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Liu B, Bai W, Ou G, Zhang J. Cdh1-Mediated Metabolic Switch from Pentose Phosphate Pathway to Glycolysis Contributes to Sevoflurane-Induced Neuronal Apoptosis in Developing Brain. ACS Chem Neurosci 2019; 10:2332-2344. [PMID: 30741526 DOI: 10.1021/acschemneuro.8b00644] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Cdh1 is a regulatory subunit of the anaphase promoting complex/cyclosome (APC/C), known to be involved in regulating neuronal survival. The role of Cdh1 in volatile anesthetics-induced neuronal apoptosis in the developing brain is unknown. In this study, we used postnatal day 7 (P7) and day 21 (P21) mice exposed to 2.3% sevoflurane for 6 h to investigate at which age and duration of exposure sevoflurane affects the expression of Cdh1 and glycolytic enzyme 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3 (PFKFB3) and that of the pentose phosphate pathway (PPP) enzyme, glucose-6-phosphate dehydrogenase (G6PD). Furthermore, we tested whether the cyclin-dependent kinases (cdks) inhibitor roscovatine could counteract the effects caused by exposure to sevoflurane. Finally, we applied the glycolysis inhibitor 3-(3-pyridinyl)-1-(4-pyridinyl)-2-propen-1-one (3-PO), G6PD inhibitor dehydroepiandrosterone (DHEA), and exogenous reduced glutathione to examine the contribution of the glycolysis pathway and PPP to sevoflurane-induced neuroapoptosis. We found that prolonged sevoflurane anesthesia significantly reduces the Cdh1 level in P7 mice compared to in the P21 ones; moreover, the decrease in Cdh1 level results in a switch in glucose metabolism from the PPP to neuronal glycolysis. This leads to an imbalance between reactive oxygen species production and reduced glutathione level in the developing brain, which is more susceptible to oxidative stress. As a result, sevoflurane induces neuroapoptosis through Cdh1-mediated glucose metabolism reprogramming. Our study demonstrates a critical role of Cdh1 in sevoflurane-induced neuroapoptosis by shifting PPP to the glycolytic pathway in the developing brain. These findings suggest that Cdh1 may be a novel target for preventing volatile anesthetics-induced neurotoxicity and memory impairment.
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Affiliation(s)
- Bin Liu
- Department of Anesthesiology, Huashan Hospital, Fudan University, Shanghai, People’s Republic of China 200040
| | - Wenjie Bai
- Department of Anesthesiology, Huashan Hospital, Fudan University, Shanghai, People’s Republic of China 200040
| | - Guoyao Ou
- Department of Anesthesiology, Huashan Hospital, Fudan University, Shanghai, People’s Republic of China 200040
| | - Jun Zhang
- Department of Anesthesiology, Huashan Hospital, Fudan University, Shanghai, People’s Republic of China 200040
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Cheng ML, Chi LM, Wu PR, Ho HY. Dehydroepiandrosterone-induced changes in mitochondrial proteins contribute to phenotypic alterations in hepatoma cells. Biochem Pharmacol 2016; 117:20-34. [DOI: 10.1016/j.bcp.2016.08.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2016] [Accepted: 08/04/2016] [Indexed: 10/21/2022]
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Miyazaki H, Takitani K, Koh M, Inoue A, Tamai H. Dehydroepiandrosterone alters vitamin E status and prevents lipid peroxidation in vitamin E-deficient rats. J Clin Biochem Nutr 2016; 58:223-31. [PMID: 27257348 PMCID: PMC4865594 DOI: 10.3164/jcbn.15-133] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2015] [Accepted: 12/16/2015] [Indexed: 12/18/2022] Open
Abstract
