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  • Author or Editor: Izabella Battonyai x
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In the procerebrum of terrestrial snails, 5-HT is a key modulatory substance of the generation of synchronous oscillatory activity and odor learning capability. In this study, we have analyzed the characteristics of the 5-HT-immunoreactive (5-HT-IR) innervation of the distinct anatomical regions of the procerebrum of Helix pomatia, applying correlative light- and electron microscopic immunocytochemistry. A dense network of 5-HT-IR innervation was demonstrated in the cell body layer, meanwhile a varicose fiber system of different density occurred in the different neuropil regions. At the ultrastructural level, labeled varicosities were found to contact both procerebral cell bodies, and different unlabeled axon profiles in the neuropils. The labeled structures established mostly close non-specialized membrane contacts with the postsynaptic profiles. The overall dense distribution of 5-HT-IR innervation supports a general modulatory role of 5-HT in processing different olfactory events.

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Distribution of the potassium channel of Kv4.3 type was investigated in the central nervous system (CNS) of Helix pomatia by immunohistochemistry. Immunopositive neurons were found widely distributed in the CNS, present mostly in smaller groups in the different central ganglia but not in the visceral ganglion. Labeled fibers were characteristic for not only the neuropils of all ganglia but also the connective tissue sheath around the CNS and the aorta wall were richly innervated. Western blot analysis revealed a clear identity with the mammalian Kv4.3 subunit, suggesting an evolutionary conserved structure of this channel type. Our preliminary results provide a steady basis for further experiments aiming partly at the identification of other potassium channel types and partly the ultrastructural localization of Kv4.3.

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Nitrergic myenteric neurons are especially susceptible to the development of neuropathy in functional gastrointestinal disorders. Investigations of the similarities and dissimilarities in the organization of nitrergic neurons in the various mammalian species are therefore important in an effort to determine the extent to which the results obtained in different animal models can be generalized. In the present work, the density and the spatial organization of the nitrergic neurons in the myenteric plexus of the duodenum were investigated in 7 mammalian species. After nicotinamide adenine dinucleotide phosphate diaphorase (NADPH-d) histochemistry, the Plexus Pattern Analysis software (PPAs) was applied to count the nuclei of nitrergic neurons, calculate the proportions of the areas covered by the plexus and perform randomization analysis. All 7 species exhibited a large population of nitrergic myenteric neurons, with densities in the range 12–56 cells/mm 2 . The distribution patterns of these neurons differed markedly in the different species, however, the rat was the only species in which the nitrergic neurons appeared to be randomly distributed. The PPAs in conjunction with NADPH-d histochemistry proved to be a simple and fast tool with which to reveal similarities and dissimilarities in the spatial arrangement of the nitrergic neurons in the different species.

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Acta Biologica Hungarica
Authors:
Károly Elekes
,
László Hiripi
,
Gábor Balog
,
Gábor Maász
,
Izabella Battonyai
,
Marina Yu. Khabarova
,
Réka Horváth
, and
Elena E. Voronezhskaya

Hatching is an important phase of the development of pulmonate gastropods followed by the adult-like extracapsular foraging life. Right before hatching the juveniles start to display a rhythmic radula movement, executed by the buccal complex, consisting of the buccal musculature (mass) and a pair of the buccal ganglia. In order to have a detailed insight into this process, we investigated the serotonergic regulation of the buccal (feeding) rhythm in 100% stage embryos of the pond snail, Lymnaea stagnalis, applying quantitative immunohistochemistry combined with the pharmacological manipulation of the serotonin (5-HT) synthesis, by either stimulating (by the 5-HT precursor 5-hydroxytryptophan, 5-HTP) or inhibiting (by the 5-HT synthesis blocker para-chlorophenylalanine, pCPA) it. Corresponding to the direction of the drug effect, significant changes of the fluorescence intensity could be detected both in the cerebral ganglia and the buccal complex. HPLC-MS assay demonstrated that 5-HTP increased meanwhile pCPA decreased the 5-HT content both of the central ganglia and the buccal complex. As to the feeding activity, 5-HTP induced only a slight (20%) increase, whereas the pCPA resulted in a 20% decrease of the radula protrusion frequency. Inhibition of 5-HT re-uptake by clomipramine reduced the frequency by 75%. The results prove the role of both central and peripheral 5-HTergic processes in the regulation of feeding activity. Application of specific receptor agonists and antagonists revealed that activation of a 5-HT1-like receptor depressed the feeding activity, meanwhile activation of a 5-HT6,7-like receptor enhanced it. Saturation binding plot of [3H]-5-HT to receptor and binding experiments performed on membrane pellets prepared from the buccal mass indicated the presence of a 5-HT6-like receptor positively coupled to cAMP. The results suggest that 5-HT influences the buccal (feeding) rhythmic activity in two ways: an inhibitory action is probably exerted via 5-HT1-like receptors, while an excitatory action is realized through 5-HT6,7-like receptors.

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