褪黑素抑制氧化应激和铁死亡缓解妊娠糖尿病大鼠病理损伤

目的:探讨褪黑素对妊娠糖尿病(GDM)大鼠的治疗作用及可能作用机制.方法:将24只雌性大鼠分成4组:正常妊娠组、GDM模型组、低剂量褪黑素[5 mg/(kg·d)]治疗组及高剂量褪黑素[10mg/(kg·d)]治疗组,每组6只.不同剂量褪黑素治疗14天后,检测大鼠胰腺组织形态病理变化及细胞凋亡水平,检测血清生化指标、细...     

褪黑素对间歇低氧大鼠海马损伤保护作用的研究

目的 探讨褪黑素(melatonin,MEL)对间歇低氧(intermittent hypoxia,IH)大鼠海马损伤的保护作用.方法 30只成年雄性Sprague-Dawley大鼠随机分成对照组(CON组)、间歇低氧组(IH组)、MEL治疗组(MEL组),每组10只.采用化学比色法测定海马组织丙二醛(MDA)、超氧化物歧化酶(SOD)水平,并采取RT-PCR方法检测海马组织中铜/锌超氧化物歧化酶(Cu/ZnSOD)、谷胱甘肽过氧化物酶(GPx)、组织过氧化氢酶(CAT)的mRNA水平.结果 IH组MDA水平显著高于对照组,SOD活性、Cu/ZnSOD、GPx、CAT的mRNA水平显著低于对照组;MEL组MDA水平明显低于IH组,SOD活性、Cu/ZnSOD、GPx、CAT的mRNA水平明显高于IH组.结论 褪黑素能抑制间歇低氧导致的氧化应激,从而对间歇低氧大鼠海马损伤具有保护作用.     

褪黑激素对增生性瘢痕成纤维细胞增殖的影响及机制研究

目的：探讨褪黑激素对人增生性瘢痕成纤维细胞增殖的影响及作用机制。方法收集人皮肤增生性瘢痕标本,原代培养人皮肤增生性瘢痕成纤维细胞(HSFBs)。将HSFBs细胞根据不同的处理方法分为空白对照组、低浓度褪黑激素组、中浓度褪黑激素组、高浓度褪黑激素组、NVP-BEZ235处理组、NVP-BEZ235+褪黑激素组、褪黑激素+siRNA-PTEN组、褪黑激素+siRNA-scramble组。MTT法检测各组细胞的增殖情况,qRT-PCR和Western blot检测各组细胞中磷酸酶与张力蛋白同源物(PTEN)、CyclinD1和Caspase-3的表达以及PI3k/AKt/mTOR通路相关蛋白p-Akt和p-mTOR的蛋白水平。结果与空白对照组比较,从低到高浓度褪黑激素均能够减少HSFBs细胞同一时间点OD值,上调PTEN和Caspase-3表达量,同时抑制CyclinD1、p-Akt和p-mTOR表达水平,组间差异具有统计学意义(P<0.05)。同时与高浓度褪黑激素组比较,NVP-BEZ235+褪黑激素组中细胞增殖显著被抑制,差异具有统计学意义(P<0.05);沉默PTEN后拮抗褪黑激素对HSFBs细胞增殖和PI3K/Akt/mTOR信号通路有抑制作用,差异具有统计学意义(P<0.05)。结论褪黑激素通过上调PTEN表达,抑制PI3K/Akt/mTOR信号通路活化从而抑制HSFBs细胞增殖。     

褪黑素对大鼠脊髓损伤后iNOS表达的影响

目的：探讨褪黑素对大鼠脊髓损伤后诱生型一氧化氮合酶（iNOS）表达的影响。方法：采用改良Allen’S撞击法制备脊髓损伤模型;成年SD大鼠110只随机分为假损伤组、损伤组和药物治疗组3组,其中损伤组和药物治疗组各50只,分5个时间点（8小时、24小时、72小时、7天、14天）处死;假损伤组10只,于手术后14天处死,采用HE染色和免疫组化检测脊髓损伤后脊髓组织中iNOS蛋白的表达。结果：与损伤组比较,药物治疗组大鼠损伤后脊髓组织iNOS表达明显降低,差异有统计学意义（P〈0．05）。结论：褪黑素可通过抑制iNOS蛋白表达对大鼠脊髓损伤起保护作用。     

热敏灸对失眠大鼠模型血清内分泌激素水平的影响

目的：观察热敏灸对失眠大鼠模型血清促肾上腺皮质激素（ACTH）、皮质酮（CORT）、甲状腺素（T4）、生长激素（GH）和褪黑素（MT）水平的影响,了解热敏灸治疗失眠的机制.方法：雄性SD大鼠32只,随机分为4组：正常组、模型组、艾灸组和热敏灸组,每组8只.采用腹腔注射对氯苯丙氨酸（PCPA）制备失眠大鼠模型,用Ethovision XT视频跟踪系统录制大鼠活动观察大鼠的行为学表现,用放射免疫分析法检测大鼠血清中ACTH、CORT、T4、GH和MT的水平.结果：与正常组相比,模型组大鼠昼夜节律消失;血清CORT、T4、GH和MT含量均升高,而血清中ACTH含量下降.与模型组相比,热敏灸组大鼠昼夜活动节律基本恢复正常;血清CORT、T4、GH和MT含量均下降,而血清中ACTH含量有所升高.结论：热敏灸能缓解失眠大鼠症状,可能与调节体内激素水平有关.     

