Ferroptosis regulating lipid peroxidation metabolism in the occurrence and development of gastric cancer

BACKGROUND Gastric cancer is one of the most common malignant tumors in the world,and its occurrence and development involve complex biological processes.Iron death,as a new cell death mode,has attracted wide attention in recent years.However,the regulatory mechanism of iron death in gastric cancer and its effect on lipid peroxidation metabolism remain unclear.AIM To explore the role of iron death in the development of gastric cancer,reveal its relationship with lipid peroxidation,and provide a new theoretical basis for revealing the molecular mechanism of the occurrence and development of gastric cancer.METHODS The process of iron death in gastric cancer cells was simulated by cell culture model,and the occurrence of iron death was detected by fluorescence microscopy and flow cytometry.The changes of gene expression related to iron death and lipid peroxidation metabolism were analyzed by high-throughput sequencing technology.In addition,a mouse model of gastric cancer was established,and the role of iron death in vivo was studied by histology and immunohistochemistry,and the level of lipid peroxidation was detected.These methods comprehensively and deeply reveal the regulatory mechanism of iron death on lipid peroxidation metabolism in the occurrence and development of gastric cancer.RESULTS Iron death was significantly activated in gastric cancer cells,and at the same time,associated lipid peroxidation levels increased significantly.Through high-throughput sequencing analysis,it was found that iron death regulated the expression of several genes related to lipid metabolism.In vivo experiments demonstrated that increased iron death in gastric cancer mice was accompanied by a significant increase in lipid peroxidation.CONCLUSION This study confirmed the important role of iron death in regulating lipid peroxidation metabolism in the occurrence and development of gastric cancer.The activation of iron death significantly increased lipid peroxidation levels,revealing its regulatory mechanism inside the cell.

Research progress of ferroptosis regulating lipid peroxidation and metabolism in occurrence and development of primary liver cancer

As a highly aggressive tumor,the pathophysiological mechanism of primary liver cancer has attracted much attention.In recent years,factors such as ferroptosis regulation,lipid peroxidation and metabolic abnormalities have emerged in the study of liver cancer,providing a new perspective for understanding the development of liver cancer.Ferroptosis regulation,lipid peroxidation and metabolic abnormalities play important roles in the occurrence and development of liver cancer.The regulation of ferroptosis is involved in apoptosis and necrosis,affecting cell survival and death.Lipid peroxidation promotes oxidative damage and promotes the invasion of liver cancer cells.Metabolic abnormalities,especially the disorders of glucose and lipid metabolism,directly affect the proliferation and growth of liver cancer cells.Studies of ferroptosis regulation and lipid peroxidation may help to discover new therapeutic targets and improve therapeutic outcomes.The understanding of metabolic abnormalities can provide new ideas for the prevention of liver cancer,and reduce the risk of disease by adjusting the metabolic process.This review focuses on the key roles of ferroptosis regulation,lipid peroxidation and metabolic abnormalities in this process.

Vicious cycle of lipid peroxidation and iron accumulation in neurodegeneration

Lipid peroxidation and iron accumulation are closely associated with neurodegenerative diseases,such as Alzheimer’s,Parkinson’s,and Huntington’s diseases,or neurodegeneration with brain iron accumulation disorders.Mitochondrial dysfunction,lipofuscin accumulation,autophagy disruption,and ferroptosis have been implicated as the critical pathomechanisms of lipid peroxidation and iron accumulation in these disorders.Currently,the connection between lipid peroxidation and iron accumulation and the initial cause or consequence in neurodegeneration processes is unclear.In this review,we have compiled the known mechanisms by which lipid peroxidation triggers iron accumulation and lipofuscin formation,and the effect of iron overload on lipid peroxidation and cellular function.The vicious cycle established between both pathological alterations may lead to the development of neurodegeneration.Therefore,the investigation of these mechanisms is essential for exploring therapeutic strategies to restrict neurodegeneration.In addition,we discuss the interplay between lipid peroxidation and iron accumulation in neurodegeneration,particularly in PLA2G6-associated neurodegeneration,a rare neurodegenerative disease with autosomal recessive inheritance,which belongs to the group of neurodegeneration with brain iron accumulation disorders.

