OBJECTIVETo constitute the animal model of unilateral olfactory nerve transection and observe the expression level and distribution of odorant receptors.

METHODSThirty-two rats were divided into two groups: the olfactory nerve transection group (20) and the control group (12). The former group received the operation to transect the left olfactory nerve following the left olfactory bulb was exposed under microscope and the latter group did not give any disposal. At every stage of five days, two weeks, four weeks and six weeks after the operation, five rats from the nerve transection group and three from the control group were anaesthetized simultaneously, and olfactory epithelium were taken out after transcardial perfusion, then paraffin imbedding. Coronal sections were sliced for HE staining to observe the thickness changes of the olfactory epithelium, and for in situ hybridization (ISHs) to investigate the expression of olfactory receptor genes (Olr287, Olr226, Olr1493 and Olr1654) in the epithelium, also to evaluate the changes of the expression level and location of the selected receptors during the regeneration of olfactory epithelium.

RESULTSHE staining showed that 5 days after the operation cell quantity and thickness of the olfactory epithelium decreased obviously, which increased gradually 2 or 4 weeks after operation. After 6 weeks' recovery, the thickness of the epithelium could reach the control level. The pattern of cell staining by ISH showed a specific spatial distribution along the anteroposterior (AP) and dorsoventral (DV) axis. Evidence suggested that odorant receptors were distributed in continuous and multiple overlapping bands in the normal or nerve transected-recovered epithelium rather than in the conventionally accepted three or four zones. The data also demonstrated that the distribution of sensory neuron types, as identified and defined by odorant receptor expression, was restored to normal or nearly so by 6 weeks after operation. Likewise, the numbers of probe-labeled neurons in the nerve transected-recovered had an obvious decrease 5 days after olfactory nerve transection. Reactive cells (x(-) +/- s) of Olr1493 in the operated side was (53.9 +/- 19.9), compared with (419.0 +/- 21.2) in the unoperated side, there was statistic significance between them (t = 63.960, P < 0.01). Reactive cells increased gradually according to the regeneration of the epithelium, and were nearly equivalent to the normal side 6 weeks later without significant differentiation (t = 2.600, P > 0.05), according to the absolute positive cells in the operated and unoperated side of (417.8 +/- 32.4) and (445.3 +/- 10.0) respectively.

CONCLUSIONThe regeneration of the sensory neurons and receptors, both the number and the distribution, can recover to normal after olfactory nerve transection.

Animals ; Male ; Olfactory Mucosa ; metabolism ; Olfactory Nerve ; metabolism ; surgery ; Olfactory Nerve Injuries ; Olfactory Receptor Neurons ; cytology ; metabolism ; Rats ; Rats, Sprague-Dawley ; Receptors, Odorant ; genetics ; metabolism

BACKGROUND AND OBJECTIVES: The vomeronasal organ of the rat is a chemosensory organ located at the nasal septum. The distribution of nitroxidergic nerve fiber in olfactory system such as olfactory bulb, accessory olfactory bulb and olfactory epithelium was well documented, but vomeronasal organ which is a component of olfactory system and the receptor structure of the accessory olfactory system was rarely reported and discorded. The aim of this study was to determine the distribution and role of nitirc oxide (NO) in the rat vomeronasal organ using NADPH-diaphorase histochemistry. MATERIALS AND METHODS: Histochemical staining for NADPH-diaphorase in the rat vomeronasal organ was done. RESULTS: The NADPH-diaphorase positive reaction was observed in the blood vessels, nerve fibers around vessels and submucosal glands of vomeronasal organ. However, receptor area which is generally called the neuroepithelium and receptor free area were not seen. CONCLUSION: These results suggest that NADPH-diaphorase positive reaction shows tissue specific expression in the rat vomeronasal organ.
Animals ; Blood Vessels ; Nasal Septum ; Nerve Fibers ; Olfactory Bulb ; Olfactory Mucosa ; Rats* ; Vomeronasal Organ*

