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  • 1
    Electronic Resource
    Electronic Resource
    Rise in blood pressure increases the release of endogenous catecholamines in the anterior hypothalamus of the cat (1980)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 310 (1980), S. 237-240 
    Details
    ISSN: 1432-1912
    Keywords: Hypothalamus ; Arterial Blood Pressure ; Catecholamines ; Splanchnic Nerve ; Rise in Blood Pressure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In anaesthetized cats, anterior and posterior hypothalamic areas were simultaneously superfused with artificial CSF using two push-pull cannulae. The rates of release of endogenous catecholamines were determined in the superfusates which were continuously collected in periods of 10 seconds. In both areas, the rate of release of dopamine was higher than the rates of release of noradrenaline and adrenaline. Electrical stimulation of the splanchnic nerve elicited a rise in the arterial blood pressure and increased the rates of release of noradrenaline, adrenaline and dopamine in the anterior hypothalamic area. The rates of release of the catecholamines in the posterior hypothalamic area were not influenced by the pressor response to stimulation of the splanchnic nerve. Transection of the brain caudal to the hypothalamus reduced the rates of release of the catecholamines in the anterior hypothalamus and abolished the releasing effect of the stimulation of the splanchnic nerve. The results indicate that acute rise in blood pressure activates catecholamine cell bodies in the lower brain stem, which in turn stimulate the anterior hypothalamus to counteract the pressor response.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00499916
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  • 2
    Electronic Resource
    Electronic Resource
    Effects of short-lasting and long-lasting blood pressure changes on the release of endogenous catecholamines in the hypothalamus of the conscious, freely moving rabbit (1983)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 322 (1983), S. 203-209 
    Details
    ISSN: 1432-1912
    Keywords: Endogenous catecholamines ; Push-pull cannula ; Rhythmic release ; Blood pressure ; Hypothalamus ; Conscious rabbit
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In anaesthetized rabbits guide cannulae were stereotaxically inserted into the anterior hypothalamic area and into the posterior hypothalamic nucleus. Additionally, catheters were inserted into the carotid artery and the jugular vein. Some days after the operation push-pull cannulae were inserted through the guide cannulae into the hypothalamic regions of the conscious, freely moving animal. The areas were superfused with artificial CSF and the release of the endogenous catecholamines dopamine, noradrenaline and adrenaline was determined in the superfusates. In the two hypothalamic regions the resting release of the catecholamines rhythmically varied with time at approximately 70 min cycles. A rise in blood pressure induced by the intravenous injection of noradrenaline or tramazoline enhanced the rates of release of the catecholamines in the anterior hypothalamic area. A fall of blood pressure elicited by the intravenous injection of nitroprusside or chlorisondamine decreased the release of the catecholamines in this hypothalamic area. The changes in blood pressure coincided with the changes in the rates of release of the catecholamines in the anterior hypothalamic area. These and previous results concerning changes in the release of endogenous catecholamines in the posterior hypothalamic nucleus also indicate that in the conscious, freely moving rabbit changes in blood pressure lead to counteracting alterations in the release of catecholamines in the two hypothalamic regions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00500766
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Pulsatile release of catecholamines in the hypothalamus of conscious rats (1993)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 347 (1993), S. 28-33 
    Details
    ISSN: 1432-1912
    Keywords: Ultradian rhythm ; Hypothalamus ; Pushpull cannula ; Dopamine ; Noradrenaline ; Adrenaline
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary To investigate the patterns of catecholamine release in the brain, the hypothalamus of conscious, freely moving rats was superfused through a push-pull cannula with artificial cerebrospinal fluid and the catecholamines dopamine, noradrenaline and adrenaline were determined in the superfusate radioenzymatically. Superfusate was continuously collected in time periods of 20 min for at least 20h. Dopamine, noradrenaline and adrenaline release rates fluctuated according to an ultradian rhythm with a frequency of 1 cycle/92 min (dopamine and noradrenaline) or 99 min (adrenaline). Additionally, the three catecholamines were released according to an ultradian rhythm with the following frequencies: noradrenaline and adrenaline 1 cycle/ 12 h, dopamine 1 cycle/8 h. The release rates of dopamine and adrenaline were similar during light and dark periods, while the release rate of noradrenaline in the dark period was slightly lower than that during the light period. It is concluded that in the hypothalamus of the conscious rat the release rates of dopamine, noradrenaline and adrenaline fluctuate according to two ultradian rhythms with different frequencies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00168768
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  • 4
    Electronic Resource
    Electronic Resource
    In vivo release of endogenous catecholamines in the hypothalamus (1979)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 308 (1979), S. 137-142 
