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At least 163 records · Page 9Linked to original sources
PubMed1989

[Infiltration of India ink from subarachnoid space to nasal mucosa along olfactory nerves in rabbits].

The mode of the transportation of India ink to the nasal cavity was studied when it was given to the subarachnoid space chiefly through facial nerve sheath and partly by cisterna magna injection. From subarachnoid space India ink infiltrated through perineurium, epineurium and perineural space of the fila olfactoria and of olfactory nerve fibers to lamina propria of the olfactory mucosa and spread also to the respiratory mucosa. It was further taken into lymphatic vessels and accumulated in bilateral cervical lymph nodes. In normal rabbits, India ink didn't penetrate the basement membrane into the epithelial layer at all, but in rabbits with chronic rhinitis showing edema, degeneration and destruction of mucosa, India ink was found to pass easily through the basement membrane into the epithelial layer and further to leak into the nasal cavity in all cases. It was a new finding that in cases with rhinitis large particles like India ink could infiltrate from the subarachnoid space to the nasal cavity passing through the nasal mucosa, and was considered to be a possible cause of idiopathic cerebrospinal fluid rhinorrhea.

Animals↗
PubMed2003

Differential effects of lesions of the vomeronasal and olfactory nerves on garter snake (Thamnophis sirtalis) responses to airborne chemical stimuli.

The roles of the main (MOS) and accessory (AOS) olfactory systems of garter snakes in response to airborne chemicals were investigated. Preoperatively, all snakes responded to airborne odors with increased tongue-flick rate and duration. Postoperatively, sham-operated snakes responded to airborne odors with increased tongue-flick rates, but snakes with main olfactory nerve cuts failed to respond to the odors, and snakes with vomeronasal nerve cuts responded to nonprey odors only. Preoperatively, exposure to earthworm odor produced more frequent and shorter duration tongue-flicks during locomotion compared with exposure to water. Postoperatively, only sham-lesioned snakes exhibited differential responding to earthworm odors. This study demonstrates that the MOS is critical for the initiation of tongue-flick behavior in response to airborne odors and that discrimination of odors with biological significance requires a functional AOS.

Animals↗
PubMed2000

Physical structure of the excitable membrane of unmyelinated axons: X-ray scattering study and electrophysiological properties of pike olfactory nerve.

The aim of this work was to elicit correlations between physical structure and physiological functions in excitable membranes. Freshly dissected pike olfactory nerves were studied by synchrotron radiation X-ray scattering experiments and their physiological properties were tested by electrophysiological techniques. The scattering spectra contained a sharply oriented equatorial component (i.e. normal to the nerve axis), and an isotropic background. After background subtraction, the equatorial component displayed a weak and fairly sharp spectrum of oriented microtubules, and a strong and diffuse band of almost the same shape and position as the band computed for an isolated myelin membrane. We ascribed this spectrum to the axonal membranes. Under the action of temperature and of two local anesthetics, the spectrum underwent a contraction (or expansion) in the s-direction, equivalent to the structure undergoing an expansion (or contraction) in the direction perpendicular to the plane of the membrane. The main observations were: (i) with increasing temperature, membrane thickness decreased with a thermal expansion coefficient equal to -0.97(+/-0.19) 10(-3) degrees C(-1). The polarity and amplitude of this coefficient are typical of lipid-containing systems with the hydrocarbon chains in a disordered conformation. The amplitude and propagation velocity of the compound action potentials were drastically and reversibly reduced by lowering the temperature from 20 degrees C to 5 degrees C. (ii) Exposing the nerve to two local anesthetics (tetracaine and dibucaine) had the effect of decreasing membrane thickness. Action potentials were fully inhibited by these anesthetics. (iii) Upon depolarization, induced by replacing NaCl with KCl in the outer medium, approximately 25 % of the membranes were found to associate by apposing their outer faces. Electrophysiological activity was reversibly impaired by the KCl treatment. (iv) No detectable structural effect was observed upon exposing the nerves to tetrodotoxin or veratridine. Electrophysiological activity was fully impaired by tetrodotoxin and partially impaired by veratridine. The main conclusions of this work are that axonal membranes yield highly informative X-ray scattering spectra, and that these spectra are sensitive to the functional state of the nerve. These results pave the way to further studies of more direct physiological significance.