In humans, dehydroepiandrosterone and its sulfate ester metabolite DHEA-S are secreted predominantly from the adrenal cortex, and dehydroepiandrosterone is converted to steroid hormones, including androgens and estrogens, and neurosteroid. Dehydroepiandrosterone exerts protective effects against several pathological conditions. Although there are reports on the association between dehydroepiandrosterone and vitamins, the exact relationship between dehydroepiandrosterone and vitamin E remains to be determined. Therefore, we attempted to elucidate the effect of dehydroepiandrosterone on vitamin E status and the expression of various vitamin E-related proteins, including binding proteins, transporters, and cytochrome P450, in vitamin E-deficient rats. Plasma α-tocopherol levels in vitamin E-deficient rats increased in response to dehydroepiandrosterone administration. The expression of hepatic α-tocopherol transfer protein was repressed in vitamin E-deficient rats compared to that in control rats; however, dehydroepiandrosterone administration significantly upregulated this expression. Hepatic expression of CYP4F2, an α-tocopherol metabolizing enzyme, in vitamin E-deficient rats was decreased by dehydroepiandrosterone administration, whereas hepatic expression of ATP-binding cassette transporter A1, an α-tocopherol transporter, was not altered following dehydroepiandrosterone administration. Dehydroepiandrosterone repressed lipid peroxidation in the liver of vitamin E-deficient rats. Therefore, adequate dehydroepiandrosterone supplementation may improve lipid peroxidation under several pathological conditions, and dehydroepiandrosterone may modulate α-tocopherol levels through altered expression of vitamin E-related proteins.
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Affiliation(s)
- Hiroshi Miyazaki
- Department of Pediatrics, Osaka Rosai Hospital, 1179-3 Nagasone-cho, Kita-ku, Sakai-shi, Osaka 591-8025, Japan
| | - Kimitaka Takitani
- Department of Pediatrics, Osaka Medical College, 2-7 Daigaku-machi, Takatsuki-shi, Osaka 569-8686, Japan
| | - Maki Koh
- Department of Pediatrics, Osaka Medical College, 2-7 Daigaku-machi, Takatsuki-shi, Osaka 569-8686, Japan
| | - Akiko Inoue
- Department of Pediatrics, Osaka Medical College, 2-7 Daigaku-machi, Takatsuki-shi, Osaka 569-8686, Japan
| | - Hiroshi Tamai
- Department of Pediatrics, Osaka Medical College, 2-7 Daigaku-machi, Takatsuki-shi, Osaka 569-8686, Japan
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Hecker PA, Leopold JA, Gupte SA, Recchia FA, Stanley WC. Impact of glucose-6-phosphate dehydrogenase deficiency on the pathophysiology of cardiovascular disease. Am J Physiol Heart Circ Physiol 2012; 304:H491-500. [PMID: 23241320 DOI: 10.1152/ajpheart.00721.2012] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Glucose-6-phosphate dehydrogenase (G6PD) catalyzes the rate-determining step in the pentose phosphate pathway and produces NADPH to fuel glutathione recycling. G6PD deficiency is the most common enzyme deficiency in humans and affects over 400 million people worldwide; however, its impact on cardiovascular disease is poorly understood. The glutathione pathway is paramount to antioxidant defense, and G6PD-deficient cells do not cope well with oxidative damage. Limited clinical evidence indicates that G6PD deficiency may be associated with hypertension. However, there are also data to support a protective role of G6PD deficiency in decreasing the risk of heart disease and cardiovascular-associated deaths, perhaps through a decrease in cholesterol synthesis. Studies in G6PD-deficient (G6PDX) mice are mixed and provide evidence for both protective and deleterious effects. G6PD deficiency may provide a protective effect through decreasing cholesterol synthesis, superoxide production, and reductive stress. However, recent studies indicate that G6PDX mice are moderately more susceptible to ventricular dilation in response to myocardial infarction or pressure overload-induced heart failure. Furthermore, G6PDX hearts do not recover as well as nondeficient mice when faced with ischemia-reperfusion injury, and G6PDX mice are susceptible to the development of age-associated cardiac hypertrophy. Overall, the limited available data indicate a complex interplay in which adverse effects of G6PD deficiency may outweigh potential protective effects in the face of cardiac stress. Definitive clinical studies in large populations are needed to determine the effects of G6PD deficiency on the development of cardiovascular disease and subsequent outcomes.
