Postprandial Hyperglycemia Stimulates Neuroglial Plasticity in Hypothalamic POMC Neurons after a Balanced Meal

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Adaptive responses in hypothalamic neuropeptide Y in the face of prolonged high-fat feeding in the rat

While a dysregulation in neuropeptide Y (NPY) signaling has been described in rodent models of obesity, few studies have investigated the time-course of changes in NPY content and responsiveness during development of diet-induced obesity. Therefore we investigated the effect of differing lengths (2-17 weeks) of high-fat diet on hypothalamic NPY peptide content, release and NPY-induced hyperphagia. Male Sprague-Dawley rats (211 +/- 3 g) were fed either a high-fat diet (30% fat) or laboratory chow (5% fat). Animals were implanted with intracerebroventricular cannulae to investigate feeding responses to NPY (0.5 nmol, 1 nmol) after 4 or 12 weeks of diet. At the earlier stage of obesity, NPY-induced hyperphagia was not altered; however, animals maintained on the high-fat diet for the longer duration were hyper-responsive to NPY, compared to chow-fed control rats (p < 0.05). Overall, hypothalamic NPY peptide content tended to be decreased from 9 to 17 weeks of diet (p < 0.05). Total hypothalamic NPY content was negatively correlated with plasma leptin concentration (p < 0.05), suggesting the hypothalamic NPY system remains responsive to leptin's inhibitory signal. In addition, hypothalamic NPY overflow was significantly reduced in high-fat fed animals (p < 0.05). Together these results suggest a reduction in hypothalamic NPY activity in high-fat fed animals, perhaps in an attempt to restore energy balance.     

Endurance training prevents inflammation and apoptosis in hypothalamic neurons of obese mice

This study investigated the effects of exercise training in regulating inflammatory processes, endoplasmic reticulum stress, and apoptosis in hypothalamic neurons of obese mice. Swiss mice were distributed into three groups: Lean mice (Lean), sedentary animals fed a standard diet; obese mice (Obese), sedentary animals fed a high-fat diet (HFD); trained obese mice (T. Obese), animals fed with HFD and concurrently subjected to an endurance training protocol for 8 weeks. In the endurance training protocol, mice ran on a treadmill at 60% of peak workload for 1 hr, 5 days/week for 8 weeks. Twenty-four hours after the last exercise session, the euthanasia was performed. Western blot, quantitative real-time polymerase chain reaction, and terminal deoxynucleotide transferase biotin-dUTP nick end-labeling (TUNEL) techniques were used for the analysis of interest. The results show exercise training increased phosphorylation of leptin signaling pathway proteins (pJAK2/pSTAT3) and reduced the content of tumor necrosis factor α, toll-like receptor 4, suppressor of cytokine signaling 3, protein–tyrosine phosphatase 1B as well as the phosphorylation of IkB kinase in the hypothalamus of T. Obese animals. A reduction of macrophage activation and phosphorylation of eukaryotic initiation factor 2α, and protein kinase RNA-like endoplasmic reticulum kinase (PERK) were also observed in exercised animals. Furthermore, exercise decreased the expression of the proapoptotic protein (PARP1) and increased anti-inflammatory (IL-10) and antiapoptotic (Bcl2) proteins. Using the TUNEL technique, we observed that the exercised animals had lower DNA fragmentation. Finally, physical exercise preserved pro-opiomelanocortin messenger RNA content. In conclusion, exercise training was able to reorganize the control of the energy balance through anti-inflammatory and antiapoptotic responses in hypothalamic tissue of obese mice.     

The effects of centrally administered apelin-13 on food intake, water intake and pituitary hormone release in rats

Apelin is the recently identified endogenous ligand for the G-protein-coupled receptor, APJ. Preproapelin and APJ mRNA are found in hypothalamic regions known to be important in the regulation of food and water intake, and pituitary hormone release. The effects of intracerebroventricular (ICV) administration of pyroglutamylated apelin-13 on food and water intake and pituitary hormone release in rats were investigated. Apelin-13 had little effect on food intake, but dose-dependently increased drinking behaviour and water intake at 1 h. Apelin-13 (10 nmol) increased water intake by up to sixfold compared to saline. Compared to saline control, apelin-13 (10 nmol) significantly increased plasma ACTH and corticosterone and decreased plasma prolactin, LH and FSH at 30 min. In vitro, apelin-13 stimulated the release of CRH and AVP from hypothalamic explants, but had no effect on NPY release. These results suggest that apelin may play an important role in the hypothalamic regulation of water intake and endocrine axes.     

