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  • 1
    Electronic Resource
    Electronic Resource
    Modulation of mRNA expression of the neurotrophins of the nerve-growth-factor family and their receptors in the septum and hippocampus of rats after transient postnatal thyroxine treatment. II. Effects on p75 and trk receptor expression (1999)
    Springer
    Experimental brain research 127 (1999), S. 307-313 
    Details
    ISSN: 1432-1106
    Keywords: Key words Thyroid hormone ; RT-PCR ; p75 receptor ; trkA ; trkB ; trkC ; Septum ; Hippocampus ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Early postnatal application of thyroid hormones to rats results in morphological changes of the septo-hippocampal cholinergic and the hippocampal mossy fiber systems. Modulation in the expression of either neurotrophins and/or their receptors is postulated to be involved in these effects. In a recent study, we showed that, after thyroxine application, the mRNA expression of neurotrophins of the nerve-growth-factor (NGF) family is significantly upregulated both in septum and hippocampus. To test whether the neurotrophin receptors (the low-affinity neurotrophin receptor p75 and the specific high-affinity receptors trkA, trkB, and trkC) were also affected by hormone administration, newborn rats were treated daily with subcutaneous injections of thyroxine until postnatal day 12 (P12) at latest. Control animals received corresponding injections of saline. The pups were sacrificed at defined intervals from P9 to P14. The septal areas and the hippocampi were analyzed using the reverse-transcription polymerase chain reaction (RT-PCR) method for quantification of p75, trkA, trkB, and trkC mRNA levels. Analysis of variance over the total investigation period revealed no significant general increases of the gene expressions of either neurotrophin receptor, neither in the septum nor in the hippocampus, although previous results have shown marked changes in neurotrophin levels. On particular postnatal days, significant upregulation could be observed in hippocampus for trkB and trkC. From these and recent data, we conclude that modulation of neurotrophin expression rather than neurotrophin-receptor expression contributes to the morphological modifications within the hippocampal mossy fiber system and the septo-hippocampal cholinergic system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002210050800
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  • 2
    Electronic Resource
    Electronic Resource
    Modulation of mRNA expression of the neurotrophins of the nerve growth factor family and their receptors in the septum and hippocampus of rats after transient postnatal thyroxine treatment I. Expression of nerve growth factor, brain-derived neurotrophic factor, neurotrophin-3, and neurotrophin 4 mRNA (1998)
    Springer
    Experimental brain research 119 (1998), S. 1-8 
    Details
    ISSN: 1432-1106
    Keywords: Key words Thyroid hormone ; Neurotrophins ; Septum ; Hippocampus ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Early postnatal application of thyroid hormones to rats results in morphological changes in septum and hippocampus. Modulation in the expression of either neurotrophins and/or their receptors is postulated to be responsible for these effects. In the present study we tested whether thyroxine administration leads to changes in the expression of neurotrophins of the nerve growth factor (NGF) family. Newborn rats were treated daily with subcutaneous injections of thyroxine until postnatal day (P) 12 at maximum. The pups were killed at defined intervals from P2 to 21. The septal area and the hippocampi were analyzed using the reverse transcriptase-PCR method for quantitation of NGF, brain-derived neurotrophic factor (BDNF), NT-3, and NT-4 messenger RNA (mRNA) levels. In hippocampus of hyperthyroid rats, as compared to controls, we found higher levels of BDNF and NT-3 mRNA over the total investigation period, whereas in the septum a thyroxine-dependent increase in NT-3 mRNA expression was observed. In addition, significant thyroxine-induced effects were found for all variables (except for NGF in the septum) at particular postnatal days. From these data we conclude that modulation of neurotrophin expression is a possible mechanism for the morphological modifications within the hippocampal mossy fiber system and the septohippocampal cholinergic system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002210050313
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  • 3
    Electronic Resource
    Electronic Resource
    Dissociation between changes in cyclic AMP and subsequent induction of TH in the rat superior cervical ganglion and adrenal medulla (1973)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 280 (1973), S. 129-140 
    Details
    ISSN: 1432-1912
    Keywords: Cyclic AMP ; Tyrosine Hydroxylase ; Enzyme Induction ; Stress ; Reserpine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Changes in the levels of cyclic AMP were studied in the superior cervical ganglion and adrenal medulla of male Sprague-Dawley rats under experimental conditions which lead to a trans-synaptic induction of tyrosine hydroxylase (TH) in these organs. In the superior cervical ganglion an intermittent 2-hour swimming stress or treatment with reserpine (5 or 10 mg/kg s.c.) failed to change cyclic AMP levels significantly (P〉0.1) while 48 h later TH was markedly (P〈0.001) increased. In the adrenal medulla the increase in cyclic AMP occurring during cold exposure was much greater than that observed during swimming stress. However, the increase in TH activity resulting from swimming stress was markedly greater then that resulting from cold exposure. The same inverse relationship holds true when comparing the effect of reserpine with that of cold stress. Moreover, during cold exposure cyclic AMP levels were maximal (700%) within 20 min and had fallen almost to control levels (180%) after 60 min. However, no significant increase in TH (P〉0.1) was observed 48 h after a 1-hour cold stress whereas a 2-hour cold stress produced a marked (P〈0.001) increase in TH activity. Thus, the second hour of cold stress during which cyclic AMP was only marginally elevated seems to be essential for initiating the biochemical events ultimately leading to an increased synthesis of TH. It is concluded that either cyclic AMP is not involved in trans-synaptic induction of TH or that changes in a small pool are essential and are overshadowed by a much larger pool of cyclic AMP not reacting in the same way.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00499174
