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  • 1
    Electronic Resource
    Electronic Resource
    Enhancement of In Vivo Tyrosine Hydroxylation in the Rat Adrenal Gland Under Hypoxic Conditions (1990)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 54 (1990), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: We examined the effects of hypoxia (8% O2) on in vivo tyrosine hydroxylation, a rate-limiting step for catecholamine synthesis, in the rat adrenal gland. The hydroxylation rate was determined by measuring the rate of accumulation of 3,4-dihydroxyphenylalanine (DOPA) after decarboxylase inhibition. One hour after hypoxic exposure. DOPA accumulation decreased to 60% of control values, but within 2 h it doubled. At 2 h, the apparent Km values for tyrosine and for biopterin cofactor of tyrosine hydroxylase (TH) in the soluble fraction were unchanged, whereas the Vmax value increased by 30%. The content of total or reduced biopterin was unchanged, but the content of tyrosine increased by 80%. Tyrosine administration had little effect on DOPA accumulation under room air conditions but enhanced DOPA accumulation under hypoxia. After denervation of the adrenal gland, the hypoxia-induced increase in DOPA accumulation and in the Vmax value was abolished, whereas the hypoxia-induced increase in tyrosine content was persistent. These results suggest that in vivo tyrosine hydroxylation is enhanced under hypoxia, although availability of oxygen is reduced. The enhancement is the result of both an increase in tyrosine content coupled with increased sensitivity of TH to changes in tyrosine tissue content and of an increase in dependence of TH on tyrosine levels. The increase in the sensitivity of TH and in the Vmax value is neurally induced, whereas the increase in tyrosine content is regulated by a different mechanism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1990.tb01937.x
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  • 2
    Electronic Resource
    Electronic Resource
    Effects of Choline Administration on In Vivo Release and Biosynthesis of Acetylcholine in the Rat Striatum as Studied by In Vivo Brain Microdialysis (1990)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 54 (1990), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The purpose of the present study is to clarify the effects of the administration of choline on the in vivo release and biosynthesis of acetylcholine (ACh) in the brain. For this purpose, the changes in the extracellular concentration of choline and ACh in the rat striatum following intracerebroventricular administration of choline were determined using brain microdialysis. We also determined changes in the tissue content of choline and ACh. When the striatum was dialyzed with Ringer solution containing 10 μM physostigmine, ACh levels in dialysates rapidly and dose dependently increased following administration of various doses of choline and reached a maximum within 20 min. In contrast, choline levels in dialysates increased after a lag period of 20 min following the administration. When the striatum was dialyzed with physostigmine-free Ringer solution, ACh could not be detected in dialysates both before and even after choline administration. After addition of hemicholinium-3 to the perfusion fluid, the choline-induced increase in ACh levels in dialysates was abolished. Following administration of choline, the tissue content of choline and ACh increased within 20 min. These results suggest that administered choline is rapidly taken up into the intracellular compartment of the cholinergic neurons, where it enhances both the release and the biosynthesis of ACh.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1990.tb01904.x
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  • 3
    Electronic Resource
    Electronic Resource
    NR2 to NR3B subunit switchover of NMDA receptors in early postnatal motoneurons (2005)
    Oxford, UK : Blackwell Science Ltd
    European journal of neuroscience 21 (2005), S. 0 
    Details
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The NR3B NMDA receptor subunit is selective to somatic motoneurons in the adult nervous system. Here we report its developmental expression in the mouse brain and spinal cord by in situ hybridization. NR3B mRNA was detected in few neural regions during embryonic and neonatal periods. It first appeared in motoneurons at postnatal day (P)10−P14, and attained the maximal level at P21 and adult stage. This developmental profile was reciprocal with that of NR2 subunits, of which NR2A mRNA was most predominant in embryonic and neonatal motoneurons and downregulated by P14. Interestingly, mRNA of the NR1 subunit, which is required for functional NMDA receptors, displayed a ‘V’-shaped change, decreasing with the early postnatal decline of NR2 mRNAs and increasing with the subsequent appearance of NR3B mRNA. Therefore, the major regulatory subunit of NMDA receptors is likely to switch from NR2 to NR3B in somatic motoneurons during the early postnatal period.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1460-9568.2005.03957.x
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  • 4
    Electronic Resource
    Electronic Resource
    Effects of hypoxia on noradrenaline release and neuronal reuptake in isolated rabbit thoracic aortic strips (1989)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 339 (1989), S. 503-508 
