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  • 1
    Electronic Resource
    Electronic Resource
    Importance of adrenergic neurons of the brain for the rise of blood pressure evoked by hypothalamic stimulation (1971)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 271 (1971), S. 311-319 
    Details
    ISSN: 1432-1912
    Keywords: Hypothalamus ; Noradrenaline ; Electrical Stimulation ; Chemical Sympathectomy ; Blood Pressure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The third ventricle and the aqueduct of the anaesthetized cat were cannulated and the hypothalamus was superfused with artificial cerebrospinal fluid. Electrical stimulation of the nucleus posterior of the hypothalamus elicited a rise of the blood pressure of 58±3 mm Hg (n=20). Superfusion of the hypothalamus with artificial cerebrospinal fluid containing bretylium (5×10−3 M) caused a gradual and long lasting impairment of the rise of blood pressure due to stimulation of the nucleus posterior. Tetracaine (1×10−3 M) diminished the rise of blood pressure to about the same extent as did 5×10−3M of bretylium; the inhibitory action of tetracaine was completely reversed within 120 min. Pretreatment of cats with 6-hydroxydopamine, which was applied through a Collison cannula implanted into the lateral ventricle, evoked a decrease of the noradrenaline content of the hypothalamus and of the rest of the brain and an impairment of the rise of blood pressure during stimulation of the nucleus posterior (33±3 mm Hg;n=6). The blood pressure of the anaesthetized cats was not affected by pretreatment with 6-hydroxydopamine. Superfusion of the hypothalamus with desipramine (1×10−4M) enhanced the rise of blood pressure elicited by electrical stimulation. The results are compatible with the assumption that the rise of blood pressure during stimulation of the nucleus posterior of the hypothalamus is mediated by adrenergic neurons of the brain.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00997225
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  • 2
    Electronic Resource
    Electronic Resource
    Uptake of dopamine into fractions of pig caudate nucleus homogenates (1975)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 287 (1975), S. 181-190 
    Details
    ISSN: 1432-1912
    Keywords: Caudate Nucleus ; Dopamine ; Ouabain ; Reserpine ; Prenylamine ; Uptake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Homogenates of the caudate nucleus of the pig were submitted to differential centrifugation. The 20 000 g and 80 000 g fractions were isolated and a part of them was osmotically shocked. The highest dopamine content per mg protein was found in the intact 80 000 g fraction. Incubation experiments with the intact and the osmotically shocked fractions at 25°C revealed that the particles of the intact 20 000 g fraction took up dopamine; the influx of the amine was not enhanced by addition of ATP and magnesium to the incubation medium. On the other hand after osmotic shock the uptake of dopamine into the particles of this fraction was greatly enhanced by addition of ATP and magnesium. The uptake of dopamine into the particles of both intact and osmotically shocked 80 000 g fractions was likewise enhanced by ATP and magnesium. The uptake in all fractions was not influenced by ouabain. The influx of dopamine into the particles of the intact 80 000 g fraction was competitively inhibited by reserpine (K i 0.96×10−8 M) and prenylamine (K i 1.74×10−8 M). It is concluded that the intact 20,000 g fraction contains intact synaptosomes; the uptake of dopamine is independent of the presence of ATP and magnesium. The shocked 20 000 g fraction and the 80 000 g fractions contain synaptic vesicles; the uptake of dopamine into these vesicles is enhanced by ATP and magnesium.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00510449
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  • 3
    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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  • 4
    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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  • 5
    Electronic Resource
    Electronic Resource
    Release of endogenous histamine in the hypothalamus of anaesthetized cats and conscious, freely moving rabbits (1982)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 321 (1982), S. 282-286 
    Details
    ISSN: 1432-1912
    Keywords: Release of endogenous histamine ; Hypothalamus ; Cat ; Freely moving rabbit ; Electrical stimulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The hypothalamus of anaesthetized cats and conscious, freely moving rabbits was superfused with CSF through double-walled, push-pull cannulae and the release of endogenous histamine was determined in the superfusates by a radioenzymatic assay. In the posterior hypothalamic area of the anaesthetized cat, the rate of release of endogenous histamine varied rhythmically; phases of high rate of release appeared at 60 min cycles. The release of histamine was increased by electrical stimulation of the superfused area, as well as by hypothalamic superfusion with potassium-rich CSF. In the conscious rabbit, the anterior hypothalamic area and the posterior hypothalamic nucleus were superfused simultaneously. In both regions, the resting release of histamine varied rhythmically at approximately 70 min cycles. Phases of high or low-rate of release in the anterior hypothalamic area coincided with the corresponding phases in the posterior hypothalamic nucleus. The rhythmic release of endogenous histamine in the hypothalamus, as well as the ability of depolarizing stimuli to enhance the release of the amine support the idea that histamine acts as a neurotransmitter in the central nervous system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00498514
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  • 6
    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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  • 7
    Electronic Resource
    Electronic Resource
    Hypothalamic superfusion with muscarinic drugs (1976)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 292 (1976), S. 1-7 
    Details
    ISSN: 1432-1912