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Affiliation(s)
- Peter A Hecker
- Division of Cardiology and Department of Medicine, University of Maryland, Baltimore, MD, USA
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Cheng ML, Shiao MS, Chiu DTY, Weng SF, Tang HY, Ho HY. Biochemical disorders associated with antiproliferative effect of dehydroepiandrosterone in hepatoma cells as revealed by LC-based metabolomics. Biochem Pharmacol 2011; 82:1549-61. [PMID: 21843511 DOI: 10.1016/j.bcp.2011.07.104] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2011] [Revised: 07/24/2011] [Accepted: 07/29/2011] [Indexed: 11/29/2022]
Abstract
DHEA is known to have chemopreventive and antiproliferative activities, and was initially thought to be mediated by inhibition of G6PD. Our previous study has shown that DHEA may act through interference with energy metabolism. To study the effect of pharmacological dose of DHEA on cellular metabolism, and to further delineate the mechanism underlying its antiproliferative effect, we applied a metabolomic approach to globally profile the changes in metabolites in SK-Hep1 cells underexpressing G6PD (Sk-Gi) and control cells (Sk-Sc) after DHEA treatment. RRLC-TOF-MS was used to identify metabolites, and tandem mass spectrometry was used to confirm their identity. DHEA induced changes in glutathione metabolism, lipid metabolism, s-adenosylmethionine (SAM) metabolism, as well as lysine metabolism. Elevation in level of glutathione disulfide, together with a concomitant decrease in level of reduced glutathione, was indicative of increased oxidative stress. Depletion of carnitine and its acyl derivatives reflected decline in fatty acid catabolism. These changes were associated with mitochondrial malfunction and reduction in cellular ATP content. Cardiolipin (CL) and phosphatidylcholine (PC) levels decreased significantly, suggesting that alterations in lipid composition are causally related to decline in mitochondrial function after DHEA treatment. The decline in cellular SAM content was accompanied by decreased expression of methionine adenosyltransferase genes MAT2A and MAT2B. SAM supplementation partially rescued cells from DHEA-induced growth stagnation. Our findings suggest that DHEA causes perturbation of multiple pathways in cellular metabolism. Decreased SAM production, and cardiolipin depletion and the resulting mitochondrial dysfunction underlie the antiproliferative effect of DHEA.
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Affiliation(s)
- Mei-Ling Cheng
- Department of Medical Biotechnology and Laboratory Science, Chang Gung University, 259, Wen-Hwa 1st Rd., Kwei-San, Tao-Yuan, Taiwan.
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Magyar Z, Bekesi G, Racz K, Feher J, Schaff Z, Lengyel G, Blazovics A, Illyes G, Szombath D, Hrabak A, Szekacs B, Gergics P, Marczell I, Dinya E, Rigo J, Tulassay Z. Increased total scavenger capacity and decreased liver fat content in rats fed dehydroepiandrosterone and its sulphate on a high-fat diet. Gerontology 2010; 57:343-9. [PMID: 20881377 DOI: 10.1159/000321385] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2009] [Accepted: 07/14/2010] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Weak androgens have an antioxidant effect in vitro which is represented as a beneficial change in the antioxidant status. OBJECTIVE Our aim was to clarify whether dehydroepiandrosterone (DHEA) and dehydroepiandrosterone-sulphate (DHEAS) oral administration results in beneficial antioxidant changes in Sprague-Dawley adult male rats in vivo. METHODS Groups of experimental animals were fed a high-fat or a normal-fat diet and treated with DHEA or DHEAS in the drinking fluid. The control group was fed a high-fat diet together with untreated drinking fluid. Total scavenger capacity (TSC) was measured before and after 4 weeks of treatment in blood samples using a chemiluminometric assay. Fat content, superoxide dismutase (SOD), catalase and glutathione S-transferase (GST) activity in the liver were determined by Sudan staining and spectrophotometric assessments, respectively, from the fresh frozen tissue. RESULTS DHEA and the DHEAS treatment showed significantly increased TSC in the groups fed a high-fat diet. The control group and the DHEA- or DHEAS-treated groups on normal diets showed no significant changes in TSC. The total score of liver fat content in the high-fat diet groups showed a marked positivity with Sudan staining, and the groups treated with DHEA or DHEAS had a markedly decreased amount of fat in the liver slides compared to the untreated group on the high-fat diet. Liver SOD activity was decreased in all high-fat diet groups and elevated only in the groups on a normal diet with DHEA or DHEAS treatment. Liver catalase and GST activities were decreased in the groups where TSC was significantly increased. CONCLUSION Our results support the hypothesis that DHEA and DHEAS supplementation can improve the antioxidant status in lipid-rich dietary habits.
