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PubMed1994

[Definitive diagnosis of Alzheimer's disease using olfactory mucosal biopsy].

Characteristic changes appearing in the biopsied olfactory mucosa of Alzheimer's disease (AD) patients were investigated using immunohistochemical staining. Specimens were obtained from 6 patients who were clinically diagnosed with AD, 2 patients with cerebrovascular dementia and 5 age-matched patients with olfactory disturbance without dementia. In most AD cases, polyclonal tau protein immunoreactivity was seen in the dendrites, perikarya of the olfactory receptor cells in the olfactory epithelium and the olfactory nerve bundles in the lamina propria. In a few cases, tau protein immunoreactivity was found in the extracellular mass in the epithelium. Ubiquitin immunoreactivity was seen is the dendrites of olfactory receptor cells. On the other hand, in control cases, only dendrites and olfactory nerve bundles reacted to anti-polyclonal tau protein antiserum in a few cases. These results indicate that the neurofibrillary tangle-like tau protein immunoreactivity in the perikarya senile plaque-like extracellular mass and ubiquitin immunoreactivity in the olfactory epithelium were characteristic changes in AD, and olfactory mucosal biopsy is a useful method for the definitive diagnosis of AD.

Aged↗
PubMed1994

Expression of the tight junction protein ZO-1 in the olfactory system: presence of ZO-1 on olfactory sensory neurons and glial cells.

The olfactory system is a unique part of the central nervous system since it retains neuronal turnover and regenerative capacities in adulthood. Thus it provides an ideal model to study plasticity of membrane moities involved in cell-cell interactions. One structure particularly involved in cell-cell interaction is the tight junction, which establishes polarization of epithelial cells and creates diffusion barriers to paracellular passages. ZO-1 is a phosphoprotein peripherally associated with tight junctions. We have studied expression of ZO-1 protein in the developing and adult olfactory system of the mouse in order to get information about the localization and developmental expression of this tight junction component. ZO-1 expression has also been determined in cell cultures of olfactory bulbs. ZO-1 was present in the olfactory placode prior to formation of tight junctions. ZO-1 was localized in the developing and mature olfactory epithelium at heterotypic contacts between supporting cells and olfactory neurons as well as at homotypic contacts between both these cell types. Confocal microscopy showed quantitative differences in the ZO-1 expression among different olfactory dendrites. In the olfactory nerves ZO-1 immunolabeling was detectable between olfactory ensheathing cells. From the seventh postnatal day ZO-1 immunolabeling was detected at the mitral cell layer of the bulb on cells tentatively identified as oligodendrocytes. Myelinated tracts of the bulb were ZO-1 negative. Cell cultures of olfactory bulbs showed ZO-1 immunoreaction, mostly localized on glial fibrillary acidic protein (GFAP)-positive cells. Our results provide further evidence that ZO-1 serves functions unrelated to the tight junction complex and indicate molecular heterogeneity of these cell-cell contacts.

Animals↗
PubMed1996

Peripherally obtained electrophysiological responses to olfactory stimulation in man: electro-olfactograms exhibit a smaller degree of desensitization compared with subjective intensity estimates.

After chemical stimulation of the human olfactory epithelium it is possible to record a negative response (electro-olfactogram, EOG) which is interpreted as the summated receptor potentials of the olfactory nerve. The aim of the present investigation was to test the EOG's changes in relation to pairs of stimuli. Stimulation was performed with vanillin (0.8 ppm) regarded to exclusively excite fibers of the olfactory nerve. Ten healthy volunteers participated in the experiments. Pairs of stimuli were applied at different interstimulus intervals ISIs (2-8 s). EOG could be recorded in 6 out of 10 subjects. After olfactory stimulation the responses' peak amplitude was found to range from 0.15 to 1.8 mV. When pairs of olfactory stimuli were applied responses obtained at an ISI of 8 s were clearly separated whereas at an ISI of 2 s responses were superimposed on each other. As with an ISI of 8 s, the amplitude produced by the second stimulus was nearly as great as the first responses' amplitude (decrease by approximately 20%). In contrast, intensity estimates obtained in an additional experiment (n = 10) decreased by 40-60%. Based on the present data peripheral encoding in the olfactory system appears to be less subject to desensitization compared to the decrease of intensity estimates.