BACKGROUND AND OBJECTIVES: Nitric oxide (NO) has been reported to play important roles in the regulation of olfactory information in the mammarian olfactory bulb. Although the distribution of nitric oxide synthase (NOS)-immunoreactive neurons in the olfactory bulb in the rat and other animals have been investigated by light microscopy, ultrastructures of the synaptic organization between NOS-immunoreactive neurons have not been studied yet. This study was conducted in order to identify NOS- immunoreactive neurons in the rat olfactory bulb and to define their synaptic organizations under the electron microscope using the preembedding immunocytochemical method which utilizes anti-NOS antiserum. MATERIALS AND METHODS: The olfactory bulbs of the rats were cut into 50 micromiter thick vertical sections and immunostained using the ABS method. Stained sections were observed under the light microscope. Some of the stained sections, additionally stained with uranyl acetate and dehydrated, were embedded in Epon 812 and prepared into 80 nm thick sections to be observed under the electron microscope. RESULT: NOS-immunoreactive neurons of the rat olfactory bulb made up 25.0% of periglomerular cells and 18.9% of granule cells. NOS-immunoreactive periglomerular cells received synaptic input from unlabeled axon terminals of the olfactory nerve and unlabeled periglomerular cells within the glomeruli. The output targets of NOS immunoreactive periglomerular cells were unlabeled axon terminals of the olfactory nerve and unlabeled periglomerular cells. NOS-immunoreactive granule cells received synaptic input from unlabeled processes of granule cells and axon terminals of mitral cells, and made output synapses onto the unlabeled axon terminals of mitral cells. CONCLUSION: NOS-immunoreactive neurons are periglomerular cells and granule cells, and NO liberated from NOS cells may play important roles in the modulation of olfactory transmission.
Animals ; Microscopy ; Neurons* ; Nitric Oxide Synthase* ; Nitric Oxide* ; Olfactory Bulb ; Olfactory Nerve ; Presynaptic Terminals ; Rats* ; Synapses

Schwannoma is a benign, slowly growing nerve sheath tumor which can arise from any peripheral nerve containing schwann cells. The olfactory and optic nerves, the extentions of the central nerve system, are encased by glial cells and they lack of schwann cells. They do not give rise to schwannomas in the head and neck area. Therefore, it is generally known that schwannomas seldom occur in the nasal cavity occupied by the olfactory nerve. We have experienced a tumor that developed in the upper nasal cavity including the olfactory cleft and ethmoid sinus. Based on the location of tumor development, we initially diagnosed it as an olfactory neuroblastoma, and its biopsy results reported the tumor to be a schwannoma in the nasal cavity. The tumor was completely removed through craniofacial resection. We herein report a case of an olfactory schwannoma with a brief review of the literature in order to alert other clinicians to this rare tumor to expedite appropriate management.
Biopsy ; Esthesioneuroblastoma, Olfactory* ; Ethmoid Sinus ; Head ; Nasal Cavity* ; Neck ; Neurilemmoma* ; Neuroglia ; Olfactory Nerve ; Optic Nerve ; Peripheral Nerves ; Schwann Cells

Nitric oxide(NO) has recently been identified as a short-lived intracellular messenger in the central and peripheral nervous systems. Nitric oxide synthase(NOS) is a key enzyme for NO biosynthesis by formation of citrulline from L-arginine. This enzyme reaction requires reduced nicotine adenine dinucleotide phosphate(NADPH) as a co-factor and the electron transferring c-terminal sequence of NOS give rise to its NADPH-diaphorase activity. However, it has yet to prove that NO is a sensory neurotransmitter in olfactory nervous system. The purpose of this study was to localize histochemically the distribution of NADPH-diaphorase in the olfactory system of rats. In the olfactory mucosa, NADPH-diaphorase positive cells were demonstrated in the ciliary layers, Bowmann's glands and olfactory nerve bundles. In main olfactory bulb, a large number of NADPH-diaphorase positive cells were also demonstrated in nerve fibers of olfactory nerve layer, periglomerular cell, superficial short axon cells of external plexiform layer and deep short axon cells between granular and subependymal layers. Furthermore there were NADPH-diaphorase positive cells of plexiform and granular cell layers of the accessory olfactory bulb. Therefore, it is suggested that the presence of NADPH-diaphorase acitivity in nerve fibers of olfactory system may be involved in odor processing.
Adenine ; Animals ; Arginine ; Axons ; Citrulline ; Nerve Fibers ; Nervous System ; Neurotransmitter Agents ; Nicotine ; Nitric Oxide ; Odors ; Olfactory Bulb ; Olfactory Mucosa ; Olfactory Nerve ; Peripheral Nervous System ; Rats*

