Regional distribution of a high-affinity enkephalin-degrading peptidase (‘enkephalinase’) and effects of lesions suggest localization in the vicinity of opiate receptors in brain

Malfroy, Bernard; Swerts, Jean-Paul; Llorens, C.; Schwartz, Jean‐Charles

doi:10.1016/0304-3940(79)90017-x

Cited by 118 publications

(40 citation statements)

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“…Peroxidase immunocytochemistry confirmed the presence of enkephalinase immunostaining along the plasma membrane of both dendritic shafts and dendritic spines. This finding is consistent with the marked decrease in enzymatic activity (Malfroy et al, 1979), enkephalinase immunoreactivity (Pollard et al, 1987b), and binding of tritiated enkephalinase inhibitors (Waksman et al, 1987) reported in the rat neostriatum following local injection of kainic acid. It also conforms to the presence of a large number of neostriatal perikarya reactive for enkephalinase in material processed by histochemistry (Back and Gorenstein, 1989) or found to express enkephalinase mRNA by in situ hybridization (Pollard et al, 1989b;Wilcox et al, 1989).…”

Section: Discussion Topographic Distribution Of Enkephalinase Immunorsupporting

confidence: 78%

“…Accordingly, the regional distribution of the enzyme, as assessed here by immunoradioautography in unfixed sections of rat basal ganglia, broadly conformed to that previously observed by immunohistochemistry using the same antibody (Pollard et al, 1989a) or by radioautography after binding of the tritiated inhibitors of the enzyme 3H-HA-COB-gly or 3H-thiorphan (Waksman et al, 1986a, b;Pollard et al, 1987b). The presence of dense enkephalinase immunolabeling in the nebstriatum, nucleus accumbens, and ventral pallidum was also in keeping with the results of earlier biochemical assays that had shown an intense activity of the enzyme within these areas (Llorenz-Cortes et al, 1982;Malfroy et al, 1979).…”

Section: Discussion Topographic Distribution Of Enkephalinase Immunorsupporting

confidence: 67%

“…A cortical origin appears unlikely, however, given that cortical ablation was found to not modify the binding of the enkephalinase inhibitor 3H-HACBO-gly in the rat neostriatum (Waksman et al, 1987). In contrast, lesions of the dopaminergic neostriatal pathway were found to induce a small but significant decrease of enkephalinase activity in rat striatal membranes, suggesting that a proportion of the enkephalinase-immunoreactive axons might be originating from the substantia nigra (Malfroy et al, 1979). However, substantia nigra neurons are unlikely to contribute substantially to striatal enzymatic pools, given that no enkephalinase mRNA-hybridizing cells were found to be present in this area (Pollard et al, 1989b;Wilcox et al, 1989) and that no modification in the binding of enkephalinase inhibitors was detected in sections from rat neostriatum following selective destruction of the nigrostriatal pathway by 6-hydroxydopamine (Waksman et al, 1987 Quantitative analysis of electron microscopic radioautographs revealed that immunoreactive enkephalinase was not concentrated at the level of specific membrane interfaces but showed an overall distributional pattern comparable to that of shared hypothetical grains, implying a fairly diffuse investment of labeled plasma membranes.…”

Section: Discussion Topographic Distribution Of Enkephalinase Immunormentioning

confidence: 92%

“…Also, intense enkephalinase activity was observed over fiber bundles linking the neostriatum to the globus pallidus, the entopeduncular nucleus, and the substantia nigra (Waksman et al, 1986b(Waksman et al, , 1987Pollard et al, 1987b;Barnes et al, 1988a). Additional lines of evidence supporting the concept of a neuronal localization of enkephalinase include the presence of intense peptidase activity within synaptosomal membrane fractions (Alstein and Vogel, 1980;De la Baume et al, 198 1) and the decrease of enkephalinase activity (Malfroy et al, 1979) enkephalinase immunoreactivity (Pollard et al, 1987b), and binding of enkephalinase inhibitors (Waksman, 1986b(Waksman, , 1987 observed after intracerebral injections of neurotoxins. Whether enkephalinase is also associated with glial components in the CNS remains a matter of controversy.…”

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confidence: 92%

“…Early studies based on the measurement of enkephalinase activity in mouse (Malfroy et al, 1978(Malfroy et al, , 1979, pig (Relton et al, 1983) and human (Llorens-Cortes et al, 1982) brain homogenates demonstrated a highly heterogeneous distribution of this enzyme in the mammalian CNS. Further work, based on the autoradiographic localization of selectively bound 3H-labeled enkephalinase inhibitors (Waksman et al, 1984(Waksman et al, , 1986aPollard et al, 1987a) or on the immunohistochemical localization of either monoclonal (Gros et al, 1985;Matsas et al, 1986;Pollard et al, 1987aPollard et al, , b, 1989a or polyclonal (Barnes et al, 1988a) antibodies raised against the enzyme, confirmed these biochemical findings and provided detailed information concerning the topographic localization of enkephalinase in the rat and pig CNS.…”