Gas stunning with CO_2 affected meat color,lipid peroxidation, oxidative stress, and gene expression of mitogen-activated protein kinases, glutathione S-transferases,and Cu/Zn-superoxide dismutase in the skeletal muscles of broilers

Background: Meat color and lipid peroxidation are important traits related to meat quality. CO_2 concentration is a critical factor that can affect meat quality in the commercial use of gas stunning(GS). However, the effect and mechanism of CO_2 stunning on meat color and lipid peroxidation during long-term storage remain poorly studied. We aimed to study the effects of GS methods, especial y CO_2 concentration, on meat color and meat lipid peroxidation in broilers during long-term storage at 4 °C and to explore the potential mechanism of meat color change via lipid peroxidation and the inner lipid peroxide scavenging system.Methods: Eighteen broilers were sacrificed after exposure to one of the following gas mixtures for 90 s: 40% CO_2+21% O_2+ 39% N2(G40%), 79% CO_2+ 21% O_2(G79%), or no stunning(0% CO_2, control). Meat color, serum variables,enzyme activities, and the gene expression of mitogen-activated protein kinase(MAPK), nuclear factor-erythroid2-related factor 2(Nrf2), glutathione S-transferase(GST) and superoxide dismutase(SOD) were determined.(Continued on next page)Results: The concentrations of serum triiodothyronine(T3, P = 0.03) and the ratio of serum free triiodothyronine/free thyroxine(FT3/FT4, P < 0.01) were decreased, whereas levels of serum cortisol(P < 0.01) were increased in the 40%CO_2 group compared with the control group. Additionally, the thiobarbituric acid-reactive substances(TBARS)3 d(P < 0.01) and TBARS6 d(P = 0.01) in breast meat and the TBARS3 din thigh meat(P < 0.01) were increased in the40% CO_2 group compared with the control group. Serum T3 was negatively correlated with TBARS6 dboth in the breast and thigh meat(r =-0.63, P < 0.01 and r =-0.47, P = 0.05 respectively). T3/T4 was negatively correlated with TBARS6 din the breast meat and in the thigh meat(r =-0.57, P = 0.01; and r =-0.53, P = 0.03 respectively). Compared with the control group, Lightness(L*)1 d(P = 0.03) and L*9 d(P < 0.01) were increased, whereas total chromatic aberration(E*)1 d(P = 0.05) and E*3 d(P < 0.01) were decreased in the breast meat of both the G40% and G79% groups. The values of yel owness(b*)3 d(P = 0.01), b*6 d(P < 0.01) and E*6 d(P < 0.01) in the thigh meat were lower in both the G40% and G79% groups than in the control group. In the breast muscle, the m RNA levels of c-Jun N-terminal kinase 2(JNK2, P = 0.03),GSTT1(P = 0.04), and SOD1(P = 0.05) were decreased, and the m RNA levels of JNK1(P = 0.07), Nrf2(P = 0.09), and GSTA3(P = 0.06) were slightly lower in both the G40% and G79% groups compared with the control group. However, among these genes, only the m RNA level of JNK1 was decreased in the G40% group compared with the control group and the G79% group(P = 0.03) in the thigh muscle.Conclusions: Compared with the control group, meat color quality in the breast meat was decreased, and the expression of genes in the MAPK/Nrf2/ARE(antioxidant responsive element) antioxidant pathway in breast muscle was partly suppressed by GS of both 40% and 79% CO_2. However, oxidative stress and meat lipid peroxidation during storage were aggravated by GS with 40% CO_2 compared to GS with 79% CO_2 and no GS.

Changes in erythrocyte membrane ATPases and plasma lipid peroxides in upper abdominal surgery under intravenous procaine-balanced anesthesia

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Effect of lipid peroxidation on the allergenicity and functional properties of soybeanβ-conglycinin(7S)and glycinin(11S)

This study aimed to analyze the effect of lipid peroxidation on the allergenicity and functional properties of soybeanβ-conglycinin(7 S)and glycinin(11 S).Oxidation complexes were determined using the lipid peroxidation method.Functional properties were analyzed based on emulsifying and foaming properties.The potential allergenicity was evaluated by in vitro and in vivo methods.The results found that oxidation altered structures of the proteins and resulted in the formation of cross-linked protein polymers.The emulsion and foaming properties of the proteins were improved after oxidation.The IgE-binding capacity of 7 S and11 S reduced after oxidation.KU812 cell assays showed that both histamine and IL-4 release decreased after oxidation treatment.A mouse model showed that oxidation reduced the IgE,IgG,and IgG1 levels,as well as reduced histamine and mMCP-1 release in serum,which might suppress the allergic reaction.In conclusion,the lipid peroxidation treatment likely causes changes to the functional properties of soybean,decreasing the potential allergenicity of 7 S and 11 S.

