Biomedical subjects

Salvador Guirado

Publications and source records attributed to Salvador Guirado.

14 recordsLinked to original sources

PubMed2006

Calcium-binding proteins, neuronal nitric oxide synthase, and GABA help to distinguish different pallial areas in the developing and adult chicken. I. Hippocampal formation and hyperpallium.

To better understand the formation and adult organization of the avian pallium, we studied the expression patterns of gamma-aminobutyric acid (GABA), calbindin (CB), calretinin (CR), and neuronal nitric oxide synthase (nNOS) in the hippocampal formation and hyperpallium of developing and adult chicks. Each marker showed a specific spatiotemporal expression pattern and was expressed in a region (area)-specific but dynamic manner during development. The combinatorial expression of these markers was very useful for identifying and following the development of subdivisions of the chicken hippocampal formation and hyperpallium. In the hyperpallium, three separate radially arranged subdivisions were present since early development showing distinct expression patterns: the apical hyperpallium (CB-rich); the intercalated hyperpallium (nNOS-rich, CB-poor); the dorsal hyperpallium (nNOS-poor, CB-moderate). Furthermore, a novel division was identified (CB-rich, CR-rich), interposed between hyper- and mesopallium and related to the lamina separating both, termed laminar pallial nucleus. This gave rise at its surface to part of the lateral hyperpallium. Later in development, the interstitial nucleus of the apical hyperpallium became visible as a partition of the apical hyperpallium. In the hippocampal formation, at least five radial divisions were observed, and these were compared with the divisions proposed recently in adult pigeons. Of note, the corticoid dorsolateral area (sometimes referred as caudolateral part of the parahippocampal area) contained CB immunoreactivity patches coinciding with Nissl-stained cell aggregates, partially resembling the patches described in the mammalian entorhinal cortex. Each neurochemical marker was present in specific neuronal subpopulations and axonal networks, providing insights into the functional maturation of the chicken pallium.

Animals↗

PubMed2006

Immunohistochemical localization of the vesicular glutamate transporter VGLUT2 in the developing and adult mouse claustrum.

We studied the immunoreactive expression pattern for the vesicular glutamate transporter VGLUT2 in the embryonic, postnatal and adult mouse dorsal claustrum, at the light and electron microscopic levels. VGLUT2 immunoreactivity in the dorsal claustrum starts to be observed at E16.5, with a dramatic increase towards P0. At this age, abundant VGLUT2-immunoreactive axons and puncta are observed in all pallial regions, including the claustral complex. From the first postnatal week, VGLUT2 immunoreactivity declines in several telencephalic areas, including the pallium, but abundant VGLUT2-immunoreactive fine axons and puncta remain in the claustrum. Beginning at E18.5, VGLUT2 immunoreactivity within the claustrum shows a characteristic arrangement: a central part of the region is practically devoid of VGLUT2 immunoreactivity, and it is surrounded by plenty of immunoreactive axon terminals forming a shell around it. This core/shell arrangement of the VGLUT2 immunoreactivity resembles the complementary expression of parvalbumin and calretinin described in the mouse claustrum [Real, M.A., Dávila, J.C., Guirado, S., 2003. Expression of calcium-binding proteins in the mouse claustrum. J. Chem. Neuroanat. 25, 151-160]. We observed immunoreactive neuronal cell bodies as well in the dorsal claustrum, but only at P0. Electron microscopic analysis reveals that VGLUT2 immunoreactivity in the developing and adult dorsal claustrum consists predominantly of presynaptic boutons making asymmetric synaptic contacts. These VGLUT2-immunoreactive boutons are observed as early as E16.5 and may be related to thalamo-claustral incoming fibers.

Animals↗

PubMed2005

Development of neurons and fibers containing calcium binding proteins in the pallial amygdala of mouse, with special emphasis on those of the basolateral amygdalar complex.

