OBJECTIVETo study whether apoptosis plays a role in controlling the number of olfactory receptor neurons, so as to reveal the specialty and mystery of neurogenesis.

METHODSUsing terminal deoxynucleotidyl transferase-mediated dUTP-fluorescein nick end labeling (TUNEL) and transmission electron microscopy to detect apoptosis in olfactory mucosa of normal adult rats and damaged olfactory mucosa of 16, 32, 48 hours and 3, 7, 30 days after bulbectomy.

RESULTSIn normal olfactory epithelium, a subpopulation of immature neurons, as well as mature neurons, showed internucleosomal DNA-fragmentation. The number of TUNEL-labeled neurons increased dramatically 32 hours after removal of olfactory bulb. Then it declined quickly and remained at low level. Ultrastructural data of olfactory mucosa showed that the feature of apoptotic neurons was chromatin condensation and cell shrinkage. Besides, some dying cells were characterized by the formation of numerous autophagic vacuoles, and few had some of the features of necrosis but without obvious mitochondrial swelling.

CONCLUSIONSApoptosis might play a role in turnover of the olfactory epithelium and regeneration in adult rats. There might be other two types of neural death through different mechanism.

Animals ; Apoptosis ; Male ; Olfactory Bulb ; surgery ; Olfactory Mucosa ; cytology ; pathology ; Olfactory Receptor Neurons ; cytology ; Postoperative Period ; Rats ; Rats, Sprague-Dawley

BACKGROUND AND OBJECTIVES: The purpose of this study was to evaluate the effect of intranasal Mometasone furoate instillation into the nasal cavity of mice which had peripherally induced anosmia. SUBJECTS AND METHOD: Three groups of mice were studied: normal control group (nasal instillation of normal saline, n=6), Mometasone furoate non-instillation group (no treatment after nasal instillation of zinc sulfate, n=12), and Mometasone furoate instillation group (daily mometasone furoate instillation after nasal instillation of zinc sulfate, n=12). Tissues of olfactory mucosa were obtained on 1, 2, 3, 4 weeks after the instillation of zinc sulfate, and processed for immunohistochemistry using antisera to olfactory marker protein (OMP) for evaluation of olfactory regeneration. RESULTS: No OMP-positive cells were observed in the first week after the instillation of zinc sulfate in both groups. However, OMP-positive cells began appearing in the second week in both groups and gradually increased as time goes by. In the Mometasone furoate instillation group, the increase of OMP-positive cells was significantly greater than that of Mometasone furoate non-instillation group. CONCLUSION: Mometasone furoate instillation enhances regeneration of olfactory receptor cells after injury. Mometasone furoate instillation can be suggested as an effective treatment modality for olfactory dysfunction.
Animals ; Immune Sera ; Immunohistochemistry ; Mice* ; Nasal Cavity ; Olfaction Disorders ; Olfactory Marker Protein ; Olfactory Mucosa ; Olfactory Receptor Neurons ; Regeneration ; Smell ; Zinc Sulfate ; Mometasone Furoate

BACKGROUND AND OBJECTIVES: This study was undertaken to evaluate the effect of superior cervical ganglionectomy (SCG) on anosmia, which is peripherally induced in the mice. MATERIALS AND METHOD: Three groups of mice (BCF1) were studied: normal control (nasal instillation of saline, n=6); zinc sulfate group (nasal instillation of 64 mM zinc sulfate, n=25); SCG group (superior cervical ganglionectomy after nasal instillation of 64 mM zinc sulfate, n=25). Tissues of olfactory mucosa were obtained at 1, 2, 3, 4 and 7 weeks after instillation of zinc sulfate, and processed for immunohistochemistry using antisera to olfactory marker protein (OMP) to evaluate the olfactory regeneration. RESULTS: No OMP-positive cells were observed in the first two weeks after the instillation of zinc sulfate in both zinc sulfate group and the SCG group. However, the OMP-positive cells appeared first at 3 weeks after the instillation in both groups, and gradually increased in number at 4 and 7 weeks. In the SCG group, the increase of OMP-positive cells was significantly greater than those of the zinc sulfate group. The number of OMP-positive cells in the SCG group at 7 weeks was almost similar to that of the normal control group. CONCLUSION: SCG enhances regeneration of olfactory receptor cells at 3 weeks after injury. It was inferred from the above results that SCG has a significant effect on the regeneration of olfactory receptor cells and we suggest that SCG could be an effective treatment modality for olfactory dysfunction.
Animals ; Autonomic Nerve Block ; Ganglionectomy* ; Immune Sera ; Immunohistochemistry ; Mice* ; Olfaction Disorders ; Olfactory Marker Protein ; Olfactory Mucosa ; Olfactory Receptor Neurons ; Regeneration ; Smell* ; Zinc Sulfate