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Affiliation(s)
- Zoltan Magyar
- 1st Department of Obstetrics and Gynecology, Faculty of Medicine, Semmelweis University, Budapest, Hungary
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O'Brien ML, Spear BT, Glauert HP. Role of Oxidative Stress in Peroxisome Proliferator-Mediated Carcinogenesis. Crit Rev Toxicol 2008; 35:61-88. [PMID: 15742903 DOI: 10.1080/10408440590905957] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
In this review, the evidence about the role of oxidative stress in the induction of hepatocellular carcinomas by peroxisome proliferators is examined. The activation of PPAR-alpha by peroxisome proliferators in rats and mice may produce oxidative stress, due to the induction of enzymes like fatty acyl coenzyme A (CoA) oxidase (AOX) and cytochrome P-450 4A1. The effect of peroxisome proliferators on the antioxidant defense system is reviewed, as is the effect on endpoints resulting from oxidative stress that may be important in carcinogenesis, such as lipid peroxidation, oxidative DNA damage, and transcription factor activation. Peroxisome proliferators clearly inhibit several enzymes in the antioxidant defense system, but studies examining effects on lipid peroxidation and oxidative DNA damage are conflicting. There is a profound species difference in the induction of hepatocellular carcinomas by peroxisome proliferators, with rats and mice being sensitive, whereas species such as nonhuman primates and guinea pigs are not susceptible to the effects of peroxisome proliferators. The possible role of oxidative stress in these species differences is also reviewed. Overall, peroxisome proliferators produce changes in oxidative stress, but whether these changes are important in the carcinogenic process is not clear at this time.
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Affiliation(s)
- Michelle L O'Brien
- Graduate Centerfor Toxicology, University of Kentucky, Lexington, Kentucky 40506-0054, USA
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Ameho CK, Chen CYO, Smith D, Sánchez-Moreno C, Milbury PE, Blumberg JB. Antioxidant activity and metabolite profile of quercetin in vitamin-E-depleted rats. J Nutr Biochem 2007; 19:467-74. [PMID: 17904346 DOI: 10.1016/j.jnutbio.2007.06.004] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2007] [Revised: 05/30/2007] [Accepted: 06/07/2007] [Indexed: 11/30/2022]
Abstract
Dietary antioxidants interact in a dynamic fashion, including recycling and sparing one another, to decrease oxidative stress. Limited information is available regarding the interrelationships in vivo between quercetin and vitamin E. We investigated the antioxidant activity and metabolism of quercetin (Q) in 65 F-344 rats (n=13 per group) randomly assigned to the following vitamin E (VE)-replete and -deficient diets: (a) VE replete (30 mg alpha-tocopherol acetate/kg diet) control ad libitum (C-AL), (b) VE replete pair fed (C-PF), (c) VE replete+5.0 g Q/kg diet (R-VE+5Q), (d) VE deplete (<1 mg/kg total tocopherols)+5.0 g Q/kg diet (D-VE+5Q) and (e) D-VE. After 12 weeks, blood and tissue were collected for measurement of plasma vitamin E, quercetin and its metabolites, serum pyruvate kinase (PK), plasma protein carbonyls, malondialdehyde (MDA) and oxygen radical absorbance capacity. D-VE diets decreased serum alpha-tocopherol and increased PK activity in a time-dependent manner. The D-VE diet increased plasma protein carbonyls but did not affect MDA. Dietary quercetin supplementation increased quercetin and its metabolites in plasma and liver but did not affect D-VE-induced changes in plasma alpha-tocopherol, PK or protein carbonyls. Plasma isorhamnetin and its disposition in muscle were enhanced by the D-VE diet, as compared to the R-VE diet. Conversely, tamarixetin disposition in muscle was decreased by the D-VE diet. Thus, quercetin did not slow vitamin E decline in vivo; neither did it provide antioxidant activity in vitamin-E-depleted rats. However, vitamin E status appears to enhance the distribution of isorhamnetin into the circulation and its disposition in muscle.