    Details
    ISSN: 1432-1912
    Keywords: Hypothalamus ; Superfusion ; Catecholamine release ; Electrical stimulation ; Locus coeruleus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The posterior hypothalamus of anaesthetized cats was superfused with a push-pull cannula and the release of the endogenous catecholamines noradrenaline, adrenaline and dopamine was determined in the superfusate. The rate of release of the three catecholamines followed an ultradian rhythm, the time interval between two adjacent phases of high rate of release being about 70 min. Pretreatment of the animals with reserpine decreased the levels of catecholamines in the hypothalamus and rest of the brain and reduced their rate of release into the superfusate. Hypothalamic superfusion with superfusing fluid of high concentration of potassium and low concentration of sodium enhanced the rate of release of noradrenaline and adrenaline; this effect was abolished when the hypothalamus was superfused with calcium-free solution. Electrical stimulation of the locus coeruleus ipsilateral to the superfused hypothalamus increased the release of noradrenaline and adrenaline, stimulation of the contralateral locus coeruleus enhanced the release of noradrenaline, adrenaline and dopamine. In both cases, the rate of release of adrenaline was enhanced to a lesser extent than the rate of release of noradrenaline. The release of noradrenaline and adrenaline was increased to a higher extent on stimulation of the ipsilateral locus coeruleus than on stimulation of the contralateral one.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00499055
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  • 5
    Electronic Resource
    Electronic Resource
    In vivo release of endogenous GABA in the cat hypothalamus (1979)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 308 (1979), S. 143-147 
    Details
    ISSN: 1432-1912
    Keywords: Hypothalamus ; GABA release ; Superfusion ; Electrical stimulation ; Potassium chloride ; Locus coeruleus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The posterior hypothalamus of anaesthetized cats was superfused with artificial cerebrospinal fluid through a push-pull cannula and the release of endogenous GABA from the hypothalamus into the superfusate was studied. The resting release of GABA varied rhythmically, since phases of high rate of release were separated from each other by phases of low rate of release. The time interval between two adjacent phases of high rate of release was about 70 min. Electrical stimulation of the posterior hypothalamus with the tip of the cannula enhanced the rate of release of GABA in a frequency-dependent way. Superfusion of the hypothalamus with CSF which contained a high concentration of potassium and a low concentration of sodium increased the rate of release of GABA; this effect was dependent on the presence of calcium ions in the superfusing fluid. Pretreatment of the cats with reserpine reduced the levels of GABA in hypothalamus and rest of brain and the concentration of GABA in the superfusate as well. Stimulation of the locus coeruleus with a bipolar electrode elicited an increased release of GABA in the hypothalamus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00499056
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  • 6
    Electronic Resource
    Electronic Resource
    In vivo release by histamine agonists and antagonists of endogenous catecholamines in the cat hypothalamus (1984)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 326 (1984), S. 116-123 
    Details
    ISSN: 1432-1912
    Keywords: Hypothalamus ; Push-pull cannula ; Catecholamines ; Histamine ; Histamine receptor agonists ; Histamine receptor antagonists
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The posterior hypothalamus of anaesthetized cats was superfused through a push-pull cannula with histamine agonists and antagonists and the release of endogenous catecholamines was determined in the superfusate. Hypothalamic superfusion with histamine, 2-methylhistamine (H1-agonist), dimaprit (H2-agonist) or metiamide (H2-antagonist) enhanced the release of the catecholamines dopamine, noradrenaline and adrenaline. The releasing effects of these substances depended on the presence of calcium ions. Superfusion with 2-pyridylethylamine (H1-agonist) was virtually ineffective, while superfusion with 2-thiazolethylamine (H1-agonist) enhanced the rate of release of noradrenaline and adrenaline without influencing the release of dopamine. Superfusion with mepyramine (H1-antagonist) inhibited the release of noradrenaline and adrenaline without affecting the release of dopamine. Hypothalamic superfusion with a concentration of procaine which was equi-anaesthetic to that of mepyramine was ineffective. Ranitidine (H2-antagonist) did not alter the rates of release of the catecholamines. The releasing effect of histamine was inhibited on hypothalamic superfusion with mepyramine and ranitidine. Ranitidine also inhibited the releasing effects of dimaprit and 2-methylhistamine thus indicating that the releasing action of the latter compound was mainly due to stimulation of H2-receptors. These data suggest that blockade of H1-receptors of the posterior hypothalamus reduces the release of noradrenaline and adrenaline, while stimulation of H1-receptors seems to increase the rates of release of these two catecholamines. Stimulation of H2-receptors enhances the release of all three catecholamines. Thus, dopaminergic neurones of the hypothalamus seem to possess H2-receptors, while noradrenergic and adrenergic neurones possess H1- and H2-receptors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00517307
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