Differences in central noradrenergic and behavioural responses of Maudsley non-reactive and Maudsley reactive inbred rats on exposure to an aversive novel environment

The present experiments compared the noradrenaline and behavioural responses of inbred Maudsley reactive (MR) and non-reactive (MNRA) rats when they are exposed to the light or dark arena of a light/dark shuttle-box. Behavioural scores confirmed that both strains of rats perceived the light arena to be more aversive than the dark one. Using in vivo microdialysis, exposure to the light, but not the dark, arena was found to increase noradrenaline efflux in both the frontal cortex and the hypothalamus of MNRA and MR rats. However, whereas the increase in the frontal cortex of both strains and the hypothalamus of MR rats was transient, the hypothalamic response in MNRA rats was maintained throughout exposure to the test zone. Strain differences in activity/visit and time/visit were evident but it was not possible to discern whether this could be attributed to the strain difference in the hypothalamic noradrenaline response. Nevertheless, it remains possible that, by comparison with MR rats, the prolonged noradrenaline response in the hypothalamus of MNRA rats could contribute to their well-documented, greater resistance to aversive environmental stimuli.     

下丘脑局部损毁对大鼠双侧催产素神经元爆发放电的影响

为探究授乳大鼠双侧下丘脑巨细胞催产素神经元同步化射乳反射爆发放电的中枢所中,我们采用双微电极细胞外记录技术,观察了选择性脑切割损毁后的大鼠双侧视上核内催们素神经元在仔鼠吸吮刺激下射乳反射爆发放电。结果显示：在腹侧这画以上横向民单侧中脑中部,不同能阻断双侧催产素神经元的同步化爆发放 单侧下丘脑中间内侧部横切则可阻断这种经爆发放电。这些结果表明;中脑中部至一丘脑中部这一脑区在双侧视上核内催产素神经元的     

Mining Microarrays for Metabolic Meaning: Nutritional Regulation of Hypothalamic Gene Expression

DNA microarray analysis has been used to investigate relative changes in the level of gene expression in the CNS, including changes that are associated with disease, injury, psychiatric disorders, drug exposure or withdrawal, and memory formation. We have used oligonucleotide microarrays to identify hypothalamic genes that respond to nutritional manipulation. In addition to commonly used microarray analysis based on criteria such as fold-regulation, we have also found that simply carrying out multiple t tests then sorting by P value constitutes a highly reliable method to detect true regulation, as assessed by real-time polymerase chain reaction (PCR), even for relatively low abundance genes or relatively low magnitude of regulation. Such analyses directly suggested novel mechanisms that mediate effects of nutritional state on neuroendocrine function and are being used to identify regulated gene products that may elucidate the metabolic pathology of obese ob/ob, lean Vgf-/Vgf-, and other models with profound metabolic impairments.     

Isoforms of Aldehyde Dehydrogenase in the Brain Structures of Rats with Different Inclinations to Ethanol Consumption

We measured the levels of activity of aldehyde dehydrogenase (AdhDH, EC 1.2.1.3) manifested at different concentrations of acetaldehyde (AcAdh) in cytosol fractions from the tissues of the hypothalamus, midbrain, and neocortex of rats preferring an ethanol solution or pure water as liquids for drinking (ethanol- and water-preferring, EP and WP groups, respectively). Two AdhDH isoforms, with a high and a low affinity for AcAdh, were identified in the above brain structures. An AdhDH-1 isoform characterized by a higher affinity for AcAdh and a low value of the apparent Michaelis constant (K _m) was found in all studied brain structures of the EP rats. An analogous AdhDH-1 isoform found in cytosol fractions from the hypothalamus and midbrain of the WP rats showed a lower affinity for AcAdh and provided a lower maximum rate of reaction (V _max). In the neocortex cytosol fractions of the rats of this group, AdhDH-1 could not be identified. In EP rats, the level of AcAdh metabolism mediated by AdhDH was noticeably higher in cytosol fractions from the hypothalamus and midbrain, as compared with that in the respective fraction from the neocortex.     

NO调控下丘脑钙激活钾通道的机制研究

目的 :研究NO对下丘脑神经元钙激活钾通道 (KCa)的作用及其机制。方法 :采用膜片钳技术内面向外式及细胞贴附式。结果 :NO可直接或通过升高cGMP来提高KCa通道的开放概率 (Po) ,这种增强作用是因为通道开放时间延长及开放频率增加。结论 :下丘脑神经元中NO可通过不同机制激活KCa。     

Involvement of Accessory Neurosecretory Nuclei of Hypothalamus in the Formation of Hypothalamohypohysial System during Prenatal and Postnatal Development in Rats