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

The distributions of calretinin (CR)- and parvalbumin (PV)-immunoreactive neurons in the main olfactory bulb (MOB) of the goat were examined in this study. As in other animals, the goat MOB has a characteristic laminar structure with laminar types and distribution patterns in each layer. CR-immunoreaction was observed in all layers of the MOB, except for the olfactory nerve layer. Most of CR-immunoreactive neurons were observed in the glomerular and granule cell layers. Relatively small number of CR-immunoreactive neurons was detected in other layers. These CR-immunoreactive neurons were interneurons. PV-immunoreaction was detected in all layers. In contrast to CR, olfactory nerve bundles were immunostained with PV. Most of PV-immunoreactive neurons were distributed in the glomerular and granule cell layers. PV-immunoreactive neurons were interneurons. This result suggests that CR and PV may play important roles in the olfactory signal modulation through interneurons in the goat MOB.
Animals ; Calcium-Binding Protein, Vitamin D-Dependent ; Calcium-Binding Proteins ; Goats ; Immunohistochemistry ; Interneurons ; Neurons ; Olfactory Bulb ; Olfactory Nerve ; Smell

OBJECTIVETo analyze the impact of olfactory nerve transection on the apoptosis of mice olfactory receptor neurons (ORN), and discuss the reliability of this experimental model.

METHODSAfter olfactory nerve transection of mice, anterograde horseradish peroxidase (HRP) tracing was performed to confirm the completion of nerve transection. On 8 h, 2 d, 3 d and 5 d after surgery, TdT mediated deoxyuridine triphosphate-biotin nick end labelling (TUNEL) was used to observe the apoptosis of ORN, while relative semi-quantitative RT-PCR and immunohistochemistry were used to reflect the expression of olfactory marker protein (OMP, special marker of mature ORN) in olfactory epithelium.

RESULTSNo HRP label was observed in olfactory bulb after olfactory nerve transaction. Both TUNEL-positive and OMP-positive cells were ORN. After the surgery, TUNEL-positive cells increased remarkably and peaked on 2 d after the surgery. Meanwhile OMP mRNA in olfactory epithelium began to decrease markedly till 5 d after the surgery, and the olfactory epithelium got thinner accordingly.

CONCLUSIONSThis experimental model can be used reliably to sever mice olfactory nerve and manipulate simultaneous apoptosis of mice ORN.

Animals ; Apoptosis ; Denervation ; Mice ; Mice, Inbred C57BL ; Olfactory Nerve ; cytology ; metabolism ; surgery ; Olfactory Receptor Neurons ; metabolism ; pathology

Intracranial schwannomas preferentially arise from the vestibular branch of the eighth nerve, and rarely from the trigeminal nerve, facial nerve, and lower cranial nerves. Anterior cranial fossa schwannomas are extremely uncommon and few details about them have been reported. The patient was a 39-year-old woman whose chief complaints were anosmia and frontal headache for 2 years. The gadolinium (Gd)-enhanced magnetic resonance imaging (MRI) showed an extra-axial mass from ethmoid sinus to right frontal base region near the midline, with solid enhancement in lower portion and multicystic formation in upper portion. The tumor was totally resected via basal subfrontal approach. At operation, the tumor had cystic portion with marginal calcification and the anterior skull base was destructed by the tumor. The olfactory bulb was involved, and the tumor capsule did not contain neoplastic cells. The histopathological diagnosis was schwannoma. We report a rare case of anterior cranial fossa schwannoma with literature review.
Adult ; Cranial Fossa, Anterior ; Cranial Nerves ; Ethmoid Sinus ; Facial Nerve ; Female ; Gadolinium ; Headache ; Humans ; Magnetic Resonance Imaging ; Neurilemmoma ; Olfaction Disorders ; Olfactory Bulb ; Olfactory Nerve ; Skull Base ; Trigeminal Nerve

Neurilemmoma is a benign tumor which is known to originate from the myelin-producing Schwann cells of the spinal nerve root, peripheral nerve and all kinds of cranial nerves except the optic nerve and olfactory nerve. Approximately, 25% to 40% of all neurilemmomas are found in the neural structures of the head and neck. Neurilemmoma of the 12th cranial nerve is rare ; multiple neurilemmoma is even more rare. Recently, the authors experienced a case of multiple (x3) hypoglossal neurilemmoma in the submandibular space. The tumor was removed completely and verified histopathologically as neurilemmoma.
Cranial Nerves ; Head ; Hypoglossal Nerve ; Neck ; Neurilemmoma ; Olfactory Nerve ; Optic Nerve ; Peripheral Nerves ; Schwann Cells ; Spinal Nerve Roots