Investigation of heavy metals and lipid peroxidation level in the muscles of Clarias gariepinus from IBI,Gindin-Dorowa and D onga community rivers in Taraba State,Nigeria

Heavy metals have harmful effects on human health,and exposure to these metals has been increased by industrial and anthropogenic activities and modern industrialization.Heavy metals content of the liver tissues was determine d using Atomic Absorption Spectrophotometer method,while lipid peroxidation was carried out.Heavy metals analyzed include;lead(Pb),cadmium(Cd),zinc(Zn),Arsenic(As),and Mercury(Hg).The findings revealed that the heavy metal Zinc(Zn)has high concentrations in the muscles of the fish species,the concentration of this heavy metal Zinc is high in River Gindin Dorowa th a n in River Ibi and River Donga shows less concentration of this heavy metal though it’s above WHO permissible limits.Results revealed that only Zn and Cd were present in the muscle from the three rivers.Pb was found only in the liver from Gindin-Dorowa at the concentration of 0.017 mg/kg,which is not significant(P<0.05)when compared with other locations,while Hg and As were absent in all the muscle samples.The highest concentration of Zn was found in the muscle sample from Gindin-Dorowa(7.450 mg/kg)followed by Ibi(6.16 mg/kg)and the least being Donga(4.365 mg/kg)which are significantly(P<0.05)different from one another.However,there was no significant(P<0.05)difference among the Cd composition of muscle from Gindin-Dorowa(0.025 mg/kg),Donga(0.024 mg/kg)and Ibi(0.015 mg/kg),respectively.The TBA was found in the hepatic tissue sample from Gidin-Dorowa,which has the highest Zn,Cd and no Pb content,followed by Ibi and then the Donga sample.This suggests that there is a positive relationship between heavy metals and the effect of TBA on the hepatic tissues,justifying the fact that heavy metals affect the hepatic tissues of fish,while on the cerebral tissue.In conclusion,it revealed that there is a negative relation between heavy metals and the effect of TBA on the cerebral tissues to protect or save aquatic habitat s of fish quality and aquatic life.

Potential role and therapeutic implications of glutathione peroxidase 4 in the treatment of Alzheimer's disease

Alzheimer's disease is an age-related neurodegenerative disorder with a complex and incompletely understood pathogenesis. Despite extensive research, a cure for Alzheimer's disease has not yet been found. Oxidative stress mediates excessive oxidative responses, and its involvement in Alzheimer's disease pathogenesis as a primary or secondary pathological event is widely accepted. As a member of the selenium-containing antioxidant enzyme family, glutathione peroxidase 4 reduces esterified phospholipid hydroperoxides to maintain cellular redox homeostasis. With the discovery of ferroptosis, the central role of glutathione peroxidase 4 in anti-lipid peroxidation in several diseases, including Alzheimer's disease, has received widespread attention. Increasing evidence suggests that glutathione peroxidase 4 expression is inhibited in the Alzheimer's disease brain, resulting in oxidative stress, inflammation, ferroptosis, and apoptosis, which are closely associated with pathological damage in Alzheimer's disease. Several therapeutic approaches, such as small molecule drugs, natural plant products, and non-pharmacological treatments, ameliorate pathological damage and cognitive function in Alzheimer's disease by promoting glutathione peroxidase 4 expression and enhancing glutathione peroxidase 4 activity. Therefore, glutathione peroxidase 4 upregulation may be a promising strategy for the treatment of Alzheimer's disease. This review provides an overview of the gene structure, biological functions, and regulatory mechanisms of glutathione peroxidase 4, a discussion on the important role of glutathione peroxidase 4 in pathological events closely related to Alzheimer's disease, and a summary of the advances in small-molecule drugs, natural plant products, and non-pharmacological therapies targeting glutathione peroxidase 4 for the treatment of Alzheimer's disease. Most prior studies on this subject used animal models, and relevant clinical studies are lacking. Future clinical trials are required to validate the therapeutic effects of strategies targeting glutathione peroxidase 4 in the treatment of Alzheimer's disease.

