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She M, Laudon M, Yin W. Melatonin receptors in diabetes: a potential new therapeutical target? Eur J Pharmacol 2014; 744:220-3. [PMID: 25160745 DOI: 10.1016/j.ejphar.2014.08.012] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2014] [Revised: 08/08/2014] [Accepted: 08/18/2014] [Indexed: 01/13/2023]
Abstract
Melatonin is synthesized and secreted mainly by the pineal gland in a circadian fashion, and it thus mediates endogenous circadian rhythms and influences other physiological functions. Both the G-protein coupled receptors MT1 (encoded by MTNR1A) and MT2 (encoded by MTNR1B) in mammals mediate the actions of melatonin. Evidence from in vivo and in vitro studies proved a key role of melatonin in the regulation of glucose metabolism and the pathogenesis of diabetes, as further confirmed by the recent studies of human genetic variants of MTNR1B. Remarkably, it was also suggested that genetic variations within MTNR1B disordered β-cells function directly, i.e. insulin secretion. This indicated the functional link between MT2 and T2D risk at the protein level, and it may represent the prevailing pathomechanism for how impaired melatonin signaling causes metabolic disorders and increases the T2D risk. It is speculated that melatonin and its receptors may be a new therapeutic avenue in diabetes.
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Affiliation(s)
- Meihua She
- Institute of Cardiovascular Research, Key Laboratory for Arteriosclerology of Hunan Province, University of South China, Hengyang 421001, China; Department of Biochemistry and Molecular Biology, School of Pharmaceutical and Biological Science, University of South China, Hengyang, China
| | - Moshe Laudon
- Drug Discovery, Neurim Pharmaceuticals Ltd., Tel Aviv, Israel
| | - Weidong Yin
- Institute of Cardiovascular Research, Key Laboratory for Arteriosclerology of Hunan Province, University of South China, Hengyang 421001, China; Department of Biochemistry and Molecular Biology, School of Pharmaceutical and Biological Science, University of South China, Hengyang, China.
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Resveratrol- and melatonin-abated ovariectomy and fructose diet–induced obesity and metabolic alterations in female rats. Menopause 2014; 21:876-85. [DOI: 10.1097/gme.0000000000000187] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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53
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Amaral FG, Turati AO, Barone M, Scialfa JH, do Carmo Buonfiglio D, Peres R, Peliciari-Garcia RA, Afeche SC, Lima L, Scavone C, Bordin S, Reiter RJ, Menna-Barreto L, Cipolla-Neto J. Melatonin synthesis impairment as a new deleterious outcome of diabetes-derived hyperglycemia. J Pineal Res 2014; 57:67-79. [PMID: 24819547 DOI: 10.1111/jpi.12144] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/02/2014] [Accepted: 05/09/2014] [Indexed: 01/13/2023]
Abstract
Melatonin is a neurohormone that works as a nighttime signal for circadian integrity and health maintenance. It is crucial for energy metabolism regulation, and the diabetes effects on its synthesis are unresolved. Using diverse techniques that included pineal microdialysis and ultrahigh-performance liquid chromatography, the present data show a clear acute and sustained melatonin synthesis reduction in diabetic rats as a result of pineal metabolism impairment that is unrelated to cell death. Hyperglycemia is the main cause of several diabetic complications, and its consequences in terms of melatonin production were assessed. Here, we show that local high glucose (HG) concentration is acutely detrimental to pineal melatonin synthesis in rats both in vivo and in vitro. The clinically depressive action of high blood glucose concentration in melatonin levels was also observed in type 1 diabetes patients who presented a negative correlation between hyperglycemia and 6-sulfatoxymelatonin excretion. Additionally, high-mean-glycemia type 1 diabetes patients presented lower 6-sulfatoxymelatonin levels when compared to control subjects. Although further studies are needed to fully clarify the mechanisms, the present results provide evidence that high circulating glucose levels interfere with pineal melatonin production. Given the essential role played by melatonin as a powerful antioxidant and in the control of energy homeostasis, sleep and biological rhythms and knowing that optimal glycemic control is usually an issue for patients with diabetes, melatonin supplementation may be considered as an additional tool to the current treatment.
