Dissertation > Excellent graduate degree dissertation topics show

Effects of Psychological Stress on Zinc Metabolism and its Mechanism in Rats

Author: LiYingJie
Tutor: LiMin
School: Second Military Medical University
Course: Nutrition and Food Hygiene
Keywords: zinc psychological stress zinc transporters hippocampus
CLC: R363
Type: Master's thesis
Year: 2013
Downloads: 36
Quote: 0
Read: Download Dissertation

Abstract

BackgroundPsychological stress （PS）is a process that the body through cognition, evaluation andaware of the stressors, the threat of the psychological and physiological function, which isindividual to the threat or challenge to adapt and cope with the process. With the developmentof society and all aspects of pressure increases, comes from the spirit of the socialpsychological factors of stress effects on human health becomes more and more intense, andbecome the important source of stress. Many studies have confirmed that stress is not asbiological or physical and chemical factors can lead to a particular disease, but can causebody damage nonspecific, such as induced by coronary heart disease, hypertension, pepticulcer, neurological diseases such as mental illness, etc.Zinc is one of the essential trace elements in human body, second only to iron in the bodycontent. Zinc participate in numerous biological reaction, but it also has a variety of biologicalfunctions, its main functions include catalytic function, structure, function and regulationfunction, in addition, zinc also widely involved in cell signal identification regulation,metabolism of second messenger and the function of the protein kinase and proteinphosphatesadjustment,etc. Zinc homeostasis maintenance depends on some zinc metabolismrelated to the regulation of protein function, including metallothionein （MT) andtransmembrane transporter, and the latter mainly includes zrt, irt-like protein（ZIP) and zinctransportors (ZnT).The cells are vulnerable to pathological physiological and environmental factors, such asinflammation, oxidative stress, etc. Experiments show that under the condition of stress,intracellular free zinc ion concentration can significantly increase, leading to cell damage.Thermal environment were also found in a previous study, acceleration stimulation, noise,etc.all can cause the serum zinc level dropped significantly. Combining the above research,we speculate that the trace element zinc may play an important role in the process of stress.On the one hand, various stress increase intracellular free zinc concentration, make the zinc inthe intracellular produces toxic effect, cause cell damage; Stress causes the body serum zinc,on the other hand, fall, and could lead to the redistribution of zinc in the body, thus affectingthe body’s antioxidant capacity, etc. affect the body’s ability to resist stress. Therefore,understanding the body zinc metabolism in the process of psychological stress variation characteristics and its possible mechanism, solve stress induced damage to provide clues forstudies.ObjectiveThe aim of this study is to observe the characteristic effects of psychological stress on zincmetabolism, especially the hippocampus zinc level changes and to explore the possiblemechanisms of these changes will not only help understand the changes in the characteristicsof the process of psychological stress and zinc metabolism mechanism, and further researchon the basis of psychological stress-related illness and provide experimental evidence andtheoretical reference.Methods1.Animals and groupsMale SD rats (180-200g body weight) were purchased from the Shanghai-BK ltd. Co.After adaptation for3days, the rats were divided into the psychological stress group and thecontrol group.Each group was divided two small groups:7d-PS group and the control group;14d-PS group and the control group; after depart from stress for7d group and the controlgroup: after depart from stress for14d group and the control group.2.Psychological stress modelA communication box system was used to establish the rat PS model． Theconcentrations of serum CORT was measured by the radioimmunfocus assays (RI) kit.3. Measurement of tissue and serum zinc concentrations in ratsThe concentrations of serum zinc, spleen zinc, liver zinc, heart zinc, intestinal zinc andkidney zinc were measured on the Z-2000atomic absorption spectrophotometer (Hitachi,Japan). Standard zinc solution of1g/L was provided by National Standard Substance Center.4.The apparent absorption of zinc under psychological stress.The apparent absorption of zinc=(zinc in diets--zinc in fecal)x100％/zinc in diets． 5. Determination of liver ZIP14and hippocampusZnT1, ZnT3and ZIP1mRNA expression in rats.Real time PCR was performed using IQ5Real-Time PCR Detection System. Two stepRT-PCR method was performed using Real Time PCR Master Mix. Primers used to analyzeall the transcripts have been reported elsewhere.6.Measurement of liver and hippocampus MT contents in ratsThe concentrations of MT in the hippocampus and liver were measured by ELISAkits.7. Measurement of hippocampusfree zinc ions in ratsHippocampus free zinc ions content in rats was measured by TSQ fluorescence stainingmethod..8. Measurement of behavioral changes after psychological stress in ratsThe spontaneous activity and the forced swimming test were used to detect the behaviorindex of rats.9. Statistical analysisStatistical analysis was carried out by using SPSS16.0statistical software. Usingtwo-sample t test and one-way ANVOA compare for the analysis of the biochemical indices.Differences were considered significantly at P<0.05level.Results1. The effect of PS on the serum CORT content in ratsCompared with the control group, the concentrations of serum CORT of thepsychological stress group after7d-and14-period increased respectively (P<0.05), The concentrations of serum CORT after depart from the stress for one week and two