EFFECTS OF COMBINATION OF ACUPUNCTURE AND MOXIBUSTION WITH CHINESE DRUGS ON LIPIDS PEROXIDE AND ANTIOXIDASE IN PATIENTS OF VASCULAR DEMENTIA

In the present paper, blood lipids peroxide(LPO) level and activities of glutathione peroxidase(GSH-Px) and superoxide dismutase(SOD) were investigated before and after combined treatment of acupuncture and moxibustion and Chinese drugs in patients of vascular dementia(VD), and their results were compared with those in healthy persons with the similar ages to the patients. The results showed that the blood LPO level increased significantly, and the activities of SOD and GSH-Px reduced significantly in patients of VD as compared with those in the control group. Degrees of patient’s condition were related with amplitudes of the increase of LPO and the reduction of activities of GSHPx and SOD. Combined treatment of acupuncture and moxibustion and Chinese drugs could raise markedly activitles of blood GSH-Px and SOD, and lowered LPO level in the patients of VD, which are related to clinical therapeutic effects. It is considered that combination of acupuncture and moxibustion with Chinese drugs can increase the action of the antiperoxidative system in the patients of VD, exerting anti-peroxidative ability and clearing LPO and reducing the oxidative injury of the organism by oxygen free radical, which is one of mechanisms of combined treatment of acupuncture and moxibustion with Chinese drugs.

Studies on Free Radical EPR,Superoxide Dismutase Water-soluble Lipidperoxide in Tears

By means of electron paramagnetic resonance(EPR), chemistry luminescence and fluorescent spectroscopy, the free radical, superoxide dismutase and water soluble lipid peroxide in tears of normal eyes(150 eyes, 100 cases), Moorens ulcer(9 eyes), coreal grafts rejection(16 eyes) were studied. The results showed that the spin density of the free radical was 36(±058)×1012 spins/mL tear, the content of the superoxide dismutase(SOD) was 384(±145) ng/mL tear, the opposite fluorescent density of the water soluble lipid peroxide was 12912(±1691) U/mL tear in normal tears. The normal values are 25—48×1012 spins/mL tear for free radical, 239—529 ng/mL tear for SOD, 9598—16225 U/mL tear for water soluble lipid peroxide. There are significant differences in different eyes, different sexes and different ages. The free radical and lipid peroxide are higher obviously in the tears of patients with Moorens ulcer and rejected corneal grafts, compared with those of the normal control subjects(P<001), SOD is lower evidently(P<001). The above fact shows the pathogenic mechanism of Moorens ulcer and keractoplasty rejection is significantly related to toxicities injuring effect of the free radical. These results have provided important experimental data for studying lacrimalogy and new methods for clinical diagnosis and treatrment.

Changes of Selenium Metabolism Glutathione Peroxidase Activity and Lipid Peroxides Content in Severely Scalding-injured Rats

The changes of sclenium metabolism, glutathione peroxidase activity and lipid peroxidescontent in the tissues of rats suffering from 30% TBSA full thickness scalding were observed in thefirst 7 days after injury. It was found that selenium content in the rat tissues decreased remarkably af-ter injury, which in turn resulted in serious reduction of glutathione peroxidasc activity and significantincrease of lipid peroxides in the scrum, crythrocytcs and liver. However the muscular tissue showedno significant changes. These facts imply that after burn injury, the body is in a state of selenium deficiency, the lossof selenium might be responsible for the reduction of anti - peroxidation ability of glutathioneperoxidase, and conscqucntly there is an increase of lipid peroxides in the tissues. Only the musculartissue is insensitive to lipid peroxidation. It is believed that the reduction of anti-peroxidation abilityof glutathione peroxidasc after bum injury might be one of the main causes to intensify, the injury re-suiting from free radicals.

Level of lipid peroxides and cuprozinc superoxide dismutase in gastric mucosa and serum of gastrectomized patients

The level of lipid peroxides (LPO) and copper-zinc containing superoxide dismutase (SOD-Ⅰ) in the gastric mucosa and serum was determined in 141 samples from 25 patients after con-ventional subtotal gastrectomy (11 cases of Billroth Ⅰ and 14 cases of Billroth Ⅱ) and 11 patientsafter pylorus and antroseromuscular flap preserving gastrectomy (PAFPG).Those of 11 normal subjects were examined likewise to serve as control.It was found that:(1) The average LPO levelwas much higher and the average SOD-Ⅰ level much lower in the gastric mucosa of the patientsafter conventional subtotal gastrectomy especially the Billroth Ⅱ type than in that of those afterPAFPG.(2) In 36 specimens of stump mucosa,the average LPO level was significantly higher inthe tissue around the anastomotic ring than in that of the body of the stump;no marked differ-ence of SOD-Ⅰ level between the 2 was revealed.(3) The LPO value in the stump mucosa waspositively correlated to and the SOD-Ⅰ value negatively correlated to the pH value of gastric juice.These rindings suggest that the reation of oxygen free radicals in the stump mucosa may be influ-enced by the intragastric pH or by the type of digestive continuity reconstruction,and that thereaction of oxygen free radicals especially the lipid peroxidation may play a role in the pathogenesisof the lesions in the anastomotic stoma.