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Affiliation(s)
- Fernanda G Amaral
- Laboratory of Neurobiology, Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, Brazil
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Mori A, Kappen KL, Dilger AC, Swanson KS. Effect of photoperiod on the feline adipose transcriptome as assessed by RNA sequencing. BMC Vet Res 2014; 10:146. [PMID: 24992939 PMCID: PMC4092351 DOI: 10.1186/1746-6148-10-146] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2014] [Accepted: 06/26/2014] [Indexed: 12/24/2022] Open
Abstract
Background Photoperiod is known to cause physiological changes in seasonal mammals, including changes in body weight, physical activity, reproductive status, and adipose tissue gene expression in several species. The objective of this study was to determine the effects of day length on the adipose transcriptome of cats as assessed by RNA sequencing. Ten healthy adult neutered male domestic shorthair cats were used in a randomized crossover design study. During two 12-wk periods, cats were exposed to either short days (8 hr light:16 hr dark) or long days (16 hr light:8 hr dark). Cats were fed a commercial diet to maintain baseline body weight to avoid weight-related bias. Subcutaneous adipose biopsies were collected at wk 12 of each period for RNA isolation and sequencing. Results A total of 578 million sequences (28.9 million/sample) were generated by Illumina sequencing. A total of 170 mRNA transcripts were differentially expressed between short day- and long day-housed cats. 89 annotated transcripts were up-regulated by short days, while 24 annotated transcripts were down-regulated by short days. Another 57 un-annotated transcripts were also different between groups. Adipose tissue of short day-housed cats had greater expression of genes involved with cell growth and differentiation (e.g., myostatin; frizzled-related protein), cell development and structure (e.g., cytokeratins), and protein processing and ubiquitination (e.g., kelch-like proteins). In contrast, short day-housed cats had decreased expression of genes involved with immune function (e.g., plasminogen activator inhibitor 1; chemokine (C-C motif) ligand 2; C-C motif chemokine 5; T-cell activators), and altered expression of genes associated with carbohydrate and lipid metabolism. Conclusions Collectively, these gene expression changes suggest that short day housing may promote adipogenesis, minimize inflammation and oxidative stress, and alter nutrient metabolism in feline adipose tissue, even when fed to maintain body weight. Although this study has highlighted molecular mechanisms contributing to the seasonal metabolic changes observed in cats, future research that specifically targets and studies these biological pathways, and the physiological outcomes that are affected by them, is justified.
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Affiliation(s)
| | | | | | - Kelly S Swanson
- Department of Animal Sciences, University of Illinois, 1207 West Gregory Drive, 162 Animal Sciences Laboratory, Urbana, IL 61801, USA.
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Abstract
PURPOSE OF REVIEW Accumulating evidence supports a role for the circadian clock in the development of metabolic disease. We discuss the influence of the circadian clock on glucose homeostasis, intermediary factors in this relationship, and potential therapies for the prevention or attenuation of metabolic disease associated with circadian misalignment. RECENT FINDINGS Murine studies with tissue-specific deletion of core clock genes in key metabolic tissues confirm a mechanistic relationship between the circadian clock and the development of metabolic disease. Circadian misalignment increases insulin resistance and decreases pancreatic function. Clock gene polymorphisms or altered expression of clock genes induced by circadian misalignment appear to play a role in the development of obesity and diabetes in humans. Circadian disruption caused by exposure to light at night is associated with lower nocturnal melatonin, which in turn seems to affect glucose metabolism. Potential therapies for circadian misalignment include entraining the central pacemaker with timed light exposure and/or melatonin and restricting food intake to the biological day. SUMMARY Completing the understanding of how genetic and environmental factors influence the circadian clock and the effect these have on human circadian metabolic physiology and disease will allow us to develop therapies for treating and preventing associated metabolic disease.
