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  • 1
    ISSN: 1432-0568
    Keywords: CRF-granules ; Sodium chloride ; Adrenalectomy ; Rat ; Histology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Bilaterally adrenalectomized female SPF Wistar rats were given tap water containing various concentrations of sodium chloride to drink ad lib. After a survival period of 14 days the animals were killed by perfusion-fixation. Their brains were removed, fixed in pieric acid formalin solution and embedded in Paraplast. Serial sections of median eminence and hypophysial posterior lobe were cut and stained with crotonaldehyde-fuchsine. In the stained sections the amount of CRF-granules visible in the external zone of the median eminence, and the amount of “classical” neurosecretory material (NSM) occuring in the internal zone of the median eminence and in the posterior lobe of the hypophysis were estimated. After administration of drinking solutions to which 0%–1% sodium chloride were added, the amount of CRF-granules increased with increasing NaCl uptake, whereas the amount of “classical” NSM was not changed. Application of tap water containing 2% NaCl led to a marked decrease in the amount of “classical” NSM but did only slightly impair the amount of CRF-granules. From the findings it is concluded that 1. following bilateral adrenalectomy administration of sodium chloride inhibits the secretion of CRF-granules; 2. CRF-granules and “classical” NSM, although histochemical identical, have different functional significances; 3. the mechanisms regulating the secretion of CRF-granules are different from those controlling the release of “classical” NSM.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0568
    Keywords: Corticotropin releasing factor ; Neurosecretion ; Hypophysis ; X-irradiation ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In 195 female Wistar rats the influence of adrenalectomy, total body X-irradiation and dexamethasone treatment on the amount of CRF-granules in the external zone of the median eminence and “classical” neurosecretory material (NSM) in the internal zone of the median and in the posterior lobe of the hypophysis has been studied. In the normal rat only very few CRF-granules occur. 15 days after adrenalectomy increased amounts of CRF-granules but normal amounts of “classical” NSM are found. X-irradiation leads to a slight diminishment of “classical” NSM in normal rats. In adrenalectomized animals X-irradiation causes no changes in the amount of “classical” NSM but a marked decrease in the amount of CRF-granules. Application of dexamethasone from the 15th to 18th day after adrenalectomy enhances the augmentation of CRF-granules in irradiated and non-irradiated rats but does not influence the amount of “classical” NSM. The findings show that no correlation exists between the quantitative changes of CRF-granules and “classical” NSM under the experimental conditions used. Therefore it is to be assumed that the release of the two substances is regulated by different control mechanisms and that the substances have a different functional significance. The observations do not exclude the possibility that CRF-granules and “classical” NSM are biochemically identical.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-0568
    Keywords: Neurosecretion ; Adrenalectomy ; Diabetes insipidus ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The influence of adrenalectomy on the amount of “Gomori-positive” neurosecretory material in the outer layer of the median eminence and in the supraoptico-hypophysial system was studied in normal Long-Evans rats and in Long-Evans rats heterozygous and homozygous for hypothalamic diabetes insipidus. In all non-adrenalectomized rats very few “Gomori-positive” granules were found in the outer median eminence layer. After adrenalectomy the amount of the granules increased markedly in normal Long-Evans rats and only slightly in Long-Evans rats heterozygous for diabetes insipidus. However, no augmentation of the granules occurred in homozygous diabetes insipidus rats. The amount of “Gomori-positive” substances demonstrable in the supraoptic and paraventricular nuclei, in the inner layer of the median eminence, and in the neural lobe of the hypophysis was less in rats heterozygous for diabetes insipidus than in normal Long-Evans rats and the smallest in homozygous diabetes insipidus rats. No differences in the amounts of the substances were observed between adrenalectomized and non-adrenalectomized animals. The findings suggest that the “Gomori-positive” granules occurring in the outer layer of the median eminence of adrenalectomized rats are of similar origin as those of the supraoptico-hypophysial system and represent a vasopressin-neurophysin-complex. The results support the concept that vasopressin is involved in the regulation of ACTH release.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 185 (1977), S. 215-229 
    ISSN: 1432-0878
    Keywords: CRF-granules ; Adrenalectomy ; Hypothalamic lesions ; Rat ; Histology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Axons terminating in the outer layer of the median eminence of rats contain light microscopically visible granules. The granules are assumed to represent a corticotropin-releasing factor and, therefore, are called CRF granules. To find out whether neurons containing CRF-granules originate and run together with the neurons of the hypothalamus-neural lobe system (HNS), the effect of unilateral lesions in the HNS on the amount and distribution of CRF-granules was studied in bilaterally adrenalectomized rats. HNS lesions prevented the adrenalectomy-induced increase in CRF granules on the side of the lesion. Lesions outside the HNS or sham lesions did not influence the amount and distribution of the granules. The findings suggest that CRF-granules are located in terminals of neurons whose perikarya are situated in magnocellular hypothalamic nuclei. It can also be concluded that the axons of these neurons run within the HNS and do not decussate.
    Type of Medium: Electronic Resource
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