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  • 1
    ISSN: 1432-0568
    Keywords: Pineal organ ; Perivascular contact ; HIOMT ; Median eminence ; Adrenal cortex ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In the pineal organ of the female rat, proportional changes in the area of contact of pinealocyte processes and glial processes with the perivascular space were found after bilateral adrenalectomy. The contact area was evaluated by measuring the length of pinealocyte and glial cell membranes directly abutting on the basal lamina. In the normal female rat, 40% of the contact area is occupied by pinealocyte and 60% by glial cell processes. Fourteen days after bilateral adrenalectomy, this proportion is reversed. In addition, cell counts demonstrate that more pinealocytes gain access to the pericapillary space due to the experimental conditions. In order to prove whether or not these results indicate an increase of pineal endocrine activity, the melatonin-forming enzyme hydroxyindole-O-methyltransferase (HIOMT, E.C. 2.1.1.4) was assayed. After bilateral adrenalectomy the HIOMT activity was found to significantly increase.
    Type of Medium: Electronic Resource
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  • 2
    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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  • 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
    ISSN: 1435-1463
    Keywords: Corticotropin-releasing factor ; stress ; median eminence ; rat ; histology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effect of an experimentally induced stress reaction on the amount of “Gomori-positive” granules, demonstrable in the median eminence of bilaterally adrenalectomized rats was studied. Application of formalin s.c. or histamine i.m. from the 15th to the 17th day p.o., or i.p. injection of Pyrifer® from the 15th to 21st day p.o., with simultaneous administration of 1% NaCl drinking fluid, has no effect on the amount of granules. On the other hand, the amount of granules diminishes if the animals, during a 3-day treatment with formalin, histamine or Pyrifer®, are given solely tap water to drink. Water deprivation from the 15th to the 17th day after bilateral adrenalectomy also causes a marked reduction in the amount of granules. It is assumed that the granules represent the morphological correlate of the corticotropin-releasing factor (CRF). The findings are related to the results of pharmacological studies on the behaviour of the CRF-activity during stress.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In adrenalectomized rats, histochemical and immunohistochemical properties of the following secretion products have been investigated: 1. CRF-granules in the outer layer of the median eminence; 2. neurosecretory material (NSM) in the supraoptico-hypophysial system of the hypothalamus; 3. secretory granules in the TSH-cells of the anterior lobe of the hypophysis; 4. secretory granules in the ependymal cells of the subcommissural organ (SCO); 5. β-cell-granules in the islets of Langerhans in the pancreas. All these substances are characterized by their stainability with the so-called “Gomorimethod”. The experiments have included studies into: a) the extractability of the substances by various solvents; b) the digestability of the substances by pepsin or trypsin; c) their histochemically detectable content of disulfide groups, arginine and periodic acid-Schiff (PAS) reactive carbohydrates; d) their reaction with porcine-neurophysin-II-antibodies. All substances exhibited a positive reaction for disulfide groups. Based on their solutility properties, their resistance to pepsin or trypsin, their respective content of PAS-reactive carbohydrates and their failure to react with anti-neurophysin serum the “Gomori-positive” granules in TSH-, SCO- and pancreatic β-cells can be distinguished from one another and from CRF- and neurosecretory granules. In contrast, CRF-granules and NSM showed identical properties. Taking into consideration data from the biochemical and histochemical literature, the present findings suggest that CRF-granules and NSM consist of closely related biochemical substances.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Proteins reacting with neurophysin antibodies and “Gomori-positive” substances were demonstrated histochemically in hypothalamic neurosecretory material of normal and bilaterally adrenalectomized rats after two different fixations: a) picric acid-formalin (PAF) for 7 days at 37°C; b) Bouin's fluid for 20 h at 4°C. After PAF-fixation anti-neurophysin reactive neurosecretory granules are found in all parts of the supraoptico-hypophysial system and in the suprachiasmatic nucleus of normal and adrenalectomized animals. In the latter they can additionally be demonstrated in the outer layer of the median eminence. Amount and distribution of “Gomori-positive” sustances correspond to those described for the immunoreactive material, except for the suprachiasmatic nucleus, in which the substances can not be detected. Following fixation in Bouin's fluid the immunohistochemical reactions are unchanged whereas the staining of “Gomori-positive” substances is remarkably impaired. The amounts of the substances demonstrable in the neural lobe are diminished and in the cells of the supraoptic and paraventricular nuclei as well as in both median eminence layers only traces of the substances are to be seen. The findings indicate that negative results in demonstrating “Gomori-positive” substances may be caused by inappropriate fixation and need to be controlled by immunohistochemical techniques.
    Type of Medium: Electronic Resource
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