Changes in erythrocyte membrane ATPase and plasma lipid peroxides during perioperative period

Changes in erythrocyte membrane ATPases and plasma lipid peroxides（LPO） were studiedperioperatively in 15 abdominal surgical patients under intravenous procaine-balanced anesthesia.The resultsrevealed that erythrocyte membrne Na+-K+ATPase,Mg2+ATPase and Ca2+-Mg2+ATPase activities werenot significantly changed at 60～90 min after incision as compared with 30 min before anesthesia,but weredecreased markedly at 10 rain and 24 hours after completion of operation（P【0.01）.Plasma LPO wereincreased significantly by 24 hours after surgery（P【0.01） following an initially marked but transientreduction.Plasma LPO changes were not correlated with erythrocyte membrane ATPase activities,r=-0.0396,-0.0097 and-0.4383 respeetively（P】0.05）.These correlations are suggested to be inducedby neuroendoerine responses after anesthesia and/or surgical trauma.

Effects of Silica on Serum Phospholipid,Lipid Peroxide and Morphological Characteristics of Rat Lung

The effects of instilled silica have been studied on the serum-phospholipid (PL), lipid peroxide (LPO) and histopathology of rat lung up to 140 days from the first day of instillation. Silica induced relatively higher serum-PL throughout the experiment. The level of LPO also increased appreciably. They presented positive linear correlation. The early lesion was acute alveolitis with silica particles. These lesions became silicotic nodules on the 30th day, which then were enlarged gradually and fused by fibrosis. Alveolar macrophages (AM) were activated and surface structure was damaged. These results indicate that instilled sillca can induce lipid peroxidation of cell membrane and selective accumulation of lung PL

Flavonoids Reduce Lipid Peroxides and Increase Glutathione Levels in Pooled Human Liver Microsomes (HLMs)

The effects of each of the flavonoids;genistein (G), quercetin (Q) and kaempferol (K) at several doses on lipid peroxides (LP) and reduced glutathione (GSH) in pooled human liver microsomes (HLMs) were investigated following the oxidative damage for 4, 6, 18 and 24 hr. HLMs (1 mg/ml) were exposed to each of the above flavonoids at 0, 5, 10, 15, 20 or 25 μM and incubated for the respective times as previously stated. Our hypothesis was that HLMs exposed to the flavonoids for the respective exposure times can decrease LP and increase GSH in HLMs to better cope with the oxidative stress. The results of our studies indicate that each of the flavonoids significantly (p < 0.01) decreased LP compared to their respective controls. The highest decrease in LP was observed for K followed by Q and G. Significant increases (p < 0.01) in GSH were observed for the flavonoid doses tested with the highest levels observed for Q for the 24-hr. incubation. The findings suggest that the flavonoids modulate oxidative stress in HLMs by decreasing LP and such decreases in LPs may be due to the increasing and or the replenished levels of GSH in the said cells to better cope with the oxidative stress.

Mechanisms of Inhibitory Effects of Breviscapine on Lipid Peroxidation in Rat Brain Mitochondria

本文研究了灯盏花素抑制脂质过氧化的作用机制。大鼠脑线粒体脂质过氧化物用硫代巴比妥酸比色法测定。灯盏花素与铁的螯合活性用差示光谱法测定。黄嘌呤黄嘌呤氧化酶（ＸａｎＸＯ）体系产生的超氧阴离子自由基（Ｏ２）及ＦｅＳＯ４Ｈ２Ｏ２体系产生的羟自由基（·ＯＨ）用比色法测定。结果表明：灯盏花素能有效地抑制ＸａｎＸＯ和ＦｅＳＯ４Ｈ２Ｏ２诱导的脑线粒体脂质过氧化反应，其ＩＣ５０分别为９３０１和６２１８μｍｏｌ·Ｌ－１。灯盏花素也能清除ＸａｎＸＯ体系产生的Ｏ２和ＦｅＳＯ４Ｈ２Ｏ２体系产生的·ＯＨ，其ＩＣ５０分别为３２６３和２０２２μｍｏｌ·Ｌ－１。灯盏花素还具有螯合Ｆｅ２＋的活性。由此可见，灯盏花素是在氧自由基与线粒体膜的反应中（１）·ＯＨ的形成（通过与Ｆｅ２＋螯合）（２）脂质过氧化的启动（通过清除Ｏ２和·ＯＨ）两个环节抑制脂质过氧化反应的。