Adult↗
PubMed1995

The earliest events in vesicular stomatitis virus infection of the murine olfactory neuroepithelium and entry of the central nervous system.

After intranasal instillation of mice with vesicular stomatitis virus (VSV), olfactory receptor neurons are infected. By 12 to 24 hr postinfection, VSV antigens are observed in adjoining supporting and basal cells and in other structures of the olfactory epithelium and lamina propria. Peripheral deafferentation of the olfactory epithelium with Triton X-100 or bilateral surgical bulbectomy does not prevent spread of VSV to the central nervous system (CNS); the route of spread differs considerably from the route taken when the olfactory nerve is intact. In contrast to rabies virus and HSV-1, VSV does not use the trigeminal nerve for entry into the brain, as the trigeminal ganglion remains virus-free following intranasal infection. These results indicate that VSV has a strong tropism for olfactory receptor cells, using them for entry into the CNS. Both retrograde and anterograde transneuronal and nonneuronal (ependymal cells and cerebrospinal fluid) pathways are utilized by VSV within the CNS.

Animals↗
PubMed1985

Identification of an olfactory receptor neuron subclass: cellular and molecular analysis during development.

Development of olfactory receptor neuron populations was studied using the previously described monoclonal antibody (Mab) 2B8 which binds to cell surface glycoproteins of presumptive olfactory receptor neurons. In order to definitively demonstrate that the cells recognized were olfactory receptor neurons and to better characterize these cells during development, a well-established receptor cell marker, olfactory marker protein (OMP), was studied at the same time as the 2B8 antigens in double-label immunofluorescence analyses of olfactory structures in rats from Day 13 of gestation (E13) to the early postnatal period. Olfactory epithelium cryostat sections of E13 rats showed binding of the 2B8 Mab to bipolar cells in caudal regions of the nasal cavity. The 2B8 Mab also recognized a large number of cells in the vomeronasal organ (VNO) at this stage. No specific binding of anti-OMP was seen until E15. At this time approximately half of the 2B8 reactive cells also expressed OMP. By birth, greater than 90% of the 2B8 reactive cells expressed OMP. The percentage of total fluorescent labeled cells which are double labeled remained relatively constant at 23-33% as the total number of cells increased between E15 and 2 days postnatal. 2B8 immunoreactivity can be found in the olfactory nerve layer of the olfactory bulb and the presumptive accessory olfactory bulb at E15. In double-label experiments the 2B8 Mab did not bind to all anti-OMP-labeled glomeruli of postnatal to adult rats. In summary, the 2B8 Mab recognizes cells early during development and appears to recognize a subclass of olfactory receptor cells and their axon terminals. Developmental changes in the electrophoretic profile of the olfactory 2B8 antigens were also studied. In the olfactory epithelium a single band at Mr of 200,000 was seen at E19. After birth three bands at 220,000, 180,000 and 110,000 were observed but in adults only two bands of Mr 215,000 and 163,000 were detected. During olfactory bulb development the Mr of the two major 2B8 reactive bands did not change but remained the same as the two major bands seen in the adult olfactory epithelium. The olfactory bulb band at Mr of 215,000 showed a 3 to 4-fold increase and the band at 163,000 showed a 10-fold increase in specific activity from birth to adulthood.

Animals↗
PubMed1988

Purification and characterization of an antigen that is spatially segregated in the primary olfactory projection.