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confidence: 99%

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Electron microscopic localization of immunoreactive enkephalinase (EC 3.4.24.11) in the neostriatum of the rat

et al. 1990

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The fine structural distribution of the enzyme-neutral endopeptidase EC 3.4.24.11 (enkephalinase) was examined by immunoradioautography (using an iodinated monoclonal antibody) and peroxidase immunocytochemistry (using the same probe in nonradioactive form) in the neostriatum of the rat. At the light microscopic level, both techniques revealed a heterogeneous distribution of immunoreactive enkephalinase in the caudoputamen, characterized by the presence of patches of intense immunolabeling prominent against a relatively strong immunoreactive matrix, a pattern reminiscent of mu opioid receptors radioautographically labeled in the same region. Pilot experiments indicated that fixation of the brain with a mixture of 4% paraformaldehyde, 0.05% glutaraldehyde, and 0.2% picric acid did not modify the distribution and only slightly reduced the intensity of striatal enkephalinase antigenicity, provided that the post-fixation period did not exceed 1 hr. In the neostriatum of animals fixed according to this protocol, enkephalinase immunoreactivity was found by electron microscopic immunoradioautography to be exclusively confined to neuronal and glial membrane interfaces. Immunoperoxidase cytochemistry confirmed the association of immunoreactive enkephalinase with the plasma membrane of neurons and, to a lesser extent, of astrocytes and oligodendrocytes. Both immunoradioautographic and immunoperoxidase techniques revealed a predominant association of the enzyme with neuronal perikarya and dendrites. The morphological features of the labeled perikarya, together with the presence of immunoreactive dendritic spines, suggested that some of these neurons corresponded to striatofugal medium spiny neurons. Immunoreactive enkephalinase was also detected at the level of myelinated and unmyelinated axons and axon terminals. These axons could potentially have originated from intrinsic striatal neurons or from the substantia nigra. Statistical analysis of silver grain distribution in electron microscopic immunoradioautographs indicated that immunoreactive enkephalinase was not preferentially concentrated at the level of specific membrane interfaces, but rather, was more or less uniformly distributed on the surface of neurons and/or glial cells. A similarly diffuse localization of the enzyme was apparent in peroxidase-reacted material, though the latter technique also revealed a microheterogeneity in the deposition of the reaction product along the labeled membranes. Finally, quantitative analysis of immunoradioautographs clearly indicated an absence of enkephalinase enrichment at the level of synaptic junctions. The similarity between the light and electron microscopic distribution of enkephalinase observed in the present study, and that previously reported for mu opioid receptors, lends support to the concept that this ectoenzyme may be involved in the inactivation of endogenous opioids in the mammalian neostriatum.

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Section: Discussion Topographic Distribution Of Enkephalinase Immunorsupporting

confidence: 78%

Section: Discussion Topographic Distribution Of Enkephalinase Immunorsupporting

confidence: 67%

Section: Discussion Topographic Distribution Of Enkephalinase Immunormentioning

confidence: 92%

mentioning

confidence: 92%

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confidence: 99%

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Electron microscopic localization of immunoreactive enkephalinase (EC 3.4.24.11) in the neostriatum of the rat

et al. 1990

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Fluorescent histochemical localization of neutral endopeptidase‐24.11 (enkephalinase) in the rat spinal cord

Back

Gorenstein

1989

J of Comparative Neurology

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The localization of neutral endopeptidase-24.11 (E.C. 3.4.24.11; enkephalinase) in rat spinal cord was investigated by a novel fluorescent histochemical method. Enkephalinase was localized by using a coupled enzyme assay based upon the sequential cleavage of the synthetic peptide substrate glutaryl-ala-ala-phe-4-methoxy-2-naphthylamide by enkephalinase and exogenous aminopeptidase M. Enzyme distribution was examined in segments from cervical, thoracic, lumbar, and sacral cord. At all spinal cord levels, enkephalinase was localized to discrete regions of the gray matter. The substantia gelatinosa displayed rich enkephalinase staining which overlapped the inner and outer zones of lamina II. A staining pattern similar to that observed in lamina II was observed in the spinal trigeminal nucleus in the medulla. In lamina III the enzyme was associated with small and medium-sized cells. Lamina IV showed staining associated with medium-sized and large cell bodies. The medial boundary of the dorsal gray of laminae IV and V had medium-sized fusiform cells which stained for enkephalinase. In the lateral reticulated areas of lamina V, enkephalinase reaction product was localized to scattered medium-sized and large cells compressed against the white matter of axon bundles. Staining in lamina VI was similar in appearance to lamina V. Enkephalinase reaction product was widely distributed in the ventral horn. Numerous ventral horn motor neurons of varied size and morphology in laminae VIII and XI stained richly for the enzyme. The enzyme was also localized to medium-sized and large cells in lamina X and to cells of the central cervical nucleus. The size and morphology of the cell types associated with the enzyme supported a neuronal association for enkephalinase. The regional distribution of the enzyme overlapped that of enkephalin- and substance-P rich regions of the spinal cord. These findings support a role for enkephalinase in the metabolic regulation of centrally acting neuropeptides.