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  • 4
    Electronic Resource
    Electronic Resource
    Evidence against a causal relationship between increase in c-AMP and induction of tyrosine hydroxylase in the rat adrenal medulla (1974)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 285 (1974), S. 233-242 
    Details
    ISSN: 1432-1912
    Keywords: Trans-Synaptic Enzyme Regulation ; Tyrosine Hydroxylase ; c-AMP ; Reserpine ; Propranolol ; Aminophylline
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary It was the purpose of the present experiments to establish whether the reserpine-mediated changes in adrenomedullary c-AMP result from α- or β-adrenergic activation of adenylate cyclase by catecholamines liberated from adrenal chromaffin cells and whether a causal relationship exists between these changes and subsequent induction of tyrosine hydroxylase (TH). The reserpine-mediated increase in c-AMP was blocked by neither α- nor β-adrenergic blocking agents. However, propranolol abolished the increase in c-AMP by a mechanism which is not related to the β-blocking properties of this drug. Although propranolol abolished the reserpine-mediated increase in c-AMP it did not interfere with the subsequent TH induction. Moreover, administration of aminophylline together with reserpine produced a larger and more prolonged increase in c-AMP in denervated adrenals than reserpine alone in intact glands. Denervation prevented TH induction in spite of the more extensive increase in c-AMP in the adrenal medulla after the combined treatment. It is concluded that there is no causal relationship between the overall increase in c-AMP in the adrenal medulla and the subsequent TH induction. However, the possibility that a small pool of c-AMP which is overshadowed by the non-related overall changes may be involved in trans-synaptic TH induction cannot be excluded.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00498993
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  • 5
    Electronic Resource
    Electronic Resource
    Lack of correlation between changes in cyclic nucleotides and subsequent induction of tyrosine hydroxylase in rat adrenal medulla (1976)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 293 (1976), S. 105-108 
    Details
    ISSN: 1432-1912
    Keywords: cAMP/cGMP ratio ; Tyrosine hydroxylase induction ; Reserpine ; Dexamethasone ; Hypophysectomy ; Adrenal medulla
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Pretreatment of rats with dexamethasone (2.5 μmol/kg, a dose which blocks the release of ACTH from the pituitary gland) abolished the reserpine-mediated increase in cAMP and the increase in the cAMP/cGMP ratio in the adrenal medulla. In contrast, the reserpine-mediated induction of tyrosine hydroxylase (TH) remained unchanged. Hypophysectomy had a similar effect to dexamethasone treatment. Since changes in cAMP and changes in the cAMP/cGMP ratio are not indispensible prerequisites for the subsequent induction of TH, a causal relationship between the two phenomena seems to be excluded.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00498878
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  • 6
    Electronic Resource
    Electronic Resource
    The role of sodium influx mediated by nicotinic receptors as an initial event in trans-synaptic induction of tyrosine hydroxylase in adrenergic neurons (1980)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 313 (1980), S. 199-203 
    Details
    ISSN: 1432-1912
    Keywords: 22Na influx ; Superior cervical ganglion ; Cholinomimetics ; Tyrosine hydroxylase induction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. Isolated superior cervical ganglia of the rat were incubated for 2–30 min (37°C) in Krebs' solution or tissue culture medium (BGJb) containing 22Na and then washed for 30 min in ice-cold 22Na-free Krebs' solution (to clear the extracellular space). The radioactivity remaining in the ganglia was taken as a measure of 22Na influx into the intracellular compartment of the ganglion. 2. Addition of cholinomimetics (100 μM nicotine or 100 μM carbachol) to the incubation medium led to an increase in 22Na influx. This increase reached maximal values after 10 min of incubation; it was more pronounced after incubation in Krebs' solution than in BGJb medium. 3. While chlorisondamine (3 μM) or dopamine (100 μM) greatly reduced the carbachol-induced 22Na influx, tetrodotoxin (2 μM) did not have any effect. 4. In ganglia obtained from animals treated with 6-hydroxydopamine in the early postnatal phase (resulting in an extensive destruction of peripheral sympathetic neurons) neither carbachol (100 μM) nor nicotine (100 μM) produced an increase in 22Na influx demonstrating that the intraneuronal compartment is responsible for this enhanced influx. 5. The effects of dopamine, chlorisondamine and tetrodotoxin on the carbachol-induced 22Na uptake into superior cervical ganglia are similar to their effects on carbachol-mediated induction of tyrosine hydroxylase in superior cervical ganglia kept in tissue culture (Thoenen and Otten 1977b). It is concluded that the induction of tyrosine hydroxylase via nicotinic receptors is closely linked to the enhanced sodium influx into the adrenergic neurons mediated by the same receptors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00505734
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