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  • 1
    Electronic Resource
    Electronic Resource
    Intraventricular Prolactin Inhibits Hypothalamic Vasoactive-Intestinal Polypeptide-Expression in Doves (1995)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neuroendocrinology 7 (1995), S. 0 
    Details
    ISSN: 1365-2826
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: While the role of prolactin in promoting the development of the crop-sac in members of the pigeon family (Columbiformes) is well established, its action in the central nervous system is less well understood. In the present study, prolactin was administered intracerebroventricularily (i.c.v.) in ring doves, and central expression of vasoactive-intestinal polypeptide (VIP) and gonadotropin-releasing hormone (GnRH), and the display of sexual behavior was investigated. Ovine-prolactin (1 μg in 2 μl o-prl) was injected daily for six days through chronically implanted cannula either prior to a 2-h period of courtship, or late in incubation. Control subjects were given vehicle injections and were otherwise identical to experimental animals. Prolactin administered prior to courtship resulted in a reduction of sexual behavior, and in a decrease in testicular weight but had no detectable effect on the number of neurons expressing VIP or GnRH. In contrast, i.c.v. prolactin during incubation resulted in a reduced number of infundibular VIP-positive neurons and decreased crop weight. We conclude that during incubation prolactin regulates its own synthesis and/or release by modulating VIP expression in infundibular neurons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2826.1995.tb00730.x
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  • 2
    Electronic Resource
    Electronic Resource
    Temporal and spatial expression patterns of canonical clock genes and clock-controlled genes in the suprachiasmatic nucleus (2004)
    Oxford, UK : Blackwell Science, Ltd
    European journal of neuroscience 19 (2004), S. 0 
    Details
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: In mammals, the suprachiasmatic nuclei (SCN) of the hypothalamus control endogenous circadian rhythms and entrainment to the environment. A core SCN region of calbindin (CalB)-containing cells is retinorecipient and the cells therein lack rhythmic expression of clock genes and electrical activity. The core is surrounded by a ‘shell’ of rhythmic oscillator cells. In the present experiments, we studied the spatial arrangement of oscillator cells by examining the spatial and temporal patterns of expression of the canonical clock genes Per1, Per2 and vasopressin mRNA, a clock-controlled gene. Surprisingly, in the SCN shell, the dorsomedial cells were the first to rhythmically express both Per1 and VP mRNA, with gene expression then spreading very slowly through much of the nucleus for the next 12 h then receding to baseline levels. Following a light pulse, Per expression increased after 1 h in the core SCN and after 1.5 h in the shell. Although expression in the shell occurred earlier in light-pulsed animals than in those housed in constant darkness, it still followed the same spatial and temporal expression pattern as was observed in constant darkness. The results suggest that not only is the SCN organized into light-responsive and rhythmic regions but also that the rhythmic region of the SCN itself has an ordered arrangement of SCN oscillator cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1460-9568.2004.03275.x
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  • 3
    Electronic Resource
    Electronic Resource
    Resetting the brain clock: time course and localization of mPER1 and mPER2 protein expression in suprachiasmatic nuclei during phase shifts (2004)
    Oxford, UK : Blackwell Science Ltd
    European journal of neuroscience 19 (2004), S. 0 
    Details
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The mechanism whereby brief light pulses reset the mammalian circadian clock involves acute Per gene induction. In a previous study we investigated light-induced expression of mPer1 and mPer2 mRNA in the suprachiasmatic nuclei (SCN), with the aim of understanding the relationship between gene expression and behavioural phase shifts. In the present study, we examine the protein products of mPer1 and mPer2 genes in the core and shell region of SCN for 34 h following a phase-shifting light pulse, in order to further explore the molecular mechanism of photic entrainment. The results indicate that, during the delay zone of the phase response curve, while endogenous levels of mPER1 and mPER2 protein are falling, a light pulse produces an increase in the expression of both proteins. In contrast, during the advance zone of the phase response curve, while levels of endogenous mPER1 and mPER2 proteins are rising, a light pulse results in a further increase in mPER1 but not mPER2 protein. The regional distribution of mPER1 and mPER2 protein in the SCN follows the same pattern as their respective mRNAs, with mPER1 expression in the shell region of SCN correlated with phase advances and mPER2 in the shell region correlated with phase delays.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1460-9568.2004.03189.x
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  • 4
    Electronic Resource
    Electronic Resource
    Expression of the circadian clock gene Period 1 in neuroendocrine cells: an investigation using mice with a Per1::GFP transgene (2003)
