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ABSTRACT: In Xenopus laevis, we analyzed the origin of the projection neurons and interneurons in the developing olfactory bulbs by studying the expression patterns of the genes x-Eomes, x-Lhx5, x-Dll3 and x-Pax6. Olfactory bulb interneurons were characterized by using four conserved molecular markers for distinct subpopulations: gamma-aminobutyric acid, calretinin, calbindin, and tyrosine hydroxylase. Immunohistochemistry was combined with tract-tracing experiments to demonstrate the projection neurons and the interneurons of the olfactory bulbs simultaneously. Taken together, the results showed: (1) the pallial nature of the olfactory bulb and its projection neurons in Xenopus, like in mammals with comparable central projection areas, (2) the subpallial origin of the interneurons that, most likely, follow migratory pathways comparable to those described for mammals, (3) the different interneuron types possess neurochemical characteristics similar to mammals. Therefore, the present results show that the origin, chemoarchitecture and central connections of the olfactory bulbs are highly conserved in evolution.
Brain Research Bulletin 04/2008; 75(2-4):241-5. · 2.82 Impact Factor
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ABSTRACT: A previous study in the lizard Gekko gecko has revealed that neuropeptide FF (NPFF, a neuropeptide involved in nociception, cardiovascular regulation, and endocrine function) is widely distributed throughout the brain and spinal cord. Although the distribution of NPFF immunoreactivity shares many features with that found in other vertebrates, it was noted that Gekko shared more features with anamniotes in terms of number of cell groups, more elaborate networks of fibers, and lack of colocalization with catecholamines, than with mammals. To assess the primitive or derived character of these features, NPFF and tyrosine hydroxylase (TH) antibodies have been applied to the brain and spinal cord of the turtle, Pseudemys scripta elegans, which belongs to a different radiation of reptiles. As in Gekko, major NPFF-ir cell groups were found in the diagonal band nucleus of Broca and in the hypothalamus, whereas additional cells were identified in the anterior olfactory nucleus, lateral and dorsal cortices, dorsal ventricular ridge, and the intergeniculate leaflet formation. Notable differences are the presence of NPFF-ir cells in the medial cortex and striatum of Pseudemys, which are lacking in Gekko. On the other hand, no NPFF-ir cells could be detected in the septal region and dorsal horn of the spinal cord in Pseudemys. Double staining with NPFF and TH antibodies revealed an intimate relationship between NPFF-ir and TH-ir structures but colocalization could not be established. In conclusion, the distribution of NPFF in the brain of Pseudemys has corroborated previous results in Gekko, but also revealed some notable species differences.
Brain Research Bulletin 04/2008; 75(2-4):256-60. · 2.82 Impact Factor
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ABSTRACT: In the present study we have analyzed the distribution of the calcium binding proteins calbindin-D28k (CB) and calretinin (CR) immunoreactive cells in the retina of the anuran Rana perezi using poly- and mono-clonal antibodies that were proven to be specific in the amphibian brain, without cross-reactivity. Double immunohistofluorescence techniques were used to demonstrate colocalization of both proteins in the same retinal cells. In addition, retrograde tracing experiments from the optic nerve were conducted to labeled ganglion cells and these were observed in combination with CB and/or CR immunohistochemistry. Cells containing CB were identified as all cones, scattered bipolar and amacrine cells together with cells in the ganglion cell layer. The pattern of CR immunoreactivity was strikingly different. Abundant cells contained CR in the inner retinal layers including horizontal, bipolar and amacrine cells, and cells in the ganglion cell layer. By means of double immunohistochemistry it was found that only subpopulations of amacrine cells and cells in the ganglion cell layer contained both CB and CR. Tracing from the optic nerve revealed retrogradely labeled ganglion cells with different morphologies and most of them contained CB and/or CR. All these data taken together suggest that in amphibians CB and CR are distinctly and precisely distributed in retinal neurons showing, however, peculiar features not observed previously in other vertebrates.
Brain Research Bulletin 04/2008; 75(2-4):379-83. · 2.82 Impact Factor
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ABSTRACT: The analysis of the distribution of the calbindin-D28k and calretinin immunoreactive (CBir and CRir) systems recently described in the brain of anuran and urodele amphibians was very useful for the interpretation of many otherwise indistinct brain regions and cell masses. In the present study we have followed a similar approach to investigate the distribution of CBir and CRir cell bodies and fibers in the brain of Dermophis mexicanus, a member of the much neglected third amphibian order of gymnophionans. The pattern of distribution obtained showed particular characteristics in Dermophis, such as the existence of abundant CRir elements in the olfactory bulbs and CBir and CRir cell populations in pallial areas. The distinct distribution of the two proteins allowed the tentative identification of currently described subregions, mainly in the amygdaloid complex and hypothalamic areas. The analysis of the diencephalon and brainstem distribution framed in the neuromeric model highlighted common traits with other amphibians but also specific features. Therefore, the immunohistochemical detection of calcium-binding proteins has served to discern cell populations and has helped to demonstrate neuronal heterogeneity. However, it should be pointed out that a straightforward comparison based only on the presence of these proteins should not be made due to the great variability observed in well-established homologous regions in the brain of different vertebrates, as evidenced within the class Amphibia.
