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  • 1
    ISSN: 1432-0878
    Schlagwort(e): Key words: Secretoneurin ; Pineal gland ; Neuropeptide immunocytochemistry ; Sympathetic nervous system ; Superior cervical ganglion ; Pinealocytes ; Cell culture ; Rat (Wistar) ; Syrian hamster ; Mesocricetus auratus ; Siberian hamster ; Phodopus sungorus (Rodentia)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract. The pineal gland of mammals is richly innervated by nerve fibres containing various peptides of central or sympathetic origin. In this study, we have investigated the presence, regulation and effect of secretoneurin (SN), a 33-amino-acid peptide discovered recently in the central and sympathetic nervous systems. The rat pineal gland contains about 34 fmol SN/pineal, although only 20% of the secretoneurin immunoreactivity (SN-IR) is the free peptide. SN-IR is localised in only a few nerve fibres found in the parenchyma of the gland and along the pineal stalk. In the rat pineal, SN-IR shows no midday/midnight differences but is significantly decreased (55%–65%) after superior cervical ganglionectomy or exposure to constant light. These observations suggest that, in the rat pineal, SN-IR originates partly from central areas and partly from the superior cervical ganglia. The pineal of the Syrian hamster contains much more SN-IR: 120 fmol SN-IR/pineal (about 20% being the free peptide). SN-IR is found both in nerve fibres and pineal cells. Some of the fibres run along the pineal stalk, indicating that they are of central origin, although a sympathetic origin cannot be ruled out. Pineal SN-IR is below detectable levels in the Siberian hamster. In cultured rat pinealocytes, SN significantly inhibits serotonin release and, to a lower extent, melatonin release.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 279 (1995), S. 565-573 
    ISSN: 1432-0878
    Schlagwort(e): Pineal gland ; Aging ; X-ray microanalysis ; Calcium concretions ; Rat (Wistar)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract The genesis of calcium concretions in aged rats was studied by means of transmission and scanning electron microscopy. The potassium pyroantimonate method, combined with X-ray microanalysis, allowed us to study the distribution of cations and calcium. Notable accumulations of calcium (associated with phosphorus) were localized in vesicles, vacuoles, lipid droplets, lipopigments, and mitochondria of dark pinealocytes. The results obtained in the present investigation suggest that these organelles are involved in the genesis of the concretions. The presence of sulfur indicates the existence of an organic matrix. We propose that genesis takes place in dark pinealocytes, which contain more calcium than light pinealocytes. Mineralization foci are some-times associated with cellular debris and enlarge by further apposition of material. Two types of concretions, as determined by electron microscopy and confirmed by electron diffraction, could be observed: the “amorphous” type with concentric layers and the crystalline type with needle-shaped crystals. Once formed, the concretions reach the extracellular space and the cell breaks down. Possible extracellular calcification is suggested in the extracellular calcium-rich floculent material. The mineralization process is interpreted as being an age-related phenomenon and mainly a consequence of the degeneration of pinealocytes.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    ISSN: 1432-0878
    Schlagwort(e): Key words Hydroxyindole-O-methyltransferase ; Pineal gland ; In situ hybridisation ; Melatonin ; 5-Methoxyindoles ; Rat (Wistar)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract  Hydroxyindole-O-methyltransferase (HIOMT) is the enzyme involved in the last step of the melatonin synthesis pathway. Recently, a cDNA encoding HIOMT has been isolated from a rat pineal gland library. Using this cDNA, we developed a highly sensitive in situ hybridisation protocol to investigate the distribution of HIOMT mRNA in both the rat brain and dissociated pinealocytes maintained in primary cell culture. In the rat brain, HIOMT mRNA was only detected in the three parts of the pineal complex: the superficial pineal, the stalk and the deep pineal. No extra-pineal hybridisation labelling was observed. These results strongly suggest that melatonin synthesis also occurs in the deep part and the stalk of the pineal gland. HIOMT mRNA was markedly expressed in cultured pinealocytes. No particular subcellular area was observed to express HIOMT mRNA specifically, as the labelling was homogeneously distributed in the cytosol and in the axon-like processes. In conclusion, the use of in situ and in vitro hybridisation with a pineal riboprobe has detected notable HIOMT expression restricted to pinealocytes.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    ISSN: 1432-0878
    Schlagwort(e): Key words: Calcification ; Concretions ; Collagen ; Pineal gland ; Aging ; Rat (Wistar)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract. The relationship between collagen fibrils and calcified concretions exclusively appearing in the pineal gland of adult/aging rats has been investigated. Deposits of lanthanum, which replace calcium ions are distributed along collagen fibrils with a repeating period of about 70 nm. Calcium has been detected histochemically between collagen bundles surrounding extracellular concretions by means of the pyroantimonate method and by X-ray microanalysis. It is associated with phosphorus. The data presented here suggest that collagen fibrils are involved in the genesis and growth of extracellular concretions located in the connective tissue surrounding the pineal gland of aging rats.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 263 (1991), S. 593-596 
    ISSN: 1432-0878
    Schlagwort(e): Pineal gland ; Concretions ; Calcium ; X-ray microanalysis ; Rat (Wistar)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Calcium content and pineal concretions were studied in young (2–3 months) and old (28 months) Wistar rats. Samples, deep-frozen by liquid propane/isopentane and freeze-dried were analysed by means of X-ray microanalysis in a scanning electron microscope. Total semi-quantitative measurements revealed that pineals of old rats showed a marked increase of calcium compared with the pineals of young rats. It is thus suggested that a calcium-rich environment is responsible for the growth of pineal concretions, which only appear in old rats. Pineal calcifications in rats could thus be an indicator of aging and/or of a degenerating state.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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