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  • 1
    Electronic Resource
    Electronic Resource
    Responsiveness of Pineal N-Acetyltransferase and Melatonin in the Cotton Rat Exposed to Either Artificial or Natural Light at Night (1985)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of pineal research 2 (1985), S. 0 
    Details
    ISSN: 1600-079X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: In three separate experiments, the effect of acute exposure to either artificial or natural light during darkness of pineal N-acetyltransferase (NAT) activity and melatonin content was studied in the cotton rat (Sigmodon hispidus). The exposure of animals to an artificial-light irradiance of 160,000 μW/cm2 during darkness for either 1 s, 5 s, or 30 min was followed by a precipitous decline in pineal NAT activity and melatonin content when measured at either 15 or 30 min after light onset. When cotton rats were acutely exposed to light at night for 5 s, irradiances of either 3.2, 32, 320, and 3,200 did not suppress either pineal NAT or melatonin 30 min later; however, if the 5-s exposure had an irradiance of either 32,000 or 160,000 μW/cm2, the pineal enzyme activity and indole content were depressed. Moonlight, which had a maximal irradiance of 0.32 μW/cm2, was unable to suppress pineal NAT activity and melatonin content even when the animals were exposed to the moonlight for 30 min. The treatment of cotton rats with either norepinephrine or its agonist, isoproterenol, before their exposure to light at night retarded slightly the suppressive effect of light on the pineal constituents measured. Also, these drug treatments suppressed the pre-exposure levels of both NAT activity and melatonin content in the cotton rat pineal gland.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1600-079X.1985.tb00717.x
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  • 2
    Electronic Resource
    Electronic Resource
    Hibernation-related changes in the immunoreactivity of neuropeptide systems in the suprachiasmatic nucleus of the ground squirrel, Spermophilus richardsonii (1990)
    Springer
    Cell & tissue research 262 (1990), S. 293-300 
    Details
    ISSN: 1432-0878
    Keywords: Suprachiasmatic nucleus ; Neuropeptide immunocytochemistry ; Image analysis ; Neuropeptide Y ; Substance P ; Thyrotropin-releasing hormone ; Vasoactive intestinal peptide ; Vasopressin ; Spermophilus richardsonii (Rodentia) ; Erinaceus europaeus (Insectivora)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The pattern of distribution and reactivity of the neuropeptides vasopressin (AVP), vasoactive intestinal peptide (VIP), neuropeptide Y (NPY), substance P (SP), and thyrotropin-releasing hormone (TRH) were studied in the suprachiasmatic nucleus (NSC) of 20 Richardson's ground squirrels (and 7 European hedgehogs) of both sexes during hibernation and euthermia. The total area of immunostained structures revealed by application of the individual immunocytochemical techniques was measured by means of computer-aided image analysis. In both species, elements of all peptide systems examined were related to particular subdivisions of the NSC. The pattern of immunoreactivity was strongly correlated with the physiological stage of hibernation or euthermia both in ground squirrels and hedgehogs. The immunoreactivities to AVP and SP increased in area during hibernation (AVP: 25%; SP: 25%), whereas the respective area immunoreactive to NPY and VIP decreased (NPY: 45%; VIP: 100%) in comparison to nonhibernating controls. The TRH-immunoreactive nerve fibers were rare and rather scattered; thus, the quantitative procedure was not applicable for this immunoreaction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00309884
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  • 3
    Electronic Resource
    Electronic Resource
    The neuroendocrine system in hibernating mammals: present knowledge and open questions (1995)
    Springer
    Cell & tissue research 281 (1995), S. 391-412 
    Details
    ISSN: 1432-0878
    Keywords: Hibernation ; Hypothalamo-hypophysial system ; Neuroendocrine regulation ; Peptidergic neurosecretion ; Peptidergic neurotransmission ; Aminergic projection ; Erinaceus europaeus (Insectivora) ; Cricetus cricetus ; Glis glis ; Golden hamster ; Spermophilus columbianus ; Spermophilus richardsonii (Rodentia)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The present review describes the distribution and the function-dependent reactivity pattern of those peptidergic and aminergic components of the neuroendocrine system of hibernating mammals that have been studied by histological, pharmacological and physiological techniques. Particular attention has been paid to the intrinsic connectivity of the peptidergic apparatus and its input systems. Since the reactivity patterns of the neuroendocrine system show remarkable fluctuations in relation to the various stages of hibernation and euthermia, these fluctuations have been analyzed with respect to (1) their causative role in the regulation of hibernation and (2) their secondary response to physiological changes during hibernation. The author's investigations described in this review have mainly been performed in European hedgehogs (Erinaceus europaeus), European and golden hamsters (Cricetus cricetus, Mesocricetus auratus), dormice (Glis glis), and in Richardson's and Columbian ground squirrels (Spermophilus richardsonii, Spermophilus columbianus), by the use of light- and electron-microscopic immunocytochemistry and histochemistry, in situ hybridization, radioimmunoassays and stereotaxically guided application techniques. These experiments were also performed in hypothermic animals. The (partially published) results obtained by the author and his associates are reviewed with reference to the body of evidence found in the recent literature. With respect to their reactivity patterns, several neuropeptide and transmitter systems can be regarded as candidates for control systems of hibernation. Neuronal complexes immunoreactive for endogenous opiates, in particular enkephalin, and also for vaspressin, somatostatin, substance P, corticotropin-releasing factor and serotonin are probably involved in the neuroendocrine control of hibernation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00417858
