/L, P = 0.01) and returned to ZA levels by d 17. The activities of the NE and NPY systems in the PVN were altered in rats fed a zinc-deficient diet; however, it is unclear whether the disruption in the NE and NPY neural systems in the PVN results in the altered feeding behavior accompanying zinc deficiency.     

Plasma apolipoprotein B-48, hepatic apolipoprotein B mRNA editing and apolipoprotein B mRNA editing catalytic subunit-1 mRNA levels are altered in zinc-deficient rats.

Apolipoprotein B (apoB) exists as two major isoforms and serves as an obligatory component of lipid-rich plasma lipoprotein particles. Apolipoprotein B mRNA editing is a zinc-dependent, site-specific cytidine deamination that determines whether the apoB-100 or apoB-48 isoform is synthesized. The objective of this work was to examine whether dietary zinc levels affect apoB mRNA editing in vivo. Adult male Sprague-Dawley rats were randomly assigned to zinc-deficient (ZD, <0.5 mg Zn/kg diet), zinc-adequate (ZA, 30 mg Zn/kg diet) or zinc-replenished (ZDA, ZD rats fed the ZA diet for last 2 d) dietary groups for 18 d. The ratio of plasma apolipoprotein B-48 (apoB-48) to total apoB was significantly lower in zinc-deficient compared with zinc-adequate rats. Primer extension analysis indicated a modest but significant reduction in hepatic apoB mRNA editing in ZD rats compared with that of the ZA group. In ZDA rats, hepatic apoB mRNA editing and the percentage of plasma apoB-48 to total apoB were not different from ZA rats. The mRNA abundance of hepatic apobec-1 (apoB mRNA editing catalytic subunit 1) was significantly lower in ZD and ZDA rats than in ZA rats. In summary, the plasma ratio of apoB-48 to total apoB protein as well as hepatic apoB mRNA editing and hepatic apobec-1 mRNA levels were reduced in rats consuming a zinc-deficient diet. These data suggest that one or more components of apoB metabolism may be influenced by dietary zinc status.     

Polyunsaturated fatty acid patterns in lymphoid and nonlymphoid tissues of zinc deficient and pair-fed rats

The influences of zinc-deficiency and reduced food intake on levels of polyunsaturated fatty acids (PUFA) of phospholipids (PL) of lymphoid and nonlymphoid tissues were studied. Weanling male Long-Evans rats were fed ad libitum either a zinc-deficient (ZD) or a zinc-adequate (ZA) diet for 21 days. A pair-fed (PF) group was given the ZA diet in an amount equal to that consumed on the previous day by the ZD group. Linoleic acid (18:2ω6), 18:3ω6 and 20:3ω6 were either equivalent or significantly higher, but arachidonic acid (20:4ω6) and 22:5ω6 were either equivalent or significantly lower in tissues of ZD and PF rats compared to ZA rats. Total ω6 acids and metabolites were either equivalent or significantly lower in tissues of ZD and PF rats compared to ZA rats. In contrast, total ω3 acids and metabolites, and total ω9 acids and emtabolites were either equivalent or significantly higher in ZD and PF rats compared to ZA rats. Changes in PUFA patterns of lymphoid and nonlymphoid tissues of ZD rats were influenced by reduced food intake.     

The cognitive impairment induced by zinc deficiency in rats aged 0∼2 months related to BDNF DNA methylation changes in the hippocampus

Objective: This study was carried out to understand the effects of zinc deficiency in rats aged 0～2 months on learning and memory, and the brain-derived neurotrophic factor (BDNF) gene methylation status in the hippocampus.

Methods: The lactating mother rats were randomly divided into three groups (n?=?12): zinc-adequate group (ZA: zinc 30?mg/kg diet), zinc-deprived group (ZD: zinc 1?mg/kg diet), and a pair-fed group (PF: zinc 30?mg/kg diet), in which the rats were pair-fed to those in the ZD group. After weaning (on day 23), offspring were fed the same diets as their mothers. After 37 days, the zinc concentrations in the plasma and hippocampus were measured, and the behavioral function of the offspring rats was measured using the passive avoidance performance test. We then assessed the DNA methylation patterns of the exon IX of BDNF by methylation-specific quantitative real-time PCR and the mRNA expression of BDNF in the hippocampus by RT-PCR.

