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H Luppa

Publications and source records attributed to H Luppa.

At least 19 recordsLinked to original sources
PubMed1992

Aminopeptidases in the circumventricular organs of the mouse brain: a histochemical study.

The localization of four membrane-bound aminopeptidases--aminopeptidase A, aminopeptidase M, dipeptidylpeptidase IV, and gamma-glutamyl transpeptidase--known as characteristic enzymes of the blood-brain barrier was studied in the microvasculature of some circumventricular organs of the mouse brain (subfornical organ, area postrema, choroid plexus, and neurohypophysis). Enzyme activities were demonstrated histochemically in chloroform-acetone-pretreated cryostat sections applying an azo-coupling method. Reactions were evaluated using light microscopy and end-point microdensitometry. The results revealed differences in microvascular enzyme pattern between circumventricular organs and regions having a blood-brain barrier. Moreover, the cytochemical picture of the circumventricular organs themselves was not uniform. Dipeptidylpeptidase IV reaction showed a strongly reduced activity in the microvessels of all studied circumventricular organs. On the other hand, aminopeptidase M seemed to be present in both the leaky and the tight capillaries. Only a low activity of aminopeptidase A was found in parts of the choroid endothelium and the subfornical organ microvasculature. gamma-Glutamyl transpeptidase could neither be detected in the capillary part of the choroid plexus nor in the neurohypophysis. We are led to conclude that at least dipeptidylpeptidase IV might be involved in special mechanisms of the blood-brain barrier.

Aminopeptidases↗
PubMed1992

[Histochemical investigations on the localization of acetylcholinesterase in the kidney of selected vertebrates].

The light and electron microscopical localization of AChE activity in the kidney of selected vertebrates was studied using the method of Karnovsky and Roots (1964) for light microscopy and the modification of the Koelle and Friedenwald's technique according to Tsuji (1974, 1984) for electron microscopy. AChE activity could be demonstrated light microscopically mainly within the glomeruli of some mammals (golden hamster, mouse, rat) and non-mammalian vertebrates (carp, frog). No activity was found in the glomeruli of guinea pig, of chicken and tortoise. In the mammalians, the strongest AChE activity could be demonstrated in the guinea pig, the lowest in the rat. A strong AChE enzyme activity was also detected within the interlobular arteries and the cells of Bowman's capsule. With the electron microscopical method AChE activity was demonstrated in mesangial cells and endothelial cells of the glomeruli (golden hamster and carp) and in the cells of Bowman's capsule (carp). Reaction product was localized within the cisterns of endoplasmic reticulum and the perinuclear space (nuclear envelope). A high amount of electron opaque material could be observed in the cells of Bowman's capsule and their lamina basalis. The functional significance of the localization of AChE activity in the glomeruli will be discussed.

Acetylcholinesterase↗
PubMed1991

Second messenger enzymes in glial cells: a cytochemical point of view.

Knowledge about second messenger metabolizing enzymes in neuroglia is still rather fragmentary. Therefore, the aim of the present investigation was to localize adenylate cyclase, guanylate cyclase, cyclic nucleotide phosphodiesterase and protein kinase A in glial cells of the rat hippocampus and cerebellum. Enzyme histochemical and immunohistochemical methods were used to detect the enzymes at the light and electron microscopic level. Astroglial cells were found to contain all 4 enzymes. Especially the microvascular glial cell processes were reactive. Oligodendroglial cells were only stained for adenylate cyclase acticity. Intracellularly, microtubules and intracellular membranes were frequently stained. The results point to the regulation of glial cell metabolism and of transport processes by cyclic nucleotides.

2',3'-Cyclic-Nucleotide Phosphodiesterases↗
PubMed1991

Pattern of NADPH-diaphorase active neurons in rat forebrain is unchanged after pentylenetetrazol kindling.

The activity of NADPH-diaphorase in rat telencephalic structures has been revealed by use of a histochemical method. Multiple neurons belonging to different nuclei were found to contain the enzyme. Furthermore, diaphorase reactive nerve fibres and terminal fields were observed to be widely distributed throughout rat brain. Chemical kindling induced by pentylenetetrazol (PTZ) did not effect the regional distribution and cellular localization of the enzyme in the rat CNS.

Animals↗
PubMed1991

Inhibition of acetylcholinesterase and butyrylcholinesterase by the organophosphorus insecticide methylparathion in the central nervous system of the golden hamster (Mesocricetus auratus).

