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Salagre D, Chayah M, Molina-Carballo A, Oliveras-López MJ, Munoz-Hoyos A, Navarro-Alarcón M, Fernández-Vázquez G, Agil A. Melatonin induces fat browning by transdifferentiation of white adipocytes and de novo differentiation of mesenchymal stem cells. Food Funct 2022; 13:3760-3775. [PMID: 35274657 DOI: 10.1039/d1fo04360a] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The role of melatonin in obesity control is extensively accepted, but its mechanism of action is still unclear. Previously we demonstrated that chronic oral melatonin acts as a brown-fat inducer, driving subcutaneous white adipose tissue (sWAT) into a brown-fat-like function (beige) in obese diabetic rats. However, immunofluorescence characterization of beige depots in sWAT and whether melatonin is a beige-fat inducer by de novo differentiation and/or transdifferentiation of white adipocytes are still undefined. Lean (ZL) and diabetic fatty (ZDF) Zücker rats were subdivided into two groups, control (C) and oral melatonin-supplemented (M, 10 mg kg-1 day-1) for 6 weeks. Mesenchymal stem cells (MSCs) were isolated from both rat inguinal fat and human lipoaspirates followed by adipogenesis assays with or without melatonin (50 nM for 12 h in a 24 h period, 12 h+/12 h-) mimicking the light/dark cycle. Immunofluorescence and western-blot assays showed the partial transdifferentiation of white adipocytes in both ZL and ZDF rats, with increasing thermogenic and beige markers, UCP1 and CITED1 and decreasing white adipocyte marker ASC-1 expression. In addition, melatonin increased UCP1, CITED1, and PGC1-α expression in differentiated adipocytes in both rats and humans. These results demonstrate that melatonin increases brown fat in obese diabetic rats by both adipocyte transdifferentiation and de novo differentiation. Furthermore, it promotes beige MSC adipogenesis in humans. This may contribute to the control of body weight attributed to melatonin and its metabolic benefits in human diabesity.
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Affiliation(s)
- Diego Salagre
- Department of Pharmacology and Neurosciences Institute, School of Medicine & Biomedical Research Center, University of Granada, 18016 Granada, Spain.
| | - Meriem Chayah
- Department of Pharmacology and Neurosciences Institute, School of Medicine & Biomedical Research Center, University of Granada, 18016 Granada, Spain.
| | - Antonio Molina-Carballo
- Department of Pediatrics, School of Medicine, University of Granada (Spain). Unit of Pediatric Neurology and Neurodevelopment, Clínico San Cecilio University Hospital, the Andalusian Health Service, Granada, Spain.
| | - María-Jesús Oliveras-López
- Department of Molecular Biology and Biochemical Engineering, University Pablo de Olavide, 41013, Seville, Spain
| | - Antonio Munoz-Hoyos
- Department of Pediatrics, School of Medicine, University of Granada (Spain). Unit of Pediatric Neurology and Neurodevelopment, Clínico San Cecilio University Hospital, the Andalusian Health Service, Granada, Spain.
| | - Miguel Navarro-Alarcón
- Department of Nutrition and Bromatology, School of Pharmacy, University of Granada, 18071 Granada, Spain
| | | | - Ahmad Agil
- Department of Pharmacology and Neurosciences Institute, School of Medicine & Biomedical Research Center, University of Granada, 18016 Granada, Spain.
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Agil A, Chayah M, Visiedo L, Navarro-Alarcon M, Rodríguez Ferrer JM, Tassi M, Reiter RJ, Fernández-Vázquez G. Melatonin Improves Mitochondrial Dynamics and Function in the Kidney of Zücker Diabetic Fatty Rats. J Clin Med 2020; 9:jcm9092916. [PMID: 32927647 PMCID: PMC7564180 DOI: 10.3390/jcm9092916] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Revised: 09/04/2020] [Accepted: 09/08/2020] [Indexed: 12/13/2022] Open
Abstract
Obesity and associated diabetes (diabesity) impair kidney mitochondrial dynamics by augmenting fission and diminishing fusion, which results in mitochondrial and renal dysfunction. Based on available evidence, the antioxidant activities of melatonin may improve impaired renal mitochondrial function in obese diabetic animals by restoring the imbalanced dynamics through inhibiting fission and promoting fusion. Male Zücker diabetic fatty (ZDF) rats and lean littermates (ZL) were orally treated either with melatonin (10 mg/kg BW/day) (M-ZDF and M-ZL) or vehicle (C-ZDF and C-ZL) for 17 weeks. Kidney function was evaluated by measurement of total urine volume, proteinuria, creatinine clearance, and assessment of kidney mitochondrial dynamics and function. C-ZDF exhibited impaired dynamics and function of kidney mitochondria in comparison to C-ZL. Melatonin improved nephropathy of ZDF rats and modulated their mitochondrial dynamics by reducing expression of Drp1 fission marker and increasing that of fusion markers, Mfn2 and Opa1. Furthermore, melatonin ameliorated mitochondrial dysfunction by increasing respiratory control index and electron transfer chain complex IV activity. In addition, it lowered mitochondrial oxidative status. Our findings show that melatonin supplementation improves nephropathy likely via modulation of the mitochondrial fission/fusion balance and function in ZDF rats.
