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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 54 (1984), S. 571-574 
    ISSN: 1432-1106
    Keywords: Baroreceptors ; Supraoptic nucleus ; Brattleboro rats
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In Brattleboro rats, many more supraoptic neurones are baroresponsive than in normal rats. This may reflect the more widespread noradrenergic innervation of the supraoptic nucleus in Brattleboro rats. If so, the present data suggest that baroreceptor influences on vasopressin secretion are mediated by a noradrenergic pathway and that the altered responsiveness reflects the altered innervation.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 689 (1993), S. 0 
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 689 (1993), S. 0 
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 255 (1975), S. 734-735 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Groups of male Wistar rats (Porton strain) of approximately 200 g body weight were given daily intramuscular injections of either 0.5 IU vasopressin tannate in oil or the same volume (0.1 ml) of the vehicle alone. This dose of vasopressin is sufficient to raise urinary osmolality and reduce water ...
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 252 (1974), S. 486-488 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Female rats were anaesthetised with urethane and prepared for extracellular recording of single unit activity8. Action potentials were recorded through glass micropipettes?filled with 4.0 M sodium chloride?with a tip resistance of 5?15MW, which constituted the centre barrel of multi-barrelled ...
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 216 (1967), S. 584-584 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Eraser4 confirmed Heller's2 results when he assayed antidiuretic activity by subcutaneous injection of the hormone into rats or dogs. When, however, he administered the hormone intravenously, to dogs he found that the antidiuretic potency of the treated hormone, so determined, was the same as its ...
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Journal of neuroendocrinology 9 (1997), S. 0 
    ISSN: 1365-2826
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Secretion of vasopressin (VP) and oxytocin (OT) displays a daily rhythm. Using electrophysiological methods, we investigated the projections from the optic nerve to the supraoptic nucleus (SON) and its perinuclear zone (PNZ) which might underlie the rhythm. Extracellular recordings were made from magnocellular cells in the SON and its PNZ in 22 urethane-anaesthetized female Wistar rats while stimulating the optic nerve. The responses of magnocellular and PNZ cells were classified as orthodromic excitatory (OD+) or inhibitory (OD-) after creating peri-stimulus time histograms (PSTHs). Twenty-six of 73 (35.6%) VP and OT cells and 16 of 42 (38.1%) PNZ cells were excited by optic nerve stimulation. PNZ cells displayed both short (for 7 cells 30 ms or less) and long (〉60 ms) latency responses. Most (6/7) short latency responses had a short duration but longer latency responses were longer. No magnocellular cells showed responses with both short latency and short duration. Short latency responses with a short duration probably reflect direct monosynaptic inputs whereas longer latency responses with longer duration may reflect complex inputs. Thus the retina projects to the PNZ and to the SON but the PNZ receives a stronger direct input. Such projections might provide a light-related input to SON cells and suggest a role for the PNZ in this input.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1365-2826
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Neurohypophysical hormone release, and the electrical activity of single neurons of the supraoptic nucleus, were monitored in urethane-anaesthetized rats. Immediately after electrolytic lesions of the region anterior and ventral to the third ventricle (AV3V region), supraoptic neurons showed little spontaneous activity and their responses to ip injection of hypertonic saline were severely impaired; corresponding deficits were found in the secretion of both oxytocin and vasopressin. Similar deficits in oxytocin secretion were also found in rats following electrolytic lesions which destroyed all or part of the subfornical organ; however the effects of the lesions were not additive: rats with lesions of both the AV3V region and the subfornical organ region showed a similar degree of impairment of osmotically stimulated oxytocin secretion to rats with lesions of either site alone. Such deficits might occur either as a result of destruction of osmoresponsive projections to the magnocellular nuclei, or as a result of destruction of an afferent input which is essential for the full expression of the innate osmosensitivity of supraoptic neurons. To test the latter possibility, supraoptic neurons in AV3V-lesioned rats were activated by continuous