Leptin transiently antagonizes ghrelin and long-lastingly orexin in regulation of Ca^(2+) signaling in neuropeptide Y neurons of the arcuate nucleus

AIM： To explore the mechanism for interactions of leptin with ghrelin and orexin in the arcuate nucleus （ARC） activating neuropeptide Y （NPY） neurons during physiological regulation of feeding, METHODS： Single neurons from ARC of adult rats with matured feeding function were isolated. [Ca2＋]i was measured to monitore their activities. The time course of leptin effects on ghrelin-induced versus orexin-induced [Ca2＋]i increases in NPY neurons was studied. RESULTS： Administration of ghrelin or orexin-A at 101~ mol/L increased cytosolic Ca2~ concentration （[Ca2＋]~） in NPY neurons isolated from the ARC of adult rats. Upon administration of leptin at 10^-14-10^-12 mol/L, ghrelin-induced [Ca2＋]i increases were initially （〈 10 min） inhibited but later restored, exhibiting a transient pattern of inhibition. In contrast, orexin-induced [Ca2＋]i increases were inhibited by leptin in a long- lasting manner. Furthermore, a prior administration of leptin inhibited orexin action but not ghrelin action to increase ICa 2＋li, CONCLUSION： Leptin counteracted ghrelin effects transiently and orexin effects long-lastingly in NPY neurons. The transient property with which leptin counteracts ghrelin action in NPY neurons may allow the fasting-associated increase in ghrelin levels to activate NPY neurons in the presence of physiological leptin and to stimulate feeding.

Role of Nociceptive Arcuate Nucleus Neurons in Chloroquine-induced Pruritic Behaviors in Mice

Despite its clinical importance, the underlying central mechanisms of pruritic behaviors are poorly understood. To investigate the role of nociceptive arcuate nucleus neurons in chloro-quine-induced pruritic behaviors in mice, we tested the effect of arcuate nucleus neurons and interscapular brown adipose tissue (IBAT) on itch produced by intradermal injection of chloroquine in the nape of the neck. Our results provide several lines of evidence for an important role of nociceptive arcuate nucleus neurons in chloroquine-induced pruritic behavior: (1) Intradermal microinjection of chloro-quine resulted in a dramatic increase in itch behaviors accompanied by the activation of c-Fos positive neurons in arcuate nucleus; (2) Microinjection of chloroquine significantly increased IBAT temperature in the mice. These findings suggested that chloroquine-induced pruritic behaviors were associated with the activity of nociceptive arcuate nucleus neurons.

Modulation of hypothalamic arcuate nucleus on gastric motility in rats

AIM To investigate whether the arcuate nucleus (ARC) could modulate gastric motility, and if so, what are the mechanisms or pathways.METHODS Wistar rats, anaesthetized with urethan, parameters of stimulation and electrolytic lesion sites were determined according to the Paxinos and Watson 'ATLAS of rat brain in steriotaxic coordinate'. Intragastric pressure (IGP) and gastric motility were measured by Reybould′s method.RESULTS Electrical stimulation of ARC could obviously decrease the IGP by 42.2%±5.4%, n=15, P＜0.01, and the phasic gastric contractions disappeared. The analysis showed that the locus coeruleus (LC) and dorsal raphe (DR) nuclei may be involved in central, but without the invovement of β-endorphinergic neurons rich in the ARC, while in periphery, the peripheral neural pathways are both vagus and sympathetic nerves. The fibers in vagus may be non-cholinergic. Humoral factors may also be involved. At the receptor level, Tonic action of adrenergic nerve in the stomach is mainly inhibitory; β-receptors, which may be present on the stomach wall and mediate inhibition; and α-receptors, which come into play through vagus, mediate inhibition, but those present on the smooth muscle mediate sympathetic excitation. Microinjection of TRH into ARC could significantly increase the IGP by 183.02% (0.53kPa±0.08kPa vs 1.5kPa±0.6kPa, n=10, P＜0.001), the rate and amplitude of phasic gastric contraction were also increased (3cpm vs 6cpm-8cpm). The peripheral pathway of such excitatory effects were transmitted with cholinergic vagus nerve mediated by M-receptor.CONCLUSION ARC could modulate gastric motility biphasically, inhibitory and excitatory, depending on the nature of stimuli.