    Details
    ISSN: 1432-1912
    Keywords: Hypoxia ; Aortic strips ; Noradrenaline release ; Neuronal uptake ; Rabbit
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary To clarify the effects of hypoxia on stimulus-evoked noradrenaline release and on neuronal reuptake of the released noradrenaline, we examined the effects of hypoxia on contraction responses of rabbit thoracic aortic strips to transmural electrical stimulation and on the stimulation-evoked overflow of total [3H] and [3H]noradrenaline from the strips prelabelled with [3H]noradrenaline. This was done in the presence or absence of an inhibitor of neuronal uptake (cocaine). In a medium equilibrated with a gas mixture of 95% O2/5% CO2 (control), cocaine doubled the stimulation-evoked overflow of total [3H] and [3H]noradrenaline; there was a concomitant increase (130%) in contractions to electrical stimulation. At 0% O2 (95% N2/5% CO2, hypoxia), cocaine had no significant effects on either the stimulation-evoked overflow of total [3H] and [3H]noradrenaline or contractions. In the absence of the drug, hypoxia decreased the stimulation-evoked overflow of total [3H] and [3H]noradrenaline to 47% and 43%, respectively, of the control values, whereas these values were 31% and 28%, respectively, after exposure to cocaine. The inhibition by hypoxia of contraction responses to electrical stimulation was greater in the presence of cocaine than in its absence. These results show that hypoxia inhibits both noradrenaline release evoked by a given stimulus and neuronal uptake.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00167252
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  • 5
    Electronic Resource
    Electronic Resource
    Effects of hypoxia on contractile responses of rabbit aortic strips to transmural electrical stimulation (1988)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 338 (1988), S. 275-281 
    Details
    ISSN: 1432-1912
    Keywords: Hypoxia ; Aortic strips ; Transmural electrical stimulation ; Noradrenaline release ; α-Adrenoceptor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary To clarify the effects of hypoxia on adrenergic transmission, we examined the contractile responses of isolated rabbit aortic strips to electrical stimulation, the concentration-response relationships for noradrenaline and KCl, and the electrical stimulation-evoked overflows of total [3H] and [3H]noradrenaline from strips preloaded with [3H]noradrenaline in media equilibrated with gas mixtures containing various concentrations of 02. Contractile responses to electrical stimulation were completely inhibited by tetrodotoxin and α-adrenoceptor antagonists such as phentolamine and phenoxybenzamine, but were not affected by indomethacin. When the concentration of O2 in the gas mixture was decreased from 95% to 20%, the contractile responses to electrical stimulation remained unchanged, but as the concentration of OZ was further decreased, the responses were inhibited concentration-dependently. At 0% O2, the response was inhibited by about 80% when compared with control values obtained at 95% O2, and the electrical stimulation-evoked overflows of total [3H] and [3H]noradrenaline into the superfusates were decreased by about 55%. At 0% 02, the concentration-response curve for exogenous noradrenaline was shifted to the right about 50-fold and the maximum response was decreased by 25%. The maximum contractile responses of aortic strips from animals pretreated with reserpine or 6-hydroxydopamine to high KCl were decreased slightly (about 15%). These results suggest that inhibition of adrenergic transmission under hypoxic conditions is mainly the result of a decrease in the stimulus-evoked release of noradrenaline and of a decrease in the affinity of α-adrenoceptor for noradrenaline and/ or inhibition of signal transduction mechanisms, although hypoxia also causes a slight decrease in the contractility of vascular smooth muscle.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00173400
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  • 6
    Electronic Resource
    Electronic Resource
    Role of a metabotropic glutamate receptor in synaptic modulation in the accessory olfactory bulb (1993)
    [s.l.] : Nature Publishing Group
    Nature 366 (1993), S. 687-690 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Our previous study indicated that two extended L-isomers of 2-(carboxycyclopropyl)glycines (L-CCGs) are potent and selective agonists for the mGluR family6. An L-CCG derivative, (2S,l'R,2'R,3'R)-2-(2,3-dicarboxycydopropyl)glycine (DCG-IV; Fig. 1) has recently been reported7'8. We determined agonist ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/366687a0
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  • 7
    Electronic Resource
    Electronic Resource
    Cloning and expression of cDNA for a human thromboxane A 2 receptor (1991)
    [s.l.] : Nature Publishing Group
    Nature 349 (1991), S. 617-620 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Human platelet receptor for thromboxane A2(TXA2), purified as described3, was subjected to proteolysis, and four partial amino-acid sequences were determined. Part of the sequence was used to design a 41-mer oligonucleotide probe, with which we screened a cDNA library of MEG-01 cultured human ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/349617a0
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