We studied the development of neurons and fibers containing calbindin, calretinin, and parvalbumin in the mouse pallial amygdala, with special emphasis on those of the basolateral amygdalar complex. Numerous calbindin-immunoreactive (CB+) cells were observed in the incipient basolateral amygdalar complex and cortical amygdalar area from E13.5. At E16.5, CB+ cells became more abundant in the lateral and basolateral nuclei than in the basomedial nucleus, showing a pattern very similar to that of gamma-aminobutyric acid (GABA)ergic neurons. Many CB+ cells observed in the pallial amygdala appeared to originate in the anterior entopeduncular area/ganglionic eminences of the subpallium. The density of CB+ cells gradually increased in the pallial amygdala until the first postnatal week and appeared to decrease later, coinciding with the postnatal appearance of parvalbumin cells and raising the possibility of a partial phenotypic shift. Calretinin (CR) immunoreactivity could be observed in a few cells and fibers in the pallial amygdala at E14.5, and by E16.5 it became a good marker of the different nuclei of the basolateral amygdalar complex. Numerous CB+ and CR+ varicosities, part of which have an intrinsic origin, were observed in the basolateral amygdalar complex from E16.5, and some surrounded unstained perikarya and/or processes before birth, indicating an early formation of inhibitory networks. Each calcium binding protein showed a distinct spatiotemporal expression pattern of development in the mouse pallial amygdala. Any alteration in the development of neurons and fibers containing calcium binding proteins of the pallial amygdala may result in important disorders of emotional and social behavior.

Amygdala↗

PubMed2005

Distribution of nitric oxide-producing neurons in the developing and adult mouse amygdalar basolateral complex.

We analysed the expression of neuronal nitric oxide synthase (nNOS) in the mouse amygdalar basolateral complex (BLC) from embryonic day 15.5 to adult, using standard immunohistochemical methods. Our results indicate that each nucleus of the amygdalar basolateral complex displays a distinct nNOS expression pattern, which is established during the ontogenesis with minor changes in the adult. The basomedial nucleus (BM) exhibited the highest nNOS immunoreactivity in the basolateral complex, observable from early embryonic stages, whereas the lateral nucleus displayed the lowest level of immunoreactivity. The expression pattern for nNOS in the basolateral nucleus differed substantially from that of the lateral and basomedial nuclei, showing a slightly increase in the number of nNOS cells and neuropil staining from intermediate developmental until early postnatal stages. Two distinct types of nitrergic neurons, densely and lightly stained neurons, were observed in the developing basolateral complex. Both types of putative nitrergic neurons were unevenly distributed in the basolateral complex. On the basis of previous data regarding the colocalization between nNOS and GABA in the mouse claustrum, we suggest that nNOS expressing neurons in the basolateral amygdalar complex are both GABAergic and non-GABAergic.

Amygdala↗

PubMed2005

Semaphorin5A expression in the developing chick telencephalon.

In the present study, we analyzed the expression of Semaphorin5A (Sema5A), a gene implicated in axon guidance and many other processes of neuronal development, in the developing chick telencephalon. By using a heterologous mouse probe and in situ hybridization techniques, we showed distinct patterns of Sema5A expression within the chick telencephalon. In early development, Sema5A was present in pallial regions, mainly in the neuroepithelium and in the deep mantle of ventral and lateral pallia, and in the subpallium. As development proceeds, some ventral pallial derivatives maintained a moderate to strong Sema5A expression, whereas other lateral or dorsal pallial derivatives showed low to moderate expression of Sema5A. The overall expression of Sema5A during development in the chick telencephalon was similar to that reported in mouse. Moreover, the expression of Sema5A in mesencephalic, diencephalic, and telencephalic centers related to the tectofugal system suggests an important role of this gene in the development.

Age Factors↗

PubMed2005

Distribution of GABA, calbindin and nitric oxide synthase in the developing chick entopallium.