weeksshowed no significant difference when compared with the control group (P>0.05).2. The effect of PS on body weight in ratsWe found there were no changed in the weight of rats between psychological stress andthe control group (P>0.05).3. The effect of PS on the zinc absorption in ratsThere were no significantly changed of the food intake between psychological stressgroup and the control group. So there were no changed in the zinc content in the dietsbetween PS and the control group (P>0.05). Also, we found there were significantlydecreased the apparent absorption of zinc at day7and day14of psychological stress vs thecontrol group (P<0.05). And the apparent absorption of zinc after depart from the stress forone week and two weeks showed no significant difference when compared with the controlgroup (P>0.05).4. The effect of PS on the serum zinc and tissue zinc in rats4.1The effect of PS on the serum zinc in ratsCompared with the control group, the concentrations of serum zinc of the psychologicalstress group after7d-and14-period increased respectively (P<0.05), The concentrations ofserum zinc after depart from the stress for one week and two weeks showed no significantdifference when compared with the control group (P>0.05).4.2.The effect of PS on the tissue zinc in rats4.2.1The effect of PS on the heart, liver, spleen, kidney and intestine zinc inratsThe concentration of zinc in heart, spleen, kidney and intestine after stressing for oneweek and two weeks showed no significantly changed when compared with the blank controlgroup (P>0.05).But we found there were significantly increased in liver zinc when comparedwith the control group (P<0.05). And the concentrations of liver zinc after depart from thestress for one week and two weeks showed no significant difference when compared with thecontrol group (P>0.05).4.3.2The effect of PS on the encephalic region zinc in ratsThe concentration of zinc in cerebellum, cortex and hypothalamus after stressing for one week and two weeks showed no significantly changed when compared with the blank controlgroup (P>0.05). But we found there were significantly decreased in hippocampal zinc whencompared with the control group (P<0.05). And the concentrations of hippocampal zinc afterdepart from the stress for one week and two weeks showed no significant difference whencompared with the control group (P>0.05).5. The effect of PS on the zinc regulated protein MT in the liverCompared with the control group, the concentrations of MT in the liver after stressing fortwo weeks showed significantly increased (P<0.05). And the concentrations of MT in the liverafter depart from the stress for one week and two weeks showed no significant differencewhen compared with the control group (P>0.05).6. The effects of PS on the ZIP14mRNA expression in the liverCompared with the control group, ZIP14mRNA levels in the liver after stressing for oneweek showed significantly increased (P<0.05).7. The effects of PS on the ZIP1，ZnT1and ZnT3mRNA levels in thehippocampus.The real-time PCR results showed that the ZnT1mRNA and ZnT3mRNA levels of thepsychological stress group after7d-and14-period increased respectivlely (P<0.05), TheZnT1mRNA and ZnT3mRNA levels after depart from the stress for one week and two weeksshowed no significant difference when compared with the control group (P>0.05). And theZIP1mRNA levels after stressing for one week showed significantly decreased whencompared with the blank control group (P<0.05).8. The effect of PS on MT contents in hippocampusCompared with the control group, the concentrations of MT in the hippocampus afterstressing for two weeks showed significantly increased (P<0.05). And the concentrations ofMT in the hippocampus after depart from the stress for one week and two weeks showed nosignificant difference when compared with the control group (P>0.05).9. The effect of PS on the free zinc ions in the hippocampusThe TSQ fluorescence results showed that the fluorescence staining levels of the psychological stress group after7d-and14-period increased respectively (P<0.05) whencompared with the control group (P<0.05).10. The effects of PS on spontaneous activity and the forced swimmingtest in ratsCompared with the control group, the rat immobility time of the psychological stressgroup after7d-and14-period increased respectively during the forced swimming test(P<0.05),The movement time and total distance in the psychological stress group were lower thanthose in the control group (P<0.05). And the breaking time in the psychological stress groupwas longer than those in the control group (P<0.05).ConclusionsWe used the communication box for PS to reascrh the zinc metabolize and themechanism of regulation during PS. Conclusions were made as follows:1. With the time prolonged of PS, the apparent absorption of zinc in rats duringpsychological stress can reduced, this change may be affected by the increasing of theexcretion of zinc in rats.2. The reasons of serum zinc concentration decrease are that the apparent absorption ofzinc decreased and liver zinc increased by MT and ZIP14.3. Psychological stress result in significant decrease of the concentration of thehippocampus zinc. Together with significantly decreased ZnT1and ZnT3and increased ZIP1indicate the relationship between them. Integrated the findings of this study, it shows that longperiods of psychological stress may reduce the ZnT1and ZnT3mRNA levels, and increase theZIP1mRNA level, thus affecting the concentration of the hippocampus zinc in a certaindegree.4. After psychological stress rats behavior changed, this may be linked to psychologicalstress in rats hippocampus zinc content of falling and rising of free zinc ions influence onhippocampal function, eventually led to the behavioral changes in rats.

Effects of Psychological Stress on Zinc Metabolism and its Mechanism in Rats

Abstract

Related Dissertations