Antiobesity effect of recombinant human caseinomacropeptide in Sprague-Dawley rat

Caseinomacropeptide (CMP) is a glycopeptide of 64 amino acid residues derived from theC-terminal of mammalian milkk-casein. Recently, human CMP (hCMP) was produced from the recombinant yeastSaccharomyces cerevisiae. In this study, the antiobesity activity of the recombinant hCMP (rhCMP) was investigatedin vivo using Sprague-Dawley rats. The rhCMP did not affect the rats fed with a normal fat diet (fat content, 5.0%), but decreased the body weight gain of the rats fed with a high fat diet (fat content, 20%) by up to 19%. Autopsies revealed that the weights of the liver, kidney and adipose tissues decreased when the rats were given the rhCMP, which also reduced the lipid concentrations in the plasma and liver, but enhanced the fecal excretion of lipids. These results suggest that rhCMP prevent the accumulation of lipid by stimulating its fecal excretion, so could be used as a food supplement to alleviate the obesity problem caused by a high fat diet.     

A novel role for calcium/calmodulin kinase II within the brainstem pedunculopontine tegmentum for the regulation of wakefulness and rapid eye movement sleep

Considerable evidence suggests that the brainstem pedunculopontine tegmentum (PPT) neurons are critically involved in the regulation of rapid eye movement (REM) sleep and wakefulness (W); however, the molecular mechanisms operating within the PPT to regulate these two behavioral states remain relatively unknown. Here we demonstrate that the levels of calcium/calmodulin kinase II (CaMKII) and phosphorylated CaMKII expression in the PPT decreased and increased with 'low W with high REM sleep' and 'high W/low REM sleep' periods, respectively. These state-specific expression changes were not observed in the cortex, or in the immediately adjacent medial pontine reticular formation. Next, we demonstrate that CaMKII activity in the PPT is negatively and positively correlated with the 'low W with high REM sleep' and 'high W/low REM sleep' periods, respectively. These differences in correlations were not seen in the medial pontine reticular formation CaMKII activity. Finally, we demonstrate that with increased PPT CaMKII activity observed during high W/low REM sleep, there were marked shifts in the expression of genes that are involved in components of various signal transduction pathways. Collectively, these results for the first time suggest that the increased CaMKII activity within PPT neurons is associated with increased W at the expense of REM sleep, and this process is accomplished through the activation of a specific gene expression profile.     

Epigenetic dysregulation of the dopamine system in diet-induced obesity

Chronic intake of high-fat (HF) diet is known to alter brain neurotransmitter systems that participate in the central regulation of food intake. Dopamine (DA) system changes in response to HF diet have been observed in the hypothalamus, important in the homeostatic control of food intake, as well as within the central reward circuitry [ventral tegmental area (VTA), nucleus accumbens (NAc), and pre-frontal cortex (PFC)], critical for coding the rewarding properties of palatable food and important in hedonically driven feeding behavior. Using a mouse model of diet-induced obesity (DIO), significant alterations in the expression of DA-related genes were documented in adult animals, and the general pattern of gene expression changes was opposite within the hypothalamus versus the reward circuitry (increased vs. decreased, respectively). Differential DNA methylation was identified within the promoter regions of tyrosine hydroxylase (TH) and dopamine transporter (DAT), and the pattern of this response was consistent with the pattern of gene expression. Behaviors consistent with increased hypothalamic DA and decreased reward circuitry DA were observed. These data identify differential DNA methylation as an epigenetic mechanism linking the chronic intake of HF diet with altered DA-related gene expression, and this response varies by brain region and DNA sequence.     