Anesthetics, Local↗
PubMed1985

[Electric stimulation of the human olfactory nerve--an approach to short-term memory?].

Electrical stimulation of the human olfactory mucosa was performed by means of an electrode, which was attached to a rhinoscope. Stimulations of the nasal mucosa did not evoke the sensation of smell, but suppressed smell sensations of presented odorants. When electrical stimulation followed the exposure to an odorant within a certain interval, the stimulus recalled the faded sensation of the preceding odorant. Electrical stimulation without prior natural stimulation produced unpleasant sensations in three patients with a history of temporal lobe seizures and olfactory auras, but not in patients with primary generalized or focal epilepsy.

Electric Stimulation↗
PubMed2004

X-ray scattering study of pike olfactory nerve: intensity of the axonal membrane, solution of the phase problem and electron density profile.

Synchrotron radiation X-ray scattering experiments were performed on unmyelinated pike olfactory nerves. The difference between the meridional and the equatorial traces of the 2-D spectra yielded the 1-D equatorial intensity of the macromolecular components oriented with respect to the nerve: axonal membranes, microtubules and other cytoskeletal filaments. These 1-D spectra display a diffuse band typical of bilayer membranes and, at small s, a few sharper bands reminiscent of microtubules. All the spectra merge at large s. The intensity of the axonal membrane was determined via a noise analysis of the nerve-dependent spectra, involving also the notion that the thickness of the membrane is finite. The shape of the intensity function indicated that the electron density profile is not centrosymmetric. The knowledge of intensity and thickness paved the way to the electron density profile via an ab initio solution of the phase problem. An iterative procedure was adopted: (i) choose the lattice D of a 1-D pseudo crystal, interpolate the intensity at the points sh = h/D, adopt an arbitrary set of initial phases and compute the profile; (ii) determine the phases corresponding to this profile truncated by the thickness D/2; (iii) repeat the operation with the updated phases until a stable result is obtained. This iterative procedure was carried out for different D-values, starting in each case from randomly generated phases: stable results were obtained in less than 10,000 iterations. Most importantly, for D in the vicinity of 200 A, the overwhelming majority of the profiles were congruent with each other. These profiles were strongly asymmetric and otherwise typical of biological membranes.

Actin Cytoskeleton↗
PubMed1979

The initial heat production in garfish olfactory nerve fibres.

A study has been made of the temperature changes associated with the passage of a single impulse in the non-myelinated fibres of the garfish olfactory nerve: and the time course of these temperature changes has been compared with the time course of the electrical events during the action potential. As in other non-myelinated nerves studied the observed temperature changes result from a biphasic initial heat production consisting of a transient evolution of heat (the positive heat) followed by a rapid heat reabsorption (referred to as the negative heat). There is no evidence of any additional phases of initial heat production. At 0 degrees C the measured positive initial heat is 224 mucal/g impulse (937 muJ/g impulse); and the corresponding negative initial heat is 230 mucal/g impulse (962 muJ/g impulse). The residual initial heat is very small, being about -6 mucal/g impulse (-25 muJ/g impulse). In the range 0-10 degrees C there is no significant effect of temperature on the magnitude of either the positive or the negative phases of heat production. The experimental thermal records were analysed to determine the true time course of the temperature changes in the nerve undistorted by the recording system. The time course of the temperature changes does not fit with that of the transmembrane voltage change as represented by the monophasic compound action potential recorded externally from the same point on the nerve. A better fit is obtained if the temperature changes are compared with the square of the voltage change in accordance with the view that the heat derives almost wholly from free energy changes and entropy changes in the membrane capacity. The best fit is obtained if it is assumed that the membrane potential does not discharge to zero during the action potential but that at the peak of the action potential the charge (and hence the p.d.) across the membrane capacity retains about 24% of its resting value.

