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Objective To investigate the genotypic and allele frequency differences of melatonin receptor 1B (MTNR1B)-rs4753426 between gestational diabetes mellitus (GDM) pregnancies and normal pregnancies , and to explore the association between single nucleotide polymorphism ( SNP ) of rs4753426 and gestational diabetes mellitus.Methods Totally 93 GDM pregnancies and 165 normal pregnancies were recruited from the Affiliated Hospital of Qingdao University.The age, gestational weeks, height, early pregnant weight , and the levels of fasting plasma glucose ( FPG) , fasting insulin ( FIN) were determined in every participants.By using PCR and DNA sequencing , we detected the distribution of the rs 4753426 genotypes and alleles in all individuals.The homeostasis model assessment-insulin resistance ( HOMA-IR) and the homeostasis model assessment-βcell function ( HOMA-β) were calculated.The allele and genotype frequencies and the FPG , FIN, body mass index ( BMI) , HOMA-IR, HOMA-βlevels between GDM group and control group were compared.Results (1) The genotype frequencies in the GDM group and the control group of rs4753426-CC, CT, TT were 72.0% (67/93), 21.5% (20/93), 6.5% (6/93), and 53.9%(89/165), 40.0% (66/165), 6.1% (10/165) respectively.The allele frequencies in the GDM group and the control group of T and C were 17.2% ( 32/186 ) , 82.8% ( 154/186 ) and 26.1% ( 86/330 ) , 73.9% ( 244/330 ) respectively.There were statistical differences in genotype frequencies and allele frequencies between two groups ( all P<0.05 ).( 2 ) The levels of FPG , FIN and HOMA-IR in the GDM group were obviously higher than those in the control group (P<0.05).The level of HOMA-βwas lower in the GDM group than that of the control group (P<0.05).(3)The FPG of CC and CT genotypes was higher than that of TT genotype in the GDM group (P<0.05), while the level of HOMA-βwas lower than that of TT genotype (P<0.05).Conclusions The MTNR1B-rs4753426 SNP is associated with the pathogenesis of GDM, and rs4753426 is the predisposing locus of GDM.The C-allele is the susceptibility allele of GDM.
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Objective To investigate the expression of melatonin MT1 receptor in rats with acute necrotizing pancreatitis (ANP) and the protective effects of melatonin (MT) pre-intervention for the pancreas. Methods Fifty-four male Sprague-Dawley (SD) rats were randomly divided into three groups:sham-operation group, ANP group and MT-pretreated group. The models of ANP were induced by retrograde injection sodium taurocholate into the bili-pancreatic duct. MT group undergoing intraperitoneal injection 50 mg/kg 30 minutes before the establishment of ANP models. Four, 8 and 12 hours after the onset of operation, the levels of serum amylase and pathological changes of the pancreas were observed. The contents of malondialdehyde (MDA), superoxide dismutase (SOD) and tumor necrosis factor-alpha (TNFα) in the pancreas were measured. The expression of MT1 protein and MT1 mRNA in pancreas were separately analyzed by immunohistochemistry and real-time PCR. Results (1) Pancreatic pathological damage in ANP groups was progressive exacerbated. It was obviously ameliorated in MT group as compared with ANP group ( P ＜ 0.05 ); (2) Compared with SO group, the levels of serum amylase, MDA and TNFα in the pancreas were significantly increased in ANP group (P ＜0.05 or P ＜0.01 ). They were markedly decreased in MT group as compared with ANP group [ 12 h, (2348.00 ±278.90)U/L vs (3194. 83 ±538.10)U/L,(2.255 ± 0.472 ) μmol/L vs ( 2.960 ± 0.722 ) μ mol/L, ( 102.929 ± 29.399 ) ng/L vs ( 378. 544 ±183.454)ng/L, P ＜ 0.05 ]. The level of SOD was decreased in ANP group compared with SO group (P ＜0.05) and increased in MT group[ 12h, (11.448 ± 1.594)U/L vs (8.427 ± 1.950)U/L, P＜0.05] ;(3)Compared with SO group, the expression of MT1 protein and MT1 mRNA in ANP group were down-regulated as the severity of the disease increased ( P ＜ 0.05 ). They were significantly higher in MT group than ANP group. Conclusions Melatonin pre-intervention is able to increase SOD level and decrease MDA, TNFα levels, thereby reducing pancreatic injury. The MT1 might play an important role in the pathogenesis of ANP. MT might exert protective effects for the pancreas in ANP rats through increase the expression of MT1.