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Affiliation(s)
- Ahmad Agil
- Department of Pharmacology and Neurosciences Institute, School of Medicine, University of Granada, 18016 Granada, Spain; (M.C.); (L.V.)
- Biosanitary Research Institute of Granada (ibs.GRANADA), University Hospital of Granada, 18016 Granada, Spain
- Correspondence: ; Tel.: +34-625-143-359
| | - Meriem Chayah
- Department of Pharmacology and Neurosciences Institute, School of Medicine, University of Granada, 18016 Granada, Spain; (M.C.); (L.V.)
- Biosanitary Research Institute of Granada (ibs.GRANADA), University Hospital of Granada, 18016 Granada, Spain
| | - Lucia Visiedo
- Department of Pharmacology and Neurosciences Institute, School of Medicine, University of Granada, 18016 Granada, Spain; (M.C.); (L.V.)
- Biosanitary Research Institute of Granada (ibs.GRANADA), University Hospital of Granada, 18016 Granada, Spain
| | - Miguel Navarro-Alarcon
- Department of Nutrition and Bromatology, School of Pharmacy, University of Granada, 18071 Granada, Spain;
| | | | - Mohamed Tassi
- Service of Microscopy, CIBM, University of Granada, 18016 Granada, Spain;
| | - Russel J. Reiter
- Department of Cellular and Structural Biology, University of Texas Health Science at San Antonio, San Antonio, TX 78229, USA;
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Agil A, El-Hammadi M, Jiménez-Aranda A, Tassi M, Abdo W, Fernández-Vázquez G, Reiter RJ. Melatonin reduces hepatic mitochondrial dysfunction in diabetic obese rats. J Pineal Res 2015; 59:70-9. [PMID: 25904243 DOI: 10.1111/jpi.12241] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/10/2015] [Accepted: 04/20/2015] [Indexed: 12/20/2022]
Abstract
Hepatic mitochondrial dysfunction is thought to play a role in the development of liver steatosis and insulin resistance, which are both common characteristics of obesity and type 2 diabetes mellitus (T2DM). It was hypothesized that the antioxidant properties of melatonin could potentially improve the impaired functions of hepatic mitochondria in diabetic obese animals. Male Zucker diabetic fatty (ZDF) rats and lean littermates (ZL) were given either melatonin (10 mg/kg BW/day) orally for 6 wk (M-ZDF and M-ZL) or vehicle as control groups (C-ZDF and C-ZL). Hepatic function was evaluated by measurement of serum alanine transaminase and aspartate transaminase levels, liver histopathology and electron microscopy, and hepatic mitochondrial functions. Several impaired functions of hepatic mitochondria were observed in C-ZDF in comparison with C-ZL rats. Melatonin treatment to ZDF rats decreases serum levels of ALT (P < 0.001), alleviates liver steatosis and vacuolation, and also mitigates diabetic-induced mitochondrial abnormalities, glycogen, and lipid accumulation. Melatonin improves mitochondrial dysfunction in M-ZDF rats by increasing activities of mitochondrial citrate synthase (P < 0.001) and complex IV of electron transfer chain (P < 0.05) and enhances state 3 respiration (P < 0.001), respiratory control index (RCR) (P < 0.01), and phosphorylation coefficient (ADP/O ratio) (P < 0.05). Also melatonin augments ATP production (P < 0.05) and diminishes uncoupling protein 2 levels (P < 0.001). These results demonstrate that chronic oral melatonin reduces liver steatosis and mitochondria dysfunction in ZDF rats. Therefore, it may be beneficial in the treatment of diabesity.