Microarray analysis of the developing rat mandible

To analyze the molecular events that occur in the developing mandible, we examined the expression of 8803 genes from samples taken at different time points during rat postnatal mandible development. Total RNA was extracted from the mandibles of 1-day-old, 1-week-old, and 2-week-old rats. Complementary RNA (cRNA) was synthesized from cDNA and biotinylated. Fragmented cRNA was hybridized to RGU34A GeneChip arrays. Among the 8803 genes tested, 4344 were detectable. We identified 148 genes with significantly increased expression, and 19 genes with significantly decreased expression. A comprehensive analysis appears to be an effective method of studying the complex process of development.     

大鼠脑组织中胆囊收缩素基因表达与发育的关系

研究CCK基因在不同日龄大鼠脑中转录水平上的表达。取出生后不同日龄Wistar大鼠脑组织,提取总RNA,甲醛凝胶电泳,Northern印迹与α-32P标记CCKcDNA的探针杂交,放射自显影后,经激光扫描测定自显影图中斑点光密度,以估量CCKmRNA表达的相对水平。结果表明,刚出生的大鼠脑中CCK的mRNA含量甚低,随着鼠龄增长,浓度增高,20日龄时CCKmRNA浓度急剧升高,40日龄CCKmRNA的水平稍降低。CCK基因在转录水平的表达与个体发育有关。 Abstract：In this paper the clone was used as probe to study its expression for revealing the relationship between the level of CCK mRNA and the brain development.Total RNA from Wistar rats of various stages of development was isolated by acid guanidinium-thiocyanate phenol-chloroform extraction,followed by formaldehyde gel-electrophoresis.Northern blot,hybridization with a32P-labeled CCK cDNA probe,autoradiography and quantitation were performed by the laser density scanning.It was concluded from the results that the quantites of CCK mRNA in rat brain increased during development.From those mentioned above,it can be said that brain CCK mRNA may serve as a marker for the brain development.     

大鼠急性分离下丘脑神经元的自发性放电特性

目的和方法：采用电流钳技术,观察SD大鼠急性分离下丘脑神经元的自发性放电。结果：放电形式包括不放电、连续的单个放电和簇状放电等3种,但放电过程中出现一些阈下电位,这些闯下电位会明显影响神经元的放电过程,使放电表现为规则或不规则,规则放电通常由缓慢的去极化电位触发,而不规则放电常出现较多的阈下电位。结论：急性分离神经元具有与脑片和培养神经元不完全相同的放电特性,对此展开研究,有利于揭示下丘脑参与机体稳态的调控机制。     

体外培养的人牙胚上皮细胞的成釉分化

人表皮干细胞可以作为牙齿再生中上皮源性的种子细胞,但是其成釉分化的效率低下. 本研究分离培养了人牙胚上皮细胞,利用E13.5的小鼠牙间充质与其重组,构建重组牙胚,对其成釉分化的潜能和机制进行研究. 研究结果发现,体外培养的P1代人牙胚上皮细胞成釉率高达50%. 随着传代次数的增加,成釉率明显下降. 通过对牙上皮发育分化相关基因的表达检测和分析表明,重组牙胚成牙分化能力和成釉潜能的下降与牙上皮发育相关基因的表达状态密切相关. 特别是FGF8表达水平的下调以及PITX2不同亚型在人牙胚细胞中表达量的不均衡,可能是导致人牙胚细胞成釉潜能下降并丧失的主要原因. 本研究结果为理解牙齿再生过程中上皮源性的种子细胞的成釉机制提供了新的实验数据,对进一步提高表皮干细胞在牙齿再生过程中的成釉率有指导意义.     

