L'amphetamine (AMPH) et la phenylethylamine (PEA) ont ete testees in vitro sur les activites Mg ++ -et K+ -pNPP asiques du bulbe olfactif du rat. Au niveau de l'homogenat total, ces drogues ont induit un effet biphasique sur l'activite K+ -pNPPasique: le maximum de stimulation (20 % AMPH et 38,5 % PEA) a ete obtenu a 3x 10 -5 M; alors qu'une inhibition significatifVe (46% AMPH et 21,5 % PEA) n'a ete observee qu'a 10 -2 M. Nos resultats montrent que l'effet stimulateur disparait lorsque les preparations membranaires de l'homogenat total sont traitees par un detergent (le triton X 100). Au niveau d'une fraction microsomale, cette activite K +-pNPPasique n'a pas presente de reponse biphasique: une inhibition dose -dependante est obtenue a partir de 10 -5 M. D'autre part, ces deux drogues n'ont pas eu d'effet significatif sur l'activite Mg ++-pNPP asique des differentes preparations membranaires . L'analyse de ces donnees laisse supposer que de 10 -5 a 10-4 M, l'effet stimulateur sur la K + -pNPP ase n'est qu'apparent. En effet, ces drogues reduisent l'effet inhibiteur induit physiologiquement par l'environnement membranaire sur la molecule enzymatique (K + -pNPPase) et/ou deplacent un compose endogene " ouabain- like" de son site d'action.

L'action in vitro de la dopamine (DA) et de l'amphetamine (AMPH) a ete etudiee sur la (Na +, K+)-ATPase du bulbe olfactif et du rein du rat. La reponse de cette enzyme aux deux drogues depend enormement de l'organe d'origine de la preparation enzymatique surtout pour des doses comprises entre 10-5 et 1O-4M. Sur cette gamme de concentration, au niveau renal, ces deux agents ont exerce une faible inhibition non significative; au niveau bulbaire, ils ont induit, en revanche, une stimulation significative dont le maximum est de 102% (DA) et de 25% (AMPH). La K+ _pNPPase a presente le meme comportement que la (Na +, K+)-ATPase. Celui -ci depend, egalement, de l'organe d'origine de la preparation enzymatique. Cet effet stimulateur disparait lorsque la preparation enzymatique d'origine nerveuse est traitee par le triton X 100 (0,03%). Les resultats de ce travail montrent que la DA et l'AMPH (10-5 a 1O-4M) n'ont pas d'effet direct sur la (Na+, K+)-ATPase nerveuse. l'effet stimulateur apparent pourrait etre du a une interaction entre ces drogues et l'environnement membranaire de l'enzyme au nivau de la cellule nerveuse.

In order to examine the reliability of lateralised behaviours, BALB/c mice were tested in three different situations: the Collins paw preference test (PPT), the rotatory swimming test (RST), and the T maze test (TMT). The results showed a significant correlation between the scores of lateralisation in the PPT and the RST, but a lack of lateralisation in the TMT. Considering the tasks involved in these tests, these results appear to support the hypothesis of close links between lateralised behaviours, emotional processes, and neural pathways.

Putative alterations of the functional activity in the staggerer mutant mouse olfactory bulb neuronal network have been studied by recording odor induced evoked field potentials (EFP) in the mitral cells layer. In standard conditions, the main feature observed in mutants was a significant increase in latency preceding the functional response of the mitral cells to the odorant. In these animals, all parameters of the average EFP were widely modified when compared with those recorded in wild mice. Amplitudes and most of the duration of the EFP phases were significantly decreased. Functional alterations were discussed according to the structural disorganization previously described in staggerer mutant mouse olfactory bulb.

In the present study, we describe the structural and cytological changes observed in staggerer mutant olfactory bulbs, as compared to normal mice. On the basis of photonic and ultrastructural observations we tried to define the alterations induced by the mutation: i.e. a reduction of bulb size, a reduction in the volume of three out of the six architectonic layers (glomerular, external and internal plexiform), a reduction of glomeruli size, a loss of half the mitral cells and a slight decrease in juxtaglomerular interneuron number. In staggerer, an hypertrophy of glial ensheathing cell processes was especially evident at the level of each glomerulus, whereas the density of the astrocyte network was weaker in the granular layer and the nerve layer not apparently impaired. An immunofluorescent labelling study combined with confocal scanning microscopy was performed in order to identify the cellular type and the differentiation degree of the various elements. Antibodies anti-GFAP, a protein present in both ensheathing cells and astrocytes, and anti-OMP, the specific maturation protein of the nerve layer, were used for that purpose. Data confirmed the reality of the gliosis and the persistence of the sensory component in the mutant. All the structural alterations described in staggerer olfactory bulb were in close agreement with the functional troubles previously recorded. Our results are discussed in connection with the present knowledge on embryonal origin, fetal development and adult cellular renewal of the olfactory bulb.