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Affiliation(s)
- Ahmad Agil
- Department of Pharmacology and Neurosciences Institute, School of Medicine, University of Granada, Granada, Spain
| | - Mazen El-Hammadi
- Department of Pharmacology and Neurosciences Institute, School of Medicine, University of Granada, Granada, Spain
- Department of Pharmaceutics, Faculty of Pharmacy, Damascus University, Damascus, Syria
| | - Aroa Jiménez-Aranda
- Department of Pharmacology and Neurosciences Institute, School of Medicine, University of Granada, Granada, Spain
| | - Mohamed Tassi
- Service of Microscopy, CIBM, University of Granada, Granada, Spain
| | - Walied Abdo
- Department of Pharmacology and Neurosciences Institute, School of Medicine, University of Granada, Granada, Spain
- Department of pathology, Faculty of Veterinary medicine, Kafrelsheikh University, Kafrelsheikh, Egypt
| | | | - Russel J Reiter
- Department of cellular and Structural Biology, University of Texas Health Science at San Antonio, San Antonio, TX, USA
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Roman S, Agil A, Peran M, Alvaro-Galue E, Ruiz-Ojeda FJ, Fernández-Vázquez G, Marchal JA. Brown adipose tissue and novel therapeutic approaches to treat metabolic disorders. Transl Res 2015; 165:464-79. [PMID: 25433289 DOI: 10.1016/j.trsl.2014.11.002] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/11/2014] [Revised: 10/16/2014] [Accepted: 11/04/2014] [Indexed: 01/08/2023]
Abstract
In humans, 2 functionally different types of adipose tissue coexist: white adipose tissue (WAT) and brown adipose tissue (BAT). WAT is involved in energy storage, whereas BAT is involved in energy expenditure. Increased amounts of WAT may contribute to the development of metabolic disorders, such as obesity-associated type 2 diabetes mellitus and cardiovascular diseases. In contrast, the thermogenic function of BAT allows high consumption of fatty acids because of the activity of uncoupling protein 1 in the internal mitochondrial membrane. Interestingly, obesity reduction and insulin sensitization have been achieved by BAT activation-regeneration in animal models. This review describes the origin, function, and differentiation mechanisms of BAT to identify new therapeutic strategies for the treatment of metabolic disorders related to obesity. On the basis of the animal studies, novel approaches for BAT regeneration combining stem cells from the adipose tissue with active components, such as melatonin, may have potential for the treatment of metabolic disorders in humans.
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Affiliation(s)
- Sabiniano Roman
- Biopathology and Regenerative Medicine Institute (IBIMER), Centre for Biomedical Research, University of Granada, Granada, Spain; Tissue Engineering Group, Kroto Research Institute, University of Sheffield, Sheffield, UK
| | - Ahmad Agil
- Department of Pharmacology and Neurosciences Institute, Faculty of Medicine, Biosanitary Institute of Granada (ibs.GRANADA), Hospitals Unversity/University of Granada, Granada, Spain
| | - Macarena Peran
- Biopathology and Regenerative Medicine Institute (IBIMER), Centre for Biomedical Research, University of Granada, Granada, Spain; Department of Health Sciences, University of Jaén, Jaén, Spain
| | - Eduardo Alvaro-Galue
- Biopathology and Regenerative Medicine Institute (IBIMER), Centre for Biomedical Research, University of Granada, Granada, Spain; Wake Forest Institute for Regenerative Medicine Wake Forest School of Medicine, Winston Salem, NC
| | - Francisco J Ruiz-Ojeda
- Institute of Nutrition and Food Technology, Centre for Biomedical Research, University of Granada, Granada, Spain
| | | | - Juan A Marchal
- Biopathology and Regenerative Medicine Institute (IBIMER), Centre for Biomedical Research, University of Granada, Granada, Spain; Department of Human Anatomy and Embryology, Biosanitary Institute of Granada (ibs.GRANADA), Hospitals Unversity/University of Granada, Granada, Spain.
