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  • 1
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The central ganglia of the leech,Hirudo medicinalis, were processed for the immunohistochemical localisation of bombesin-, substance P-, cholecystokinin-, vasoactive intestinal polypeptide-, enkephalin-, serotonin- and dopamine-β-hydroxylase-related substances. To varying extents all of the substances were localised in neuropile processes, and all, with the exception of substance P, were associated with specific perikarya. The most prominent neuropeptides, in terms of the number of immunoreactive neurones, were cholecystokinin and vasoactive intestinal peptide. The dopamine-β-hydroxylase positive neurones are thought to be octopaminergic, and the serotonin monoclonal antibody revealed positive staining in the Retzius cells. We were unable to demonstrate the coexistence of pairs of substances in any neurones in the leech ganglia.
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  • 2
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The localization of dopamine-β-hydroxylase in the cephalic central nervous system of the blowfly (Calliphora erythrocephala) and the cockroach (Periplaneta americana) was investigated. Immunoreactive neurons were demonstrated in both species. The results were compared with the known distribution of catecholamines in the brain of both species. In certain cell groups and neuropilar regions of both species DβH-immunoreactivity coincides with the presence of catecholamines. Additionally DβH immunoreactivity was found in several cell bodies and neuropilar regions in which no catecholamines could be detected. A correlation between the presence of octopamine and anti-DβH labelling was not found. Thus it seems that the DβH-immunoreactivity neither indicates the presence of octopamine nor is it limited to noradrenaline-containing neurons. Parallel findings in vertebrates are discussed.
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  • 3
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The localisation of tyrosine-hydroxylase immunoreactive neurones in retinas of a variety of animals were examined. Immunoreactivity was associated with specific populations of amacrine neurones in all species examined, viz; rabbit, guinea pig, monkey, cow, frog, pigeon and goldfish. Only in the goldfish was immunoreactivity also associated with processes situated in the outer plexiform layer showing that in this species catecholamine interplexiform cells exist. The development of tyrosine-hydroxylase immunoreactive neurones in the rabbit retina was also analysed. The first immunoreactive positive cells were observed by the third postnatal day. The immunoreactive positive neurones at this stage are weak and lack processes. The intensity of the immunoreactivity increases with development, but processes are lacking, until the 10th postnatal day. The immunoreactive neurones only appear fully developed by the 22nd to 28th postnatal day. Autoradiographical analysis of 3H-dopamine uptake strongly suggests that neurones containing tyrosine-hydroxylase immunoreactivity in the different retinas have the capacity to take up exogenous dopamine. It is therefore concluded that localisation of either 3H-dopamine uptake or tyrosine-hydroxylase provides a means of locating catecholamine neurones.
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  • 4
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Immunohistochemical procedures revealed the occurrence of histamine-like immunoreactivity in specific neurones in the gastropod nervous system. Positive staining was also associated with a characterised neurone known from previous biochemical studies to contain histamine. The proof of the restriction of histamine to specific neurones and the availability of a suitable antiserum to localise the amine makes it possible to examine the role of the compound in different nervous systems.
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  • 5
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary A monoclonal antibody against substance P was used for immunocytochemical staining of the central ganglia of the snail Helix aspersa and several peripheral tissues including the gut, reproductive system, cardiovascular system, tentacle and other muscles. Within the central ganglia many neurones, and many fibres in the neuropile and the nerves entering the ganglia, were stained for the SP-like material. The largest numbers of reactive cell bodies were in the pleural ganglia and on the dorsal surfaces of the pedal ganglia. A group of cells was also found, surrounding the right pedal-cerebral connective, that did not fluoresce, but were enveloped by reactive processes terminating directly onto the neurone somata. Specific staining was observed in all peripheral tissues examined and always appeared to be concentrated in nerve terminals. Most particularly these occurred in the heart and aorta, the pharyngeal retractor muscle and the tentacle. Although mostly present in muscular tissues, some fluorescence was also observed in the nervous layer surrounding the retina. The tentacular ganglion also contained immunoreactive cell bodies.
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  • 6
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Monoclonal antibodies to DARPP-32 recognise an antigen which is present in specific neurones in the snail (Helix aspersa). Consecutive sections 10-μm-thick processed for the localisation of DARPP-32 and tyrosine-hydroxylase immunoreactivity did not show a coexistence in any neuronal structures. DARPP-32 positive cells were, however, often morphologically closely associated with tyrosine-hydroxylase positive cells, implying a functional relationship consistent with the proposed role of DARPP-32. Immunochemical analysis of the DARPP-32 immunoreative material in the snail nervous system shows that the substance has a molecular weight of 28 kDa and therefore different from the DARPP-32 protein found in the rat brain.