Changes in beta-endorphin neuron numbers and serum hormone levels in the arcuate nucleus of ovariectomized rats undergoing treadmill exercise

BACKGROUND： The arcuate nucleus, when damaged in young rats, can lead to pathological changes in adults, such as osteoporosis. Ovariectomized rats suffer from osteoporosis at eight weeks following surgery and the number of β -endorphin immunoreactive neurons in the arcuate nucleus of the hypothalamus is significantly decreased. OBJECTIVE： To establish a rat model of osteoporosis using ovariectomy and to explore changes in the number of β-endorphin neurons and to correlate any such change with serum hormone levels in response to exercise or rest. DESIGN, TIME AND SETTING： The completely randomized block design, neural morphology study was performed at the Key Laboratory of Physiology, Guangdong Medical College, China between March 2004 and January 2005. MATERIALS： Sixteen healthy female rats were selected for ovariectomy. METHODS： Following model establishment, rats were assigned to either rest or exercise groups and each rat was housed individually. Rats in the exercise group underwent an exercise regimen using a treadmill. MAIN OUTCOME MEASURES： Eight weeks following exercise, radioimmunoassay was performed to detect serum growth hormone, estrogen and osteocalcin levels. Immunohistochemistry was used to measure changes in the number of β -endorphin neurons in the arcuate nucleus of the hypothalamus. Changes in bone metabolism were assessed using bone histomorphometry. RESULTS： In the exercise group, the β -endorphin immunoreactive neurons were high in number, darkly stained, and the nucleus was not obvious. In the rest group, the β -endorphin immunoreactive neurons were low in number and lightly stained. The number of β-endorphin immunoreactive neurons in the exercise group was higher compared with the rest group （t = 2.83, P 〈 0.05）. Estrogen levels were similar between the rest and exercise groups （P 〉 0.05）. Serum osteocalcin and growth hormone levels were significantly higher in the exercise group compared with the rest group （t = 2.78, 2.32, P 〈 0.05）. Compared with the rest group, the percentage of trabecular bone area, trabecular thickness, and trabecular number were significantly increased, but trabecular separation was significantly reduced （t=2.48, 2.57, 2.32, 3.06, P 〈 0.05） in the exercise group. In the exercise group, the trabeculae of the tibia were arranged regularly and were high in number. In the rest group, the trabeculae of the tibia were organized in a disorderly manner and were low in number, with many fat particles. CONCLUSION： Exercise promotes bone growth and delays osteoporosis by inducing an increase in the number of β-endorphin immunoreactive neurons in the arcuate nucleus of the hypothalamus and by increasing serum growth hormone and osteocalcin levels.

TEMPORAL ALTERATIONS OF PROOPIOMELANOCORTIN mRNA LEVEL IN RAT HYPOTHALAMIC ARCUATE NUCLEUS FOLLOWING ELECTROACUPUNCTURE

Alterations of proopiomelanocortin (POMC) rnRNA level in the hypothalamic arcuatenucleus were studied in rats grouped under 6h, 24h l 72h, 96h and 96h (EAX2 ) after elec-troacupuncture(EA) using rnolecular hybridization techniques. It was found that after EA, the levelof POMC mRNA rose significantly (P【0.001 ), a maximun being in the 72h group and declining inthe 96h group. In the 96h (EAX2 ) group, where EA was given at the beginning of the 72nd hour after the first one, instead of declining, the mRNA leve1 rose again. The findings may provide an expla-nation for the long postueffect of EA and its accumulation.