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  • 4
    Electronic Resource
    Electronic Resource
    The neuroendocrine system in hibernating mammals: present knowledge and open questions (1995)
    Springer
    Cell & tissue research 281 (1995), S. 391-412 
    Details
    ISSN: 1432-0878
    Keywords: Key words: Hibernation ; Hypothalamo-hypophysial system ; Neuroendocrine regulation ; Peptidergic neurosecretion ; Peptidergic neurotransmission ; Aminergic projection ; Erinaceus europaeus (Insectivora) ; Cricetus cricetus ; Glis glis ; Golden hamster ; Spermophilus columbianus ; Spermophilus richardsonii (Rodentia)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. The present review describes the distribution and the function-dependent reactivity pattern of those peptidergic and aminergic components of the neuroendocrine system of hibernating mammals that have been studied by histological, pharmacological and physiological techniques. Particular attention has been paid to the intrinsic connectivity of the peptidergic apparatus and its input systems. Since the reactivity patterns of the neuroendocrine system show remarkable fluctuations in relation to the various stages of hibernation and euthermia, these fluctuations have been analyzed with respect to (1) their causative role in the regulation of hibernation and (2) their secondary response to physiological changes during hibernation. The author’s investigations described in this review have mainly been performed in European hedgehogs (Erinaceus europaeus), European and golden hamsters (Cricetus cricetus, Mesocricetus auratus), dormice (Glis glis), and in Richardson’s and Columbian ground squirrels (Spermophilus richardsonii, Spermophilus columbianus), by the use of light- and electron-microscopic immunocytochemistry and histochemistry, in situ hybridization, radioimmunoassays and stereotaxically guided application techniques. These experiments were also performed in hypothermic animals. The (partially published) results obtained by the author and his associates are reviewed with reference to the body of evidence found in the recent literature. With respect to their reactivity patterns, several neuropeptide and transmitter systems can be regarded as candidates for control systems of hibernation. Neuronal complexes immunoreactive for endogenous opiates, in particular enkephalin, and also for vasopressin, somatostatin, substance P, corticotropin-releasing factor and serotonin are probably involved in the neuroendocrine control of hibernation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410050437
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  • 5
    Electronic Resource
    Electronic Resource
    The somatostatin system of the brain and hibernation in the European hamster (Cricetus cricetus) (1997)
    Springer
    Cell & tissue research 288 (1997), S. 441-447 
    Details
    ISSN: 1432-0878
    Keywords: Key words: Growth hormone cells ; Hibernation ; Hypothalamo-hypophysial system ; Somatostatin ; Cricetus cricetus (Rodentia)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The depression of physiological processes characteristic of mammalian hibernation is precisely regulated by the central nervous system, especially by the neuropeptidergic apparatus of the hypothalamus. Because of inhibitory influences on neuronal circuits within the brain and suppressive effects on the metabolism via the endocrine axis, somatostatin has been implicated in the regulation of hibernation. The somatostatin system of the brain was investigated with immunocytochemistry, in situ hybridization, and radioimmunoassays in euthermic summer, euthermic winter, and hibernating European hamsters (Cricetus cricetus). Numerous somatostatin-immunoreactive perikarya were observed in the periventricular hypothalamic nucleus. The striatum, amygdala, and cortex contained only scattered immunoreactive perikarya. These entities also contained immunoreactive fiber profiles, although the highest density of immunoreactive fibers was found in the median eminence. Immunocytochemistry and radioimmunoassays showed that the number of somatostatin-immunoreactive perikarya and fibers and the content of somatostatin in the hypothalamus and the median eminence was conspicuously lower in euthermic winter animals than in euthermic summer animals. This decrease was more pronounced in hibernating specimens. In situ hybridization also demonstrated a decrease in the expression and synthesis rate of somatostatin in euthermic winter animals; again, this was even more dramatic in hibernating hamsters. These changes were less pronounced or non-significant in the extrahypothalamic somatostatin-immunoreactive perikarya and fiber systems, as shown by immunocytochemistry and radioimmunoassay, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410050831
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  • 6
