Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.3.5 (5'-nucleotidase)
 3,167 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The fine structural localization of the 5'-nucleotidase was investigated in the CA3 region of the rat hippocampus. The attention was focussed on the occurrence of the enzyme in the synaptic region. The 5'-nucleotidase activity was demonstrated at the surface membranes of axons and dendrites. Prominent portions of enzyme activity were detectable in the nuclei and the nuclear envelope, whereas the cytoplasmic organelles were nearly devoid of reaction product. In synapses five types of 5'-nucleotidase localization were revealed. A participation of the enzyme in the process of neurotransmission is discussed.
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PMID:Cytochemical investigations on the localization of 5'-nucleotidase in the rat hippocampus with special reference to synaptic regions. 64 Aug 65

The distributions of adenosine A1 receptors, as demonstrated by 3H-cyclohexyladenosine (3H-CHA) binding, and the adenosine-producing enzyme 5'-nucleotidase were examined in the hippocampal formation of the rat, mouse, gerbil, cat, hamster, rabbit, and guinea pig. The enzyme and binding sites were restricted to subregions and often individual layers of this structure. The distribution of 3H-CHA binding was consistent among the species with the strata radiatum and oriens of fields CA1 and CA3 exhibiting the highest levels of binding. A distinct band of 3H-CHA binding was observed in the stratum moleculare of the dentate gyrus; and in most species, this band was restricted to the inner one-third of the stratum moleculare (i.e., proximal to the stratum granulosum). The strata pyramidale, granulosum, and lucidum were in general only weakly positive for 3H-CHA binding. The binding to the stratum lacunosum/moleculare (or the distinct strata lacunosum and moleculare in the rabbit and cat) was moderate. In contrast to the relative consistency of the patterns of 3H-CHA binding in these species, 5'-nucleotidase exhibited wide variations in both the absolute amount of activity and its localization. In all species, the strata granulosum and pyramidale appeared devoid of 5'-nucleotidase activity. The only clear exception to this rule was the CA3 region of the cat where activity was seen between the cell bodies of stratum pyramidale. The strata radiatum and oriens of CA1 were strongly positive in the rat and hamster but only low to moderately stained in the other species examined.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:The distribution of adenosine A1 receptors and 5'-nucleotidase in the hippocampal formation of several mammalian species. 300 62

The effect of cyclic adenosine 3',5'-monophosphate (cAMP) on epileptiform activity in rat hippocampal slices was investigated. Bath-applied cAMP reversibly decreased the frequency of extracellularly recorded discharges in the CA3 subfield induced by bethanechol- or theophylline-containing solutions. Because cAMP was presumed to be relatively membrane impermeant, we developed and tested the hypothesis that this cAMP-mediated effect occurred extracellularly through the catabolic conversion of cAMP to 5'-AMP and, in turn, to adenosine, a known inhibitory neuromodulator. Three predictions derived from this catabolic hypothesis were tested. First, blockers of the enzymes involved were predicted to antagonize this effect of cAMP. In contrast, the coapplication of a cAMP-phosphodiesterase inhibitor, 3-isobutyl-1-methylxanthine (IBMX), or a 5'-nucleotidase inhibitor, adenosine 5'-[alpha, beta-methylene] diphosphate (AMP-CP), enhanced the cAMP-induced suppressive effect. Second, the nonhydrolyzable cAMP analogs, dibutyryl- and 8-bromo-cAMP, were predicted to be ineffective. Low concentrations (5-40 microM) of these two derivatives, however, also suppressed bethanechol-induced discharges, while, at a higher concentration (100 microM), both analogs increased discharge frequencies. Third, enzymatic catabolism of adenosine was predicted to antagonize cAMP's effect, but coapplying adenosine deaminase (10 U/mL) did not diminish this action. Because these data did not support the catabolic hypothesis, other, as yet undefined, mechanisms must be responsible for the discharge-suppressant effect of cAMP.
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PMID:Suppression of drug-induced epileptiform discharges by cyclic AMP in rat hippocampus. 933 68

