Hyperphagia and obesity of OLETF rats lacking CCK1 receptors: developmental aspects

Otsuka Long Evans Tokushima Fatty (OLETF) rats have a deletion in the gene encoding the cholecystokinin-1 (CCK1) receptor. This deletion prevents protein expression, making the OLETF rat a CCK1 receptor knockout model. Consistent with the absence of CCK1 receptors, OLETF rats do not reduce their food intake in response to exogenously administered CCK and consume larger than normal meals. This deficit in within-meal feedback signaling is evident in liquid as well as solid meals. Neonatal OLETF rats show similar differences in independent ingestion tests. Intake is higher and is reflected in greater licking behavior. Neonatal OLETF rats also have diminished latencies to consume and higher initial ingestion rats. Adult OLETF rats are hyperphagic and obese. Although arcuate nucleus peptide gene expression is apparently normal in OLETF rats, when obesity is prevented through pair-feeding to amounts consumed by control Long Evans Tokushima Otsuka (LETO) rats, dorsomedial hypothalamic NPY mRNA expression is significantly elevated in OLETF rats. NPY overexpression is also evident in preobese, juvenile OLETF rats suggesting a causal role for this overexpression in the hyperphagia and obesity. Running wheel exercise normalizes food intake and body weight in OLETF rats. When access to exercise is provided at a time when OLETF rats are obese, the effects are limited to the period of exercise. When running wheel access is available to younger, preobese OLETF rats, exercise results in long lasting reductions in food intake and body weight and improved glucose regulation. These lasting metabolic effects of exercise may be secondary to an exercise induced reduction in DMH NPY mRNA expression.     

Neuropeptide Y as a possible homeostatic element for changes in cortical excitability induced by repetitive transcranial magnetic stimulation

Background

Repetitive transcranial magnetic stimulation (rTMS) is able to modify cortical excitability. Rat rTMS studies revealed a modulation of inhibitory systems, in particular that of the parvalbumin-expressing (PV+) interneurons, when using intermittent theta-burst stimulation (iTBS).

与人体肥胖相关的神经肽Y受体Y2基因的克隆及序列分析

目的 克隆与肥胖相关的人神经肽Y受体Y2(NPY2R)基因,并鉴定该克隆基因序列的正确性.方法 从人的脂肪组织中提取总RNA并进行反转录,以此为模板用PCR扩增NPY2R基因的eDNA,然后与pET 28a+载体重组,筛选阳性克隆和DNA序列分析鉴定,测序后与GeneBank中NPY2R基因进行同源性比较和序列分析.结果 PCR扩增出一个1100 bp左右的DNA片段,与载体重组和DNA序列分析鉴定,DNA序列分析显示克隆的DNA片段是人NPY2R基因,且所克隆的基因共编码381个氨基酸,分子量为4.2 kD,与GeneBank中NPY2R基因序列同源性达100%.结论 克隆的人NPY2R基因与GeneBank中NPY2R序列完全一致,为进一步应用分子生物学技术深入研究NPY2R与人体肥胖发生、发展及转化等相关作用机制及应用该基因进行其基因蛋白表达奠定了基础.     

缺氧缺血性脑病患儿血清IL-6、TNF—α和NPY水平检测的临床意义

目的探讨缺氧缺血性脑病患儿血清IL-6、TNF—α和NPY水平检测的临床意义。方法应用放射免疫分析法对32例缺氧缺血性脑病患儿进行了血清IL-6、TNF-α和NPY水平测定,并与35名健康人作比较。结果缺氧缺血性脑病患儿血清IL-6、TNF—α和NPY水平非常显著地高于正常人组（P〈0．01）,且血清IL-6、TNF-α和NPY水平呈正相关（r=0．6045、0．5714．P〈0．01）。结论检测血清IL-6、TNF-α和NPY水平的变化对了解病情、观察预后均具有十分重要的临床价值。     