No abstract available.
Olfactory Mucosa*

The olfactory epithelium is the main end organ for the sense of smell in humans and vertebrates. Specially differenciated neuronal cells called olfactory receptor neurons (ORNs) play a key role in the olfactory epithelium by expressing the olfactory receptors (ORs) on their apical surface membrane. The ORs are G-protein coupled receptors that transmit signals from odorants to ORNs by molecular cascades using cyclic adenosine monophosphate, calcium ions and other molecules, which result in the depolarization of ORN. Unlike other mammalian animals, only about 30% of OR genes in the human genome are expressed. The Nobel Prize was awarded to the scientists who cloned these ORs for the first time. Each ORN expresses only a single type of OR, and ORNs which express the same type of OR converge together into the same glomeruli in the olfactory bulb. A single OR recognizes multiple odorants, and a single odorant is recognized by multiple ORs with varying affinities. At the higher neurons beyond the bulb, neuronal connections are divergent. The combinatorial model of odor identification and discrimination is well established at the convergence level, but little is known about the action mechanisms of neuronal divergence for odor identification and discrimination and further study is required.
Adenosine Monophosphate ; Animals ; Awards and Prizes ; Calcium ; Clone Cells ; Discrimination (Psychology) ; Genome, Human ; GTP-Binding Proteins ; Humans ; Ions ; Membranes ; Neurons ; Nobel Prize ; Odors ; Olfactory Bulb ; Olfactory Mucosa ; Olfactory Pathways ; Olfactory Receptor Neurons ; Receptors, Odorant ; Smell* ; Vertebrates

BACKGROUND AND OBJECTIVES: This study was performed to investigate, through immunohistochemical analysis, the thyroid hormone's effect on the olfactory receptor neurons of adult rats. MATERIALS AND METHODS: Hypothyroidism was induced by adding reversible goitrogen propylthiouracil (PTU) to the rats' drinking water (30 mg/kg weight). Sprague-Dawly rats aged nine to ten weeks were divided into three groups : control, six weeks or PTU therapy, and 12 weeks of PTU therapy. Light microscopic investigation of the olfactory mucosa was conducted with an immunohistochemical stain to observe for proliferating cell nuclear antigen (PCNA) and protein genepeptide (PGP) 9.5. RESULTS: The rats in the experimental groups gained less weight compared with normal rats of the same age. Light microscopic examination revealed no statistically significant differences in the thicknesses of the olfactory epithelium and the numbers of cells among the three groups in H-E stains, but the ratio of PCNA(+) supporting cells decreased significantly with longer durations of PTU treatment. As PTU therapy continued, immunoreactivities to PGP 9.5 in olfactory receptor cells decreased remarkably. After 12 weeks of PTU treatment, no immunoreactivity was observed in the olfactory receptor cells. CONCLUSION: These results indicate that the thyroid hormone is essential for maturation of the olfactory receptor neuron.
Adult ; Animals ; Coloring Agents ; Drinking Water ; Humans ; Hypothyroidism ; Immunohistochemistry ; Olfactory Mucosa* ; Olfactory Receptor Neurons ; Proliferating Cell Nuclear Antigen ; Propylthiouracil ; Rats* ; Thyroid Gland

Over the last decades, piles of data have been accumulated to understand the olfactory sensation in every aspect, ranging from the intracellular signaling to cognitive perception. This review focuses on the ion conduction through multiple ion channels expressed in olfactory sensory neurons (OSNs) to describe how odorant binding to olfactory receptors is transduced into an electrical signal. Olfactory signal transduction and the generation of the depolarizing receptor current occur in the cilia, where the unique extraciliary environment of the nasal mucosa assists in the neuronal activation. Upon contacting with odorants, OSNs dissociate G protein-coupled receptors, initiating a signal transduction pathway that leads to firing of action potential. This signaling pathway has a unique, two step organization: a cAMP-gated Ca2+ (CNG) channel and a Ca2+-activated Cl- channel (CACC), both of which contribute to signal amplification. This transduction mechanism requires an outward-directed driving force of Cl- established by active accumulation of Cl- within the lumen of the sensory cilia. To permit Cl- accumulation, OSNs avoid the expression of the 'Chloride Sensor: WNK3', that functions as the main Cl- exclusion co-transporter in neurons of the central nervous system (CNS). Cl- accumulation provides OSNs with the driving force for the depolarization, increasing the excitatory response magnitude. This is an interesting adaptation because of the fact that the olfactory cilia reside in the mucus, outside the body, where the concentrations of ions are not as well regulated as they are in normal interstitial compartments.
Action Potentials ; Central Nervous System ; Cilia ; Fires ; Ion Channels ; Ions ; Mucus ; Nasal Mucosa ; Neurons ; Odors ; Olfactory Receptor Neurons ; Sensation ; Sensory Receptor Cells* ; Signal Transduction ; Smell

No abstract available.
Animals ; Olfactory Bulb* ; Olfactory Mucosa* ; Rats* ; Synapses*

No abstract available.
Animals ; Cadmium Poisoning* ; Cadmium* ; Olfactory Mucosa* ; Rats*

Olfactory neuroblastoma is a rare malignant tumor of the nasal cavity arising from the olfactory neuroepithelium. It usually present as a polypoid mass in the superior nasal cavity including the cribriform plate, superior turbinate, and superior portion of nasal septum. The development of olfactory neuroblastoma outside of the region, in which olfactory epithelium exists, is exceedingly rare. In this report, we present an interesting case of an isolated sphenoid sinus olfactory neuroblastoma with a brief review of the literature.
Esthesioneuroblastoma, Olfactory ; Ethmoid Bone ; Nasal Cavity ; Nasal Septum ; Olfactory Mucosa ; Sphenoid Sinus ; Turbinates