    Electronic Resource
    Electronic Resource
    Changes in physiological and neuroendocrine properties during thermal adaptation of golden hamsters (Mesocricetus auratus) (1990)
    Springer
    Journal of comparative physiology 160 (1990), S. 153-159 
    Details
    ISSN: 1432-136X
    Keywords: Golden hamster ; Thermal adaptation ; Noradrenaline ; Arginine vasopressin ; Corticotropin releasing factor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Golden hamsters raised at 22°C were adapted in the early summer for 3 weeks to either 28°C or 5°C. To achieve profound changes the photoperiod was also shortened from 14 h to 11 h during adaptation to cold. During the investigation body weight, food consumption, water intake, urine production, and osmolality, as well as secreted amounts of noradrenaline (NA) and dopamine (DA), were recorded in each animal before, during, and after the adaptation period. In another group of golden hamsters the brains were processed for immunocytochemical detection of arginine-vasopressin (AVP) and corticotropin releasing factor (CRF) in the third week of adaptation to a cold or warm environment. In warm-adapted animals food and water consumption and urine production remained unchanged or were only slightly reduced. NA and DA secretion were reduced by 50%. The AVP-immunoreactivity reflected an antidiuretic state in these animals. In fibers influencing the adrenal axis, AVP-immunoreactivity was weak compared to CRF fibers. Food and water consumption, urine production, and DA secretion increased two-fold during cold adaptation. Daily secreted amounts of NA increased nine-fold. AVP-immunoreactivity was weak in projections to the neurohypophysis. Fibers influencing the adrenal axis, however, displayed strong AVP-immunoreactivity in comparison to that of CRF. The immunocytochemically determined patterns of AVP and CRF distribution indicated an activation of the osmoregulative axis in the warm-adapted animals and of the adrenal axis in the cold-adapted golden hamsters.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00300947
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  • 7
    Electronic Resource
    Electronic Resource
    Somatostatin-immunoreactive cells in the gastrointestinal tract of the frog Rana esculenta (1995)
    Springer
    Cell & tissue research 279 (1995), S. 437-440 
    Details
    ISSN: 1432-0878
    Keywords: Enteric nervous system ; Enteroendocrine system ; Gastrointestinal tract ; Somatostatin ; Rana esculenta (Anura)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The morphology and topographic distribution of somatostatin-immunoreactive cells in the stomach and small intestine of the frog Rana esculenta were studied at the light-microscopic level by the use of the peroxidase-antiperoxidase method. Scattered immunostained cells occurred in all regions of the gastrointestinal tract investigated. In the small intestine, the number of these cells decreased gradually in the oral to anal direction, i.e. from the pyloric (antral) stomach to the entrance into the colon. Most of the immunostained cells possessed thick, short cytoplasmic processes, which did not display a preferential spatial orientation. Other somatostatin-immunoreactive cells, which were exclusively located in the small intestine, gave rise to a single long extension oriented toward the lumen. In both stomach and small intestine, a complete penetration of the epithelial surface by these processes of somatostatin-immunoreactive cells was observed only occasionally. The morphological features of the somatostatin-immunostained cells speak in favor of endocrine, paracrine, and possibly also intraluminal secretory functions of the enteroendocrine somatostatin system in frogs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00318502
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  • 8
    Electronic Resource
    Electronic Resource
    Somatostatin-immunoreactive cells in the gastrointestinal tract of the frog Rana esculenta (1995)
    Springer
    Cell & tissue research 279 (1995), S. 437-440 
    Details
    ISSN: 1432-0878
    Keywords: Key words: Enteric nervous system ; Enteroendocrine system ; Gastrointestinal tract ; Somatostatin ; Rana esculenta (Anura)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. The morphology and topographic distribution of somatostatin-immunoreactive cells in the stomach and small intestine of the frog Rana esculenta were studied at the light-microscopic level by the use of the peroxidase-antiperoxidase method. Scattered immunostained cells occurred in all regions of the gastrointestinal tract investigated. In the small intestine, the number of these cells decreased gradually in the oral to anal direction, i.e. from the pyloric (antral) stomach to the entrance into the colon. Most of the immunostained cells possessed thick, short cytoplasmic processes, which did not display a preferential spatial orientation. Other somatostatin-immunoreactive cells, which were exclusively located in the small intestine, gave rise to a single long extension oriented toward the lumen. In both stomach and small intestine, a complete penetration of the epithelial surface by these processes of somatostatin-immunoreactive cells was observed only occasionally. The morphological features of the somatostatin-immunostained cells speak in favor of endocrine, paracrine, and possibly also intraluminal secretory functions of the enteroendocrine somatostatin system in frogs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410050301
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