The monoclonal antibody RB-8 heavily labels axons from the ventrolateral olfactory epithelium and their terminals in the glomeruli of the ventrolateral olfactory bulb, but leaves the axons from the dorsomedial epithelium unstained or lightly stained. RB-8 reacts with a 125 kDa membrane protein in both olfactory nerve and other parts of the CNS (Schwob and Gottlieb, 1986). Here we report further characterization of the molecular nature and cellular localization of the RB-8 antigen. The RB-8 antigen is exposed on the surface of olfactory axons. Individual axons and axon bundles stain when explant cultures of the fetal olfactory epithelium are incubated with monoclonal RB-8 antibody while living. The cell membrane is demonstrably intact, and access to the cell interior is blocked under these conditions, since the living axons do not stain if exposed to an antibody against a known intracellular constituent. The RB-8 antigen is an integral membrane protein. When assayed by direct radioimmunoassay (RIA), the antigen remains associated with brain membranes after extraction at pH 11, which solubilizes numerous other protein bands. The 125 kDa RB-8 antigen was purified to homogeneity from whole rat brains by extracting membranes with sodium deoxycholate, immunoaffinity chromatography over an RB-8 antibody column, and preparative one-dimensional SDS-PAGE. The NH2-terminal amino acid sequence is apparently unique among neuron-specific proteins that have been sequenced and has only an insignificant degree of homology with other known proteins. Two polyclonal rabbit antisera raised against the purified antigen recognize only the 125 kDa protein on immunoblots. Immunohistochemical staining of the primary olfactory projection with the antisera exactly matches that seen with monoclonal RB-8 antibody. Thus, the RB-8 antigens in brain and in olfactory nerve are highly homologous, if not identical. Furthermore, the results with the antisera suggest that the expression of the entire 125 kDa protein is regulated differentially between ventral and dorsal zones of the olfactory epithelium. The additional characterization of the RB-8 antigen reported here places constraints on the potential functions of this protein. The availability of polyclonal antisera may prove useful in assessing the role of this spatially segregated antigen in the primary olfactory projection.

Amino Acid Sequence↗
PubMed1989

Comparative pathogenesis of three strains of pseudorabies virus in pigs.

Three strains of pseudorabies virus were intranasally inoculated into 10-week-old pigs and the pathogenesis of the infection was compared. Virulent NIA-3 virus caused widespread necrotic lesions in nasal mucosa, rapidly invading the stroma and infecting axons of olfactory nerves within 24 h of inoculation. Intermediate virulent virus 2.4N3A, a mutant strain derived from NIA-3, caused less necrosis of the mucosa and did not reach axons of olfactory nerves until 72 h after inoculation. Bartha virus strain K, a non-virulent virus strain, caused a mild infection in the superficial layers of nasal epithelium. Viral antigens were not detected in stromal fibroblasts or nerve cells. The inflammatory response of the pigs varied with the virus strains used: after infection with NIA-3 virus mainly neutrophils infiltrated the nasal mucosa, whereas after infection with 2.4N3A virus and Bartha virus, mainly macrophages and lymphocytes infiltrated the nasal mucosa.

Animals↗
PubMed1993

The origin of rapid changes in birefringence, light scattering and dye absorbance associated with excitation of nerve fibers.

By comparing the time-courses of rapid optical changes in the garfish olfactory nerve evoked by electric stimulation with those of mechanical changes observed at the site of optical recording, the origin of optical changes in the nerve has been investigated. Based on the finding that the time-course of the birefringence change accurately coincides with that of swelling of the nerve, optical changes are interpreted as being brought about by invasion of water into the superficial layer of the nerve fibers. A close relationship has also been demonstrated between nerve swelling and changes in light scattering and in dye absorbance.

Animals↗
PubMed1993

Comparative distribution of mammalian GnRH (gonadotrophin-releasing hormone) and chicken GnRH-II in the brain of the immature Siberian sturgeon (Acipenser baeri).