Chemical destruction of the olfactory mucosa leads to a neuronal regeneration. A new organotypic culture model is perfected to improve the regenerating processes study. Explants of neuroepithelium attached to olfactory bulbs were removed from adult mice and cultured, 12 h after ZnSO4 intranasal application. After 3 days in culture, explants showed a necrosis in the olfactory epithelium and a thinning of the olfactory bulb nervous layer. From the fifth day of culture, and mostly the tenth, new cells showed positive immunoreactivity with the olfactory marker protein (OMP), meaning they were regenerating olfactory neurons. Simultaneously, OMP immunoreactivity increased in the nervous and glomerular layers of the olfactory bulb, indicating epithelio-bulbar reconnection. This organotypic culture model could allow further investigations on the regenerating process kinetic.

Though immunoelectrodes can allow direct detection of very low protein amounts (about 0.1 pmol) in vitro and in vivo, they are not yet widely used because they need quality improvement. Based on a few works devoted to the basic electrochemical phenomenon occurring when antibodies are linked onto a solid support and during antigen/antibody complex formation, we have coated two different supports with antibodies: the classical glassy carbon fiber or an epoxy plate covered with an amorphous semimetallic (nickel/phosphorus) thin film obtained by means of an electrochemical deposit. The antibody/antigen complex formation induces direct and/or indirect ionic movements and a current flow through the conductive support toward a very low-noise and high-sensitivity preamplifier stage in an I/V configuration. The proposed electrochemical treatment (hydrophilization), applied to both carbon and Ni/P electrodes, improves antibody binding and reliability of the response to antigens. The Ni/P probes present several advantages when compared to carbon fiber: better conductivity, possibility of surface quality control, and semimetallic nature, making them unbreakable. Several applications were proposed: somatostatin-14 detection with both carbon fiber and Ni/P plate electrodes, and histamine detection in simple and complex fluid media. Dose-response curves and analysis of the results lead us to conclude that the obtained currents are directly related to the quantity of antigen.

In the present work, we have shown electrochemically that in the rat olfactory bulb (OB), extracellular dopamine (DA) was highest in the glomerular layer (GL), whereas extracellular noradrenaline (NA) appeared to be more uniformly distributed across layers. The GL catecholamine (CA) responses to amphetamine (AMPH) and phenylethylamine (PEA) were also characterized electrochemically using an in vivo model. Results of this investigation show that at a lower dose (1 mg/kg), PEA had no effect on CA release. In contrast, at a higher dose (10 mg/kg), it produced similar increases in either extracellular DA (17.5 ± 7%) or extracellular NA (14 ± 3%), and DA exhibited dose-independent increases to AMPH (93 ± 8%: 1 mg/kg vs. 97 ± 6%: 10 mg/kg) whereas NA exhibited dose-dependent increases to AMPH (24.5 ± 6%: 1 mg/kg vs. 39 ± 7%: 10 mg/kg). These data indicate that (i) PEA may increase CA release but less efficiently than AMPH. (ii) AMPH is more efficient on the DAergic than on the NAergic system since AMPH-induced DA release exceeded 2–4 times the AMPH-induced NA release.

Immunoelectrodes have been developed which can be used to detect minute amounts of somatostatin. They were made with electrochemically treated glassy carbon fibres coated with anti-somatostatin antibodies. Calibration and various controls were carried out to ensure that the immunoelectrodes responded specifically to the presence of femtomolar somatostatin. Electrophysiological experiments were performed on anti-somatostatin immunoreactive neurones in the snails Helix aspersa and H. pomatia. Somatostatin-like material was released in response to sustained firing. The release was measured at the soma, which means that it occurred in the extrasynaptic area. The finding that the fluorescent dye FM 1–43 was incorporated into somatic vesicles confirmed that exocytosis actually occurred during sustained neuronal firing.

La voltamétrie différentielle sur impulsions normales (D.N.P.V.) associée à une fibre de carbone traitée électrochimiquement a été conçue pour la détermination des catécholamines. Une étude in vitro a permis de mettre au point un traitement électrochimique pour la détection des catécholamines qui a amplement amélioré les performances de l'électrode en termes de sélectivité, de sensibilité et de stabilité de la réponse. In vivo, l'électrode ainsi traitée a servi pour l'évaluation de très faibles concentrations (10.7 à 10.8 M) des catécholamines extracellulaires au niveau du bulbe olfactif du rat. Voltammetric detection of catecholamines in the rat olfactory bulb Differential normal pulse voltammetry (DNPV) associated to electrochemically treated carbon fiber electrode has been used for catecholamines determination. In vitro, study has permittèd to take out electrochemical treatment for catécholamines detection. This treatment has widely improved selectivity, sensibility and stability ofresponse. In vivo, treated electrode was used for determination of very low concentrations (10.7 to 10.8 M) of extracellular catecholamines in the rat olfactory bulb.

Olfactory learning experiments were performed using urine odor in a T maze on male and female mice normals or staggerer mutants. Anosmy was realized on these animals by mean of intranasal ZnSO4 10 % administration. Neuroepithelium necrosis was obtained in some days during which olfactory sensitivity was tested. Results have shown that, in spite of a large olfactory cells destruction, the animals remained able to localized the odor partly because the vomeronasal organ was not destroyed by ZnSO4. As soon as 48 hours, a sensitivity reappeared and increased until day 15. We have not noted some behavioral differences in the normal mice comparing, male and female; however in mutant mice we have observed that regeneration is faster than in normal mice and that female behaviour recovery was done earlier than in male. These results were discussed in regard to the recognizing and adhesive molecules evolution. An hypothesis on a sexual hormones control on the olfactory cells and axons regeneration which can be influenced by the mutation was proposed.

