Association of polymorphisms of the acetyl-coA acetyltransferase 1 gene and the melatonin receptor 1B gene with the susceptibility to nonalcoholic fatty liver disease / 临床肝胆病杂志

ObjectiveTo investigate the association of the polymorphisms of the acetyl-CoA acetyltransferase 1 （ACAT1） gene and the melatonin receptor 1B （MTNR1B） gene with the susceptibility to nonalcoholic fatty liver disease （NAFLD）. MethodsA total of 164 healthy controls and 228 NAFLD patients were enrolled in this study. PCR and sequencing methods were used to determine the genotypes of the polymorphisms of the ACAT1 gene at the rs1044925 and rs1157651 loci and the MTNR1B gene at the rs10830963 locus， and fasting venous blood samples were collected for biochemical analysis. The t-test was used for comparison of normally distributed continuous data between groups， and the non-parametric Mann-Whitney U test was used for comparison of non-normally distributed continuous data between groups； the chi-square test was used for comparison of categorical data between groups. ResultsThere were no significant differences between the NAFLD group and the healthy control group in the genotype distribution of the ACAT1 gene at the rs1044925 and rs1157651 loci and the MTNR1B gene at the rs10830963 locus （all P>0.05）. The carriers of AA genotype at the rs1044925 locus of the ACAT1 gene had a significantly higher level of low-density lipoprotein than the carriers of C allele （Z=-2.08， P=0.04）， and the carriers of G allele at the rs10830963 locus of the MTNR1B gene had a significantly higher level of fasting blood glucose than the carriers of CC genotype （Z=-3.01， P<0.01）. ConclusionThe polymorphisms of the ACAT1 gene at the rs1044925 and rs1157651 loci and the MTNR1B gene at the rs10830963 locus were not associated with the susceptibility to NAFLD. The rs1044925 locus of the ACAT1 gene and the rs10830963 locus of the MTNR1B gene are associated with the levels of low-density lipoprotein and fasting blood glucose， respectively.

The extent of involvement of ouabain, hippocampal expression of Na+/K+-ATPase, and corticosterone/melatonin receptors ratio in modifying stress-induced behavior differs according to the stressor in context

The aim of this study was to assess the effect of two types of stressors, regarding the extent of involvement of ouabain (OUA), hippocampal sodium/potassium ATPase (NKA) expression, and the hippocampal corticosterone receptors (CR)/melatonin receptors (MR) expression ratio, on the behavioral and cardiovascular responses and on the hippocampal cornu ammonis zone 3 (CA3) and dentate gyrus (DG). Thirty adult male Wistar albino rats aged 7-8 months were exposed to either chronic immobilization or a disturbed dark/light cycle and treated with either ouabain or vehicle. In the immobilized group, in the absence of hippocampal corticosterone (CORT) changes, rats were non-responsive to stress, despite experiencing increased pulse rate, downregulated hippocampal sodium/potassium pump, and enhanced hippocampal CR/MR expression ratio. Prolonged darkness precipitated a reduced upright attack posture, with elevated CORT against hippocampal MR downregulation. Both immobilization and, to a lesser extent, prolonged darkness stress resulted in histopathological and ultrastructural neurodegenerative changes in the hippocampus. OUA administration did not change the behavioral resilience in restrained rats, despite persistence of the underlying biochemical derangements, added to decreased CORT. On the contrary, with exposure to short photoperiods, OUA reverted the behavior towards a combative reduction of inactivity, with unvaried CR/MR and CORT, while ameliorating hippocampal neuro-regeneration, with co-existing NKA and MR repressions. Therefore, the extent of OUA, hippocampal NKA expression, and CR/MR expression, and subsequent behavioral and cardiac responses and hippocampal histopathology, differ according to the type of stressor, whether immobilization or prolonged darkness.