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Navarro-Alarcón M, Ruiz-Ojeda FJ, Blanca-Herrera RM, A-Serrano MM, Acuña-Castroviejo D, Fernández-Vázquez G, Agil A. Melatonin and metabolic regulation: a review. Food Funct 2014; 5:2806-32. [DOI: 10.1039/c4fo00317a] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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Jimenéz-Aranda A, Fernández-Vázquez G, Mohammad A-Serrano M, Reiter RJ, Agil A. Melatonin improves mitochondrial function in inguinal white adipose tissue of Zücker diabetic fatty rats. J Pineal Res 2014; 57:103-9. [PMID: 24867433 DOI: 10.1111/jpi.12147] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/08/2014] [Accepted: 05/23/2014] [Indexed: 12/19/2022]
Abstract
Mitochondrial dysfunction in adipose tissue may contribute to obesity-related metabolic derangements such as type 2 diabetes mellitus (T2DM). Because mitochondria are a target for melatonin action, the goal of this study was to investigate the effects of melatonin on mitochondrial function in white (WAT) and beige inguinal adipose tissue of Zücker diabetic fatty (ZDF) rats, a model of obesity-related T2DM. In this experimental model, melatonin reduces obesity and improves the metabolic profile. At 6 wk of age, ZDF rats and lean littermates (ZL) were subdivided into two groups, each composed of four rats: control (C-ZDF and C-ZL) and treated with oral melatonin in the drinking water (10 mg/kg/day) for 6 wk (M-ZDF and M-ZL). After the treatment period, animals were sacrificed, tissues dissected, and mitochondrial function assessed in isolated organelles. Melatonin increased the respiratory control ratio (RCR) in mitochondria from white fat of both lean (by 26.5%, P < 0.01) and obese (by 34.5%, P < 0.01) rats mainly through a reduction of proton leaking component of respiration (state 4) (28% decrease in ZL, P < 0.01 and 35% in ZDF, P < 0.01). However, melatonin treatment lowered the RCR in beige mitochondria of both lean (by 7%, P < 0.05) and obese (by 13%, P < 0.05) rats by maintaining high rates of uncoupled respiration. Melatonin also lowered mitochondrial oxidative status by reducing nitrite levels and by increasing superoxide dismutase activity. Moreover, melatonin treatment also caused a profound inhibition of Ca-induced opening of mPTP in isolated mitochondria from both types of fat, white and beige, in both lean and obese rats. These results demonstrate that chronic oral melatonin improves mitochondrial respiration and reduces the oxidative status and susceptibility to apoptosis in white and beige adipocytes. These melatonin effects help to prevent mitochondrial dysfunction and thereby to improve obesity-related metabolic disorders such as diabetes and dyslipidemia of ZDF rats.
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Affiliation(s)
- Aroa Jimenéz-Aranda
- Department of Pharmacology and Neurosciences Institute, School of Medicine, University of Granada, Granada, Spain
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Jiménez-Aranda A, Fernández-Vázquez G, Campos D, Tassi M, Velasco-Perez L, Tan DX, Reiter RJ, Agil A. Melatonin induces browning of inguinal white adipose tissue in Zucker diabetic fatty rats. J Pineal Res 2013; 55:416-23. [PMID: 24007241 DOI: 10.1111/jpi.12089] [Citation(s) in RCA: 124] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/06/2013] [Accepted: 08/06/2013] [Indexed: 01/24/2023]
Abstract
Melatonin limits obesity in rodents without affecting food intake and activity, suggesting a thermogenic effect. Identification of brown fat (beige/brite) in white adipose tissue (WAT) prompted us to investigate whether melatonin is a brown-fat inducer. We used Zücker diabetic fatty (ZDF) rats, a model of obesity-related type 2 diabetes and a strain in which melatonin reduces obesity and improves their metabolic profiles. At 5 wk of age, ZDF rats and lean littermates (ZL) were subdivided into two groups, each composed of four rats: control and those treated with oral melatonin in the drinking water (10 mg/kg/day) for 6 wk. Melatonin induced browning of inguinal WAT in both ZDF and ZL rats. Hematoxylin-eosin staining showed patches of brown-like adipocytes in inguinal WAT in ZDF rats and also increased the amounts in ZL animals. Inguinal skin temperature was similar in untreated lean and obese rats. Melatonin increased inguinal temperature by 1.36 ± 0.02°C in ZL and by 0.55 ± 0.04°C in ZDF rats and sensitized the thermogenic effect of acute cold exposure in both groups. Melatonin increased the amounts of thermogenic proteins, uncoupling protein 1 (UCP1) (by ~2-fold, P < 0.01) and PGC-1α (by 25%, P < 0.05) in extracts from beige inguinal areas in ZL rats. Melatonin also induced measurable amounts of UCP1 and stimulated by ~2-fold the levels of PGC-1α in ZDF animals. Locomotor activity and circulating irisin levels were not affected by melatonin. These results demonstrate that chronic oral melatonin drives WAT into a brown-fat-like function in ZDF rats. This may contribute to melatonin's control of body weight and its metabolic benefits.