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The secretion of melatonin in human is related to age, and of circadian rhythm. Our researches indicated that melatonin receptor existed in many tissues and also had a circadian rhythm. Melatonin has biological effects on genital, immunological and cardiovascular systems as well as the effects of antioxidation and antisenescence.
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To investigate the different expression of melatonin receptor between adult thyroid neoplasm and its adjacent normal thyroid tissue, we extracted the total RNA of all kinds of thyroid tissue, synthesized the primer of mt 1, MT 2, and analyzed the mRNA of melatonin receptor by RT-PCR method. mt 1, MT 2 melatonin receptor subtype positive strap expressed in thyroid adenoma as well as in adenocarcinoma. MT 2 in adenocarcinoma had a higher quantity than that in normal thyroid tissue(P0.05). Therefore, mt 1 and MT 2 subtype is present in human thyroid neoplasm tissue, and MT 2 subtype is associated with the occurrence of human adenocarcinoma.
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The aim of this study was to observe the changes of melatonin and its receptor in ischemic cerebral apoplexy(ICA) rats and the effect of melatonin pretreatment on The ICA rats. The ICA rat model was reproduced by using Pulsinelli′s method. Serum corticosterone and melatonin concentration were determined in each group. The radioactivity of melatonin receptor in the brain and peripheral leucocytes was deteced by -Mel radioligand binding assay. Bmax and Kd of melatonin receptor were calculated. The results indieated serum corticosterone in apoplexy group was higher than in sham operation group (P
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To investigate the role of malnutrition on expression of thymus melatonin receptor(MR), rats were fed with low protein diet to induce an experimental animal model of malnutrition. MR was detected by radioligand binding assay. In malnourished rats before pregnancy and those during pregnancy, the thymus development in their offsprings was retarded, and the expression of MR was lower than that of the controls. After fed with standard diet,the development of the thymus and the MR in the infant rats improved significantly. The results suggest that malnutrition can retard the development of thymus, so the production of MR in thymus is lowered, and this may affect the physiological role of melatonin.
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Objective: To make it clear whether there exists melatonin receptor in the thyroid of human embryo. Methods: Thyroid was collected and sliced up to be stained with methods of immunohistochemistry and in situ hybridization. Results: The thyroid tissue was positively dyed, melatonin receptor mt 1 and MT 2 were with both immunohistochemistry and in situ hybridization while brown granules deposited in the membrane, plasma and nuclear of the thyroid cell were with the immunohitochemistry. Conclusion: There exists melatonin receptors in human embryo thyroid, either mt 1 or MT 2, and they exist in the membrane, plasma and nuclear.
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Objective: To investigate the circadian ryhthm variation of 2 125 I iodomelatonin ( 125 I Mel) binding sites in the human peripheral leukocytes in patients with acute cerebral infarction. Methods: Melatonin binding sites in the human peripheral leukocytes were studied using 125 I Mel as a radioligand (radioligand binding assays).All patients [age: (70.18? 11.70) years] were diagnosed by CT according to the standard [Chin J Nerv, 1996,29(6):379]. We also studied 15 age matched healthy old people as the control [age: (68.33?7.76) years]. Results: The circadian ryhthm variation of 125 I Mel specific binding in control remained significant ( P 0.05). The specific binding in the peripheral leukocytes at midlight in the patients with acute cerebral infarction were lower than that of the control. Conclusion: The expression of Mel receptor decreases in the patients with acute cerebral infarction and the circadian ryhthm variation of 2 125 I Mel appears abnormal.