Relationship between lateral hypothalamus and melatonin-induced reduction of wakefulness in rats and the receptor mechanism / 中华麻醉学杂志

Objective:To investigate the relationship between lateral hypothalamus and melatonin-induced reduction of wakefulness in rats and the receptor mechanism.Methods:Forty clean-grade adult male Sprague-Dawley rats, weighing 250-300 g, were divided into 4 groups ( n=10 each) using a random number table method: control group (group C), melatonin group (group M), melatonin type-1/2 receptor (MT 1R) antagonist luzindole plus melatonin group (group L+ M), and melatonin type-2 receptor (MT 2R) antagonist 4P-PDOT plus melatonin group (P+ M group). In group C, 0.5 μl of 0.9% NaCl solution was microinjected into the lateral hypothalamus.In group M, 1 μmol/L melatonin 0.5 μl was microinjected into the lateral hypothalamus.In group L+ M, 1 μmol/L MT 1/2R and 1 μmol/L melatonin (0.5 μl in total) was microinjected into the lateral hypothalamus.The microinjection time was from 19: 30 to 20: 00.The changes in sleep-wake duration and the oscillating energy in different frequency bands of electroencephalogram were detected by using electroencephalogram and electromyogram recording technology. Results:Compared with group C, the percentage of wakefulness time was significantly decreased, the percentage of non-rapid eye movement sleep and rapid eye movement sleep time was increased, the energy for delta oscillation was increased, the energy for theta oscillation was decreased, and no significant change was found in the energy for alpha oscillation in M and P+ M groups ( P<0.01), and no significant change was found in the parameters mentioned above in group L+ M ( P>0.05). Compared with group M, the percentage of wakefulness time was significantly increased, the percentage of non-rapid eye movement sleep and rapid eye movement sleep time was decreased, the energy for delta oscillation was decreased, and the energy for theta oscillation was increased in group L+ M ( P<0.01), and no significant change was found in the parameters mentioned above in group P+ M ( P>0.05). Conclusion:The lateral hypothalamus may be involved in melatonin-induced reduction of wakefulness in rats, and the mechanism may be related to activating MT 1R in the lateral hypothalamus.

Melatonin inhibits adipogenic differentiation of bone marrow mesenchymal stem cells through retinoid-related orphan receptor alpha / 中国组织工程研究

BACKGROUND:Our previous studies have demonstrated that melatonin inhibits the adipogenic differentiation of bone marrow mesenchymal stem cels. However, the mechanism underlying the effect of melatonin on adipogenesis is stil unknown. OBJECTIVE:To determine whether melatonin can inhibit the adipogenesis of bone marrow mesenchymal stem cels through retinoid-related orphan receptor α. METHODS:Bone marrow mesenchymal stem cels were isolated and purified by density gradient centrifugation combined with cellattachment culture. The phenotype was investigated by flow cytometry. Then, cels were induced for adipogenic differentiation with melatonin, CGP52608 and normal adipose tissue, respectively. The levels of retinoid-related orphan receptor α mRNA and protein were investigated by real-time RT-PCR and western blot assay, respectively. Further, the effect of retinoid-related orphan receptor α on the dipogenic differentiation of bone marrow mesenchymal stem cels was investigated by CGP52608. RESULTS AND CONCLUSION:The primary isolated bone marrow mesenchymal stem cels were spindle-shaped fibroblast-like cels. These cels did not express hematopoietic stem cels markers: CD34 and CD45; and highly expressed MSC markers: CD29, CD44, and CD10. The result of RT-PCR demonstrated that melatonin nuclear receptor, retinoid-related orphan receptor α, was highly expressed in bone marrow mesenchymal stem cels and the expression of retinoid-related orphan receptor α was further enhanced by melatonin in a dose-dependent manner, which was confirmed at protein level by western blot assay. During adiogenesis, the expression of retinoid-related orphan receptor αmRNA was up-regulated in the early stage, but maintained at a low level in the mild-later stage. While the retinoid-related orphan receptor α was activated by agonist CGP52608, the adipogenic differentiation of bone marrow mesenchymal stem cels was inhibited, which was similar to the inhibitory effect of melatonin. Therefore, melatonin inhibited the adipogenic differentiation of bone marrow mesenchymal stem cels through retinoid-related orphan receptor α, suggesting that melatonin plays an important role in the differentiation of adipocytes.