The distribution of GABA, calbindin and neuronal nitric oxide synthase (nNOS) was analyzed in the developing avian entopallium. The study was carried out in chick embryos from embryonic day (E)8 to hatching postnatal day (P)0, using immunohistochemical methods. At E8, GABA-positive cells were observed in pallial regions. Neither calbindin nor nNOS-immunoreactive cells were observed. At E10, the number of GABA neurons in the prospective entopallium increased and also nNOS cells were observed. Lightly stained nNOS neurons predominated over intensely stained ones. Calbindin immunoreactivity was not observed in the entopallium. At E12, the entopallial complex appeared as the pallial region displaying the highest density of GABA neurons. Also the whole entopallium displayed an intensely stained calbindin neuropil with many embedded stained cells. From E12 on, there was a decrease in the expression of nNOS. At E14-16, both GABA and calbindin-immunoreactive neurons were numerous and homogeneously distributed within the entopallium. The whole entopallium displayed a moderately stained neuropil. From E18 to P0, GABA and nNOS immunoreactivities remained similar to previous stages. At these stages, calbindin immunoreactivity within the entopallium consisted of a moderately stained central region bordered dorsally by a pale stained region. These two areas could correspond to the entopallial core and the perientopallial belt, respectively.

Age Factors↗

PubMed2005

The ascending tectofugal visual system in amniotes: new insights.

Ascending tectal axons carrying visual information constitute a fiber pathway linking the mesencephalon with the dorsal thalamus and then with a number of telencephalic centers. The sauropsidian nucleus rotundus and its mammalian homologue(s) occupy a central position in this pathway. The aim of this study was analyzing the rotundic connections in reptiles and birds in relation with comparable connections in mammals, by using biotinylated dextran amines and the lipophilic carbocyanine dye DiI as tracing molecules. In general, rotundic connections in reptiles and birds are quite similar, especially with regards to pretectal and tectal afferences; as a novel finding, we describe varicose fibers arising from nucleus rotundus that reached the developing chick striatum. In addition, this study described the dorsal claustrum as a novel telencephalic target for the suprageniculate nucleus in mammals. Overall, telencephalic projections from the posterior/intralaminar complex of the mammalian thalamus can be compared with the telencephalic projections of the reptilian nucleus rotundus. With the exception of the isocortical connections, the mouse suprageniculate nucleus shares a number of afferent and efferent connections with the sauropsidian nucleus rotundus. Especially significant were the suprageniculate fibers reaching the striatum and then following to reach pallial derivatives such as the lateral amygdala (ventral pallium) and the dorsal claustrum (lateral pallium). These connections can be compared with the rotundic fibers reaching the ventromedial part of the anterior dorsal ventricular ridge in reptiles/entopallium in birds (ventral pallium) and the dorsolateral part of the anterior dorsal ventricular ridge in reptiles (lateral pallium), and probably the mesopallium in birds.

Amnion↗

PubMed2005

Embryonic and postnatal development of GABA, calbindin, calretinin, and parvalbumin in the mouse claustral complex.

We analyzed the development of immunoreactive expression patterns for the neurotransmitter gamma-aminobutyric acid (GABA) and the calcium-binding proteins calbindin, calretinin, and parvalbumin in the embryonic and postnatal mouse claustral complex. Each calcium-binding protein shows a different temporal and spatial pattern of development. Calbindin-positive cells start to be seen very early during embryogenesis and increase dramatically until birth, thus becoming the most abundant cell type during embryonic development, especially in the ventral pallial part of the claustrum. The distribution of calbindin neurons throughout the claustrum during embryonic development partly parallels that of GABA neurons, suggesting that at least part of the calbindin neurons of the claustral complex are GABAergic and originate in the subpallium. Parvalbumin cells, on the other hand, start to be seen only postnatally, and their number then increases while the density of calbindin neurons decreases. Based on calretinin expression in axons, the core/shell compartments of the dorsal claustrum start to be clearly seen at embryonic day 18.5 and may be related to the development of the thalamoclaustral input. Comparison with the expression of Cadherin 8, a marker of the developing dorsolateral claustrum, indicates that the core includes a central part of the dorsolateral claustrum, whereas the shell includes a peripheral area of the dorsolateral claustrum, plus the adjacent ventromedial claustrum. The present data on the spatiotemporal developmental patterns of several subtypes of GABAergic neurons in the claustral complex may help for future studies on temporal lobe epilepsies, which have been related to an alteration of the GABAergic activity.

