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D Saucier

Publications and source records attributed to D Saucier.

34 records · Page 2Linked to original sources
PubMed1991

Spread of the CVS strain of rabies virus and of the avirulent mutant AvO1 along the olfactory pathways of the mouse after intranasal inoculation.

After intranasal instillation in the mouse, rabies virus (CVS strain) selectively infected olfactory receptor cells. In the main olfactory bulb (MOB), infection was observed in periglomerular, tufted, and mitral cells and in interneurons located in the internal plexiform layer. Beyond the MOB, CVS spread into the brain along the olfactory pathways. This infection is specific to chains of functionally related neurons but at the death of the animal some nuclei remain uninfected. CVS also penetrated the trigeminal system. The avirulent mutant AvO1, carrying a mutation in position 333 of the glycoprotein, infected the olfactory epithelium and the trigeminal nerve as efficiently as CVS. During the second cycle of infection, the mutant was able to infect efficiently periglomerular cells in the MOB and neurons of the horizontal limb of the diagonal band, which indicates that maturation of infective particles is not affected in primarily infected neuronal cells. On the other hand, other neuronal cells permissive for CVS, such as mitral cells or the anterior olfactory nucleus, are completely free of infection with the mutant, indicating that restriction is related to the ability of AvO1 to penetrate several categories of neurons. From these observations, we concluded that CVS should be able to bind several different receptors to penetrate neurons, while the mutant would be unable to recognize some of them.

Administration, Intranasal↗
PubMed1989

Cellular expression of H and B antigens in the rat olfactory system during development.

Developmental expression of H and B antigens in the rat olfactory system was studied from the embryonic day 14 up to the postnatal day 30. The H antigen was detected in the olfactory and vomeronasal epithelia as early as fetal day 14, whereas the B antigen first appeared 2 days later. The anti-H reagent reacted strongly with sensory receptors and weakly with supporting cells in both epithelia, whereas the anti-B reagent was specific for olfactory receptors. In the main olfactory epithelium, the H antigen was expressed from fetal day 19 by most of the receptor cells, whereas the B determinant was expressed from fetal day 16 to postnatal day 3 by only a few neuroreceptors mostly located near the epithelial surface. After the postnatal day 3, B positive neurons increased in number from the periphery toward the deeper mucosal layers and they were distributed over 3/4 of the epithelial thickness in 15- and 30-day-old rats. In the main olfactory bulb, a widespread glomerular B staining with variable binding intensity between adjacent glomeruli was already observed at birth. The vomeronasal receptor cells and their axon terminals in the accessory olfactory bulb exhibited a comparable developmental expression of the B antigen. Results suggest that the B antigen could be regarded as a marker of neuronal maturation of both the olfactory and vomeronasal receptor cells; moreover, its first appearance in the receptor cells might be temporally related to the formation of synapses between receptor axons and deutoneurons in the bulb.

ABO Blood-Group System↗
PubMed1988

Topographical projection of the septal organ to the main olfactory bulb in rats: ontogenetic study.

Using the horseradish peroxidase (HRP) retrograde tracing method, we have studied the topographical organization of the projection of the septal organ to the main olfactory bulb in rats varying in age from 22 fetal days up to 15 postnatal days. For all developmental stages studied, receptor cells of the septal organ had their axons ending in a relatively circumscribed region of the olfactory bulb, which was the posterior ventromedial bulbar aspect. In younger animals, olfactory receptor cells were observed within the epithelial area isolating the septal organ from the olfactory epithelium, whereas this area was reported to be an exclusive respiratory region in adult rats. The complete disappearance of these receptor cells noted in 12-day-old rats was related to some ontogenetic process.

Afferent Pathways↗
PubMed1987

Topographical relationships between olfactory receptor cells and glomerular foci in the rat olfactory bulb.

We have studied the distribution patterns of olfactory receptor cells that project to glomerular foci after HRP injections in the different bulbar surfaces of 15-day-old rats. HRP label overlapped only 2-4 contiguous glomeruli and had a maximal extent of 260 micron along the antero-posterior (A-P) axis. HRP injections were confined enough to allow labeled individual receptor cells to be discerned in the epithelial sheet. Results have shown that neurons ending in a few contiguous glomeruli of a given bulbar surface were distributed in most of the regions projecting to this bulbar surface. Moreover, within these epithelial areas, labeled cells were largely dispersed in both the frontal and the A-P axes of the nose. When few HRP-filled neurons were observed on a turbinate or a recess, their distribution seemed organized according to a certain alignment along the A-P nasal axis. Our findings demonstrate for the first time that the principal features of the regional organization of epithelium projections to a given bulbar surface are reproduced in any glomerular focus of this bulbar surface, and suggest that it could be the same for any single glomerulus. Such a principle of projection supports the concept of a large redundance in the anatomical relationship between periphery and bulb.