Changes in neuropeptides related to food intake in the rat arcuate nucleus after chronic immobilization stress and the effect of comfortable music exposure

Stress is an inevitable interference factor that seriously affects health.Listening to music is an economical,noninvasive,and highly accepted tool for easing stress.However,physiological studies investigating the ability of music to reduce stress in daily life are limited.We established rat models of chronic immobilization stress(CIS)to observe changes in the hypothalamic arcuate nucleus(ARC)neurons involved in the regulation of food intake and the effect of comfortable classical music exposure.Twenty-one days of stress resulted in decreased food intake and delayed body weight gain,up-regulation of leptin receptor(Ob-R),cocaine-and amphetamine-regulated transcript(CART),proopiomelanocortin(POMC),and alpha-melanocyte-stimulating hormone(α-MSH)expression,and downregulation of neuropeptide Y(NPY)and agouti-related protein(AgRP)expression in the ARC.Thus,peripheral leptin entered the ARC under chronic stress conditions,bound to Ob-R,and affected downstream nerve pathways related to appetite,such as the NPY/AgRP and CART/POMC pathways.Gentle classical music played at 65 dB reversed the abnormal expression of Ob-R and NPY induced by chronic stress.Thus,listening to comfortable music improves changes in ARC neurons related to the regulation of food intake in CIS rats,and these results provide a reference for basic research regarding how music therapy alleviates stress and stress-related health issues.

A preliminary analysis of arcuate structures-relationship of the island arc and deep-sea trench to the dip angle of Benioff zone

The origin of arcuate islands and deep-sea trenches has been studied for a long time and various interpretations have been proposed. In this paper, some analytical models are put forward from a geometrical viewpoint and then the theoretical dip angles of the underthrusting slabs of circum-Pacific island arcs are computed and compared with those of the Benioff zone. As a result, it is found that the dip angle of the underthrusting slab is one of the main factors determining the curvature of the arcuate structure. The authors consider that this result may contribute to the plate theory.

性激素反馈调节下丘脑ARC和AVPV中kisspeptin-GPR54信号通路的核团差异

下丘脑-垂体-性腺(HPG)轴是调控生殖系统的发育和功能的重要内分泌系统。下丘脑中促性腺激素释放激素(GnRH)神经元,能够接收各种神经传导物质和神经调节物质的信号输入,引起HPG轴的级联反应。下丘脑弓状核(ARC)和前腹侧脑室周围核团(AVPV)中的kisspeptin-GPR54信号通路,可以调控GnRH的分泌和释放,影响性腺激素的分泌。近年来研究发现,性激素能够对下丘脑kisspeptin-GPR54信号通路产生反馈调节,且具有核团差异性。本文就性激素在下丘脑ARC和AVPV中对kisspeptin-GPR54信号通路反馈调节的差异性进行了综述,探讨下丘脑中不同核团对性激素刺激作用产生的不同反应。

Expression of Kisspeptin/kiss1r System is Down-regulated in the Hypothalamic Arcuate Nucleus of Pubertal Male Rats with High-fat-diet

Objective To explore the potential function of nutrition on kisspeptin/kisspeptin receptor （kisslr） system in the arcuate nucleus （ARC） of male rats. Methods Pregnant rats were obtained and male pups were used to establish obesity model. Body parameters and blood samples were evaluated. Immunohistochemistry was used to determine the localizations and protein levels of kisspeptin, kisslr, and leptin receptor （LepR） immunoreactivity （IR） in ARC. QRT-PCR was used to determine kissl-, kisslr-, LepR-, and GnRH-mRNA levels. Results The establishment of obesity model was successful as body parameters and hormones levels changed noticeably. Kisspeptin-, kisslr-, and LepR-IR were detected and protein levels decreased significantly in high-fat-diets （HFD） rats than controls. The mRNA levels of kissl, LepR and GnRH significantly decreased in the ARC of HFD-fed rats. No difference was observed in kisslr mRNA levels between the two groups. Conclusion These data suggest that failure to increase GnRH levels with HFD may be associated with pubertal down-regulation of LepR and kisspeptin/kisslr system in the ARC of male rats.

The Vertical Deformation and Horizontal Displacement Fields,Movement, and Seismicity of the Island Arc Tectonics

In this work,the vertical deformation,horizontal displacement,and stress fields of arcuate tectonics are theoretically derived from the horizontal tectonic stress; then the characteristics of tectonic movement,seismicity,and focal mechanism of arcuate tectonics of the entire world are explained.It is pointed out that the island arc and other arcuate tectonics are gradually developed under the displacement and stress fields of the arcuate tectonics and that the under-thrusting action of the ocean plate is secondary.The distance formulas between the volcanic arc and the trench are suggested and also that theoretical results are consistent with actual data.

