Light and electron microscopic characterization of cholinergic and dopaminergic structures in the striatal complex and the dorsal ventricular ridge of the lizard Gekko gecko.
The purpose of the present study was to visualize the morphological substrate underlying acetylcholine-dopamine interactions in the striatal complex of the lizard Gekko gecko and to compare the results with data obtained by others in mammals. The results are also discussed in the light of data obtained previously by us on neurochemical aspects of acetylcholine-dopamine interactions in Gekko and in rats. The study is part of a large research program in which the cholinergic and dopaminergic elements of the striatum of rats and reptiles are studied at morphological and neurochemical levels. We employed light microscopic immunocytochemistry, using single-label staining with antibodies against choline acetyltransferase (ChAT) and dopamine (DA) and double-staining with antibodies against ChAT and tyrosine hydroxylase (TH). A detailed analysis of ultrastructural characteristics of ChAT- and DA-immunolabeled striatal tissue was undertaken. The morphology and synaptic relations of the ChAT-immunopositive neurons in the basal forebrain of the lizard Gekko gecko are very similar to those of the cholinergic cells in the striatum of mammals. Probably, the cholinergic cells are in both mammals and reptiles interneurons that receive inputs of intrinsic or extrinsic origin and project upon output neurons. The location of ChAT-immunopositive somata outside the patches of high TH- or DA-immunoreactivity is at odds with the situation in the striatum of mammals and suggests the possibility of axoaxonal or axodendritic contacts at the level of these patches. We found no essential differences between the synaptic relations of the dopaminergic fibers in the striatal complex of Gekko and the conditions described for rats. In conclusion, we found little evidence for the presence of synaptic interaction between the cholinergic and dopaminergic systems in the striatum of this reptile. The possibility of nonsynaptic interaction, however, remains open.
Henselmans
J M
JM
Department of Anatomy, Vrije Universiteit, Amsterdam, The Netherlands.
Wouterlood
F G
FG
D000818:Animals; D002552:Cerebral Ventricles / Q000033:anatomy & histology* / Q000378:metabolism; D002795:Choline O-Acetyltransferase / Q000378:metabolism; D003342:Corpus Striatum / Q000033:anatomy & histology* / Q000378:metabolism; D004298:Dopamine / Q000378:metabolism*; D005260:Female; D007150:Immunohistochemistry; D008116:Lizards / Q000378:metabolism*; D008297:Male; D008854:Microscopy, Electron; D009412:Nerve Fibers / Q000378:metabolism; D010275:Parasympathetic Nervous System / Q000033:anatomy & histology*; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism
D014446:Tyrosine 3-Monooxygenase; D002795:Choline O-Acetyltransferase; D004298:Dopamine