application of glutamate, and then tested with ip injection of hypertonic saline. Five of seven cells tested responded significantly to the hyperosmotic stimulus, though the responses were significantly weaker than observed in sham-lesioned rats. We suggest that the innate osmosensitivity of supraoptic neurons does contribute to their responses to systemic osmotic stimulation, but that expression of this innate osmosensitivity requires inputs from the AV3V region and/or the subfornical organ, some of which may also be osmoresponsive. Electrical stimulus pulses applied to the AV3V region influenced the electrical activity of most supraoptic neurons strongly: the predominant response was a short-latency, short-duration inhibition followed by long-latency, long-duration excitation. Whereas intracerebroventricular administration of the angiotensin II antagonist saralasin reduced spontaneous or osmotically induced activity of supraoptic neurons, the neuronal responses to AV3V stimulation were impaired only with relatively high doses of saralasin. We conclude that angiotensin ll-sensitive neurons are an important component of the afferent pathways that sustain the excitability of supraoptic neurons, but that angiotensin is probably not the major transmitter of the projection from the AV3V region to the supraoptic nucleus.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neuroendocrinology 3 (1991), S. 0 
    ISSN: 1365-2826
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Intracellular recordings were made from cells in the hypothalamic supraoptic nucleus in the urethane-anaesthetized male rat using the ventral surgical approach. Impalements lasted from 5 min to 1 h and recorded cells had an input resistance of 55 to 170 megohms. Spikes of over 50 mV were recorded from 14 cells which could be antidromically activated by stimulation of the neural stalk. The spikes showed a hyperpolarizing afterpotential and the broadening characteristic of rapidly firing magnocellular neurons, which recovered rapidly (〈200 ms). When depolarized, the cells showed evidence of a transient potassium current. Recurrent synaptic coupling between the recorded cell and adjacent cells would be expected to alter the hyperpolarizing afterpotential of an antidromic spike as compared with a spontaneous spike; no perceptible difference in the waveforms of the different types of spike could be detected in 11 spontaneously active cells. Application of just subthreshold stimuli to the neural stalk did not evoke depolarizing or hyperpolarizing potentials. Suprathreshold shocks to the neural stalk, when the antidromic spike was prevented by collision, also had no discernible effect on membrane potential. Thus intracellular recordings from magnocellular neurons in vivo revealed electrophysiological properties similar to those seen in vitro. No evidence for synaptic interconnection between magnocellular neurons was found in male rats.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Journal of neuroendocrinology 16 (2004), S. 0 
    ISSN: 1365-2826
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Novel approaches to the characterization of coding carried by spike trains are discussed. Measuring firing frequency alone may only partially reflect spike patterning, and can only quantify changes of the most obvious kind. We have devised a method that combines probabilistic and information approaches to quantify the variability of the interspike intervals in a way that is independent of spike frequency. To illustrate the technique, the firing of an oxytocin cell and a vasopressin cell were compared before and after osmotic stimulation. A bimodal lognormal function was fitted to the interspike interval histograms. The entropy of the log interval histogram was used to measure the variability of intervals and to reflect the coding capacity of the cell per spike. A perfect metronome shows no variability in interval and thus has no greater coding capacity than is conveyed by its frequency, whereas the variability of intervals of magnocellular neurones means that their irregular activity has greater potential for coding. While the mean spike frequency increased in both the oxytocin and vasopressin cells in response to osmotic stimulation, the changes in their irregularity showed differences. Osmotic stimulation reduced the entropy of the oxytocin cell, reflecting an increase in the regularity of its spike activity. Conversely, osmotic stimulation had little effect on the entropy of the vasopressin cell. Such differences are not evident from a simple inspection of ratemeter activity. The comparison highlights the limitations of mean spike frequency as a measure of spike coding. Parameters based on the interspike intervals constitute informative measures of spike activity that allow objective comparisons to be made between the activity under different physiological conditions.
    Type of Medium: Electronic Resource
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