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Affiliation(s)
- Clement K Ameho
- Antioxidants Research Laboratory, Jean Mayer USDA Human Nutrition Research Center on Aging, Tufts University, Boston, MA 02111, USA
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Túnez I, Muñoz MC, Montilla P. Treatment with Dehydroepiandrosterone Prevents Oxidative Stress Induced by 3-Nitropropionic Acid in Synaptosomes. Pharmacology 2005; 74:113-8. [PMID: 15741754 DOI: 10.1159/000084169] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2004] [Accepted: 12/07/2004] [Indexed: 11/19/2022]
Abstract
This study evaluates the antioxidative effect of dehydroepiandrosterone (DHEA) treatment on 3-nitropropionic acid (3-NPA)-induced oxidative stress in striatal and brain cortex synaptosomes. The oxidative derangement was confirmed by a high level of lipid peroxidation products and protein carbonyls, as well as by an enhanced superoxide dismutase activity (p < 0.001). These changes were partially prevented by DHEA. Moreover, 3-NPA induced a drop in succinate dehydrogenase activity, while DHEA treatment restored the succinate dehydrogenase activity. These results show that DHEA reduces oxidative stress in synaptosomes isolated from the brain of 3-NPA-treated rats, and they suggest this neurosteroid may protect mitochondrial and maintain synaptic integrity against damage induced by this acid.
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Affiliation(s)
- Isaac Túnez
- Department of Biochemistry and Molecular Biology, School of Medicine, University of Cordoba, Cordoba, Spain
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Pelissier MA, Trap C, Malewiak MI, Morfin R. Antioxidant effects of dehydroepiandrosterone and 7alpha-hydroxy-dehydroepiandrosterone in the rat colon, intestine and liver. Steroids 2004; 69:137-44. [PMID: 15013692 DOI: 10.1016/j.steroids.2003.12.006] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/12/2003] [Revised: 12/16/2003] [Accepted: 12/29/2003] [Indexed: 11/18/2022]
Abstract
This study examined in healthy male Wistar rats the in vivo antioxidant effect of dehydroepiandrosterone (DHEA) and 7alpha-hydroxy-DHEA administered by intraperitoneal injections (50 mg/kg body weight) for 2 or 7 days. Markers of oxidative damage to lipids (thiobarbituric acid-reacting substances, TBARS) and to proteins (protein carbonyls) were assessed in colon, small intestine, and liver homogenates. DHEA and 7alpha-hydroxy-DHEA caused a decrease in body weight. DHEA treatment significantly increased liver, colon, and small intestine cell weights. After 7 days, DHEA exerted an antioxidant effect in all organs studied. In the colon, oxidative damage protection was accompanied by a goblet cell proliferation and increase in acidic mucus production. After 2 days, the antioxidant effect of 7alpha-hydroxy-DHEA was mainly observed in the liver. Nonprotein sulfhydryl groups (mostly glutathione levels) were altered by DHEA in the liver whereas they remained unchanged after 7alpha-hydroxy-DHEA treatment. The results indicate that in healthy animals, DHEA exerts a protective effect, particularly in the colon, by reducing the tissue susceptibility to oxidation of both lipids and proteins. This effect was not limited to a specific tissue, whereas the metabolite 7alpha-hydroxy-DHEA exerted its antioxidant effect towards the two markers of oxidative damage earlier than DHEA, and mainly in the liver.