Modulatory effect of pineapple peel extract on lipid peroxidation,catalase activity and hepatic biomarker levels in blood plasma of alcoholinduced oxidative stressed rats

Objective:To investigate the ability of the methanolic extract of pineapple peel to modulate alcohol-induced lipid peroxidation,changes in catalase activities and hepatic biochemical marker levels in blood plasma.Methods:Oxidative stress was induced by oral administration of ethanol(20%w/v) at a dosage of 5 niL/kg bw in rats.After 28 days of treatment,the rats were fasted overnight and sacrificed by cervical dislocation.Blood was collected with a 2 mL syringe by cardiac puncture and was centrifuged at 3000 rpm for 10 min.The plasma was analyzed to evaluate malondialdehyde(MDA),catalase activity,aspartate aminotransferase(AST),alkaline phosphatase(ALP) and alanine aminotransferase(ALT) concentrations.Results:Administration of alcohol caused a drastic increase(87.74%) in MDA level compared with the control.Pineapple peel extract significantly reduced the MDA level by 60.16%at 2.S mL/kg bw.Rats fed alcohol only had the highest catalase activity,treatment with pineapple peel extract at 2.5 mL/kg bw however, reduced the activity.Increased AST,ALP and ALT activities were observed in rats fed alcohol only respectively,treatment with pineapple peel extract drastically reduced their activities. Conclusions:The positive modulation of lipid peroxidation,catalase activities as well as hepatic biomarker levels of blood plasma by the methanolic extract of pineapple peels under alcoholinduced oxidative stress is an indication of its protective ability in the management of alcoholinduced toxicity.

Effects of melatonin on lipid peroxidation and antioxidant enzymes in streptozotocin-induced diabetic rat testis

Aim： To examine the effects of melatonin treatment on lipid peroxidation （LPO） and the activities of antioxidant enzymes in the testicular tissue of streptozotocin （STZ）-induced diabetic rats. Methods： Twenty-six male rats were randomly divided into three groups as follows： group Ⅰ, control, non-diabetic rats （n = 9）; group Ⅱ, STZ-induced, untreated diabetic rats （n = 8）; group Ⅲ, STZ-induced, melatonin-treated （dose of 10 mg/kg·day） diabetic rats （n = 9）. Following 8-week melatonin treatment, all rats were anaesthetized and then were killed to remove testes from the scrotum. Results： As compared to group Ⅰ, in rat testicular tissues of grouap Ⅱ, increased levels of malondialdehyde （MDA） （P 〈 0.01） and superoxide dismutase （SOD） （P 〈 0.01） as well as, decreased levels of catalase （CAT） （P 〈 0.01） and glutathione peroxidase （GSH-Px） （P 〉 0.05） were found. In contrast, as compared to group Ⅱ, in rat testicular tissues of group Ⅲ, levels of MDA decreased （but this decrease was not significant, P 〉 0.05） and SOD （P 〈 0.01） as well as CAT （P 〈 0.05） increased. GSH-Px was not influenced by any of the treatment. Melatonin did not significantly affect the elevated glucose concentration of diabetic group. At the end of the study, there was no significant difference between the melatonin-treated group and the untreated group by means of body and testicular weight. Conclusion： Diabetes mellitus increases oxidative stress and melatonin inhibits lipid peroxidation and might regulate the activities of antioxidant enzymes of diabetic rat testes.

Effects of Water Stress on the Protective Enzyme Activities and Lipid Peroxidation in Roots and Leaves of Summer Maize

A systematic study was conducted to determine the effects of water stress on the activities of protective enzymes and lipid peroxidation in maize. The results showed that, under water stress, the activities of superoxide dismutase （SOD）, catalase （CAT）, and peroxidase （POD） in leaves and roots increased sharply at prophase and metaphase growth stages, such as, male tetrad stage, but then declined towards the physiological maturity. The protective enzyme activities in roots were lower than those in leaves. The content of malondialdehyde （MDA） increased according to the severity of water stress. The content of MDA in roots was lower than that in leaves. The activities of protective enzymes and lipid peroxidation in roots were positively related to that in leaves with most of the correlation coefficients being significant. The content of soluble proteins in roots and leaves decreased with increasing drought stress. The ear characteristics deteriorated and the economic yields of maize decreased significantly under water stress. The main factors that caused reduction of yields were the decrease in the number of ear kernels and 100-kernel weight.