Action Potentials↗
PubMed1975

The heat production associated with the passage of a single impulse in pike olfactory nerve fibres.

1. A study has been made of the temperature changes associated with the passage of a single impulse in the non-myelinated fibres of the pike olfactory nerve. 2. The initial heat occurs in two phases: a burst of positive heat, followed by an evolution of negative heat. The positive and negative heats, and the net initial heat, are temperature-dependent. 3. At 0 degrees C the measured positive initial heat is 44.2 mucal/g.impulse; and the corresponding negative initial heat is 48.9 mucal/g.impulse. There is thus a net initial heat that is negative, of about 4.7 mucal/g.impulse. 4. The positive heat has a positive temperature coefficient, being increased by a factor of 1.86 when the temperature is rasied from 0 degrees C to 10 degrees C. 5. The negative initial heat also increases when the temperature is raised, but less than the positive initial heat. As a result, the net initial heat tends to become positive at higher temperatures. 6. Because of temporal dispersion of the action potential over the face of the thermopile, the observed temperature changes are smaller than those that occur at a single point in the nerve close to the stimulating cathode. The value of the positive heat at 0 degrees C corrected for temporal dispersion is estimated to be about 62 mucal/g.impulse: the corresponding value for the negative heat is about 67 mucal/g.impulse. 7. All records were analysed in terms of only two phases of initial heat (one positive, one negative). No analysis required four phases; but it is unclear whether this finding reflects a true absence of four phases, or merely the inability of the recording equipment to resolve them. 8. The positive heat seems to be derived from two sources. First, there is a dissipation of the free energy stored in the membrane capacity. Secondly, there is an evolution of heat corresponding with a decrease in entropy of the membrane dielectric with depolarization.

Action Potentials↗
PubMed1982

Composition and subcellular distribution of glycoproteins and glycosaminoglycans undergoing axonal transport in garfish olfactory nerves.

The study examined the subcellular distribution of [3H]glucosamine-labeled glycoconjugates undergoing axonal transport in 100,000 x g soluble and two membranous subfractions of the garfish olfactory nerve. Analysis was made of intact glycoconjugates and of glycopeptides and glycosaminoglycans derived from these molecules by limit protease digestion. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed labeling of a variety of high-molecular-weight molecules with a lower molecular weight distribution in the soluble fraction than in the membranous fractions. Following protease digestion, nearly two-thirds of transported radioactivity in glycopeptides was recovered in the plasma membrane-enriched subfraction, with the remainder equally divided between soluble and higher density membrane fraction. Comparison of the distribution of glycopeptide radioactivity and chemically assayed hexosamine revealed transport labeling of a large variety of different-sized neutral and acidic glycopeptides in all subfractions. Transport labeling of most glycoprotein carbohydrate chains was in proportion of their hexosamine content. Transported glycosaminoglycan label was most heavily concentrated in the plasma membrane fraction, whereas hexosamine was most concentrated in the higher density membrane fraction. The labeling pattern suggested both transported and nontransported pools of these molecules. The specific glycosaminoglycans chondroitin sulfate and heparan sulfate were recovered in all subfractions, whereas hyaluronic acid was confined to the soluble fraction.

Animals↗
PubMed1999

CRBP I and CRABP I localisation during olfactory nerve development.

Retinoic acid appears to play a role during the formation of the olfactory system. Immunohistochemistry was used to localise the cellular retinoid binding-proteins for retinol (CRBP I) and retinoic acid (CRABP I) in the embryonic and adult olfactory system. Our results indicate that RA produced by the CRBP I-expressing 'glia-like' cells may act as a neurotrophic factor for the CRABP I-expressing immature olfactory axons.

Animals↗
PubMed1976

Post-tetanic hyperpolarization, sodium-potassium-activated adenosine triphosphatase and high energy phosphate levels in garfish olfactory nerve.