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Affiliation(s)
- Marie-Agnès Pelissier
- Laboratoire de Biologie, EA-3199, Conservatoire National des Arts et Métiers, 2 rue Conté, 75003 Paris, France
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de Bruin VMS, Vieira MCM, Rocha MNM, Viana GSB. Cortisol and dehydroepiandosterone sulfate plasma levels and their relationship to aging, cognitive function, and dementia. Brain Cogn 2002; 50:316-23. [PMID: 12464198 DOI: 10.1016/s0278-2626(02)00519-5] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
We have studied the relationship between dehydroepiandrosterone sulfate (DHEAS), cortisol, and cognitive function in a population of demented patients (n=29), age-matched controls (n=46), and younger subjects (n=11). All were submitted to morning collection of blood for determination of plasma cortisol and DHEAS measured by 125I radioimmunoassay. DHEAS levels and cortisol/DHEAS ratios were significantly different among groups with higher DHEAS levels and lower cortisol/DHEAS ratios in younger people (Bonferroni p<.05). Cortisol levels were associated to the presence of dementia (Odds ratio=.93; 95% CI,.86-1.01). There was no difference between DHEAS levels of demented and age-matched controls; however, demented patients showed a trend for higher cortisol/DHEAS ratios than age-matched controls and the latter showed higher ratio values than younger subjects. DHEAS and cortisol plasma values were significantly correlated in all individuals (p<.01). In this study cortisol was independently associated to the presence of dementia.
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Affiliation(s)
- V M S de Bruin
- Department of Clinical Medicine, Federal University of Ceará, Fortaleza, Ceará, Brazil.
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Yang NC, Jeng KC, Ho WM, Chou SJ, Hu ML. DHEA inhibits cell growth and induces apoptosis in BV-2 cells and the effects are inversely associated with glucose concentration in the medium. J Steroid Biochem Mol Biol 2000; 75:159-66. [PMID: 11226832 DOI: 10.1016/s0960-0760(00)00180-1] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Dehydroepiandrosterone (DHEA), a major steroid secreted by the adrenal gland which decreases with age after adolescence, is available as a nutritional supplement. DHEA is known to have antiproliferative effects but the mechanism is unclear. In this study using BV-2 cells, a murine microglial cell line, we investigated the effect of DHEA on cell viability and the interaction between DHEA and glucose concentrations in the medium. We showed that DHEA inhibited cell viability and G6PD activity in a dose-dependent manner and that the effect of DHEA on cell viability was inversely associated with glucose concentrations in the medium, i.e. lowered glucose strongly enhanced the inhibition of cell viability by DHEA. DHEA inhibited cell growth by causing cell cycle arrest primarily in the G0--G1 phase, and the effect was more pronounced at zero glucose (no glucose added, G0) than high glucose (4.5 mg/ml of the medium, G4.5). Glucose deprivation also enhanced apoptosis induced by DHEA. At G4.5, DHEA did not induce formation of DNA ladder until it reached 200 microM. However, at G0, 100 microM DHEA was able to induce apoptosis, as evidenced by the formation of DNA ladder, elevation of histone-associated DNA fragmentation and increase in cells positively stained with annexin V-FITC and annexin V-FITC/propidium iodide. The interactions between DHEA and glucose support the contention that DHEA exerts its antiproliferative effects through alteration of glucose metabolism, possibly by inhibition of G6PD activity leading to decreased supply of ribose-5-phosphate for synthesis of DNA and RNA. Although DHEA is only antiproliferative at pharmacological levels, our results indicate that its antiproliferative effect can be enhanced by limiting the supply of glucose such as by energy restriction. In addition, the present study shows that glucose concentration is an important factor to consider when studying the antiproliferative and toxicological effects of DHEA.
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Affiliation(s)
- N C Yang
- Department of Food Science, National Chung-Hsing University, 250 Kuo-Kuang Road, 402 Taichung, Taiwan, ROC
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