Novos sedativos hipnóticos / The newer sedative-hypnotics

Nas últimas décadas houve um esforço para o desenvolvimento de hipnóticos mais seguros e eficazes. Zolpidem, zaleplona, zopiclona, eszopiclona (drogas-z) e indiplona são moduladores do receptor GABA-A, os quais agem de forma seletiva na subunidade α1, exibindo, desta forma, mecanismos similares de ação, embora evidências recentes sugiram que a eszopiclona não seja tão seletiva para a subunidade α1 quanto o zolpidem. Ramelteon e tasimelteon são novos agentes crono-hipnóticos seletivos para os receptores de melatonina MT1 e MT2. Por outro lado, nos últimos anos, o consumo de drogas antidepressivas sedativas tem aumentado significativamente no tratamento da insônia. Como droga experimental, a eplivanserina tem sido testada como um potente agonista inverso do subtipo 5-HT2A da serotonina, com um uso potencial na dificuldade da manutenção do sono. Outro agente farmacológico para o tratamento da insônia é o almorexant, o qual apresenta um novo mecanismo de ação envolvendo antagonismo do sistema hipocretinérgico, desta forma levando à indução do sono. Finalmente, também discutiremos o potencial papel de outras drogas gabaérgicas no tratamento da insônia.

There has been a search for more effective and safe hypnotic drugs in the last decades. Zolpidem, zaleplon, zopiclone, eszopiclone (the z-drugs) and indiplon are GABA-A modulators which bind selectively α1 subunits, thus, exhibiting similar mechanisms of action, although recent evidence suggests that eszopiclone is not as selective for α1 subunit as zolpidem is. Ramelteon and tasimelteon are new chrono-hypnotic agents, selective for melatonin MT1 and MT2 receptors. On the other hand, the consumption of sedative antidepressant drugs is significantly increasing for the treatment of insomnia, in the last years. As an experimental drug, eplivanserin is being tested as a potent antagonist of serotonin 2-A receptors (ASTAR) with a potential use in sleep maintenance difficulty. Another recent pharmacological agent for insomnia is almorexant, which new mechanism of action involves antagonism of hypocretinergic system, thus inducing sleep. Finally we also discuss the potential role of other gabaergic drugs for insomnia.

INVESTIGATION OF MELATONIN RECEPTOR GENE AND PROTEIN EXPRESSION IN HUMAN HUT78 CELL LINE / 解放军医学杂志

To investigate the melatonin receptor(MR) gene and protein expression in human HUT78 cell line, total RNA of HUT78 cells was isolated by single-step method of acid guanidinium-thiocyanate-phenol-chloform, and mt 1 and MT 2 mRNA were determined by reverse transcription-polymerase chain reaction(RT-PCR). The Envision method was applied to immunohistochemistry to identify and localize mt 1 and MT 2 protein. The mt 1 cDNA fragment of the expected size of 370bp was determined, but the MT 2 cDNA fragment of the expected size of 320bp was not determinable by RT-PCR. Sequencing result indicated that the positive product coincided with the cDNA of human mt 1. The mt 1 protein was observed by immunohistochemistry. These buffy positive granules were scattered with some areas stronger than the others, and were primarily located in cytoplasm and membrane, with rare location in nucleus; meanwhile the MT 2 protein was not observed. These results demonstrated the mt 1 mRNA and protein expression in HUT78 cell line. It is indicated that melatonin has directly immune-regulative effects on T lymphocyte, The changes of MR in physiological and pathological stages need to be investigated.