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Affiliation(s)
- Aroa Jiménez-Aranda
- Department of Pharmacology and Neurosciences Institute (CIBM), School of Medicine, University of Granada, Granada, Spain
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Agil A, Reiter RJ, Jiménez-Aranda A, Ibán-Arias R, Navarro-Alarcón M, Marchal JA, Adem A, Fernández-Vázquez G. Melatonin ameliorates low-grade inflammation and oxidative stress in young Zucker diabetic fatty rats. J Pineal Res 2013; 54:381-8. [PMID: 23020082 DOI: 10.1111/jpi.12012] [Citation(s) in RCA: 98] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/28/2012] [Accepted: 08/14/2012] [Indexed: 12/18/2022]
Abstract
The aim of this study was to investigate the effects of melatonin on low-grade inflammation and oxidative stress in young male Zucker diabetic fatty (ZDF) rats, an experimental model of metabolic syndrome and type 2 diabetes mellitus (T2DM). ZDF rats (n = 30) and lean littermates (ZL) (n = 30) were used. At 6 wk of age, both lean and fatty animals were subdivided into three groups, each composed of 10 rats: naive (N), vehicle treated (V), and melatonin treated (M) (10 mg/kg/day) for 6 wk. Vehicle and melatonin were added to the drinking water. Pro-inflammatory state was evaluated by plasma levels of interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and C-reactive protein (CRP). Also, oxidative stress was assessed by plasma lipid peroxidation (LPO), both basal and after Fe(2+)/H2O2 inducement. ZDF rats exhibited higher levels of IL-6 (112.4 ± 1.5 pg/mL), TNF-α (11.0 ± 0.1 pg/mL) and CRP (828 ± 16.0 µg/mL) compared with lean rats (IL-6, 89.9 ± 1.0, P < 0.01; TNF-α, 9.7 ± 0.4, P < 0.01; CRP, 508 ± 21.5, P < 0.001). Melatonin lowered IL-6 (10%, P < 0.05), TNF-α (10%, P < 0.05), and CRP (21%, P < 0.01). Basal and Fe(2+)/H2O2-induced LPO, expressed as malondialdehyde equivalents (µmol/L), were higher in ZDF rats (basal, 3.2 ± 0.1 versus 2.5 ± 0.1 in ZL, P < 0.01; Fe(2+)/H2O2-induced, 8.7 ± 0.2 versus 5.5 ± 0.3 in ZL; P < 0.001). Melatonin improved basal LPO (15%, P < 0.05) in ZDF rats, and Fe(2+)/H2O2- induced LPO in both ZL (15.2%, P < 0.01) and ZDF rats (39%, P < 0.001). These results demonstrated that oral melatonin administration ameliorates the pro-inflammatory state and oxidative stress, which underlie the development of insulin resistance and their consequences, metabolic syndrome, diabetes, and cardiovascular disease.
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Affiliation(s)
- Ahmad Agil
- Department of Pharmacology and Neurosciences Institute, School of Medicine, University of Granada, Granada, Spain
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Abstract
The aim of this study was to investigate the effects of melatonin on glucose homeostasis in young male Zucker diabetic fatty (ZDF) rats, an experimental model of metabolic syndrome and type 2 diabetes mellitus (T2DM). ZDF rats (n=30) and lean littermates (ZL) (n=30) were used. At 6wk of age, both lean and fatty animals were subdivided into three groups, each composed of ten rats: naive (N), vehicle treated (V), and melatonin treated (M) (10mg/kg/day) for 6wk. Vehicle and melatonin were added to the drinking water. ZDF rats developed DM (fasting hyperglycemia, 460±39.8mg/dL; HbA(1) c 8.3±0.5%) with both insulin resistance (HOMA-IR 9.28±0.9 versus 1.2±0.1 in ZL) and decreased β-cell function (HOMA1-%B) by 75%, compared with ZL rats. Melatonin reduced fasting hyperglycemia by 18.6% (P<0.05) and HbA(1) c by 11% (P<0.05) in ZDF rats. Also, melatonin lowered insulinemia by 15.9% (P<0.05) and HOMA-IR by 31% (P<0.01) and increased HOMA1-%B by 14.4% (P<0.05). In addition, melatonin decreased hyperleptinemia by 34% (P<0.001) and raised hypoadiponectinemia by 40% (P<0.001) in ZDF rats. Moreover, melatonin reduced serum free fatty acid levels by 13.5% (P<0.05). These data demonstrate that oral melatonin administration ameliorates glucose homeostasis in young ZDF rats by improving both insulin action and β-cell function. These observations have implications on melatonin's possible use as a new pharmacologic therapy for improving glucose homeostasis and of obesity-related T2DM, in young subjects.
