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| 2. |
- Ekström, Peter, et al.
(författare)
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A morphometric study of age-related changes in serotonin-immunoreactive cell groups in the brain of the coho salmon, Oncorhynchus kisutch walbaum
- 1992
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Ingår i: Experimental Neurology. - 0014-4886. ; 116:2, s. 204-209
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Tidskriftsartikel (refereegranskat)abstract
- In the coho salmon there is a transient increase in total brain concentrations of serotonin during smolt transformation which occurs midlife, just before down-stream migration to the ocean. There is also a gradual age-related increase in total brain serotonin concentrations. These increases may be due to reorganization of the central serotonergic system, changes in serotonin turnover, or both. They may be related to the specific physiological conditions during different life stages of salmon, or to ongoing growth and plastic changes of the brain. In the present study we have compared serotonin-immunoreactive (5-HTir) cell groups in 1-year-old freshwater presmolt and 2-year-old seawater postsmolt salmon. Our data indicate a continuous growth of the 5-HTir cell groups in terms of an increase in numbers of 5-HTir neurons in the cell groups of the pretectum and the brain stem, and an increase in the volumes of such neurons and cell groups. However, when related to the increase in total brain volume, i.e., the volume that may be innervated by the 5-HTir neurons, the ratio of 5-HTir neurons per mm3 decreased. The largest decreases were observed in the median raphe nucleus (P < 0.005) and the B9 group (P < 0.05). The ratio of volumes of the brain nuclei containing 5-HTir neurons relative to total brain volume was remarkably constant when comparing pre- and postsmolt brains: only the pretectal nucleus showed a significant decrease (P < 0.01) in relative volume. The total volume of 5-HTir neurons increased in postsmolts (P < 0.005). Since there was no increase in size of 5-HTir somata in any nucleus, changes in total volume reflect the changes in numbers of 5-HTir neurons. Thus, to account for the observed age-related increase in total brain concentrations of serotonin, an increase in the net production of serotonin, possibly accompanied by an increase in the density of serotonergic innervation in certain brain areas, may be postulated. The transient surge of whole brain content of serotonin observed at smolt transformation probably reflects a transient change in serotonin metabolism rather than an increase in the number of neurons.
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| 3. |
- Jansson, M, et al.
(författare)
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Effects of luminal stimuli on polyamine metabolism in the small intestine of the rat : the role of enteric nerves
- 1993
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Ingår i: Acta Physiologica Scandinavica. - : Wiley. - 0001-6772 .- 1365-201X. ; 149:4, s. 90-483
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to investigate to what extent polyamine metabolism in the small intestine of the rat is controlled by the enteric nervous system. Polyamine metabolism was followed by measuring the activity of ornithine decarboxylase (ODC) and in some instances also the content of polyamines (putrescine, spermidine and spermine). ODC activity in the intestine was increased when intraluminal pressure was increased and 3 h after placing cholera toxin in the intestinal lumen. Cholera toxin also increased the tissue putrescine content. Atropine or hexamethonium given i.v. did not influence the evoked changes of ODC activity. The pressure induced changes were not decreased by placing lidocaine on the serosal surface. On the other hand, the ODC activity of control segments were decreased by hexamethonium or atropine. The presence of glucose in the intestinal perfusate did not augment tissue ODC activity, neither did the heat stable enterotoxin from Escherichia coli (STa). It is concluded that the effect on polyamine metabolism evoked by luminal pressure or cholera toxin seems not to be mediated via nerves, while nerves seem to influence ODC activity during control conditions. The experiments with enterotoxins suggest that cAMP is the intracellular second messenger controlling intestinal ODC activity.
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| 4. |
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| 5. |
- Vecino, E., et al.
(författare)
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Expression of the homeobox engrailed gene during the embryonic development of the nervous system of the trout (Salmo fario L.)
- 1991
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Ingår i: Neuroscience Letters. - 0304-3940. ; 129:2, s. 311-314
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Tidskriftsartikel (refereegranskat)abstract
- The expression of the engrailed homeobox gene during trout embryogenesis has been examined using immunohistochemistry and the monoclonal antibody 'Mab 4D9'. Engrailed has been suggested to play an important role during development by controlling position-specific characteristics in the CNS of the early embryo. In the present study we have analyzed the expression of engrailed at 5 stages of embryonic development of the trout (Salmo fario L.). The earliest stage analyzed was when the optic vesicles appear. Engrailed was then expressed in the posterior mesencephalon and anterior metencephalon, in a caudorostrally decreasing gradient. As the embryo develops, the pattern of the engrailed expression increases in spatial complexity. Thus, in the later stages of development, just before hatching, engrailed was found in hypothalamic areas, the germinative matrix layer of the cerebellum, the mesencephalic tegmentum, the caudal optic tectum and in the area of the trigeminal motor nucleus. This is similar to the distribution of engrailed in embryos of amphibians, birds and mammals.
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| 6. |
- Vecino, E, et al.
(författare)
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In situ hybridization of neuropeptide Y (NPY) mRNA in the goldfish brain
- 1994
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Ingår i: NeuroReport. - 0959-4965. ; 6:1, s. 31-127
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Tidskriftsartikel (refereegranskat)abstract
- The distribution of neurones expressing neuropeptide Y (NPY) mRNA in the brain of the goldfish was investigated using a non-radioactive in situ hybridization technique. Neurones expressing NPY mRNA were located in cell groups previously shown to exhibit NPY immunoreactivity in the ventral telencephalon, thalamus, optic tectum and a region adjacent to the locus coeruleus. In addition, neurones expressing NPY mRNA were observed in the diffuse nucleus of the torus lateralis and in the mesencephalic tegmentum. Our results suggest that in the two latter groups of neurones the rate of transport of NPY from the perikarya is higher, or that NPY is not synthesized at levels detectable by immunocytochemistry.
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| 7. |
- Östholm, Thomas, et al.
(författare)
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Postsmolt change in numbers of acetylcholinesterase-positive cells in the pineal organ of the Pacific coho salmon
- 1992
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Ingår i: Cell & Tissue Research. - 0302-766X. ; 270:2, s. 281-286
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Tidskriftsartikel (refereegranskat)abstract
- We have examined the occurrence of acetylcholinesterase (AChE)-positive cells in the pineal organ of different developmental stages of the Pacific coho salmon. Large numbers of AChE cells were present in fresh-water living alevins, in all stages of presmolts (n=307-544), and in adult spawners (n=696-1774) whereas seawater-living postmolts displayed a total lack of labeled cells. The AChE-reactive cells were evently distributed within the pineal end-vesicle and stalk of the presmolts and adults. However, the AChE-positive cells that occurred in the pineal stalk were of a smaller type and more uniform in shape than the cells of the pineal endvesicle. The dense populations of AChE-stained cells in the alevins, were all situated in the caudal part of the pineal end-vesicle. We conclude that changes in pineal metabolism occur in postsmolt salmon that liver in saltwater. It is not clear whether the observed change in pineal AChE expression is an "unspecific" change caused by life in the sea, reflecting alterations that are related to aspects of osmoregulation, and/or is involved in the visual function of the pineal organ resulting from changes in the environmental lighting conditions, e.g., photoperiod, light-intensity, or spectral composition. This study adds to our previous findings of changes that occur in the central nervous system of the salmon during the time of the parr-smolt transformation and migration between limnic and marine environments and indicates a possible central role of the pineal organ in the control of these events.
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