The localization and morphological assessment of plastic or newly formed synapses in the human brain remains difficult due to the lack of specific markers. The ectoenzyme 5'-nucleotidase may represent a useful marker of these structures, since in adult rodents synaptic 5'-nucleotidase activity is restricted to sites of spontaneous synaptic turnover and induced reactive synaptogenesis. However, it is unclear to what extent synaptic 5'-nucleotidase activity occurs in the normal human brain, and whether reactive synaptogenesis, as seen e.g. in temporal lobe epilepsy (TLE), is associated with this ectoenzyme. Therefore, we have investigated the histochemical distribution of 5'-nucleotidase in hippocampal control specimens (n = 3) and in the hippocampus of TLE patients (n = 13). In controls, 5'-nucleotidase activity was present in the dentate gyrus molecular layer (DG-ML) and the mossy fiber termination field within the CA4 and CA3 subfields. Compared with controls, TLE specimens revealed markedly increased 5'-nucleotidase labeling in the DG-ML, implying TLE-associated reactive synaptogenesis in this hippocampal region. In contrast to GAP-43, synaptophysin, and dynorphin A, synaptic 5'-nucleotidase activity may serve as a potential specific indicator of plastic synapses or newly formed terminals in the human brain and prove useful for the study of diseases involving aberrant sprouting or altered synaptic plasticity.
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PMID:5'-Nucleotidase activity indicates sites of synaptic plasticity and reactive synaptogenesis in the human brain. 1033 33

Sprouting of mossy fibers in the hippocampus of rats that underwent limbic epileptogenesis by amygdala kindling or kainate injection was studied at the light microscopic and ultrastructural levels by cytochemical demonstration of the enzyme 5'-nucleotidase. This adenosine-producing ectoenzyme has previously been shown to characterize malleable terminals during brain development and lesion-induced synaptogenesis, but to be otherwise associated with glial membranes. At the light microscopic level, kainate-treated but not control or kindled rats showed 5'-nucleotidase activity in the CA3 region and in the inner molecular layer of the dentate gyrus. At the ultrastructural level, in control animals, the synapses of the molecular and granular layers were enzyme negative. Only some mossy fiber boutons of the dentate hilus exhibited 5'-nucleotidase activity. In epileptic rats, synaptic labeling within the hilus appeared more intense. Moreover, 5'-nucleotidase-containing terminals within the inner molecular layer, presumably ectopic mossy fiber boutons, were found in both kindled and kainate-treated rats. It is concluded that, in both the normal and epileptic hippocampus, 5'-nucleotidase is associated with axons capable of a plastic sprouting response. The synaptic enzyme may attenuate the glutamatergic transmission of mossy fibers, in particular of the aberrant mossy fibers in epileptic rats, by producing the inhibitory neuromodulator adenosine. Alternatively, 5'-nucleotidase may influence synapse formation by its putative non-enzymatic, adhesive functions.
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PMID:5'-Nucleotidase activity of mossy fibers in the dentate gyrus of normal and epileptic rats. 1046 35

Ecto-5'-nucleotidase is regarded as being the key enzyme in the formation of the neuromodulator adenosine from released ATP. However, the association of ecto-5'-nucleotidase with nerve terminals is not consensual. Only enzyme histochemical and biochemical studies, but not immunocytochemical studies, agree on a general synaptic location of the enzyme. To clarify this issue further we tested the effect of an antibody against ecto-5'-nucleotidase, previously used in immunocytochemical studies, on the activity of ecto-5'-nucleotidase in fractions of nerve terminals isolated from different areas of rat hippocampus. The specific activity of extracellular AMP catabolism was higher in synaptosomes from the CA3 area (0.81+/-0.06 nmol/min/mg of protein) than from synaptosomes from the CA1 area or the dentate gyrus or from the whole hippocampus (0.49-0.68 nmol/ min/mg of protein). The catabolism of AMP (10 microM) was equally inhibited (85-92%) in synaptosomes from whole hippocampus, CA1, CA3, or dentate gyrus by alpha,beta-methylene-ADP (100 microM) and equally unaffected by p-nitrophenyl phosphate (0.5 mM) or rabbit IgGs (100 microg/ml). However, the antiserum against ecto-5'-nucleotidase (100 microg/ml) inhibited extracellular AMP catabolism by 44% in CA3 synaptosomes but had little or no effect in synaptosomes from CA1, dentate gyrus, or whole hippocampus. A similar difference in the inhibitory potential of the antibody was observed between fractions of isolated 5'-nucleotidase binding to concanavalin A-Sepharose (70%) and fractions not retained by the lectin column (18%). Taken together, these results suggest that immunological isoforms of ecto-5'-nucleotidase exist in the rat hippocampal nerve terminals, with predominance in the CA3 area.
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PMID:Immunologically distinct isoforms of ecto-5'-nucleotidase in nerve terminals of different areas of the rat hippocampus. 1061 37