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Affiliation(s)
- Eberta Tan
- aDepartment of Diabetes and Endocrinology, Manny Cussins Centre, St James University Hospital, Beckett Wing bDivision of Cardiovascular and Diabetes Research, The Leeds Institute of Genetics Health and Therapeutics, Clarendon Way, University of Leeds, Leeds, UK
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Kimple ME, Neuman JC, Linnemann AK, Casey PJ. Inhibitory G proteins and their receptors: emerging therapeutic targets for obesity and diabetes. Exp Mol Med 2014; 46:e102. [PMID: 24946790 PMCID: PMC4081554 DOI: 10.1038/emm.2014.40] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2013] [Revised: 02/10/2014] [Accepted: 02/17/2014] [Indexed: 12/21/2022] Open
Abstract
The worldwide prevalence of obesity is steadily increasing, nearly doubling between 1980 and 2008. Obesity is often associated with insulin resistance, a major risk factor for type 2 diabetes mellitus (T2DM): a costly chronic disease and serious public health problem. The underlying cause of T2DM is a failure of the beta cells of the pancreas to continue to produce enough insulin to counteract insulin resistance. Most current T2DM therapeutics do not prevent continued loss of insulin secretion capacity, and those that do have the potential to preserve beta cell mass and function are not effective in all patients. Therefore, developing new methods for preventing and treating obesity and T2DM is very timely and of great significance. There is now considerable literature demonstrating a link between inhibitory guanine nucleotide-binding protein (G protein) and G protein-coupled receptor (GPCR) signaling in insulin-responsive tissues and the pathogenesis of obesity and T2DM. These studies are suggesting new and emerging therapeutic targets for these conditions. In this review, we will discuss inhibitory G proteins and GPCRs that have primary actions in the beta cell and other peripheral sites as therapeutic targets for obesity and T2DM, improving satiety, insulin resistance and/or beta cell biology.
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Affiliation(s)
- Michelle E Kimple
- Department of Medicine-Division of Endocrinology, Diabetes, and Metabolism, University of Wisconsin-Madison, Madison, WI, USA
| | - Joshua C Neuman
- Department of Nutritional Sciences, University of Wisconsin-Madison, Madison, WI, USA
| | - Amelia K Linnemann
- Department of Medicine-Division of Endocrinology, Diabetes, and Metabolism, University of Wisconsin-Madison, Madison, WI, USA
| | - Patrick J Casey
- Duke University Medical Center Department of Pharmacology and Cancer Biology, Durham, NC, USA
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Modabbernia A, Heidari P, Soleimani R, Sobhani A, Roshan ZA, Taslimi S, Ashrafi M, Modabbernia MJ. Melatonin for prevention of metabolic side-effects of olanzapine in patients with first-episode schizophrenia: randomized double-blind placebo-controlled study. J Psychiatr Res 2014; 53:133-40. [PMID: 24607293 DOI: 10.1016/j.jpsychires.2014.02.013] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/09/2013] [Revised: 12/14/2013] [Accepted: 02/14/2014] [Indexed: 12/12/2022]
Abstract
UNLABELLED We aimed to determine the efficacy of melatonin 3 mg/day in prevention of olanzapine-induced metabolic side-effects. In a randomized double-blind placebo-controlled study, 48 patients with first-episode schizophrenia who were eligible for olanzapine treatment, were randomly assigned to olanzapine plus either melatonin 3 mg/day or matched placebo for eight weeks. Anthropometric and metabolic parameters as well as psychiatric symptoms using The Positive and Negative Syndrome Scale (PANSS) were assessed at baseline, week 4, and 8. Primary outcome measure was the change from baseline in weight at week 8. Data were analyzed using t-test, Mann-Whitney U test, and mixed-effects model. Thirty-six patients had at least one post-baseline measurement. At week eight, melatonin was associated with significantly less weight gain [mean difference (MD) = 3.2 kg, P = 0.023], increase in waist circumference [MD = 2.83 cm, P = 0.041] and triglyceride concentration [MD = 62 mg/dl, P = 0.090 (nearly significant)] than the placebo. Changes in cholesterol, insulin, and blood sugar concentrations did not differ significantly between the two groups. Patients in the melatonin group experienced significantly more reduction in their PANSS scores [MD = 12.9 points, P = 0.014] than the placebo group. No serious adverse events were reported. To summarize, in patients treated with olanzapine, short-term melatonin treatment attenuates weight gain, abdominal obesity, and hypertriglyceridemia. It might also provide additional benefit for treatment of psychosis. The study was registered in the ClinicalTrials.gov ( REGISTRATION NUMBER NCT01593774).