Animals↗
PubMed1986

Anatomical mapping of the neuroepithelial projection to the olfactory bulb in the rat.

The topographical organization of the epithelium-to-bulb projections was studied in 15-day-old rats by the retrograde tracing method using horseradish peroxidase (HRP). Injections of HRP were placed in the glomerular layer of the 4 bulbar surfaces; the location and the maximal extent of labeled epithelial areas were assessed. Results have shown an important but variable degree of overlapping of peripheral projections to the bulb. The dorsal aspect received inputs from only the anterior dorsal recess and endoturbinate II. Epithelial projections to the lateral side included the anterior dorsal recess and turbinates 1, 2-2' and II-II'. Peripheral projections converging to the medial surface were the most various; they comprised the septal wall, the posterior dorsal recess, ectoturbinate 3 and all endoturbinates. The ventral pole received afferents from the lateral recess, lower parts of the septal wall and turbinates 2-2', 3, III, IV and also recesses between these turbinates. Otherwise, three epithelial areas showed divergent projections to the bulb. Information processing via convergence and divergence of epithelium-to-bulb connections may represent differential functions in olfactory information coding.

Afferent Pathways↗
PubMed1986

Analysis of the topographical organization of olfactory epithelium projections in the rat.

The degree of topographical organization of epithelium-to-bulb connections in 15-day-old rats was analyzed from the complete mapping of these projections previously described by using the HRP retrograde tracing method. We performed HRP placements in the antero-posterior (anterior, central and posterior injections) and dorso-ventral bulbar axes. Results demonstrated: lack of transposition of any plane of the epithelial sheet along the antero-posterior axis in the bulb which indicated a typical diffuse distribution of projections along this bulbar plane; a general tendency of the medial, lateral, dorsal and ventral epithelial regions to project to homologous bulbar surfaces; however, this transposition was always relative; the importance of the dorso-ventral bulbar axis in the somatotopic organization of projections since this plane was a common plane on which the different mucosal axes were represented. These results suggest that the topographical organization of projections reflects the ontogenetically determined epithelium-to-bulb connections.

Afferent Pathways↗
PubMed1983

Ontogenesis of the functional activity of guinea-pig olfactory bulb: autoradiographic study with the 2-deoxyglucose method.

An ontogenetic study of [14C]2-deoxyglucose (2-DG) uptake within the olfactory bulbs was performed in 1-, 4-, 7- and 21 day-old guinea-pigs exposed to a pure chemical odor, ethyl acetoacetate (EAA). Whatever the age studied, the patterns of glomerular activity are characterized by restricted spots which extend along the bulb, and by sheets of increased density overlapping 10-30 contiguous glomeruli, found only on the lateral aspect of the bulb. Even if the main features of the 2-DG patterns related to EAA are already present at birth, a perceptible evolution of these patterns is observed during the first 3 postnatal weeks. The changes include on the one hand, an increase of the spot-like glomerular labeling which appears particularly prominently on the medial and dorsal aspects. On the other hand, whereas the restricted spots overlaying 1-3 glomeruli become more numerous with age, a decrease in size and in extension of the sheet-like glomerular activity is noted. The results confirm the high maturation level of the olfactory bulbs in newborn guinea-pigs. Some implications related to the mainly prenatal maturation of the olfactory system are discussed.

Animals↗
PubMed1981

Ontogenesis of the functional activity of rat olfactory bulb: autoradiographic study with the 2-deoxyglucose method.

An ontogenetic study of the uptake of [14C]2-deoxyglucose (2-DG) within the olfactory bulb was performed on rats of 3 age groups, 1, 9 and 21 days. Animals were exposed either to ethyl acetoacetate (EAA) or to a nest odor. Already in newborns, a glomerular activity characterized by small spots of increased 2-DG uptake, appeared in response to either odor stimulation. An ontogenetic development of this glomerular activity was observed with age: whereas the labeled glomerular foci were scanty in newborns, their number constantly increased with age until weaning; moreover, an increased proportion of foci overlaying 2 or 3 single glomeruli was noted in parallel with the postnatal maturation of the olfactory system. For the 3 age groups, whatever the odor stimulus, the glomerular activity seemed located in 2 main regions of the olfactory bulb, the lateral aspect and the posterior part of the medial aspect of the bulb. In newborns, no clear difference could be brought out between the patterns of glomerular activation related to EAA and to nest odor, respectively. In 9-day-old rats, the spatial patterns of distribution associated with the 2 odors were overlapping, but nevertheless different. These data are correlated with the postnatal maturation of the olfactory system.

