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  • 1
    ISSN: 1432-0878
    Keywords: Immunohistochemistry ; Paraganglia ; Aging ; Catecholamines ; Catecholamine-synthesizing enzymes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The catecholamine-synthesizing enzymes, tyrosine hydroxylase, dopamine-β-hydroxylase and phenylethanolamine-N-methyltransferase were examined by immunohistochemistry in hypertrophied paraganglia of aged male Fischer-344 rats. All paraganglionic cells reacted with antibodies against tyrosine hydroxylase. Dopamine β-hydroxylase was identified in most paraganglionic cells, indicating that they synthesized norepinephrine. A variable number of paraganglia were positive for phenylethanolamine-N-methyltransferase, which suggested that they synthesized epinephrine. The formaldehyde-induced fluorescence method demonstrated greenish-yellow fluorescence or yellowish-brown fluorescence. The intensity of the fluorescence was in the same range as in adrenal medullary cells. The observations indicate that paraganglia are capable of synthesizing epinephrine.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-6830
    Keywords: phenylethanolamineN-methyltransferase (PNMT) ; adrenal medulla ; glucocorticoids ; transcriptional regulation ; tyrosine hydroxylase (TH) ; adrenocorticotropin (ACTH) ; in situ hybridization ; nuclear run-on transcription assays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary 1. PhenylethanolamineN-methyltransferase (PNMT) is regulated by glucocorticoid hormones. This study investigates the ability of glucocorticoids to modulate transcription of the rat PNMT genein vivo andin vitro. 2. In the adrenal glands of hypophysectomized (HPX'd) rats, the synthetic glucocorticoid dexamethasone (DEX) stimulates production of PNMT mRNA. Quantitative hybridization reveals that the levels of PNMT mRNA increase approximately threefold in total and poly(A)+ RNA after 4 days of DEX treatment of HPX'd rats, a level which is maximal for this treatment. 3. ACTH, the hormonal stimulus of glucocorticoid biosynthesis in the adrenal cortex, enhances PNMT mRNA production to levels comparable to that achieved with DEX in this system. The steroid responsiveness of PNMT message production is specific for glucocorticoids. DEX also increases PNMT mRNA in the brain stem, although the magnitude and speed of response are lower than observed in the adrenal gland. 4. Additional confirmation of the inductive ability of glucocorticoids is demonstrated by the increase in PNMT immunoprecipitated following translationin vitro of adrenal RNAs from DEX-treated rats. Furthermore, the PNMT mRNA signal obtained byin situ hybridization histochemistry in adrenal sections and in primary cultures of dispersed rat adrenal medullae reveals that DEX effects on PNMT mRNA can be elicited bothin vivo andin vitro. 5. Specifically, glucocorticoids exert their effects on expression of PNMT mRNA by elevating the rate of PNMT gene transcription: a 2.3-fold increase in PNMT transcription persists for 18 hr following DEX treatment of HPX'd rats. In summary, this study establishes that glucocorticoids directly and rapidly stimulate transcription of the rat PNMT gene.
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 12 (1989), S. 389-396 
    ISSN: 0741-0581
    Keywords: Small intensely fluorescent (SIF) cell ; Glucocorticoids ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Light and electron microscopic immunocytochemical techniques were used to study the effect of glucocorticoids on the development of phenylethanolamine-N-methyltransferase (PNMT)-immunoreactive cells in the superior cervical ganglion (SCG) of early postnatal rats. Rats were injected daily with hydrocortisone acetate on postnatal days 2 - 6. The first PNMT-immunoreactive cells were detected 6 hours after the first glucocorticoid injection and their number increased after subsequent injections. No PNMT-immunoreactive cells were detected in uninjected controls. PNMT-immunoreactive fibres were seen in the ganglion 6 hours after the first glucocorticoid injection. The PNMT-immunoreactive cells consistently showed processes 2 days after beginning the glucocorticoid treatment, and long processes and fibre networks were seen in ganglia of 7-day-old rats. However, no PNMT-immunoreactive fibres were seen in the iris, which is innervated by the SCG.Ultrastructurally, most of the PNMT-immunoreactive cells had the look of small granule-containing (SGC) cells, including heterochromatin clumps along the nuclear envelope and in the center of the nucleoplasm as well as dense core vesicles. SGC cells, nonimmunoreactive to PNMT antiserum, also were seen. However, some PNMT-immunoreactive cells showed ultrastructural characteristics of nerve cells. In contrast to the SGC cells, these cells were characterized by a voluminous cytoplasm, dispersed nuclear heterochromatin, and a lack of granular vesicles. These results demonstrate that glucocorticoids induce PNMT immunoreactivity both in SGC cells and also in cells with characteristics of principal neurons.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
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