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Affiliation(s)
- Amirhossein Modabbernia
- Psychiatry and Psychology Research Center, Department of Psychiatry, Roozbeh Hospital, Tehran University of Medical Sciences, Tehran, Iran.
| | - Parvaneh Heidari
- Department of Psychiatry, Shafa Hospital, Guilan University of Medical Sciences, Rasht, Iran
| | - Robabeh Soleimani
- Department of Psychiatry, Shafa Hospital, Guilan University of Medical Sciences, Rasht, Iran
| | - Abdolrasoul Sobhani
- Department of Pharmacology, Guilan University of Medical Sciences, Rasht, Iran
| | - Zahra Atrkar Roshan
- Department of Biostatistics, Guilan University of Medical Sciences, Rasht, Iran
| | - Shervin Taslimi
- Psychiatry and Psychology Research Center, Department of Psychiatry, Roozbeh Hospital, Tehran University of Medical Sciences, Tehran, Iran; Department of Biostatistics, Tehran University of Medical Sciences, Tehran, Iran
| | - Mandana Ashrafi
- Psychiatry and Psychology Research Center, Department of Psychiatry, Roozbeh Hospital, Tehran University of Medical Sciences, Tehran, Iran
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She M, Hou H, Wang Z, Zhang C, Laudon M, Yin W. Melatonin rescues 3T3-L1 adipocytes from FFA-induced insulin resistance by inhibiting phosphorylation of IRS-1 on Ser307. Biochimie 2014; 103:126-30. [PMID: 24846082 DOI: 10.1016/j.biochi.2014.05.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2013] [Accepted: 05/04/2014] [Indexed: 11/18/2022]
Abstract
Melatonin is biosynthesized in the pineal gland and secreted into the bloodstream. Evidences indicate a role of melatonin in the regulation of glucose metabolism. The objective of this study was to investigate the effect of melatonin on insulin sensitivity in insulin resistant adipocytes. Following a preincubation with melatonin or vehicle for 30 min, insulin resistant cells of 3T3-L1 adipocytes were induced by palmitic acids (300 μM, 6 h). Our results showed that palmitic acids inhibited both the basal and insulin-stimulated uptake of [(3)H]-2-Deoxyglucose, down-regulated the levels of IRS-1 and GLUT-4. However, compared to the vehicle group, melatonin pre-treatment increased significantly the uptake of [(3)H]-2-Deoxyglucose as well as the level of GLUT-4, and decreased phosphorylated IRS-1 (Ser307) although total IRS-1 did not change significantly. These data suggest that palmitic acids impair insulin signal via down-regulating the expressions of IRS-1 and GLUT-4; whereas melatonin can ameliorate insulin sensitivity by inhibiting Ser307 phosphorylation in IRS-1 and increasing GLUT-4 expressions in insulin resistant 3T3-L1 adipocytes. We conclude that melatonin regulates the insulin sensitivity and glucose homeostasis via inhibiting Ser-phosphorylation and improving function of IRS-1.
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Affiliation(s)
- Meihua She
- Institute of Cardiovascular Disease, Key Laboratory for Arteriosclerology of Hunan Province, University of South China, Hengyang, China; Department of Biochemistry and Molecular Biology, University of South China, Hengyang, China
| | - Hongjie Hou
- Department of Biochemistry and Molecular Biology, University of South China, Hengyang, China
| | - Zongbao Wang
- Department of Laboratory Animal Science, University of South China, Hengyang, China
| | - Chi Zhang
- Institute of Cardiovascular Disease, Key Laboratory for Arteriosclerology of Hunan Province, University of South China, Hengyang, China
| | - Moshe Laudon
- Drug Discovery, Neurim Pharmaceuticals Ltd., Tel-Aviv, Israel
| | - Weidong Yin
- Institute of Cardiovascular Disease, Key Laboratory for Arteriosclerology of Hunan Province, University of South China, Hengyang, China; Department of Biochemistry and Molecular Biology, University of South China, Hengyang, China.