The toxic effects of the organophosphorus pesticide methylparathion are primarily caused by the inhibition of acetylcholinesterase activity in the central nervous system, whereas the relationship between butyrylcholinesterase and poisoning symptoms is unclear. The presumed different effects of methylparathion on acetylcholinesterase in various regions of brain and spinal cord suggest differences in the distribution of molecular enzyme forms. In the present work, the in vitro and in vivo effects of methylparathion on acetylcholinesterase and butyrylcholinesterase were studied in whole brain homogenates of golden hamsters with biochemical methods. Furthermore, acetylcholinesterase activity was determined in regions of the nervous system by quantitative histochemistry (microdensitometry). Biochemically, very low IC50 values of the hydrophilic and lipophilic fractions of both enzymes were measured. Analysis of the time course of enzyme inhibition revealed maximum inhibition 45 min after methylparathion application. Using microdensitometry different degrees of acetylcholinesterase inhibition were found in various areas of the brain. The highest inactivation was observed in the Substantia nigra and in thalamic nuclei; in several regions of the cerebellum, the inhibition rate was comparatively lower. In conclusion, methylparathion acts as an potent inhibitor of acetylcholinesterase and butyrylcholinesterase in the hamster nervous system. The region-specific different inactivation of acetylcholinesterase might be caused by the existence of multiple forms of the enzyme in various brain regions.

Acetylcholinesterase↗
PubMed1991

Morphology of neurons in the rat basal forebrain nuclei: comparison between NADPH-diaphorase histochemistry and immunohistochemistry of glutamic acid decarboxylase, choline acetyltransferase, somatostatin and parvalbumin.

Transversal sections through the basal forebrain of 11 adult male rats were immunostained for glutamic acid decarboxylase (GAD), choline acetyltransferase (ChAT), somatostatin (SOM) and parvalbumin (PARV). Immunohistochemistry of ChAT, PARV, and SOM was combined with histochemistry of NADPH-diaphorase (NADPH-d) to obtain information on the colocalization of various neuroactive substances and this enzyme and to facilitate the recognition of morphological details of double-stained neurons. The distribution patterns of GAD- and PARV-immunoreactive cells were only in part congruent in basal forebrain nuclei in the rat. In the medial septal nucleus (MS) and the vertical limb of the diagonal band (vDB) PARV-immunopositive neurons were homogeneously scattered inside the nucleus, whereas the GAD-immunoreactive cells were much more numerous in the lateral part of this nuclear complex. In the horizontal limb of the diagonal band (hDB) and the nucleus preopticus magnocellularis (NPM), where GAD-immunoreactive cells occurred in high number, only very few cells contained PARV-immunoreaction product. In the substantia innominata-nucleus basalis Meynert complex (SI-NB) and in the ventral pallidum (VP) the neuropil was heavily stained with the GAD-immunoreaction product. The number of GAD-positive cells appeared low in the SI-NB, but much higher in the VP. In this nucleus GAD- and PARV-immunoreactive cells seem to be identical. PARV-positive neurons are very sparse in the SI-NB. Double-staining of PARV-immunoreactivity and NADPH-d was not registered. These nuclei were the only ones in which some cells with SOM-like immunoreactivity were observed. Among ChAT-positive neurons those double-stained with NADPH-d occurred in moderate number, but with obvious regional differences. In MS-vDB and the marginal zone of hDB the two neuron groups were intermingled, but only in the innermost part of the hDB ChAT-single-immunostained cells form aggregates, which were also typical of the zone in the SI-NB that surrounds and infiltrates the globus pallidus (GP). Double-labelled cells were more frequent in the lateral aspect of the NPM and SI-NB. Cells single-stained for NADPH-d were frequent in the MS-vDB along the border toward the lateral septal nuclei, but low in number in the NPM, VP and SI-NB. The functional aspects of the occurrence of GAD-immunoreactive cell aggregates in the lateral preoptic area (LP) and the lateral hypothalamic area (LH) were discussed with special regards to extrinsic GABAergic input in the dorsal SI-NB.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1989

The cholinergic nuclei of the basal forebrain of the hamster (Mesocricetus auratus): a combined Golgi- and AChE-topochemical investigation.

The cholinergic basal forebrain nuclear complex of the golden hamster was investigated Golgi-architectonically and AChE-topochemically using enzymehistochemical and immunohistochemical methods. We demonstrated 12 different classes of neurons in the whole basal forebrain complex with the Golgi-Kopsch-technique. The classical anatomical subdivision of the septal-region into nucleus medialis septi and nucleus tractus diagonalis has not been confirmed by results elaborated with this method. We found at least one class of neurons with varicose dendrites in every part of the cholinergic basal forebrain complex. The varicosities reacted positively for AChE. This morphological feature might be characteristic for cholinergic neurons in the nuclei of the basal forebrain complex.