1. While much is now known about the Na-K-ATPase and the posttetanic hyperpolarization of nervous tissue, they have yet to be studied together in the same preparation. 2. The post-tetanic hyperpolarization was studied in desheathed garfish olfactory nerve. The rate constant of decay of the post-tetanic hyperpolarization was determined by monitoring difference potentials after stimulation at 1/sec for 2-3 min. 3. In membrane fractions prepared from these nerves, the ouabain-sensitive ATPase activity (Na-K-ATPase) was determined by spectrophotometric measurements. 4. Both the post-tetanic hyperpolarization and the Na-K-ATPase showed a similar sigmoidal dependence on K+ concentration. The sequence of cation specificities measured at the K-site of the enzyme was the same as that determined by post-tetanic hyperpolarization measurements in whole nerve. 5. The rate constants of the enzyme showed a dependence on Na+ concentration that paralleled the way in which the post-tetanic hyperpolarization rate constants varied as a function of the number of impulses. When Na+ was completely replaced by Li+, neither enzyme activity nor post-tetanic hyperpolarization could be measured. 6. The pH optimum for enzyme activity was between pH 7-0 and 7-8, while the optimal pH for post-tetanic hyperpolarization was above pH 8-0. 7. Metabolite levels in preparations of this nerve studied in vitro correspond to levels found in vivo. 8. High energy phosphate levels were measured fluorometrically in extracts of nerve samples that had been stimulated in air at 1/sec for various intervals. 9. During the first 2 min of stimulation, there was a significant accumulation of inorganic phosphate, and the ATP/ADP.Pi ratio dropped appreciably. 10. The accumulation of ATPase products was commensurate with the approach of post-tetanic hyperpolarization rate constants to their maximum level. This provides direct evidence for an ATPase functioning in active Na+ transport in nerve. 11. The garfish Na-K-ATPase is sensitive to the ATP/ADP ratio of the incubating medium, but is relatively insensitive to orthophosphate, Pi. The fall in post-tetanic hyperpolarization rate constants observed with continued nerve stimulation may have been partially due to the falling ATP/ADP ratio measured in nerve under similar conditions.

Action Potentials↗
PubMed1986

Effect of the action potential on the Raman spectrum of the pike olfactory nerve.

Raman bands due to the C-H stretching vibrations of the phospholipid acyl chains, as well as those due to resonance enhanced vibrations of carotenoid pigments, were used to probe for conformational changes during the passage of the action potential through fibers of the pike unmyelinated olfactory nerve. Our results show that if there are any spectral changes during nerve excitation, these are less than 0.5% for both the phospholipid and the carotenoid bands.

Action Potentials↗
PubMed1990

Vomeronasal and olfactory nerves of adult and larval bullfrogs: I. Axons and the distribution of their glomeruli.

The distribution of primary olfactory and vomeronasal (VMN) glomeruli is demonstrated in the forebrain of the larval (stage III tadpole) and adult bullfrog. Olfactory glomeruli are massed at the anterior end of the olfactory bulb; farther posterior, they are located at the periphery and then become distributed in a superficial layer all along the ventral surface of the bulb. Glomeruli of the accessory olfactory bulb (AOB) of the tadpole are less compact and show larger dendritic profiles and fewer synaptic junctions per unit area than those of the adult AOB. Axons of both tadpole and adult VMN nerve are ultrastructurally indistinguishable from those of the primary olfactory nerve; in comparing VMN axons of tadpole and adult, however, differences were observed in the number of neurofilament profiles in axons at the proximal and distal ends of the VMN nerve. Counts of neurofilament profiles in the two ends of the nerve suggest that neurofilament segments accumulate near terminations of their axons. The VMN nerve of tadpole and adult frog are roughly the same size, and calculations indicate that they contain comparable numbers of axons. The primary olfactory nerve of the tadpole is estimated to contain about 660,000 axons; the adherent VMN nerve of the tadpole contains about 270,000 axons (a ratio of about 2.5:1). In the adult, the ratio of primary to VMN axons is about 64:1, reflecting the quantitative growth of the primary olfactory nerve with development from an aquatic tadpole to an air-breathing adult.

Animals↗