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Cipolla-Neto J, Amaral FG, Afeche SC, Tan DX, Reiter RJ. Melatonin, energy metabolism, and obesity: a review. J Pineal Res 2014; 56:371-81. [PMID: 24654916 DOI: 10.1111/jpi.12137] [Citation(s) in RCA: 362] [Impact Index Per Article: 36.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2014] [Accepted: 03/17/2014] [Indexed: 12/15/2022]
Abstract
Melatonin is an old and ubiquitous molecule in nature showing multiple mechanisms of action and functions in practically every living organism. In mammals, pineal melatonin functions as a hormone and a chronobiotic, playing a major role in the regulation of the circadian temporal internal order. The anti-obesogen and the weight-reducing effects of melatonin depend on several mechanisms and actions. Experimental evidence demonstrates that melatonin is necessary for the proper synthesis, secretion, and action of insulin. Melatonin acts by regulating GLUT4 expression and/or triggering, via its G-protein-coupled membrane receptors, the phosphorylation of the insulin receptor and its intracellular substrates mobilizing the insulin-signaling pathway. Melatonin is a powerful chronobiotic being responsible, in part, by the daily distribution of metabolic processes so that the activity/feeding phase of the day is associated with high insulin sensitivity, and the rest/fasting is synchronized to the insulin-resistant metabolic phase of the day. Furthermore, melatonin is responsible for the establishment of an adequate energy balance mainly by regulating energy flow to and from the stores and directly regulating the energy expenditure through the activation of brown adipose tissue and participating in the browning process of white adipose tissue. The reduction in melatonin production, as during aging, shift-work or illuminated environments during the night, induces insulin resistance, glucose intolerance, sleep disturbance, and metabolic circadian disorganization characterizing a state of chronodisruption leading to obesity. The available evidence supports the suggestion that melatonin replacement therapy might contribute to restore a more healthy state of the organism.
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Affiliation(s)
- J Cipolla-Neto
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
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Reid KJ, Santostasi G, Baron KG, Wilson J, Kang J, Zee PC. Timing and intensity of light correlate with body weight in adults. PLoS One 2014; 9:e92251. [PMID: 24694994 PMCID: PMC3973603 DOI: 10.1371/journal.pone.0092251] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2013] [Accepted: 02/19/2014] [Indexed: 11/18/2022] Open
Abstract
Light exposure can influence sleep and circadian timing, both of which have been shown to influence weight regulation. The goal of this study was to evaluate the relationship between ambient light, sleep and body mass index. Participants included 54 individuals (26 males, mean age 30.6, SD = 11.7 years). Light levels, sleep midpoint and duration were measured with wrist actigraphy (Actiwatch-L) for 7 days. BMI was derived from self-reported height and weight. Caloric intake was determined from 7 days of food logs. For each participant, light and activity data were output in 2 minute epochs, smoothed using a 5 point (10 minute) moving average and then aggregated over 24 hours. The mean light timing above 500 lux (MLiT500) was defined as the average clock time of all aggregated data points above 500 lux. MLiT500 was positively correlated with BMI (r = 0.51, p<0.001), and midpoint of sleep (r = 0.47, p<0.01). In a multivariable linear regression model including MLiT500 and midpoint of sleep, MLiT500 was a significant predictor of BMI (B = 1.26 SE = 0.34, β = 0.53 p = 0.001, r2Δ = 0.22). Adjusting for covariates, MLiT500 remained an independent predictor of BMI (B = 1.28 SE = 0.36, β = 0.54, p = 0.002, r2Δ = 0.20). The full model accounted for 34.7% of the variance in BMI (p = 0.01). Exposure to moderate levels of light at biologically appropriate times can influence weight, independent of sleep timing and duration.