淫羊藿苷对去卵巢大鼠骨和下丘脑不同核团ERβ mRNA表达的影响

目的观察淫羊藿苷对去卵巢大鼠骨和下丘脑不同核团ERβmRNA表达的影响,探讨其治疗绝经后骨质疏松的作用机制。方法将10～11月龄SD♀大鼠60只,随机分为假手术组、去卵巢模型组、淫羊藿苷小、中、大剂量组(每组12只)。以双侧卵巢切除法建立大鼠骨质疏松模型。分别用淫羊藿苷小、中、大剂量给药4个月,采用RT-PCR法,观察各组大鼠骨和下丘脑室旁核、视上核、弓状核ERβmRNA表达的变化。结果大鼠卵巢切除后,血清E2水平、椎骨骨密度、子宫湿重、胫骨和下丘脑弓状核ERβmRNA表达明显降低(P<0.01),下丘脑室旁核、视上核ERβmRNA表达均明显升高(P<0.01)。与去卵巢模型组比较,淫羊藿苷50.0和100.0 mg.kg-1组治疗后,血清E2水平、椎骨骨密度、胫骨和下丘脑弓状核ERβmRNA表达明显升高(P<0.01),下丘脑室旁核、视上核ERβmRNA表达均明显降低(P<0.01),子宫湿重无明显改变(P>0.05)。结论淫羊藿苷可以改善切除卵巢所致的骨质疏松大鼠的骨密度,对子宫无不良反应。其机制可能与其选择性调节去卵巢骨质疏松大鼠下丘脑不同核团ERβmRNA表达水平有关,调节下丘脑功能活动是其途径之一。

东营河125断层几何学特征及其对浊积扇和油藏的控制作用

通过对河125断层几何学特征的分析发现弧形断裂平行于断层走向剖面上表现为断槽、断脊组合;垂直于断层走向剖面上断层分为竖滑段、倾滑段和平滑段3段,生长指数规律为弧中大于弧翼,断层倾角规律为弧中小于弧翼。断裂的几何学特征与运动学特征具有相关性。断层几何学特征对浊积扇具有重要的控制作用:平面上,弧中位置浊积扇最发育,弧翼为不同浊积扇的分界线;断槽为浊积砂体的补给通道,断脊为扇体不同补给区的分水岭;垂向上,倾滑段下部发育远岸浊积扇,中上部发育滑塌浊积岩,形成典型的弧扇对应现象。断层对油藏的控制表现为:控制储层展布、改善储层物性、沟通油源和形成生长背斜及断鼻油气藏。

新生期注射谷氨酸单钠对大鼠骨骼的影响

目的:探讨下丘脑弓状核对大鼠骨骼的影响。方法:用损毁弓状核(ARC)的方法,将SD大鼠于出生后第1、3、5、7、9 d皮下注射10%谷氨酸单钠(MSG)4 g/kg bw,对照组同法注射等体积生理盐水,存活至第200 d处死,剥净左侧股、胫、肱、桡、尺骨,测其重量、长度、横长径、横短径、体积。下丘脑作石蜡切片,HE染色,光镜观察ARC神经元,并用图像分析仪计算ARC神经细胞数。用放免法测血清中GH(生长素),E2(雌二醇)含量。结果:MSG大鼠弓状核神经细胞数量显著减少,股、胫、肱、桡、尺骨的重量、长度、横长径、横短径、体积都明显减少,与对照组比较差异非常显著(P<0.01)。但单位体积骨重量(g/cm3)与对照组差异不显著。血清GH、E2显著降低。结论:提示下丘脑弓状核通过调节与骨代谢有关的激素参与全身骨骼生长发育的调控。

新生期大鼠注射谷氨酸单钠后导致骨质疏松

目的 观察新生期大鼠注射谷氨酸单钠破坏下丘脑弓状核对 SD大鼠骨骼生长、发育的影响。方法和结果 新生期 SD大鼠腹腔注射谷氨酸单钠 ,饲养至 10 0天 ,可导致下丘脑弓状核细胞数量明显减少 ,身长明显短于对照鼠 ;实验组胫骨长为 3.69± 0 .19cm(平均数±标准误 ) ,对照组为 4 .4 6±0 .18cm,二组比较 ,P<0 .0 1;骨骼生长发育障碍、骨小梁明显破坏 ,出现明显骨质疏松。结论 提示下丘脑弓状核参与骨骼生长。