The brain of the sturgeon has recently been shown to contain at least two forms of GnRH (gonadotropin-releasing hormone), mammalian GnRH (mGnRH) and chicken GnRH-II (cGnRH-II). In this study, we compared the distribution of immunoreactive (ir) mGnRH and cGnRH-II in the brain of immature Siberian sturgeons (Acipenser baeri). The overall distribution of mGnRH was very similar to the distribution of sGnRH in teleosts such as salmonids or cyprinids. mGnRH-ir perikarya were observed in the olfactory nerves and bulbs the telencephalon, the preoptic region, and the mediobasal hypothalamus. All these cell bodies are located along a continuum of ir-fibers that could be traced from the olfactory nerve to the hypothalamopituitary interface. No ir-fibers were observed in the anterior lobe of the pituitary, but a few were seen to enter the neurointermediate lobe. mGnRH-ir fibers were detected in many parts of the brain, particularly in the forebrain. mGnRH-ir cerebrospinal fluid-contacting cells were observed in the telencephalon, the preoptic region, and the mediobasal hypothalamus. In contrast, cGnRH-II was present mainly in the posterior brain, although a few ir axons were seen in the above-mentioned territories. In particular, cGnRH-II-ir cells bodies, negative for mGnRH, were consistently observed in the nucleus of the medial longitudinal fasciculus of the midbrain tegmentum. The cGnRH-II innervation in the optic tectum, cerebellum, vagal lobe, and medulla oblongata was more abundant than the mGnRH innervation in the same areas. This study provides evidence that the organization of the GnRH systems in a primitive bony fish is highly similar to that reported in teleosts and further documents the differential distribution of two forms of GnRH in the brain of vertebrates.

Amino Acid Sequence↗
PubMed1993

Cultures of ensheathing cells from neonatal rat olfactory bulbs.

We have derived highly enriched populations of ensheathing cells (ECs) from the olfactory nerve layer of neonatal rat olfactory bulbs. Contaminating cells, such as fibroblasts, were eliminated from EC cultures by cytosine arabinoside and immunoadsorption with antiserum to Thy-1.1. At the same time, ECs were stimulated to divide by the addition of bovine pituitary extract into the culture media. Confluent cultures containing 96-99% ECs, were comprised of either spindly bipolar cells or cells bearing multiple processes oriented on opposite poles. The ECs immunostained positively for GFAP, S-100 protein, N-CAMs and Neu 5, and were negative for the presence of neurofilaments. Scanning and transmission electron microscopy showed that the ultrastructure of the ECs resembled that in vivo. The nucleus was irregular in shape, intermediate filaments were usually scattered throughout the cytoplasm instead of being grouped into bundles, and rough endoplasmic reticulum existed as isolated expanded profiles.

Animals↗
PubMed1995

Differential expression of N-CAM, vimentin and MAP1B during initial pathfinding of olfactory receptor neurons in the mouse embryo.

Olfactory receptor neurons extend their primary axons from the nasal epithelium to the olfactory bulb primordium via the frontonasal mesenchyme. In the present study, expression of neuronal markers (vimentin and MAP1B) and N-CAM was immunohistochemically investigated in the development of the olfactory system in mouse embryos. Expression of vimentin and MAP1B was first observed at early day 10 of gestation (D10) in the posterosuperior region of the medial nasal epithelium, while N-CAM was initially detected in the mesenchyme adjacent to the vimentin- and MAP1B-positive nasal epithelium. As development proceeded, the localization of neuronal marker-positive cells was mostly included in the N-CAM positive region. In addition, we adopted in situ labelling with vital dye (DiI) to directly determine the localization of the olfactory nerve and N-CAM on the same sections. We demonstrated that most extending axons were located in the N-CAM positive region. These results suggest that the expression of N-CAM plays a crucial role in the initial pathfinding of the olfactory nerve.

Animals↗
PubMed1981

Chemical and morphological studies on garfish peripheral nerves.