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Affiliation(s)
- Kathryn J. Reid
- Department of Neurology, Northwestern University, Feinberg School of Medicine, Chicago, Illinois, United States of America
| | - Giovanni Santostasi
- Department of Neurology, Northwestern University, Feinberg School of Medicine, Chicago, Illinois, United States of America
| | - Kelly G. Baron
- Department of Neurology, Northwestern University, Feinberg School of Medicine, Chicago, Illinois, United States of America
| | - John Wilson
- Department of Neurology, Northwestern University, Feinberg School of Medicine, Chicago, Illinois, United States of America
| | - Joseph Kang
- Department of Preventive Medicine, Northwestern University, Feinberg School of Medicine, Chicago, Illinois, United States of America
| | - Phyllis C. Zee
- Department of Neurology, Northwestern University, Feinberg School of Medicine, Chicago, Illinois, United States of America
- * E-mail:
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Mendes C, Lopes AMDS, do Amaral FG, Peliciari-Garcia RA, Turati ADO, Hirabara SM, Scialfa Falcão JH, Cipolla-Neto J. Adaptations of the aging animal to exercise: role of daily supplementation with melatonin. J Pineal Res 2013; 55:229-39. [PMID: 23711171 DOI: 10.1111/jpi.12065] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/08/2013] [Accepted: 05/03/2013] [Indexed: 01/13/2023]
Abstract
The pineal gland, through melatonin, seems to be of fundamental importance in determining the metabolic adaptations of adipose and muscle tissues to physical training. Evidence shows that pinealectomized animals fail to develop adaptive metabolic changes in response to aerobic exercise and therefore do not exhibit the same performance as control-trained animals. The known prominent reduction in melatonin synthesis in aging animals led us to investigate the metabolic adaptations to physical training in aged animals with and without daily melatonin replacement. Male Wistar rats were assigned to four groups: sedentary control (SC), trained control (TC), sedentary treated with melatonin (SM), and trained treated with melatonin (TM). Melatonin supplementation lasted 16 wk, and the animals were subjected to exercise during the last 8 wk of the experiment. After euthanasia, samples of liver, muscle, and adipose tissues were collected for analysis. Trained animals treated with melatonin presented better results in the following parameters: glucose tolerance, physical capacity, citrate synthase activity, hepatic and muscular glycogen content, body weight, protein expression of phosphatidylinositol 3-kinase (PI3K), mitogen-activated protein kinase (MAPK), and protein kinase activated by adenosine monophosphate (AMPK) in the liver, as well as the protein expression of the glucose transporter type 4 (GLUT4) and AMPK in the muscle. In conclusion, these results demonstrate that melatonin supplementation in aging animals is of great importance for the required metabolic adaptations induced by aerobic exercise. Adequate levels of circulating melatonin are, therefore, necessary to improve energetic metabolism efficiency, reducing body weight and increasing insulin sensitivity.
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Affiliation(s)
- Caroline Mendes
- Department of Physiology and Biophysics, Institute of Biomedical Sciences-I, University of São Paulo (USP), São Paulo, SP, Brazil
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Long-term melatonin administration improves glucose homeostasis and insulin resistance state in high-fat-diet fed rats. Open Life Sci 2013. [DOI: 10.2478/s11535-013-0211-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
AbstractEmerging evidence support an important role of reactive oxygen species in various forms of insulin resistance. It is identified that melatonin has antioxidant properties and prevents toxic effects of reactive oxygen species. In this study, we sought to assess the involvement of melatonin in the progression of insulin resistance in response to a high-fat diet (HFD) and to investigate the underlying mechanisms. Male rats were fed with a control diet, a high-fat diet, or a high-fat diet supplemented with melatonin (5 mg kg−1, i.p.) for 10 weeks. Glucose homeostasis, insulin sensitivity, antioxidative potency, and metabolic profiles in the rats were evaluated. Our results showed that a HFD led to increasing body mass, adipose tissue weight, plasma insulin, total cholesterol (TC), triglycerides (TG), free fatty acids (FFA), and decreased HDL-cholesterol (HDL-C) in rats. There was also a significant increase in the level of malondialdehyde (MDA) and decrease in superoxide dismutase (SOD) activity, oxidative stress markers both in the plasma and liver. An enhanced hepatic phosphoenolpyruvate carboxy-kinase (PEPCK) activity and RNA expression were observed. Impaired insulin signaling was evidenced by reducing insulin receptor substrate 2 (IRS2) tyrosine phosphorylation and protein kinase B (PKB) serine phosphorylation in response to insulin. Overactivation of stress-activated protein kinases JNK was also observed in the liver of HFD rats. However, simultaneous administration of melatonin to HFD rats significantly reduced oxidative stress in the system and liver, markedly improved impaired glucose homeostasis, insulin sensitivity, antioxidative potency, metabolic profiles and all the aforesaid adverse changes in HFD rats. Our results demonstrated that anti-oxidative property of melatonin is sufficient to ameliorate the insulin resistance condition, leading to the improvement of glucose homeostasis and the restoration of hepatic insulin signaling in a rat model of HFD-induced insulin resistance.
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