Acetylcholinesterase↗
PubMed1989

Ultrahistochemical demonstration of guanylate cyclase activity in the rat hippocampus.

Guanylate cyclase activity was demonstrated in the rat hippocampus at the electron microscopy level by a cerium precipitation technique. Enzymatic activity is localized in the granular cells of the dentate gyrus and in other, medium-sized neurons. The reaction product was found on the cytoplasmic membrane, in the cytoplasm, on the surface of endoplasmic reticulum and in postsynaptic densities. Glial cell processes and small dendritic processes were also stained. Besides the neurons, glial cells contained strong enzymatic activity, especially the perivascular glia and protoplasmatic glial cells neighbouring to neurons. Only little activity was detected in pyramidal cells and no activity was found in the endothelium cells of capillaries.

Animals↗
PubMed1988

Production of an antiserum against cyclic nucleotide phosphodiesterase and its use for the immunocytochemical demonstration of this enzyme in rat cerebellum.

A procedure for the separation of cyclic AMP phosphodiesterase from a commercially available preparation and for raising antibodies against this enzyme in rabbits is described. An antiserum thus obtained was used for the immunocytochemical detection of cyclic nucleotide phosphodiesterase in rat cerebellum. The molecular layer, the granular layer and the cerebellar white matter exhibited different degrees of immunoreactivity. Only a few cell bodies (possibly glial cells) were stained. Most of the antigenic sites were present in the neuropil of the molecular layer and around Purkinje cells. Cerebellar glomeruli, sites of synaptic interactions between mossy fibres, Golgi cells and granule cells, were also stained by this antiserum. Control reactions using preimmune serum were consistently negative.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1988

A comparison of the localization of acetylcholinesterase in the rat brain as demonstrated by enzyme histochemistry and immunohistochemistry.

The localization of acetylcholinesterase (AChE) as revealed either by enzyme-histochemical or by immunohistochemical methods was compared in distinct regions of the rat brain. In general, the localization of AChE observed was nearly the same, whether revealed by histochemical demonstration of its catalytic activity or by immunohistochemical detection of the enzyme molecule itself, in all regions investigated. Penetration problems of the antibodies, however, arose on strong myelin sheaths of the facial nerve, for instance, where no immunohistochemical staining was found though there was a relatively strong histochemical reaction. These problems could be partly solved by increasing the normal concentration of Triton X-100 added to the immunohistochemical solutions (0.1%) to 2.5%. Furthermore, it seems that sites containing low amounts of AChE could be better detected by the enzyme-histochemical method, whereas the depiction of structures (particularly of nerve fibres) was somewhat sharper with the immunohistochemical method.

Acetylcholinesterase↗
PubMed1986

Attempts for light microscopical demonstration of guanylate cyclase activity in rat cerebellum.

Guanylate cyclase in rat cerebellum was investigated on the light microscopical level with guanylyl imidodiphosphate as substrate. Several attempts for activation of enzymatic activity and delimitation to other enzymes were made by sodium azide, aminophylline, sodium fluoride and dithioerythrole. The localization was similar but less strong compared to adenylate cyclase (Poeggel and Luppa 1984) and differs in behaviour to the above mentioned substances. Nucleotide pyrophosphatases seem to play an unimportant role in guanylyl imidodiphosphate conversion, while alkaline phosphatase is possibly of more importance. A light microscopical demonstration of guanylate cyclase by its enzymatic activity must be considered with caution. Main reasons are the low activity and therefore the great importance of interfering enzymes with high activities.

Adenylyl Cyclases↗
PubMed1986

[Quantitative histochemical investigations on the demonstration of soluble and membrane bound acetylcholinesterase in the optic tectum of the rudd (Scardinius erythrophthalmus)].

With the aid of the method of Karnovsky and Roots (1964) which was adapted to the semi-permeable membrane technique and a scanning recording method the relative activity of soluble and membrane bound AChE as well as the influence of fixation with 5% paraformaldehyde on the enzyme activity was investigated quantitative-histochemically in the tectum opticum of the rudd. Approximately 38% of the AChE activity which can be demonstrated in the whole tectum opticum on native untreated cryostat sections are puffer-soluble and only 68% are detectable after fixation. The influence of both puffer and fixation pretreatment is different in the several layers of this brain structure.

Acetylcholinesterase↗