Brain Behavior and Evolution 08/1970; 77(4):231-269. · 2.21 Impact Factor
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ABSTRACT: Lungfishes are currently considered the closest living relatives of tetrapods and represent an interesting group for the study of evolutionary traits in the transition from fishes to tetrapods. The brains of lungfishes have received little attention in comparative studies probably due to the difficulty of obtaining these unique animals. In the present study the distribution of orexin (hypocretin)-like immunoreactivity was studied in the brain of the African lungfish Protopterus dolloi and the Australian lungfish Neoceratodus forsteri by using antibodies directed against the mammalian orexin-A and orexin-B peptides. Simultaneous detection of orexins and tyrosine hydroxylase or serotonin was used to assess the precise location of the orexins in the brain and to evaluate the possible influence of the orexin system on the monoaminergic cell groups. Although some differences were noted, a common pattern for the distribution of orexins in the two lungfishes studied was observed. In both species, most immunoreactive neurons were observed in the suprachiasmatic nucleus and dorsal hypothalamus. Only in Neoceratodus, however, were important cell populations found in the preoptic area and infundibular hypothalamus, whereas small numbers of faintly reactive neurons were present in the lateral septum and ventral striatum. Fiber labeling was widely distributed in all main brain subdivisions, but was more abundant in regions such as the septum, preoptic area, suprachiasmatic nucleus, lateral hypothalamic area, thalamus, pretectum and tegmentum. Less conspicuous was the innervation of the pallial regions, habenula, optic tectum, rhombencephalic reticular formation and spinal cord. Orexinergic innervation was found in close contact with dopaminergic, noradrenergic and serotoninergic cell groups, homologous to the substantia nigra in the midbrain tegmentum, the locus coeruleus, the nucleus of the solitary tract and the raphe nuclei. Although unique features have been found for lungfishes, the location of orexin immunoreactive elements is largely consistent with that recently reported following a similar approach in amphibians and amniotes, suggesting that the general organization of this peptidergic system occurred in the common ancestor of lungfishes and tetrapods.
Brain Behavior and Evolution 08/1970; 74(4):302-322. · 2.21 Impact Factor
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[show abstract]
[hide abstract]
ABSTRACT: In Xenopus laevis, we analyzed the origin of the projection neurons and interneurons in the developing olfactory bulbs by studying the expression patterns of the genes x-Eomes, x-Lhx5, x-Dll3 and x-Pax6. Olfactory bulb interneurons were characterized by using four conserved molecular markers for distinct subpopulations: γ-aminobutyric acid, calretinin, calbindin, and tyrosine hydroxylase. Immunohistochemistry was combined with tract-tracing experiments to demonstrate the projection neurons and the interneurons of the olfactory bulbs simultaneously. Taken together, the results showed: (1) the pallial nature of the olfactory bulb and its projection neurons in Xenopus, like in mammals with comparable central projection areas, (2) the subpallial origin of the interneurons that, most likely, follow migratory pathways comparable to those described for mammals, (3) the different interneuron types possess neurochemical characteristics similar to mammals. Therefore, the present results show that the origin, chemoarchitecture and central connections of the olfactory bulbs are highly conserved in evolution.
Brain Research Bulletin.
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[show abstract]
[hide abstract]
ABSTRACT: In the present study we have analyzed the distribution of the calcium binding proteins calbindin-D28k (CB) and calretinin (CR) immunoreactive cells in the retina of the anuran Rana perezi using poly- and mono-clonal antibodies that were proven to be specific in the amphibian brain, without cross-reactivity. Double immunohistofluorescence techniques were used to demonstrate colocalization of both proteins in the same retinal cells. In addition, retrograde tracing experiments from the optic nerve were conducted to labeled ganglion cells and these were observed in combination with CB and/or CR immunohistochemistry. Cells containing CB were identified as all cones, scattered bipolar and amacrine cells together with cells in the ganglion cell layer. The pattern of CR immunoreactivity was strikingly different. Abundant cells contained CR in the inner retinal layers including horizontal, bipolar and amacrine cells, and cells in the ganglion cell layer. By means of double immunohistochemistry it was found that only subpopulations of amacrine cells and cells in the ganglion cell layer contained both CB and CR. Tracing from the optic nerve revealed retrogradely labeled ganglion cells with different morphologies and most of them contained CB and/or CR. All these data taken together suggest that in amphibians CB and CR are distinctly and precisely distributed in retinal neurons showing, however, peculiar features not observed previously in other vertebrates.
Brain Research Bulletin.
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[show abstract]
[hide abstract]
ABSTRACT: A previous study in the lizard Gekko gecko has revealed that neuropeptide FF (NPFF, a neuropeptide involved in nociception, cardiovascular regulation, and endocrine function) is widely distributed throughout the brain and spinal cord. Although the distribution of NPFF immunoreactivity shares many features with that found in other vertebrates, it was noted that Gekko shared more features with anamniotes in terms of number of cell groups, more elaborate networks of fibers, and lack of colocalization with catecholamines, than with mammals. To assess the primitive or derived character of these features, NPFF and tyrosine hydroxylase (TH) antibodies have been applied to the brain and spinal cord of the turtle, Pseudemys scripta elegans, which belongs to a different radiation of reptiles. As in Gekko, major NPFF-ir cell groups were found in the diagonal band nucleus of Broca and in the hypothalamus, whereas additional cells were identified in the anterior olfactory nucleus, lateral and dorsal cortices, dorsal ventricular ridge, and the intergeniculate leaflet formation. Notable differences are the presence of NPFF-ir cells in the medial cortex and striatum of Pseudemys, which are lacking in Gekko. On the other hand, no NPFF-ir cells could be detected in the septal region and dorsal horn of the spinal cord in Pseudemys. Double staining with NPFF and TH antibodies revealed an intimate relationship between NPFF-ir and TH-ir structures but colocalization could not be established. In conclusion, the distribution of NPFF in the brain of Pseudemys has corroborated previous results in Gekko, but also revealed some notable species differences.
Brain Research Bulletin.