Electrophysiological observations have been made on normal C57-BL/6J and staggerer mutant mice. Morphological observations have given evidence it existed various neurones modifications which affected the olfactory bulb in the mutant mice. Olfactory bulb electrocorticograms (ECoG) of mutant have shown rare bursts of potentials of longer time duration than in normal mice. These bursts were less affected by odor stimulations (ammonia and urine of opposite sexes) than in the normal mice and never varied under urine odor influence in female mutant. Evoked potential induced by the odors had long latency and long duration (up to 50 ms vs 30 ms). In a large amount of them, the late phases and the late oscillatory potentials, which generally followed the evoked potential, were absent. All these results improved the idea that staggerer mutation, which mainly affected the N-CAM gene, not only induced cerebellar diseases, but also functionally affects the olfactory bulb.

Electrophysiological observations have been made on normal C57-BL/6J and staggerer mutant mice, Morphological observations have given evidence it existed vaious neurones modifications which affected the olfactory bulb in the mutant mice, Olfactory bulb electrocorticograms (ECoG) of mutant have shown rave bursts of potentials of longer time duration than in normal mice. These bursts were less affected by odor stimulations (ammonia and urine of opposite sexes) than in the normal mice and never varied under urine odor influence in female mutant Evoked potential induced by the odors had long latency and long duration (up to 50 ms vs 30 ms). In a large amount of them, the late phases and the late oscillatory potentials which generally followed the evoked potential, were absent. All these results improved the idea that staggerer mutation, which mainly affected the N-CAM gene, not only induced cerebellar deseases, but also fonctionally affects the olfactory bulb.

A new, fast and low-cost method using a carbon-fibre microelectrode is proposed. The microelectrode is constructed by glueing one or more carbon fibres (5 mm in diameter) with a silver resin on a silver wire or stainless steel tube. The characteristics of that microelectrode have been measured and compared with those of commercially available glass carbon-fibre microelectrodes. According to our measures, the impedance, capacity and current noise were lowered which permits these electrodes to be used in voltammetry and in detection of very low currents generated during formation of antigen-antibody complex.

Olfactory transduction is mediated by neuroepithelial cells localized on turbinal crests in naris. Odorant molecules are uptaked by the mucosa which flows on epithelial surface and some of the molecules enter in contact with olfactory cells tentacles. Odorant molecules interact with molecular receptors bound to cell membrane and induced successive reactions leading to ion channels opening and then to receptor potential appearance. The receptor cells degenerate when molecular receptors are saturated and, further regenerate, according a genetic program and olfactory learning action potentials which appear at the basal pole of the receptor cell are propagated along the small olfactory nerves to the olfactory bulb glomerulus. Several hundred axons enter in one glomerulus among others and make synaptic contacts with one dendritic tree of a mitral cell. The selection of the numerous signals which converge in the glomerulus, the codage in intensity, duration and contrast are made at this level. One odorant molecule activates some glomeruli (rarely one); a complex odor activates a great number of glomeruli according a complex spatial distribution. Following odor stimulation, the electrical signals are analysed in the olfactory bulb which delivers to the olfactory cortex various informations about the odor components that are to be selected and compared to anterior olfactory learning. Animal experimentation and clinical data show that memory storage is made using short, medium and long term memorization. This memory is integrated in the limbic system at the interface of neural structures which regulate the main behaviors and physiological functions. This explains the modulatory role of smell in some behaviors but complicate our understanding of access to olfactory memory.

Olfactory transduction is mediated by neuroepithelial cells localized on turbinal crests in naris. Odorant molecules are uptaked by the mucosa which flows on epithelial surface and some of the molecules enter in contact with olfactory cells tentacles. Odorant molecules interact with molecular receptors bound to cell membrane and induced successive reactions leading to ion channels opening and then to receptor potential appearance. The receptor cells degenerate when molecular receptors are saturated and, further regenerate, according a genetic program and olfactory learning action potentials which appear at the basal pole of the receptor cell are propagated along the small olfactory nerves to the olfactory bulb glomerulus. Several hundred axons enter in one glomerulus among others and make synaptic contacts with one dendritic tree of a mitral cell. The selection of the numerous signals which converge in the glomerulus, the codage in intensity, duration and contrast are made at this level. One odorant molecule activates some glomeruli (rarely one); a complex odor activates a great number of glomeruli according a complex spatial distribution. Following odor stimulation, the electrical signals are analysed in the olfactory bulb which delivers to the olfactory cortex various informations about the odor componants that are to be selected and compared to anterior olfactory learning. Animal experimentation and clinical datas show that memory storage is made using short, medium and long term memorization. This memory is integrated in the limbic system at the interface of neural structures which regulate the main behaviors and physiological functions. This explains the modulatory role of smell in some behaviors but complicate our understanding of access to olfactory memory.