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Murine thymocytes possess specific cell surface‐associated exoaminopeptidase activities: Preferential expression by immature CD4⁻CD8⁻ subpopulation

Bauvois

1990

Eur J Immunol

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Murine thymocytes are shown to possess at least three well-defined exo-N-aminopeptidase activities on their surface. One of them cleaves the prolyl bond in the synthetic dipeptide nitroanilide Gly-Pro-pNA (Km 0.95 mM and Vmax 8 nmol/h at pH 7.4 and 37 degrees C) and is specifically inhibited by phenylmethane sulfonyl fluoride, diprotin A, Gly-Pro-Ala and Gly-Pro-Gly-Gly. These data further support identification of this enzyme with a serine exopeptidase dipeptidyl peptidase IV (DPP IV), previously reported to be specific for collagen. The two other forms of N-exopeptidase activities are detected when Ala-pNA and Leu-pNA are used as substrates. Leu-aminopeptidase activity (Km 1.4 mM, Vmax 15 nmol/h) and Ala-aminopeptidase activity (Km 4.0 mM, Vmax 20 nmol/h) are inhibited by inhibitors for thiol- and trypsin-like proteinases, i.e. tosyl lysyl chloromethyl ketone, leupeptin and N-ethylmaleimide. Addition inhibition of Leu-aminopeptidase activity by peptstatin, a known inhibitor of carboxyl proteases, suggests that aminopeptidase activity detected with Leu-pNA is different in part from Ala-aminopeptidase activity. Among the various lymphoid cell populations tested, the three aminopeptidase activities are increased by three- to fourfold in the immature CD4-CD8- thymocyte subset as well as in the thymoma BW5147. In contrast, cortisone-resistant thymocytes, lymph node and spleen cells exhibit levels of activities almost similar to that of unfractionated thymocytes. During ontogeny, the levels of these activities are increased four- to sevenfold on fetal thymocytes (from days 14 to 16). Finally, when thymocytes or spleen cells are cultured with a mitogenic concentration of concanavalin A, their proliferative responses are correlated with an enhancement of the aminopeptidase activities (1.3- to 5-fold). From these results, a correlation between the presence of these peptidases on the cell surface of immature and mature lymphoid cells and biological responsiveness is suggested.

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Regional distribution of a high-affinity enkephalin-degrading peptidase (‘enkephalinase’) and effects of lesions suggest localization in the vicinity of opiate receptors in brain

Cited by 118 publications

References 17 publications

Electron microscopic localization of immunoreactive enkephalinase (EC 3.4.24.11) in the neostriatum of the rat

Electron microscopic localization of immunoreactive enkephalinase (EC 3.4.24.11) in the neostriatum of the rat

Fluorescent histochemical localization of neutral endopeptidase‐24.11 (enkephalinase) in the rat spinal cord

Murine thymocytes possess specific cell surface‐associated exoaminopeptidase activities: Preferential expression by immature CD4⁻CD8⁻ subpopulation

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Regional distribution of a high-affinity enkephalin-degrading peptidase (‘enkephalinase’) and effects of lesions suggest localization in the vicinity of opiate receptors in brain

Cited by 118 publications

References 17 publications

Electron microscopic localization of immunoreactive enkephalinase (EC 3.4.24.11) in the neostriatum of the rat

Electron microscopic localization of immunoreactive enkephalinase (EC 3.4.24.11) in the neostriatum of the rat

Fluorescent histochemical localization of neutral endopeptidase‐24.11 (enkephalinase) in the rat spinal cord

Murine thymocytes possess specific cell surface‐associated exoaminopeptidase activities: Preferential expression by immature CD4−CD8− subpopulation

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Murine thymocytes possess specific cell surface‐associated exoaminopeptidase activities: Preferential expression by immature CD4⁻CD8⁻ subpopulation