Gangliosides were extracted, separated by thin layer chromatography, and quantitated in three cranial nerves of the garfish (Lepisosteus osseus): the completely unmyelinated olfactory nerve (OLF), and two nerves composed of both myelinated and unmyelinated fibers, viz., the main trunk of the maxillary nerve (MAX) and a branch of the maxillary nerve (BR-MAX). Morphological studies on each of these nerves were done to verify that the OLF had been excised free of any contamination from the accompanying myelinated BR-MAX, to aid in the interpretation of the biochemical findings, and to clarify the nature of the OLF supporting cell. The chief chemical findings were (1) documentation of the presence of gangliosides in nerves previously thought not to contain them, (2) demonstration that gangliosides can be associated with unmyelinated nerves, (3) demonstration of a greater proportion of one simple ganglioside (G-6) in the OLF but greater proportions of two complex gangliosides (G-2 and G-0) in the MAX and BR-MAX, and (4) that either GM4 or a variant of the GM3 is present in OLF. The morphological findings with respect to the difficulty of ascribing only peripheral nervous system characteristics to the OLF supporting cell are discussed in relation to the ganglioside band chromatographing slightly ahead of GM4 in the OLF.

Animals↗
PubMed1996

Recovery of olfactory function in thirteen-day-old rats after olfactory bulb transplantation but not after olfactory bulb ablation.

Previous studies have shown recovery of olfactory ability along with reconnectivity of olfactory nerve (ON) following both olfactory bulb (OB) lesions and OB transplants (TX) when performed in newborn rats. The purpose of the present study is to correlate functional recovery with patterns of anatomical reconnectivity in older, postnatal (PN) 13-day-old rats (a possible critical period for plasticity in the system). Reinnervation of olfactory areas was seen in all OB TX animals regardless of the extent of functional recovery. Eight of nineteen animals with OB TXs demonstrated some degree of behavioral recovery. No reinnervation or behavioral recovery of OB lesion animals was observed. At this age, behavioral recovery is dependent upon reconnectivity within the system and transplantation may be required to facilitate this process.

Age Factors↗
PubMed1996

An in vitro preparation of frog nose and brain for the study of odour-evoked oscillatory activity.

An in vitro preparation is described that consists of frog brain rostral to the brainstem connected to the nasal epithelium by the olfactory nerves. Field potential and intracellular recordings from various brain structures can be obtained while stimulating the nasal epithelium with air-borne odours for at least 12 h after removal of the brain. Power spectra, amplitude and duration of odour-evoked and spontaneous field potentials in vitro are similar to those obtained from paralyzed, spinal cord pithed frogs. A brief puff of odorant applied to the olfactory epithelium produces a 1-2 s bout of 7-13 Hz oscillations in the field potential recorded from the ipsilateral bulb and various ventral, lateral and medial telencephalic structures. Odour evoked bulbar oscillations are maintained after removal of the telencephalon. Electrical stimulation of the olfactory nerves will not elicit oscillations like those evoked by odour stimulation. High-pressure puffs of non-odorised, moist air, elicit olfactory bulb oscillations similar to those evoked by lower pressure puffs of odorised air. Intracellular recordings from most mitral cells reveal oscillations in membrane potential that are phase-locked to the field potential. The extent to which these phase-locked oscillations produce action potentials varies, apparently as a function of the strength and duration of a long-lasting inhibitory potential that is superimposed upon the 7-13 Hz oscillations. This preparation is well-suited for the study of the cellular basis of oscillatory activity in vertebrate brain, and the function of sensory-evoked oscillatory responses in processing of sensory information.

Animals↗
PubMed1986

[Morphologic features of the chemosensory, visual and vestibular pathways of Helix lucorum].

The structure of chemosensory, visual and statocyst pathways of the snail Helix lucorum has been studied by means of five histological methods. The chemoreceptors of the optic tentacle bulb, small and large neurons of tentacle ganglion and bipolar cells of olfactory nerve send their processes to the CNS of the mollusc. In the CNS these processes divide into many clusters of branches. All protocerebral cells and the cluster of neurons of the commissural part of metacerebrum send their processes within the olfactory nerve towards the periphery. The axons of eye cells terminate in the enlargement of optic nerve near the eye; so do the CNS cells and neurons of the optic nerve. In the neuropile of pleural part of metacerebrum a region of ramification of cell axons of the visual pathway is found. Hair cells of statocyst send their axons within the static nerve to the cerebral ganglion (CG). Small cells of metacerebrum send their axons towards the statocyst. In the neuropile of ipsilateral CG some processes of statocyst pathway cells divide into many thin branches; others--cross to the contralateral cerebral neuropile via the commissure joining two CG. In the neuropile of contralateral ganglion these processes give off a spray of many branches just as in the ipsilateral ganglion. The axons of the visual pathway cells and statocyst pathway cells ramify in the same region.

