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 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

A marked depression of evoked CA1 potentials was observed with the nucleotide analogues a,b-methylene ADP (AOPCP) and adenylimido-diphosphate (AIP) and with 2'-adenosine monophosphate (2'-AMP). While the depression elicited by 5'-nucleotides was completely antagonized by the action of adenosine deaminase, AOPCP and 2'-AMP were only partially antagonized. The findings indicate that nucleotides on their own are capable of modulating synaptic transmission but that the physiologically more prevalent 5'-AMP is mediating its effect via adenosine. By producing this membrane permeable compound and allowing its re-uptake, the 5'-nucleotidase may determine the time course of purinergic action.
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PMID:Effect of adenosine versus adenine nucleotides on evoked potentials in a rat hippocampal slice preparation. 726 30

1. In the present work, we investigated the action of adenosine originating from extracellular catabolism of adenine nucleotides, in two preparations where synaptic transmission is modulated by both inhibitory A1 and excitatory A(2a)-adenosine receptors, the rat hippocampal Schaffer fibres/CA1 pyramid synapses and the rat innervated hemidiaphragm. 2. Endogenous adenosine tonically inhibited synaptic transmission, since 0.5-2 u ml-1 of adenosine deaminase increased both the population spike amplitude (30 +/- 4%) and field excitatory post-synaptic potential (f.e.p.s.p.) slope (27 +/- 4%) recorded from hippocampal slices and the evoked [3H]-acetylcholine ([3H]-ACh) release from the motor nerve terminals (25 +/- 2%). 3. alpha, beta-Methylene adenosine diphosphate (AOPCP) in concentrations (100-200 microM) that almost completely inhibited the formation of adenosine from the extracellular catabolism of AMP, decreased population spike amplitude by 39 +/- 5% and f.e.p.s.p. slope by 32 +/- 3% in hippocampal slices and [3H]-ACh release from motor nerve terminals by 27 +/- 3%. 4. Addition of exogenous 5'-nucleotidase (5 u ml-1) prevented the inhibitory effect of AOPCP on population spike amplitude and f.e.p.s.p. slope by 43-57%, whereas the P2 antagonist, suramin (100 microM), did not modify the effect of AOPCP. 5. In both preparations, the effect of AOPCP resulted from prevention of adenosine formation since it was no longer evident when accumulation of extracellular adenosine was hindered by adenosine deaminase (0.5-2 u ml-1). The inhibitory effect of AOPCP was still evident when A1 receptors were blocked by 1,3-dipropyl-8-cyclopentylxanthine (2.5-5 nM), but was abolished by the A2 antagonist, 3,7-dimethyl-1-propargylxanthine (10 microM). 6. These results suggest that adenosine originating from catabolism of released adenine nucleotides preferentially activates excitatory A2 receptors in hippocampal CAI pyramid synapses and in phrenic motor nerve endings.
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PMID:Preferential activation of excitatory adenosine receptors at rat hippocampal and neuromuscular synapses by adenosine formed from released adenine nucleotides. 888 6

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