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Affiliation(s)
- Ahmad Agil
- Deparment of Pharmacology and Neurosciences Institute, School of Medicine, University of Granada, Granada, Spain
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Velasco B, Cacicedo L, Melian E, Fernández-Vázquez G, Sánchez-Franco F. Sensitivity to exogenous GH and reversibility of the reduced IGF-I gene expression in aging rats. Eur J Endocrinol 2001; 145:73-85. [PMID: 11415855 DOI: 10.1530/eje.0.1450073] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
BACKGROUND IGF-I gene expression and IGF-I plasma concentration decline with age. A decreased sensitivity to GH has been suggested to be a contributory mechanism to this, in addition to attenuated GH secretion. OBJECTIVE This study focuses on the sensitivity to exogenous GH and the reversibility of the reduced IGF-I gene expression in aging male rats. DESIGN Three groups of male Wistar rats aged 3 months (young adult), 11 months (middle-aged) and 27 months (old), received recombinant human GH (rhGH) (150 microg/12 h s.c.) for seven consecutive days. RESULTS This rhGH treatment completely reversed plasma immunoreactive IGF-I (IR-IGF-I) and hepatic IGF-I mRNA levels in 11-month-old and 27-month-old animals to the levels of the young group of animals. The sensitivity in the old group (percentage of increment after the same or lower dose of rhGH per body weight) was increased for both parameters; serum IGF-I increment: 15% in 3-month-old, 42.6% in 11-month-old and 119.1% in 27-month-old rats; and hepatic IGF-Ib mRNA increase: 45% in 3-month-old, 27.8% in 11-month-old and 64.3% in 27-month-old rats. IGF binding protein-3 (IGFBP-3) mRNA level in the liver was significantly decreased in the old group and only a partial reversion occurred in this group after rhGH treatment; the percentage of increment was also higher in the old group of rats. In extrahepatic tissues IGF-I mRNA was not significantly different in the kidney and the testis of the three groups, and the rhGH treatment produced a significant and similar increase of IGF-I mRNA level in the kidney of the three groups of rats and in the testis of the 27-month-old animals. The GHr/GHBP mRNA remained unchanged in the liver and in the kidney or the testis of the three groups, and was not influenced by the rhGH treatment. Exogenous rhGH decreased pituitary GH mRNA accumulation in a more intense manner in the old group versus control of each group: young adult, 25%; middle-aged, 41.2%; and old rats, 55%. The action of rhGH on pituitary immunoreactive GH (IR-GH) content was only significantly evident in the young group. CONCLUSIONS These results establish that exogenous rhGH recovers the attenuated liver IGF-I gene expression and the diminished plasma IR-IGF-I in old rats to the levels of young adult animals. They also indicate that the hepatic and extrahepatic (kidney and testis) sensitivity to one established dose per weight of exogenous rhGH is not altered in old animals, or could be potentially increased in some tissues.