褪黑素防治高脂饮食大鼠脂肪肝的实验研究

目的观察褪黑素对高脂饮食大鼠脂肪肝的影响。方法将50只雄性Wistar大鼠随机分成5组:正常对照组、模型组和低、中、高3个剂量褪黑素组。采用喂饲高脂饲料复制大鼠脂肪肝模型。褪黑素组分别在造模同时以褪黑素2.5mg/(kg·d)、5.0mg/(kg·d)和10.0mg/(kg·d)剂量腹腔注射进行干预。12周后观察血清ALT、AST、血清及肝匀浆中总胆固醇(Tch)、甘油三酯(TG)以及肝脏指数和肝脏病理形态学的变化。结果与模型组相比,高剂量褪黑素组血清AST水平明显下降(P<0.01),中、高剂量褪黑素组肝指数、肝内Tch和TG明显降低(P<0.05,P<0.01)。中、高剂量褪黑素组大鼠肝脏病理变化明显减轻(P<0.001),以高剂量组更明显。结论褪黑素可明显减轻高脂饮食诱导的大鼠脂肪肝,且与剂量有一定关系。     

褪黑素对急性脊髓损伤大鼠血清及脊髓内神经生长因子表达的影响

目的研究褪黑素（MT）对脊髓损伤大鼠血清及脊髓内神经生长因子（NGF）表达水平的影响。方法84只健康成年雄性SD大鼠随机分为模型对照组（n=36）、模型MT组（n=36）及假手术组（n=12）。建立脊髓损伤模型后,模型对照组给予无水乙醇,模型MT组给予MT,均为腹腔注射。对比术后12h、3、5d大鼠血清及脊髓组织中NGF的表达及Tarlov评分。结果术后12h模型对照组及模型MT组Tarlov评分显著低于假手术组（P〈0．05）。模型MT组TarlOV评分稍高于模型对照组,但差异无统计学意义（P〉0．05）。术后3、5d模型MT组Tarlov评分均显著高于模型对照组（P〈0．05或P〈0．01）。术后12h、3、5d模型对照组和模型MT组血清NGF水平、脊髓组织NGF蛋白及NGFmRNA水平均较假手术组显著上升,模型MT组则显著高于模型对照组（P〈0．05或P〈0．01）。结论MT通过调高脊髓损伤大鼠体内NGF的表达起到减轻神经细胞损伤、促进神经细胞再生和神经功能恢复作用。     

Changes in vascularity of cartilage endplate of degenerated intervertebral discs in response to melatonin administration in rats

We carried out an experimental investigation of cartilage endplate vascularity of degenerated intervertebral discs produced by exogenous melatonin (MEL) treatment. Adult Swiss albino rats were divided into three groups: control, operated degeneration, and MEL treatment. There were five rats in each group and, using a posterior approach, cuts were made parallel to the endplates in the posterior annulus fibrosus in five consecutive intervertebral discs between the 5th and 10th vertebral segments of the rats' tails. At 8 weeks, five of these animals were treated with exogenous MEL (s.c. injection of 30 μg/100 g body weight daily for 4 weeks). In each experimental group, one animal was examined using CT scanner to study the density of the cartilage endplate of the disc. To evaluate the bone growth and vascularity of the cartilage endplate region, the animals were killed for subsequent histopathological evaluation. We found that the vascular channel counts and percentage areas from animals treated with MEL were significantly lower than from the operated degeneration animals. Accordingly, the density histogram in the MEL group showed a spike profile for both the vertebral body and the cartilage endplate, indicating an increase in the amount of higher density tissues in these regions. Our results demonstrate that the use of MEL reduces the cartilage endplate vascularity of degenerated intervertebral discs, suggesting that it may have an osteoinductive effect on bone formation. Further studies are needed to characterize fully the relevance of our findings for the treatment of disorders such as postmenopausal osteoporosis.     

Gene structures,biochemical characterization and distribution of rat melatonin receptors

G-protein coupled receptors for the pineal hormone melatonin have been partially cloned from rats. However, insufficient information about their cDNA sequences has hindered studies of their distribution and physiological responses to melatonin using rats as an animal model. We have cloned cDNAs of two rat membrane melatonin receptor subtypes, melatonin receptor 1a (MT1) and melatonin receptor 1b (MT2), using a rapid amplification of cDNA end (RACE) method. The rat MT1 and MT2 cDNAs encode proteins of 353 and 364 amino acids, respectively, and show 78–93% identities with the human and mouse counterparts. Stable expression of either rat MT1 or MT2 in NIH3T3 cells resulted in high affinity 2-[¹²⁵I]-iodomelatonin (¹²⁵I-Mel) binding (K _d = 73.2 ± 9.0 and 73.7 ± 2.9 pM, respectively), and exhibited a similar rank order of inhibition of specific ¹²⁵I-Mel binding by five ligands (2-iodomelatonin > melatonin > 6-hydroxymelatonin > luzindole > N-acetyl-5-hydroxytryptamine). RT-PCR analysis showed that MT1 is highly expressed in the hypothalamus, lung, kidney, adrenal gland, stomach, and ovary, while MT2 is highly expressed in the hippocampus, kidney, and ovary. We also performed multi-cell RT-PCR to examine the expression of mRNAs encoding MT1 and MT2 in adult GnRH neurons. MT1 was weakly expressed in male GnRH neurons, and was less expressed in the female neurons. MT2 expression was undetectable in GnRH neurons from either sex. This study delineates the gene structures, fundamental properties, and distribution of both rat melatonin receptor subtypes, and may offer opportunities to assess the physiological significance of melatonin in rats. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.