    Keywords: Hypothalamus ; Electrical stimulation ; Pressor responses ; Muscarinic drugs ; Methylatropine ; Hexamethonium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The posterior hypothalamus of cats anaesthetized with pentobarbital sodium was superfused with artificial cerebrospinal fluid through a push-pull cannula and electrically stimulated with the non-insulated tip of the cannula. The effects of muscarinic drugs on the pressor response to stimulation of the hypothalamus were investigated. Superfusion with muscarine, oxotremorine or N-benzyl-3-pyrrolidyl acetate methobromide (AHR 602) decreased the pressor responses to hypothalamic stimulation. Superfusion with methylatropine did not influence the pressor responses to hypothalamic stimulation; however, superfusion with methylatropine 60 min prior to and during superfusion with the muscarinic drugs abolished the inhibitory effects of muscarine and oxotremorine and temporarily reversed that of AHR 602 on the pressor responses. Superfusion of the posterior hypothalamus with arecoline enhanced the rise of blood pressure elicited by hypothalamic stimulation. When the hypothalamus was superfused with hexamethonium 60 min prior to and during superfusion with arecoline, arecoline reduced the pressor responses to electrical stimulation of the hypothalamus. Superfusion with methylatropine prior to and together with an ineffective concentration of arecoline increased the rise of blood pressure elicited by hypothalamic stimulation. From the drugs studied here only oxotremorine caused a fall of the “resting” arterial blood pressure; it was abolished by the intravenous injection of methylatropine. From these results it was concluded that superfusion of the posterior hypothalamus with muscarinic drugs impairs the pressor responses to hypothalamic stimulation. Drugs possessing both nicotinic and muscarinic properties either enhance or diminish the pressor responses according to their relative potencies on the two types of receptor.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00506482
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  • 8
    Electronic Resource
    Electronic Resource
    Uptake of tyramine into synaptic vesicles of the caudate nucleus (1977)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 300 (1977), S. 25-30 
    Details
    ISSN: 1432-1912
    Keywords: Synaptic vesicles ; Uptake ; Dopamine ; Tyramine ; Reserpine ; Filtration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Synaptic vesicles isolated from the caudate nucleus of the pig were preincubated with reserpine, serotonin or tyramine at concentrations which caused a 90% inhibition of the ATP-Mg2+-dependent uptake of 14C-dopamine. The preincubated vesicles were sedimented by centrifugation and resuspended in drug-free buffer. The vesicles were incubated with 14C-dopamine in the presence or in the absence of ATP-Mg2+; at the end of the incubation period they were separated from the incubation medium by centrifugation. The inhibitory effect of reserpine on the ATP-Mg2+-dependent uptake of 14C-dopamine was slightly diminished, that of serotonin reduced while the inhibitory effect of tyramine was abolished. Hence, tyramine seems to be more easily removable than the other substances. In another series of experiments the vesicles were incubated with 3H-tyramine and immediately separated by filtration through membrane filters. Addition of ATP-Mg2+ enhanced the uptake of 3H-tyramine. The Km of the ATP-Mg2+-dependent uptake of 3H-tyramine was 1.4×10−7 M, the Vmax 29.2 pmoles/mg protein/min. At 0°C the uptake of 3H-tyramine in the absence of ATP-Mg2+ was reduced, that in the presence of ATP-Mg2+ abolished. Incubation of the vesicles with 3H-dopamine revealed K m and V max values similar to those previously found when the vesicles were isolated from the incubation medium by centrifugation. Incubation in the presence of reserpine inhibited the ATP-Mg2+-dependent uptake of 3H-tyramine (IC50 1.4×10−8 M) and 3H-dopamine (IC50 4.1×10−8 M). The results demonstrate that tyramine is taken up into the vesicles by a process which is dependent on ATP-Mg2+ and temperature. Failure of previous attempts to prove an ATP-Mg2+-dependent uptake of tyramine when the vesicles were separated by centrifugation seems to be due to release of the accumulated tyramine during the centrifugation procedure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00505076
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  • 9
    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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  • 10
    Electronic Resource
    Electronic Resource
    Release of endogenous GABA in the posterior hypothalamus of the conscious rat; effects of drugs and experimentally induced blood pressure changes (1993)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 347 (1993), S. 402-406 
    Details
    ISSN: 1432-1912
    Keywords: GABA release ; Hypothalamus ; Blood pressure ; Veratridine ; Tetrodotoxin ; Push-pull cannula
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Push-pull superfusion was used to investigate the release of endogenous GABA in the posterior hypothalamus of the conscious, freely moving rat at basal conditions and in response to centrally applied drugs or to peripherally induced blood pressure changes. After an initial, exponential decline, the release rate of GABA remained fairly constant for many hours. Fluctuations in the release rate of GABA point to the existence of an ultradian rhythm with an approximate frequency of 1 cycle/65 min. Hypothalamic superfusion with a potassium-rich (50 or 90 mmol/1) artificial cerebrospinal fluid led to a concentration-dependent increase in the GABA release. The release of GABA was also enhanced by veratridine (1 or 10 μmol/1) in a concentration-dependent way. Hypothalamic superfusion with the neutrotoxin tetrodotoxin (1 gmmol/1) led to a long-lasting decrease in the GABA release. The rise in blood pressure (45 mmHg) elicited by an intravenous infusion of noradrenaline was associated with an increased release rate of GABA in the hypothalamus. Hypotension produced by nitroprusside (25 mmHg) led to a counteracting decrease in hypothalamic GABA outflow. The findings suggest that approximately 4510 of the basal outflow of GABA found in the superfusate are released from GABA-ergic neurons of the posterior hypothalamus. The release rate of GABA fluctuates according to an ultradian rhythm. The modified release of GABA in response to experimentally induced blood pressure changes suggests that, in the posterior hypothalamus of the conscious rat, GABAergic neurons are involved in cardiovascular control and possess a hypotensive function.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00165390
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