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Affiliation(s)
- B Velasco
- Servicio de Endocrinología, Hospital Carlos III-C.I.C., Instituto de Salud Carlos III, Sinesio Delgado 10-12, Madrid 28029, Spain
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Fernández-Vázquez G, Kaiser UB, Albarracin CT, Chin WW. Transcriptional activation of the gonadotropin-releasing hormone receptor gene by activin A. Mol Endocrinol 1996; 10:356-66. [PMID: 8721981 DOI: 10.1210/mend.10.4.8721981] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
It has been reported that activin A stimulates the synthesis of the GnRH receptors (GnRHR) in rat pituitary cultures. However, the role of activin A in the regulation of the GnRHR gene at the molecular level is not known. In the present work, we have studied the regulation of the GnRHR gene by activin A in the gonadotrope cell line, alpha T3-1, where the GnRHR gene is highly expressed. First, we demonstrate that these cells express the mRNAs of three types of activin receptors: I, II, and IIB. Activin A increases GnRHR mRNA levels in a dose-and time-dependent manner, with maximal stimulation (2.5 +/- 0.5-fold) occurring with a dose of 20 ng/ml after 36 h of incubation. To ascertain whether this effect occurs at the transcriptional level, we performed nuclear run-off experiments in alpha T3-1 cells, which demonstrate a 1.6-fold increase in the levels of newly synthesized GnRHR mRNA in response to activin A. To investigate further the effect of activin A on the transcription of the GnRHR gene, alpha T3-1 cells were transiently transfected with a mouse GnRHR promoter/luciferase reporter gene (GnRHR-Luc) and challenged with activin A. Luciferase activity increases in response to activin A to the same extent (2.4 +/- 0.4-fold) and with similar dose-response and time-course profiles as the mRNA levels. Follistatin (100 ng/ml), a well known activin antagonist, completely abolishes the activin A effect on both mRNA levels and GnRHR-Luc activity. Follistatin also decreases the basal expression of the GnRHR gene by 33% as determined by GnRHR-Luc activity. This, together with our demonstration of the presence of the inhibin beta B-subunit mRNA in alpha T3-1 cells, suggests a potential paracrine/autocrine role of endogenous activin B on the regulation of the GnRHR gene in these cells. To provide evidence for biological significance of activin A stimulation of GnRHR gene expression, the response of a human gonadotropin alpha-subunit promoter/luciferase reporter gene (alpha Gon-Luc) to GnRH was assessed in alpha T3-1 cells pretreated with activin A. Activin enhances the stimulation of alpha Gon-Luc activity by GnRH by 1.6 +/- 0.4-fold. These data demonstrate that activin A can stimulate the expression of the GnRHR gene at the transcriptional level. Furthermore, transfection studies localize the activin responsive element to 1.2 kb of the 5'-flanking region of the GnRHR gene. Transcriptional activation of the GnRHR gene by activin A may serve as a mechanism for the modulation of gonadotrope responsiveness to GnRH.
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Affiliation(s)
- G Fernández-Vázquez
- Department of Medicine Brigham and Women's Hospital, Howard Hughes Medical Institute, Boston, Massachusetts 02115, USA
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Fernández-Vázquez G, Cacicedo L, Lorenzo MJ, Tolón R, López J, Sánchez-Franco F. Corticosterone modulates growth hormone-releasing factor and somatostatin in fetal rat hypothalamic cultures. Neuroendocrinology 1995; 61:31-5. [PMID: 7731495 DOI: 10.1159/000126824] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
It is well known that chronic supraphysiological doses of glucocorticoids (GC) inhibit GH secretion in vivo, and stimulate GH secretion from the somatotropes in vitro. It has been suggested that GC exert an inhibitory role in the hypothalamus surpassing the GC-positive effect at the somatotrope level. To test the hypothesis that GC can affect growth hormone-releasing releasing factor (GRF) and somatostatin (SS) at the hypothalamic level, we studied the effect of corticosterone on the immunoreactive content of GRF (IR-GRF) and SS (IR-SS) in cells and media of fetal hypothalamic cells in culture. After 20 days in culture, cells were incubated with serum-free medium containing corticosterone (from 0.3 to 300 nM) for 48 h. Corticosterone had a dual effect on IR-GRF. Concentrations in the range of the glucocorticoid receptor Kd (3 nM) increased peptide content, whereas higher concentrations (30 and 300 nM) decreased IR-GRF content in cells and media. Conversely, corticosterone increased SS cell content, only at a concentration of 3 nM, inducing a 2- to 3-fold increment in media content with the highest doses (30 and 300 nM). These results demonstrated that both GRF and SS are modulated by corticosterone in primary fetal rat hypothalamic cultures. Whereas GRF exhibited a dual response, stimulatory and inhibitory, at low and high corticosterone doses, respectively, SS showed a parallel increase with the corticosterone concentrations.
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Affiliation(s)
- G Fernández-Vázquez
- Centro Nacional de Investigación Clínica, Instituto de Salud Carlos III, Madrid, España
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