    Oxford, UK : Blackwell Science, Ltd
    European journal of neuroscience 17 (2003), S. 0 
    Details
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The circadian clock located in the suprachiasmatic nuclei (SCN) of the hypothalamus regulates daily temporal organization in behaviour and neuroendocrine function. The molecular basis for circadian rhythm generation is an interacting transcriptional/translational feedback loop comprised of several ‘clock genes’ and their respective protein products. Clock genes are expressed not only in the SCN but also in numerous other locations throughout the brain, including regions rich in neuroendocrine cells. In order to investigate whether neuroendocrine cells function as autonomous oscillators, we used female transgenic mice in which an unstable, degradable jellyfish green fluorescent protein (GFP) gene is driven by a mouse Period 1 (Per1) gene promoter. Mice were injected (s.c.) with fluorogold (FG) in order to label neuroendocrine cells and brain sections were double-labelled for either FG and Per1 mRNA (labelled by GFP immunostaining) or FG and PER1 protein using fluorescence immunocytochemistry. Mice were killed during either the day or night. Neuroendocrine cells contained Per1 mRNA and PER1 protein in several brain regions with the greatest proportion of double-labelled cells occurring in the arcuate nucleus (Arc). The number of neuroendocrine cells labelled was not affected by the stage of the estrous cycle. Fewer FG-labelled cells expressed Per1 message and protein during the night compared to the day. In the Arc, staining for tyrosine hydroxylase revealed that neuroendocrine cells expressing Per1 message and protein were dopaminergic. Together, these findings suggest that neuroendocrine cells contain the molecular machinery necessary to oscillate independently. It remains to be determined whether these cells actually function as autonomous oscillators or whether these rhythms are driven by signals from the SCN. These findings also indicate that the endocrine system represents an opportunity to study the interactions between central (SCN and neuroendocrine cells) and peripheral circadian (endocrine gland) oscillators.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1460-9568.2003.02431.x
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  • 5
    Electronic Resource
    Electronic Resource
    Differential induction and localization of mPer1 and mPer2 during advancing and delaying phase shifts (2002)
    Oxford, UK : Blackwell Science Ltd
    European journal of neuroscience 16 (2002), S. 0 
    Details
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The mechanism whereby brief light exposure resets the mammalian circadian clock in a phase dependent manner is not known, but is thought to involve Per gene expression. At the behavioural level, a light pulse produces phase delays in early subjective night, phase advances in late subjective night, and no phase shifts in mid-subjective night or subjective day. To understand the relationship between Per gene activity and behavioural phase shifts, we examined light-induced mPer1 and mPer2 expression in the suprachiasmatic nucleus (SCN) of the mouse, in the subjective night, with a view to understanding SCN heterogeneity. In the VIP-containing region of the SCN (termed ‘core’), light-induced mPer1 expression occurs at all times of the subjective night, while mPer2 induction is seen only in early subjective night. In the remaining regions of the SCN (termed ‘shell’), a phase delaying light pulse produces no mPer1 but significant mPer2 expression, while a phase advancing light pulse produces no mPer2 but substantial mPer1 induction. Moreover, following a light pulse during mid-subjective night, neither mPer1 nor mPer2 are induced in the shell. The results reveal that behavioural phase shifts occur only when light-induced Per gene expression spreads from the core to the shell SCN, with mPer1 expression in shell corresponding to phase advances, and mPer2 corresponding to phase delays. The results indicate that the time course and the localization of light-induced Per gene expression in SCN reveals important aspects of intra-SCN communication.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1460-9568.2002.02224.x
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  • 6
    Electronic Resource
    Electronic Resource
    Reproductive Mechanisms: Interaction of Circadian and Interval Timing (1984)
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 423 (1984), S. 0 
    Details
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1749-6632.1984.tb23455.x
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  • 7
    Electronic Resource
    Electronic Resource
    A diffusible coupling signal from the transplanted suprachiasmatic nucleus controlling circadian locomotor rhythms (1996)
    [s.l.] : Nature Publishing Group
    Nature 382 (1996), S. 810-813 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] To show that the recovered circadian rhythm is produced by the donor tissue and is not a consequence of spontaneous recovery of function, the host animals used were male hamsters bearing the tau mutation12 and were raised in our colony. This mutation has the behavioural effect of altering the ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/382810a0
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  • 8
    Electronic Resource
    Electronic Resource