Animals↗

PubMed2003

Distinct types of nitric oxide-producing neurons in the developing and adult mouse claustrum.

We studied at the light and electron microscopic levels the nitric oxide-producing neurons in the mouse claustrum. Nicotinamide adenine dinucleotide phosphate (NADPH)-diaphorase histochemistry and neuronal nitric oxide synthase (nNOS) immunohistochemical staining were used to reveal putative nitrergic neurons. We also analyzed colocalization of nNOS with the inhibitory neurotransmitter gamma-aminobutyric acid (GABA) as well as the ontogenesis of the nNOS-immunoreactive neurons, providing evidence for different populations of nitrergic neurons in the mouse claustrum. The general staining pattern was similar for the histochemical and the immunohistochemical methods, resulting in neuron and neuropil staining throughout the whole claustrum. We described two populations of nitric oxide-producing neurons in the mouse claustrum on the basis of a different level of nNOS expression. Densely nNOS-stained neurons were mostly GABA immunoreactive, displayed ultrastructural features typically seen in aspiny neurons, and may originate in the subpallium; they were first seen in the claustrum at embryonic stage 17.5 and probably represent local inhibitory interneurons. Densely stained cells were found from rostral to caudal levels throughout the dorsal claustrum and the endopiriform nucleus. Lightly nNOS-stained neurons, on the other hand, were more numerous than densely stained ones, especially in the dorsal claustrum. These claustral lightly stained cells, barely observed in the NADPH-diaphorase reacted sections, were mostly non-GABAergic, and appeared earlier during ontogenesis than densely stained cells (at embryonic stages 15.5-16.5). We suggest that these neurons are probably projection neurons.

Animals↗

PubMed2003

Expression of calcium-binding proteins in the mouse claustrum.

The present paper describes the distribution of three calcium-binding proteins (calbindin D28k, calretinin, and parvalbumin) in the mouse dorsal claustrum and endopiriform nucleus. The three calcium-binding proteins were distinctly expressed in structures of both the claustrum and the endopiriform nucleus. Calbindin was the calcium-binding protein showing the highest expression in the claustrum and the endopiriform nucleus. In contrast, calretinin-immunoreactive structures, particularly cell bodies, were very scarce in these regions. Both calbindin-immunoreactive and parvalbumin-immunoreactive neurons were more abundant in the claustrum than in the endopiriform nucleus, and more in rostral than in caudal levels. Nevertheless, calcium-binding protein immunoreactive neurons constitute a minority population of claustral neurons. The colocalization study of calbindin and parvalbumin immunoreactivities has demonstrated that both calcium-binding proteins are mostly expressed by separate claustral neurons in the mouse. On the other hand, our results on parvalbumin and calretinin immunoreactivity match a novel subdivision of the mouse claustrum mostly based on the pattern of cadherin expression [Neuroscience 106 (2001) 505]. In this sense, we propose that a specific zone of the dorsal claustrum with cell bodies that strongly express Rcad and cadherin-8 would be the selective target for parvalbumin-expressing fibers, and that they would be mostly avoided by calretinin-expressing axons.

Animals↗

PubMed2002

Mesencephalic and diencephalic afferent connections to the thalamic nucleus rotundus in the lizard, Psammodromus algirus.