We studied the development of direct axonal connections of the accessory neurosecretory hypothalamic nuclei with the posterior pituitary lobe on the fixed rat brain from day 15 of embryogenesis until day 10 of postnatal development using the retrograde diffusion method of the lipophilic fluorescent carbocyanine dye 1,1"-dioctadecyl-3,3,3",3"-tetramethylindocarbocyanine perchlorate along the neuronal membranes. The marker was applied onto the posterior pituitary lobe and, after incubation in a fixative, fluorescing bodies of nerve cells were visualized in the hypothalamus. Neuronal axons of the retrochiasmatic nucleus were the first of the accessory nuclei to ingrow in the posterior pituitary lobe (on days 16–17 of embryogenesis). Neurons of the circular and dorsolateral nuclei and the nuclei of the median bundle of the forebrain sent their axons to the posterior pituitary lobe starting from the first days of postnatal development. No direct connections of the anterior commissure and perifornical accessory nuclei with the posterior pituitary lobe were found in perinatal development. These facts are discussed in the light of concepts about the different functional role of accessory peptidergic hypothalamic nuclei in rats.     

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.     

Differential distribution and regulation of OX1 and OX2 orexin/hypocretin receptor messenger RNA in the brain upon fasting

To further understand the functions of the orexin/hypocretin system, we examined the expression and regulation of the orexin/hypocretin receptor (OX1R and OX2R) mRNA in the brain by using quantitative in situ hybridization. Expression of OX1R and OX2R mRNA exhibited distinct distribution patterns. Within the hypothalamus, expression for the OX1R mRNA was largely restricted in the ventromedial (VMH) and dorsomedial hypothalamic nuclei, while high levels of OX2R mRNA were contained in the paraventricular nucleus, VMH, and arcuate nucleus as well as in mammilary nuclei. In the amygdala, OX1R mRNA was expressed throughout the amygdaloid complex with robust labeling in the medial nucleus, while OX2R mRNA was only present in the posterior cortical nucleus of amygdala. High levels of OX2R mRNA were also observed in the ventral tegmental area. Moreover, both OX1R and OX2R mRNA were observed in the hippocampus, some thalamic nuclei, and subthalamic nuclei. Furthermore, we analyzed the effect of fasting on levels of OX1R and OX2R mRNA in the hypothalamic and amygdaloid subregions. After 20 h of fasting, levels of OX1R mRNA were significantly increased in the VMH and the medial division of amygdala. An initial decrease (14 h) and a subsequent increase (20 h) in OX1R mRNA levels after fasting were observed in the dorsomedial hypothalamic nucleus and lateral division of amygdala. Levels of OX2R mRNA were augmented in the arcuate nucleus, but remained unchanged in the dorsomedial hypothalamic nucleus, paraventricular hypothalamic nucleus, and amygdala following fasting. The time-dependent and region-specific regulatory patterns of OX1R and OX2R suggest that they may participate in distinct neural circuits under the condition of food deprivation.     

Leptin：a multifunctional hormone

Leptin is the protein product encoded by the obese(ob) gene.It is a circulating hormone produced primarily by the adipose tissue.ob/ob mice with mutations of the gene encoding leptin become morbidly obese,infertile,hyperphagic,hypothermic,and diabetic.Since the cloning of leptin in 1994,our knowledge in body weight regulation and the role played by leptin has increased substantially.We now know that leptin signals through its receptor,OB-R,which is a member of the cytokine receptor superfamily.Leptin serves as an adiposity signal to inform the brain the adipose tissue mass in a negative feedback loop regulating food intake and energy expenditure.Leptin also plays important roles in angiogenesis,immune function,fertility,and bone formation.Humans with mutations in the gene encoding leptin are also morbidly obese and respond to leptin treatment,demonstrating that enhancing or inhibiting leptin‘s activities in vivo may have potential therapeutic benefits.     

慢病毒介导的下丘脑中过表达miR-505小鼠模型的构建

目的:本文用慢病毒定点注射的方法构建了在下丘脑中过表达mi R-505的小鼠模型,并利用荧光原位杂交方法在冰冻切片组织上快速检测mi RNAs,以确认慢病毒载体介导的mi R-505在丘脑中的表达能力。方法:实验小鼠在脑立体定位仪下定位到下丘脑位置,采用原位注射的方式进行慢病毒注射,注射后采用实时荧光定量RCR和应用了LNA探针和TSA系统的FISH(fluorescence in situ hybridization)技术,完成在慢病毒介导的mi R-505过表达老鼠下丘脑区域细胞中的mi R-505检测和示踪。结果:mi R-505慢病毒注射未成年小鼠下丘脑区5、10、20和40天后,均可检测到mi R-505在下丘脑区域的表达,且实验结果表明在慢病毒介导的过表达小鼠下丘脑注射部位,mi R-505表达量有明显的提高。结论:利用慢病毒注射未成年小鼠下丘脑脑区的方法,成功的建立了下丘脑中过表达mi R-505的小鼠模型,使用LNA标记探针的FISH方法探索mi RNA表达规律较稳定,且重复率高。