    Distribution of vasoactive intestinal peptide-like and neurophysin-like immunoreactive neurons and acetylcholinesterase staining in the ring dove hypothalamus with emphasis on the question of an avian suprachiasmatic nucleus (1990)
    Springer
    Cell & tissue research 259 (1990), S. 331-339 
    Details
    ISSN: 1432-0878
    Keywords: Vasoactive intestinal polypeptide (VIP) ; Neurophysins ; Acetylcholinesterase ; Suprachiasmatic nucleus ; Hypothalamus ; Ring dove
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Two nuclei, termed here the medial hypothalamic nucleus and the lateral hypothalamic retinorecipient nucleus, are possible homologs of the mammalian suprachiasmatic nucleus. As the mammalian suprachiasmatic nucleus is characterized by a dense concentration of vasoactive intestinal peptide (VIP)-and neurophysin (NP)-immunoreactive neurons and an absence of acetylcholinesterase (AChE) staining, we decided to examine these factors in the ring dove hypothalamus. Neither the medial hypothalamic nucleus nor the lateral hypothalamic retinorecipient nucleus contained either VIP-or NP-like immunoreactive neurons. The lateral hypothalamic retinorecipient nucleus stained darkly for AChE. Although there was some overlap in the distribution of VIP-and NP-like immunoreactive neurons, a clustering of both types into a well defined nucleus was not observed. Therefore, an avian homolog to the mammalian suprachiasmatic nucleus must differ in its chemoarchitecture from that of mammalian species described to date.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00318456
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  • 9
    Electronic Resource
    Electronic Resource
    Coexpression of opsin- and VIP-like-immunoreactivity in CSF-contacting neurons of the avian brain (1988)
    Springer
    Cell & tissue research 253 (1988), S. 189-198 
    Details
    ISSN: 1432-0878
    Keywords: Cerebrospinal fluid-contacting neurons ; Monoclonal antibodies ; Opsin ; VIP ; Extraocular photoreceptors ; Ring dove ; Coturnix coturnix ; Anas platyrhynchos
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Cerebrospinal fluid-contacting (CSF) cells in both the septal and the tuberal areas in the brain of the ring dove are labeled by RET-P1, a monoclonal antibody to opsin that reacts with inner and outer segment membranes of rod photoreceptors in a variety of vertebrates. Immunoblot analysis of proteins from diverse brain regions, however, revealed bands of anti-RET-P1 immunoreactivity that did not correspond to opsin. Binding of RET-P1 to opsin-containing membranes, was not inhibited by membranes rich in muscarinic and β-adrenergic receptor proteins (red blood cells, heart, lung) taken from doves. RET-P1-immunoreactive CSF-contacting cells emit a dendritic process that penetrates the ependyma and ends in a knob-like terminal suspended in the ventricle. These cells also possess other processes that penetrate more or less deeply into the neuropil. Additionally, a band of labeled fibers occurs in the external layer of the median eminence. A double-label technique demonstrated that RET-P1-positive cells coexpress VIP-like immunoreactivity. VIP-positive cells in other brain areas are not RET-P1-positive.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00221754
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  • 10
    Electronic Resource
    Electronic Resource
    Location of neurons projecting to the hypophysial stalk – median eminence in ring doves (Streptopelia roseogrisea) (1995)
    Springer
    Cell & tissue research 280 (1995), S. 77-86 
    Details
    ISSN: 1432-0878
    Keywords: Key words: Tracing studies (neural tracts) ; Hypothalamo-hypophysial system ; Median eminence ; Pituitary stalk ; DiI ; Neurosecretion ; Streptopelia roseogrisea (Aves ; Columbiformes)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. The median eminence/pituitary stalk represents the final common pathway for fibers from neurons that project to the pituitary gland. We have used the lipophilic fluorescent tracer 1,1′-dioctadecyl-3,3,3′,3′-tetra-methylindocarbocyanine perchlorate (DiI) to determine the location of neurons projecting to the median eminence/pituitary stalk in ring doves. The tracer can be precisely applied to fixed tissue, in areas to which it is otherwise difficult to gain a ccess. Following application of DiI to the median eminence/pituitary stalk, labeled neurons were detected in six distinct regions: the ventromedial hypothalamic nucleus, paraventricular nucleus, supraoptic nucleus, in and ventral to the lateral forebrain bundle, preoptic area, and lateral septum. Labeled fibers branched extensively in the diencephalon, particularly along the third ventricle and in the septal-preoptic area. Sparse fiber labeling occurred caudal to the tuberal hypothalamus, even though these regions were close to the application site of the tracer. Labeled cerebrospinal-fluid-contacting cells were seen in the paraventricular region of the third ventricle. The results indicate that the avian neuronal system that projects to the median eminence and neural lobe occurs in diffuse clusters largely along the midline region of the hypothalamic septal-preoptic area. The paucity of fiber staining caudal to the tuberal hypothalamic region indicates that cells of these regions do not project to the median eminence/pituitary.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00304513
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