均布压力作用下圆弧双铰拱对称和反对称失稳的折迭突变和尖点突变模型

建立了径向均布压力作用下圆弧双铰拱正对称失稳和反对称失稳的折迭和尖点突变模型，模型可以很好地描述这两个失稳过程的各种性态，求解拱失稳时的临界荷载，给出拱屈曲后路径与荷载的初步关系。

断层几何学特征及对浊积岩的控制作用

为解释断层下降盘浊积砂体横向不均一的控制机理,从河125断层几何特征入手,剖析了断层形态与浊积砂体的关系,发现弧形断裂平行于断层走向剖面上为断槽、断脊组合;在垂直于断层走向剖面上断层可分为竖滑段、倾滑段和平滑段三段。生长指数规律为弧中大于弧翼;H/L指数为弧中小于弧翼。断裂的几何学特征与动力学、运动学特征具有相关性,断裂不同位置几何学特征的不同反映了断裂动力学、运动学特征的差异。断层对浊积岩具有重要的控制作用:弧中对应浊积扇最发育区,弧翼为不同浊积扇的分界线;断槽为浊积砂体的补给通道;断脊为扇体不同补给区的分水岭,形成了典型的弧扇对应现象。

弓状核内微量注射赛庚啶与电针足三里抑制胃运动

目的:探讨弓状核(ARC)内微量注射赛庚啶(Cyp)与电针足三里穴调节胃运动的关系。方法:将健康的家兔随机分为5组:对照组、插管组、生理盐水(NaCl)组、5 -HT组、Cyp组。采用霍耳效应原理慢性记录胃运动的变化。结果:在ARC内埋值不锈钢插管,及通过插管向ARC内注入2 μl生理盐水,均不影响电针的抑制的效应。向ARC内注入5 -HT 1μg/ 2 μl时,则电针的抑制效应增强;而向ARC内注入赛庚啶8μg/ 2 μl却明显减弱电针的抑制效应。结论:ARC内的5 -HT可能通过5 -HT2 受体起加强电针抑制胃运动的效应。

岛弧构造的垂直形变场与水平位移场及其构造运动和地震活动特征

本文根据水平构造应力作用，推导了弧形构造的理论垂直形变场、水平位移场和应力场，进而对全球性的岛弧构造带在构造运动、地震活动和震源机制等方面的特征给出了新的解释；提出岛弧等弧形构造主要是在弧形构造位移场、应力场作用下逐渐形成的，而大洋板块的俯冲作用是次要的。

四川盆地中新生代未发生旋转的古地磁证据

四川盆地中生代以来沉积中心经历弧形迁移,盆地是否发生旋转具有争议。根据古地磁数据计算古纬度表明,四川盆地晚二叠世以来主要经历了大规模北向漂移、南向漂移、快速北向漂移过程。以现有精度古地磁数据分析表明,四川盆地中生代以来,其相对于欧亚大陆、扬子地块旋转量都小于数据本身的误差值,相对于欧亚大陆和扬子地块都没有有效意义的旋转。综合分析认为,四川盆地中新生代沉积中心的弧形迁移,反映了周缘造山带不同时期的构造活动对四川盆地沉降及沉积的控制。

弓状核内微量注射5-羟色胺加强电针抑制胃运动

目的 :探讨弓状核 (ARC)内注射微量 5 -HT对电针足三里穴调节胃运动的影响。方法 :采用霍耳效应原理慢性记录胃运动的变化。结果 :通过ARC内埋植不锈钢插管注入 2 μl生理盐水 ,不影响电针的抑制效应 ;而向ARC内注入 5 -HT1μg/ 2 μl时 ,则电针的抑制效应增强。结论 :ARC内微量注射 5 -HT增强电针对胃的抑制 ,ARC内的 5 -HT可能参与电针对胃的抑制效应。