Chemische Kodierung der Neurotransmission in den kranialen parasympathischen Ganglien der Ratte während der Ontogenese

The chemical coding of the classical and peptidergic neurotransmission in the cranial parasympathetic ganglia of the rat and their dynamic during ontogenesis is not fully clear yet. The main target of this study was to describe possible aminergic, serotoninergic, glutamatergic and peptidergic phenotypes in the cholinergic postganglionic neurons of the cranial parasympathetic ganglia of the rat over the time-axis of ontogenesis from embryonic to adult stadium. Therefor immunhistochemical methods, like flourescence-doublestaining and confocal lasermicroscopy were used. The finding of the expression of recent components of the aminergic neurotransmission (the vesicular monoaminetransporter vmat-2 and the enzymes l-aromatic aminoacid-decarboxylase aadc and dopamine-ß-hydroxylase dbh)gave new evidence for a developmental independent partial aminergic phenotype in the neurons of the otic, sphenopalatine and submandibular ganglion. The ratelimiting enzyme of the catecholaminesynthesis, the tyrosine-hydroxylase th on the other hand was only rudimentary expressed in the neurons ot these ganglia. The expression of aadc increased during development and dbh was permanently expressed on a high level. In the neurons of the ciliary ganglion on the contrary the expression increases during development and the expression of aadc and dbh decreased continiously. These data suggest, that a noradrenalinesynthesis in the neurons of the otic, sphenopalatine and submandibular ganglion is only possible with the existence of an uptake mechanism for L-DOPA or Dopamine. On the other hand the synthesis of noradrenaline could be guaranteed by the alternative enzyme tyrosinase. Also the synthesis of trace-amines, as octopamine by aadc and dbh could be possible. This competitive ligand to adrenoceptors could be interesting for the regulation of the cerebral blood-flow and the activity of glands or for deseases like headache or hypersalivation in the ParkinsonŽs desease. The expression of vmat-2 continously decreased in the neurons of the otic, sphenopalatine and submandibular ganglion which suggests either a vesicular release of noradrenaline/octopamine or a non-vesicular release of these substances. Totally new was the prove of the expression of the histamine-decarboxylase hdc in the neurons of all four cranial parasympathetic ganglia. This suggests the ability of histamine-production in these neurons. The new data of the expression of the neuropeptides (vesicular intestinal polypeptide vip, neuropeptide y npy, calcitonin gene-related peptide cgrp met5-enkephalin-arg6-gly7-leu8 mergl substance p sp) and the oblitatory vesiculogene chromogranin a cga in the neurons of the cranial parasympathetic ganglia partially showed a much wider range of expression as known from the literatur. In this study it could be shown new phenotypes in the neurons of the cranial parasympathetic ganglia of the rat. This new shown complex chemical coding with different neurotransmitter-systems in these ganglia suggests a much more differenciated role of the parasympathetic neurotransmission as known till now.