Animals↗
PubMed1999

Apolipoprotein E immunoreactivity in human and mouse olfactory bulb.

We evaluated the distribution of apolipoprotein E (apoE) immunoreactivity in mouse and human olfactory bulbs. ApoE immunoreactivity was present in the olfactory nerve and around the glomeruli. Immunoreactivity was seen in somata that appeared to be glial. No neuronal staining was seen. The apoE immunoreactivity was also present in the mouse olfactory bulb subependymal layer. The specificity of immunoreactivity was confirmed with apoE-deficient mice (apoE gene knock-out mice, apoE KO) which did not display any immunoreactivity. The presence of apoE around glomeruli and nerve suggest that apoE is associated with the continuous degeneration and regeneration processes that occur in the olfactory nerve. Experimental manipulation of the olfactory nerve may be a useful technique to determine the functions of apoE in a well-defined neural system.

Adult↗
PubMed2005

Glial fibrillary acidic protein and vimentin expression in the frog olfactory system during metamorphosis.

In the present study, we investigated glial cell organization in the olfactory system of adult and tadpole Xenopus laevis using glial fibrillary acidic protein and vimentin antibodies. Our results showed for the first time that glial fibrillary acidic protein was strongly expressed at the level of the olfactory nerve from tadpole to adult and was likely to be expressed by ensheathing glia. In the olfactory bulb, the nerve layer was stained, and no staining was observed in glomeruli. By contrast, vimentin decorated radial glia in the bulb but faintly stained the olfactory nerve. Interestingly, glial fibrillary acidic protein and vimentin presented complementary staining patterns, with glial fibrillary acidic protein being expressed in the peripheral olfactory system and vimentin being expressed in the central part of the olfactory system.

Animals↗
PubMed2005

Functional differences and interactions between phenotypic subpopulations of olfactory ensheathing cells in promoting CNS axonal regeneration.

We demonstrate that there are significantly more p75 neurotrophin receptor- (NTR)-expressing cells in olfactory ensheathing cell (OEC) primary cultures from olfactory nerve rootlets (ONR), but a greater proportion of O4 antigen- and PSA-NCAM-expressing cells in parallel cultures from the nerve fibre layer of the olfactory bulb (OB). By co-culturing adult rat retinal ganglion cells (RGCs) with OECs derived from either ONR or OB tissue, we compared their neurite regrowth-promoting properties. In phenotypically unsorted cultures, there is greater RGC neurite regrowth on ONR OECs compared to OB OECs. Following immunoselection of ONR cells for p75 NTR, there is increased RGC neurite regrowth on the enriched population compared to the unselected cell population or the p75 NTR depleted population. When p75 NTR-enriched cells from ONR and OB cultures are compared directly, tissue source-related differences are no longer observed. Our previous work implicated a pertussis toxin (PTx)-sensitive G protein-linked signalling pathway in OEC regulation of neurite regrowth. We show that this pathway probably operates in interactions between the p75 NTR-positive and -negative cells; separated populations lose the PTx-mediated enhancement of neurite regrowth-promoting properties seen in mixed cultures. Optimum neurite regrowth is observed when both phenotypes are present in cultures from either ONR or OB, and where glial G-protein signalling is disabled by PTx before co-culture with neurons. We thus propose that p75 NTR-positive cells, whilst being the more effective neurite regrowth promoting subpopulation in isolation, cooperate with negative cells to provide optimum support for axonal regrowth.

Animals↗