Obesity in neurobiology

Obesity reflects an imbalance between energy uptake and expenditure that is mediated by behavior. Obesity is a growing epidemic and a major risk factor for neurobiological diseases like stroke, dementia, intracranial hypertension and sleep disorders. Conversely, obesity can also be induced by neurobiological disorders and drugs. The etiology of obesity is complex and includes biology, behavior and environment. Physicians are faced with the need to manage obesity while strategies for prevention and sustained weight reduction are limited. Present treatment options comprise lifestyle modification, diet, pharmacotherapy and bariatric surgery. Considerable headway has been made into elucidating the neurobiological underpinnings of obesogenic behavior. There is now a growing understanding of the metabolic, hormonal and behavioral circuitries that contribute to the complex and redundant system for energy balance. Changing the net balance of this system to prevent or reduce obesity requires multimodal and long-term interventions.     

Leptin regulated calcium channels of neuropeptide Y and proopiomelanocortin neurons by activation of different signal pathways

The fat-derived hormone leptin regulates food intake and body weight in part by modulating the activity of neuropeptide Y (NPY) and proopiomelanocortin (POMC) neurons in the hypothalamic arcuate nucleus (ARC). To investigate the electrophysiological activity of these neurons and their responses to leptin, we recorded whole-cell calcium currents on NPY and POMC neurons in the ARC of rats, which we identified by morphologic features and immunocytochemical identification at the end of recording. Leptin decreased the peak amplitude of high voltage–activated calcium currents (I_HVA) in the isolated neurons from ARC, which were subsequently shown to be immunoreactive for NPY. The inhibition was prevented by pretreatment with inhibitors of Janus kinase 2 (JAK2) and mitogen-activated protein kinases (MAPK). In contrast, leptin increased the amplitude of I_HVA in POMC-containing neurons. The stimulations of I_HVA were inhibited by blockers of JAK2 and phosphatidylino 3-kinase (PI3-k). Both of these effects were counteracted by the L-type calcium channel antagonist nifedipine, suggesting that L-type calcium channels were involved in the regulation induced by leptin. These data indicated that leptin exerted opposite effects on these two classes of neurons. Leptin directly inhibited I_HVA in NPY neurons via leptin receptor (LEPR) –JAK2–MAPK pathways, whereas evoked I_HVA in POMC neurons by LEPR–JAK2–PI3-k pathways. These neural pathways and intracellular signaling mechanisms may play key roles in regulating NPY and POMC neuron activity, anorectic action of leptin and, thereby, feeding.     

Effects of single-prolonged stress on neurons and their afferent inputs in the amygdala

The amygdala modulates memory consolidation with the storage of emotionally relevant information and plays a critical role in fear and anxiety. We examined changes in neuronal morphology and neurotransmitter content in the amygdala of rats exposed to a single prolonged stress (SPS) as a putative animal model for human post-traumatic stress disorder (PTSD). Rats were perfused 7 days after SPS, and intracellular injections of Lucifer Yellow were administered to neurons of the basolateral (BLA) and central amygdala (CeA) to analyze morphological changes at the cellular level. A significant increase of dendritic arborization in BLA pyramidal neurons was observed, but there was no effect on CeA neurons. Neuropeptide Y (NPY) was abundant in BLA under normal conditions. The local concentration and number of immunoreactive fibers of NPY in the BLA of SPS-exposed rats were increased compared with the control. No differences were observed in this regard in the CeA. Double immunostaining by fluorescence and electron microscopy revealed that NPY immunoreactive terminals were closely associated with calcium/calmodulin II-dependent protein kinase (CaMKII: a marker for pyramidal neurons)-positive neurons in the BLA, which were immunopositive to glucocorticoid receptor (GR) and mineralocorticoid receptor (MR). SPS had no significant effect on the expression of CaMKII and MR/GR expression in the BLA. Based on these findings, we suggest that changes in the morphology of pyramidal neurons in the BLA by SPS could be mediated through the enhancement of NPY functions, and this structural plasticity in the amygdala provides a cellular and molecular basis to understand for affective disorders.