Superior Colliculus GABAergic Neurons Are Essential for Acute Dark Induction of Wakefulness in Mice

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脂肪细胞分化作用及其分子调控机理

肥胖症是影响人类健康的严重问题之一。在过去的十年中,对脂肪细胞的生物功能和分化作用的分子机理的了解方面取得了突破性的进展。脂肪组织不仅是被动的能量贮存场所,同时还是能够分泌多种生物活性物质的器官。已发现多种能调节脂肪细胞分化的转录因子。看来Ｃ／ＥＢＰα和ＰＰＡＲγ很可能是调节这种分化过程的主控基因。     

Association analysis between feed efficiency studies and expression of hypothalamic neuropeptide genes in laying ducks

Residual feed intake (RFI) is now considered a more reasonable metric to evaluate animal feed efficiency. In this study, the correlation between RFI and other feed efficiency traits was investigated and gene expression within the hypothalamus was determined in low RFI (LRFI) and high RFI (HRFI) ducks. Further, several hypothalamic neuropeptide genes were measured using quantitative real‐time PCR. The mean feed intake value was 160 g/day, whereas the egg mass laid (EML) and body weight were approximately 62.4 g/day and 1.46 kg respectively. Estimates for heritability of RFI, feed conversion ratio (FCR) and feed intake were 0.26, 0.18 and 0.23 respectively. RFI is phenotypically positively correlated with feed intake and FCR (P < 0.01). The expression of neuropeptide Y (NPY) and neuropeptide Y receptor Y5 (NPY5R) mRNA was higher in HRFI ducks compared with LRFI ducks (P < 0.05), whereas that of proopiomelanocortin (POMC), melanocortin 4 receptor (MC4R) and cholecystokinin (CCK) was lower (P < 0.05). The mRNA expression of gonadotropin‐releasing hormone 1 (luteinizing‐releasing hormone) (GNRH1) and prolactin receptor (PRLR) was unchanged between LRFI and HRFI ducks. The results indicate that selection for LRFI could reduce feed intake without significant changes in EML, whereas selection on FCR will increase EML.     

Calcium Signalling in Rat Brain Neurons and Differentiation of PC-12 Cells Induced by Application of a Probiotic Product

The effects of a biotechnological probiotic product, PP, produced by food fermentation with Lactobacilli (US patent approved), on the growth of neurites in rat pheochromocytoma cells (PC-12) and on calcium responses of rat brain neurons were studied in culture. The PP increased the length of neurites in PC-12 cells, resulting in an irreversible differentiation of cancerous cells into neuron-like structures. Moreover, a change in the neurotransmitter phenotype of differentiated cells was found; some cells, such as excitatory neurons, began to respond to glutamate application by increasing [Ca²⁺] _i . The PP directly activated PC-12 cells and neurons by the release of Ca²⁺ from the intracellular stores in a steady manner. The PP also stimulated the entry of Ca²⁺ into the cells in a Ca²⁺ add-back protocol, which was considerable upon washing out of PP. Thus, the products of Lactobacillus metabolism, such as those in PP, can act as a neuronal growth factor and manifest clear pharmacological reactions at the cellular level. By comparison, commercial lyophilized probiotic bacteria also induced a Ca²⁺ rise in neurons, but not in PC-12 cells. Some neurons did not respond to probiotic bacteria, and some neurons responded with some delay. Upon wash out of probiotic bacteria, a huge entry of Ca²⁺ into the cells was observed. Neirofiziologiya/Neurophysiology, Vol. 37, No. 3, pp. 284–293, May–June, 2005.     

逍遥散对慢性束缚应激模型大鼠相关脑区CRF基因表达的影响

目的:观察慢性束缚应激大鼠相关脑区CRF mRNA(下丘脑、垂体、海马、皮层)含量变化以及逍遥散对其影响.方法:用RT-PCR和图像分析方法测定相关脑区CRF mRNA含量变化.结果:应激组较正常对照组在下丘脑CRF-1基因表达下调(P<0.01).在下丘脑逍遥散组较应激组CRF-1基因表达显著下调(P<0.01),CRF-2基因表达显著上调(P<0.01);在海马区逍遥散组CRF-2基因表达较模型组上调(P<0.05);在皮层逍遥散组CRF-1基因表达较应激组则显著上调(P<0.01).结论:逍遥散组对慢性束缚应激中枢神经肽CRF的调节位点在下丘脑、垂体、海马和皮层,充分证实逍遥散的调节靶点与下丘脑、边缘系统及皮层中枢有关.