The present work is an analysis of the afferent projections to the thalamic nucleus rotundus in a lizard, both at the light- and electron-microscopic level, using biotinylated dextran amine (BDA) as a neuroanatomical tracer. This study has confirmed previously reported afferent projections to nucleus rotundus in reptiles and has also identified a number of new cellular aggregates projecting to this dorsal thalamic nucleus. After BDA injections into nucleus rotundus, retrogradely labelled neurons were observed consistently within the following neuronal groups in the midbrain and the diencephalon: (i) the stratum griseum centrale of the optic tectum; (ii) the nucleus subpretectalis in the pretectum; (iii) the nucleus ansa lenticularis posterior, the posterior nucleus of the ventral supraoptic commissure, and the posteroventral nucleus, in the dorsal thalamus and (iv) the lateral suprachiasmatic nucleus and part of the reticular complex in the ventral thalamus. Tectal axons entering nucleus rotundus were fine and varicose and formed exclusively asymmetric synaptic contacts, mainly on small dendritic profiles. Rotundal neurons had symmetric synapses made by large boutons probably of nontectal origin. After comparing our results with those in other reptiles, birds and mammals, we propose that the sauropsidian nucleus rotundus forms part of a visual tectofugal pathway that conveys mesencephalic visual information to the striatum and dorsal ventricular ridge, and is similar to the mammalian colliculo-posterior/intralaminar-striatoamygdaloid pathway, the function of which may be to participate in visually guided behaviour.

Animals↗

PubMedDate not supplied

Thalamo-telencephalic connections: new insights on the cortical organization in reptiles.

Tracer injections into the dorsal tier of the lacertilian dorsal thalamus revealed an extensive innervation of the cerebral cortex. The medial cortex, the dorsomedial cortex, and the medial part of the dorsal cortex received a bilateral projection, whereas the lateral part of dorsal cortex and the dorsal part of the lateral cortex received only an ipsilateral thalamic projection. Thalamocortical fibers were found superficially in all cortical regions, but in the dorsal part of the lateral cortex, varicose axons within the cellular layer were also observed. The bilateral thalamocortical projection originates from a cell population located throughout the dorsolateral anterior nucleus, whereas the ipsilateral input originates mainly from a rostral neuronal subpopulation of the nucleus. This feature suggests that the dorsolateral anterior nucleus consists of various parts with different projections. The dorsal subdivision of the lateral cortex displayed hodological and topological (radial glia processes) features of a dorsal pallium derivative. After tracer injections into the dorsal cortex of lizards, we found long descending projections that reached the striatum, the diencephalic basal plate, and the mesencephalic tegmentum, which suggests that it may represent a sensorimotor cortex.

Animals↗

PubMedDate not supplied

A putative striato-dorsal thalamic pathway in lizards.

Striatal targets related to the dorsal thalamus were studied in reptiles. The lateral striatum projects to globus pallidus and to three cellular groups associated to the lateral forebrain bundle: the anterior entopeduncular nucleus, the suprapeduncular nucleus, and the ventromedial thalamic nucleus. The projection is heavier on the suprapeduncular nucleus, which in turn projects on nucleus rotundus in the dorsal thalamus. Nucleus rotundus is the origin of a prominent projection to the lateral striatum among other forebrain areas. The intermediomedial striatum projects also to globus pallidus and to the three cellular groups associated with the lateral forebrain bundle, but in this case, the projection is heavier on the ventromedial thalamic nucleus. The latter nucleus targets a number of nuclear aggregates in the ventral tier of the dorsal thalamus, which in turn project to the intermediomedial striatum. As in mammals, the striatum in reptiles may influence through these pathways its input from the dorsal thalamus.

Animals↗

PubMedDate not supplied

A proposed homology between the reptilian dorsomedial thalamic nucleus and the mammalian paraventricular thalamic nucleus.

We have compared the reptilian dorsomedial thalamic nucleus with the mammalian paraventricular thalamic nucleus from a topographic, chemoarchitectonic, and hodological point of view. Both nuclei are localized to a similar position in the dorsalmost aspect of the dorsal thalamus (midline nuclei). They also are uniformly calretinin-immunoreactive, both their cells and neuropil are strongly immunostained for calretinin, and the dorsomedial nucleus presents a strong calbindin immunoreactivity as well. Finally, the reptilian and the mammalian nuclei share a set of afferent and efferent connections with a number of forebrain structures. On the whole, this set of data allows us to propose that the dorsomedial nucleus and the paraventricular thalamic nucleus are homologous. Both represent an important relay station in pathways connecting the hypothalamus with telencephalic areas involved in visceral and motivational aspects of behavior, such as nucleus accumbens and the central amygdala.

Animals↗