Noradrenergic and dopaminergic systems in the central nervous system of the hedgehog (Erinaceus europaeus).
The distribution of the noradrenaline (NA)- and dopamine (DA)-containing neuronal structures in the central nervous system of the hedgehog (Erinaceus europaeus), a phylogenetically old mammalian species, was immunocytochemically studied employing antibodies directed against the catecholamines (CA) themselves. Groups of DA cell bodies observed in this study were similar to those present in other species but the distributional map of the NA-containing cell bodies exhibited some peculiarities. Prominent among them were the absence of the A3 group and the paucity of CA cells in the A2 group. DA neurons in the hypothalamus, apart from the densely populated paraventricular and arcuate nuclei, were fewer and less widely distributed than in other species. In the hedgehog mesencepha- Ion, in contrast to what has been described in other species, the major DA cell group was present in the ventral tegmental area. CA immunoreactive fibers were widely distributed in the CNS of the hedgehog. However, similarly to what has been observed in other species, terminal fields of DA neurons were much more restricted when compared to those of the NA neurons. The neocortical DA projection system of the hedgehog appeared less developed but organized similar to that of the rat, and even less developed than that of the primates. The lack of profound regional and laminar variations in the density of cortical NA fibers in the hedgehog enhances the suggestion that the elaboration and differentiation of the NA cortical system parallels the phylogenetic development of the cortex. In the brainstem, interspecies differences in the distribution of the CA fibers were found to concern primarily some hypothalamic areas (medial preoptic area, suprachiasmatic nucleus, arcuate nucleus). Such differences in the thalamus concerned the NA innervation and they were notably present in the visual thalamic nuclei (dorsal lateral geniculate nucleus, lateral posterior thalamic nucleus). In the spinal cord, which was found to receive fewer CA afferents than those found in other species, the density of the DA fibers was much lower than that of the NA axons. In addition to the CNS areas that have been described in other species to receive catecholaminergic innervation, the present study showed that both types of catecholaminergic fibers are distributed in the choroid plexus and along the ventricular wall of the brain ventricles and the central canal of the hedgehog.
Michaloudi
H C
HC
Department of Anatomy, Veterinary School, University of Thessaloniki, Greece.
Papadopoulos
G C
GC
D000320:Adrenergic Fibers / Q000378:metabolism*; D000818:Animals; D001369:Axons / Q000648:ultrastructure*; D001931:Brain Mapping; D002490:Central Nervous System / Q000378:metabolism*; D004298:Dopamine / Q000378:metabolism*; D005260:Female; D006364:Hedgehogs; D007150:Immunohistochemistry; D008297:Male; D008854:Microscopy, Electron; D009434:Neural Pathways / Q000378:metabolism*; D013116:Spinal Cord / Q000648:ultrastructure
D004298:Dopamine