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Neuropeptide B/W receptor 1 (NPBWR1) is a G-protein coupled receptor, which was initially reported as an orphan receptor, and whose ligands were identified by this and other groups in 2002 and 2003. To examine the physiological roles of NPBWR1, we examined phenotype of Npbwr1-/- mice. When presented with an intruder mouse, Npbwr1-/- mice showed impulsive contact with the strange mice, produced more intense approaches toward them, and had longer contact and chasing time along with greater and sustained elevation of heart rate and blood pressure compared to wild type mice. Npbwr1-/- mice also showed increased autonomic and neuroendocrine responses to physical stress, suggesting that impairment of NPBWR1 leads to stress vulnerability. We also observed that these mice show abnormality in the contextual fear conditioning test. These data suggest that NPBWR1 plays a critical role in limbic system function and stress responses. Histological and electrophysiological studies showed that NPBWR1 acts as an inhibitory regulator on a subpopulation of GABAergic neurons in the lateral division of the CeA and terminates stress responses. These findings suggest important roles of NPBWR1 in regulating amygdala function during physical and social stress. [ABSTRACT FROM AUTHOR]

Abstract: Neuropeptide W (NPW) is a recently identified neuropeptide that binds to G-protein-coupled receptor (GPR) 7, which is highly expressed in several discrete regions of the rodent brain including the central amygdaloid nucleus and bed nucleus of the stria terminalis. Although several reports suggested that NPW is implicated in the regulation of energy homeostasis and nociception, the precise physiological role of NPW has remained unclear. In this study, we examined distribution of NPW messenger RNA and NPW immunoreactivity in the adult rat brain. NPW-immunoreactive (ir) cells were detected in the ventral tegmental area, periaqueductal gray, and Edinger–Westphal nucleus. NPW-ir fibers were observed in several brain regions, including the lateral septum, bed nucleus of the stria terminalis, dorsomedial and posterior hypothalamus, central amygdaloid nucleus, CA1 field of hippocampus, interpeduncular nucleus, inferior colliculus, lateral parabrachial nucleus, facial nucleus, and hypoglossal nucleus. NPW-ir fibers were most abundantly observed in the central amygdaloid nucleus and the bed nucleus of the stria terminalis, which are regions implicated in fear and anxiety. These results suggest that NPW might be involved in the regulation of stress and emotive responses, especially in fear and anxiety-related physiological and behavioral functions. [Copyright &y& Elsevier]

Summary Circadian behavior in mammals is orchestrated by neurons within the suprachiasmatic nucleus (SCN), yet the neuronal population necessary for the generation of timekeeping remains unknown. We show that a subset of SCN neurons expressing the neuropeptide neuromedin S (NMS) plays an essential role in the generation of daily rhythms in behavior. We demonstrate that lengthening period within Nms neurons is sufficient to lengthen period of the SCN and behavioral circadian rhythms. Conversely, mice without a functional molecular clock within Nms neurons lack synchronous molecular oscillations and coherent behavioral daily rhythms. Interestingly, we found that mice lacking Nms and its closely related paralog, Nmu , do not lose in vivo circadian rhythms. However, blocking vesicular transmission from Nms neurons with intact cell-autonomous clocks disrupts the timing mechanisms of the SCN, revealing that Nms neurons define a subpopulation of pacemakers that control SCN network synchrony and in vivo circadian rhythms through intercellular synaptic transmission. [ABSTRACT FROM AUTHOR]

Flk1 is one of the specific cell surface receptors for vascular endothelial growth factor and one of the most specific markers highlighting the earliest stage of hematopoietic and vascular lineages. However, recent new evidence suggests that these Flk1(+) mesodermal progenitor cells also contribute to muscle lineages. All evidence is based on the experiments using in vitro differentiation and in vivo transplantation systems. Although this approach revealed a differentiation potential range of Flk1(+) cells that is wider than previously expected, it fails to determine whether Flk1(+) cells contribute to muscle lineage as part of the normal developmental process. To obtain direct evidence for the fate of Flk1(+) cells in development, we used a knock-in mouse line where Cre is expressed in Flk1(+) cells. Studies with these Cre lines provide direct evidence that Flk1(+) cells are progenitors for muscles, in addition to hematopoietic and vascular endothelial cells., (Copyright 2003 Wiley-Liss, Inc.)