Acetoacetates↗
PubMed1981

Metabolic mapping of functional activity in the olfactory projections of the rat: ontogenetic study.

An ontogenetic study of the uptake of [14C]2-deoxy-D-glucose (2-DG) within the direct olfactory bulb projections and the tertiary olfactory projections was performed on rats of 1, 9 and 21 days old. Animals were exposed either to ethyl acetoacetate or to nest odor. In newborns, most of the direct olfactory bulb projections - anterior olfactory nucleus, anterior part of the olfactory tubercle, piriform cortex and nucleus of the lateral olfactory tract - appear labelled on films and therefore seem functional. No evidence of 2-DG uptake can be brought out in the cortical amygdala nucleus. AS regards the tertiary olfactory projections, there is no apparent functional activity, neither in the medio-dorsal and medio-ventral thalamic nuclei nor in the hypothalamic nuclei, e.g. the lateral preoptic area and the lateral hypothalamus. In 9-day-old pups, the direct olfactory bulb projections and the tertiary olfactory projections appear well-contrasted. Moreover, the patterns of labelling within the direct olfactory bulb projections are comparable to those observed in 21-day-old rats and in adult. These data are correlated with the postnatal development of the discriminating ability of the rat.

Aging↗
PubMed1975

[Effects of alpha-methyl-dopa on new born kitten sleep. Behavioral evolution during the first month post-birth (author's transl)].

The paradoxical sleep (PS)-suppressing effect of alpha-methyl-Dopa was studied in kittens at birth. The new burn animal received daily injections of alpha-methyl-Dopa during the 2 first weeks of life. States of sleep were studied during the treatment (days 1 to 14) and after administration of the drug way halted (days 15 and 16). Daily injections of alpha-methyl-Dopa induce an average PS-deprivation of 72%. This deprievation is compensated for by a significant increase in quiet sleep (QS)-rate which is found to be up to 3.5 times that of kittens not receiving alpha-methyl-Dopa. A progressive return of PS-ratio to normal, without PS rebound, is observed after drug administration ceases. Alpha-methyl-Dopa produces a sedative effect on the kitten which remains relatively hypotonic during the treatment. Behavioural studies carried out over the first month after birth show no significant delay in the ponderal growth nor in the acquisition of stereotyped behaviour patterns. However motor coordination is delayed 2 weeks in these kittens.

Aging↗
PubMed1975

[Polygraphic study of sleep in young chickens at hatching, evolution at third and fourth days].

A polygraphic study of the states of vigilance in the young chicken was performed in the first week after hatching. At hatching, three stages of vigilance were present and their polygraphic characteristics were similar to those of the adult. Quantitative data showed a relative immaturity of the young chicken since percentages of paradoxical sleep and slow wave sleep were high in the first 8 h after hatching (PS/TS equals 16.5%). These values diminished rapidly and reached the adult values observed on the third day (PS/TS equals 6.4%). Our experimental conditions showed the presence of a nycthemeral rhythm of the states of vigilance by the third day.

Age Factors↗
PubMedDate not supplied

[Modifications of sleep "in utero" in guinea pig after maternal administration of alpha-methyl-L-DOPA (author's transl)].

Effects of maternal administration of alpha-methyl-L-DOPA on sleep in utero were studied by polygraphic method in Guinea Pig faetus from the 53th day of gestation. Maternal injection of alpha-methyl-L-DOPA (100 and 200 mg/kg) produces a typical sedative effect on the faetus from the first hour after drug administration. But, effects appear attenuated in comparison to those of the new-born Guinea Pig: a paradoxical sleep-deprivation of only 30% is observed during the 12 hours period after drug injection. Causes of the attenuation in utero of these drug effects are discussed.

Animals↗
PubMedDate not supplied

The neuroscience of spatial navigation: focus on behavior yields advances.

The development of the water maze as a laboratory approach to the study of spatial navigation has led to a large amount of research on the brain mechanisms of this ecologically important behavior. The procedural simplicity of this task belies its underlying complexity, which can complicate the interpretation of data obtained with the standard water maze procedure. In this review, recent experiments that used novel training procedures and detailed analyses of behavior are evaluated, together with related experiments, to clarify the brain mechanisms involved in this behavior. Pharmacological, lesion, and unit recording experiments demonstrate the existence of forebrain circuits for spatial navigation that are considerably more varied and extensive than was previously proposed, and involve various extrahippocampal structures. The use of novel and specialized procedures, together with a continued detailed focus on the behavior of animals in the maze, appears to be the most promising approach to understanding the mechanisms of spatial navigation.

Animals↗