Results: Compared with the ZA and PF groups, rats in the ZD group had shorter latency period, lower zinc concentrations in the plasma and hippocampus (P?Conclusion: The learning and memory damage in offspring may be a result of the epigenetic changes of the BDNF genes in response to the zinc-deficient diet during 0～2 month period. Furthermore, this work supports the speculative notion that altered DNA methylation of BDNF in the hippocampus is one of the main causes of cognitive impairment by zinc deficiency.     

Dietary zinc deficiency decreases glutathione S-transferase expression in the rat olfactory epithelium

Zinc deficiency leads to olfactory and gustatory dysfunction, but little is known about the underlying molecular mechanism of this phenomenon. We examined the effect of dietary zinc deficiency on the rat olfactory epithelium. Immunoreactivities of glutathione S-transferase (GST) mu, neuron-specific enolase (NSE) and proliferating cell nuclear antigen (PCNA), and in situ hybridization of GST mu mRNA in the olfactory epithelia were examined under different dietary zinc intake conditions. Adult male rats were fed a zinc-deficient (ZD) diet (0.5 mg zinc/kg diet), whereas control rats, including pair-fed (PF) and zinc-adequate (ad libitum consumption, AL) groups, were fed a zinc-adequate diet (58 mg zinc/kg diet) for 7 wk. We also examined the effect of zinc replacement (ZR) by subsequently feeding half of the ZD group a zinc-adequate diet for 5 wk after the initial 7-wk deprivation. No significant differences in immunoreactivity for NSE in olfactory epithelial receptor cells or for PCNA in basal cells were noted among groups. Intense GST mu immunoreactivity and hybridization signals were observed in olfactory supporting cells of AL, PF and ZR groups, but very minimal or no such signal was noted in ZD rats. Our findings indicated that zinc deficiency reduces GST mu expression in the supporting cells of rat olfactory epithelia but does not affect receptor cell proliferation or maintenance.     

Influence of reduced food intake on polyunsaturated fatty acid metabolism in zinc-deficient rats

The influence of reduced food intake on metabolism of liver phospholipids (PL) in zinc-deficient (ZD) rats was measured. Wealing male Long-Evans rats were fed ad libitum zinc-deficient (2 micrograms Zn/g diet) and zinc-adequate (20 micrograms Zn/g diet) diets for 21 days. A pair-fed (PF) group was included. ZD and PF rats displayed significantly increased levels of linoleic (18:2 omega 6) and dihomo-gamma-linolenic acid (20:3 omega 6). Both ZD and PF rats displayed increased levels of gamma-linolenic acid (18:3 omega 6), but the increase was significant only in PF rats. ZD and PF rats displayed decreased levels of arachidonic acid (20:4 omega 6), but the decrease was significant only in PF rats. Both ZD and PF rats displayed significantly reduced levels of 22:5 omega 6. Both ZD and PF rats displayed increased products of delta 6 desaturation and decreased products of delta 5 and delta 4 desaturation. Significantly increased products of delta 9 desaturation were noted in both ZD and PF rats. ZD and PF rats displayed significant increases in C20 elongation products. ZD and PF rats displayed significantly decreased levels of omega 6 metabolites but not total omega 6 acids. ZD rats showed significantly increased levels of total omega 3 acids and omega 3 metabolites. ZD and PF rats showed significant increases in omega 9 acids but not significant changes in omega 9 metabolites. This study does not indicate that zinc affects the delta 6 desaturase in the metabolism of essential fatty acids. The aberrations previously attributed to zinc deficiency are probably due to the accompanying decreased food intake.     

锌缺乏对生长期雄性大鼠海马泛素C末端水解酶L1表达的影响

[目的]观察缺锌对生长期大鼠海马泛素C末端水解酶L1(UCH-L1)表达的影响。[方法]将SD大鼠随机分为正常组、缺锌配喂组和缺锌组,正常组喂饲常锌饲料(32.5mg/kg),缺锌配喂组喂饲高锌饲料(73.5mg/kg),缺锌组喂饲缺锌饲料(1.2mg/kg)。饲养4周后处死动物,取海马组织,RT-PCR法检测UCH-L1mRNA的表达水平,Westernblot法检测UCH-L1蛋白的表达水平。[结果]与正常组和缺锌配喂组比较,缺锌大鼠海马中UCH-L1mRNA和蛋白的表达水平均显著下调。[结论]缺锌大鼠海马UCH-L1的表达异常,可能是缺锌导致认知损伤的重要机制之一。