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  • 7
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Using a monoclonal antibody against protein kinase C (PKC) that recognises the isoenzymes α, βI, and βII, positive immunoreactivity was observed throughout the cytoplasm of bipolar cells in both rat and rabbit retinas. PKC immunoreactivity was also associated with the outer segment of photoreceptors in the rabbit retina and presumed amacrine cells in the rat retina. The PKC immunoreactivity in the retina was unaffected in content or localisation in rats kept in continuous dark or light conditions over a period of 6 days. The localisation of PKC immunoreactivity in retinas was similar in 6-day-old, 16 day-old, or adult rabbits. However, the content of PKC was lowest at the youngest stage and highest in the adult rabbit retinas. Of the two active phorbol esters studied, only phorbol 12, 13-dibutyrate (PDbut) at a concentration of 1 μM caused the PKC immunoreactivity in rabbit retina bipolar cells to be „transported” from the perikarya towards the axonal terminal processes. Biochemical analyses showed that most of the cytosolic PKC was translocated to the membrane compartment following such treatment. The other phorbol ester, phorbol 12-myristate 13-acetate, even at a concentration of 10 μM did not cause a similar transport of PKC immunoreactivity in the bipolar cells, although a partial translocation of the enzyme could be followed biochemically. Both the translocation and transport of PKC by PDbut could be reversed by simply incubating the retinas in physiological solution for 60 min. The „transport” and translocation processes were not obviously affected by the transport inhibitor colchicine or by known PKC inhibitors such as staurosporine, H-7, sphingosine, or polymyxin B. In addition, agonists known to stimulate inositol phosphates in the retina, viz., carbachol, noradrenaline, and quisqualate, or 4-aminopyridine did not cause a translocation or „transport” of PKC as observed for the phorbol esters.
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  • 8
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 36 (1981), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The occurrence, metabolism, uptake, and release of noradrenaline were studied in the bovine retina with the following results. (1) Small amounts of noradrenaline occur in the retina and are restricted to the area corresponding to the inner nuclear and plexiform layers. (2) Retinal tissue can metabolise [14C]dopamine to form quantities of [14C]noradrenaline. (3) [14C]Noradrenaline can also be partly metabolised to form [14C]normetanephrine. (4) When bovine retinas were incubated with 5 × 10-7 M-[3H]noradrenaline for 20 min and processed for autoradiography, most of the label was associated with apparent nerve processes in the inner plexiform layer. Biochemical analysis showed that more than 95% of the label was noradrenaline. (5) [14C]Noradrenaline uptake saturated with increasing noradrenaline concentrations and followed Michaelis-Menten kinetics. This uptake could be accounted for by two processes, a high-affinity system with a Km1 of 5 × 10-8 M and a Vmax1 of 0.193 pmol/mg/10 min and a low-affinity system with a Km2 of 6.3 × 10-5 M and a Vmax2 of 0.109 nmol/mg/10 min. (6) Noradrenaline uptake was strongly dependent on temperature and sodium, less dependent on potassium, and independent of calcium and magnesium ions. (7) Centrally acting drugs, such as desipramine, imipramine, desmethylimipramine, and amitriptyline, inhibited noradrenaline uptake by more than 55% at the concentration of 5 × 10-5 M. These drugs at the same concentration diminished dopamine uptake by less than 30%. (8) Noradrenaline uptake is stereospecific, the (-) isomer having a greater affinity for the uptake sites than the (+) isomer. (9) [14C]Noradrenaline in the retina could be released by increasing the external potassium concentration. This release was calcium-dependent and was blocked by 20 mM-cobalt chloride. The present studies could be interpreted as supporting the idea that noradrenaline acts as a transmitter in the retina.
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  • 9
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract— The accumulation, metabolism and stimulated-induced release of 5-HT in the nervous system of the snail was studied. When nervous tissue was incubated at 24°C in a medium containing [14C]5-HT or [3H]tryptophan, tissue: medium ratios of about 25:1 and 4:1 respectively were obtained after 45 min incubation.The process responsible for [14C]5-HT accumulation showed properties of an active transport system: it was temperature sensitive and was greatly inhibited by dinitrophenol and ouabain. Furthermore, the accumulation process was inhibited by imipramine and desipramine.Of a number of analogues of indole, N-acetyl-5-HT and 5-hydroxytryptophan were the most potent in the inhibition of the accumulation of [14C]5-HT. The presence of a large molar excess of amino acids had little effect.A small amount (less than 14 per cent) of the accumulated [14C]5-HT was metabolized to form 5-hydroxyindole acetic acid, even after long periods (2 h) of incubation. The accumulated [3H]tryptophan was metabolized to form 5-hydroxytryptophan and 5-HT; the content of formed [3H]5-HT increased with incubation time whilst the [3H]5-hydroxytryptophan remained more or less constant.The presence of p-chlorophenylalanine in the incubation medium did not interfere with the accumulation of [3H]tryptophan, though it inhibited the formation of [3H]5-hydroxytryptophan and to a greater extent [3H]5-HT.A rapid efflux of the accumulated [14C]5-HT from snail nervous tissue was observed on electrical stimulation. Slower release resulted when the Ca2+ ion content of the incubation medium was replaced by Mg2+ ions. There is also a slight efflux of radioactive substances following electrical stimulation in tissues previously incubated in [3H]tryptophan. Most of this radioactivity was attributed to the formed [3H]5-HT.The data support the idea that 5-HT is a transmitter-substance in the snail Helix pomatia, and that re-uptake of the substance is a method of inactivating the released amine.
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  • 10
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The effect of dopamine on snail (Helix pomatia) nervous tissue adenosine 3′, 5′-monophosphate content was examined. The results show support for the idea that the dopamine receptors in the snail nervous system involve adenylate cyclase. It is suggested that these are the dopamine excitatory receptors rather than the inhibitory ones.
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