Quantitative Ultrastructural Analysis of Periodontal Afferent Terminals in the Trigeminal Motor Nucleus / 대한해부학회지

Little is known about processing mechanism of sensory input from the periodontal ligaments to the trigeminal motor nucleus for the control of chewing force and modulation of chewing pattern. Low threshold mechanoreceptive periodontal afferent was labeled with horseradish peroxidase by use of intra-axonal injection technique and investigated with electron microscopy. Quantitative ultrastructural analysis was performed on the 39 serially reconstructed labeled boutons in the trigeminal motor nucleus in cat. Labeled bouton contained clear spherical vesicles and one or two large dense cored vesicles. Most of labeled boutons were dome or round shape. All the analysed labeled boutons were presynaptic to dendritic shaft or distal dendrite and those presynaptic to soma or proximal dendrite were not observed. A large number of labeled boutons (46.2%) were postsynaptic to one or two presynaptic pleomorphic vesicle containing endings. Synaptic triad, in that a presynaptic ending which is presynaptic to the labeled bouton, in turn, is presynaptic to dendrite that is postsynaptic to the labeled bouton, was observed in 10.3% of the labeled boutons. Most of the labeled boutons showed simple synaptic organization, in that 64.1% of the labeled boutons made synaptic contacts with one or two neuronal profiles. One (2.6%) of the 39 analyzed labeled boutons showed synaptic contacts with 5 or more neuronal profiles. Labeled bouton volume, mitochondrial volume, apposed surface area and active zone area showed wide variation. These ultrastructural parameters were positively correlated with bouton volume. The values for apposed surface area and active zone area with presynaptic p-endings, in contrast to those with postsynaptic dendrites, showed narrow range and had little correlation with bouton volume. The present study revealed characteristic features on ultrastructural parameters of labeled boutons from periodontal afferent which is involved in periodontal masseteric reflex, and that influence on the postsynaptic trigeminal motoneurons showed wide variability.

The Effects of Essential Aroma Oils on Brain Activation: Olfactory Functional MRI and c-Fos Expression / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: For centuries, fragrance had beneficial psychological and physiological effects on humans. Aromatherapy, the use of concentrated essential oils extracted from herbs, flowers, and other parts of plants to treat various diseases, is becoming more commonly accepted within the health service. However, there are very few published articles, which provide a sound rationale for the use of aromatherapy as a medical intervention. The purpose of this study was to find a scientific explanation for the effect of aromatherapy by investigating 1. whether or not essential aroma oils caused increased brain activity and 2. which areas of the brain were activated by the essential aroma oils. MATERIALS AND METHODS: Olfactory fMRI (functional magnetic resonance imaging), which is capable of monitoring and recording regional pathophysiological fluctuations in living brains, was performed on 11 healthy adult humans during exposure to essential aroma oils (lavender and lemon oils) and buthanol. The c-fos immunohistochemical staining was also performed on brain tissues of 24 Mongolian gerbils after exposure to the essential aroma oils. RESULTS: In the human fMRI study, the olfactory cortex was activated in all subjects by the essential aroma oils and buthanol. Additionally, lavender oil also activated the hearing and language-related regions of brain. In the animal study, similar results were observed: immunoreactive cells were detected in the hearing and language related regions of gerbil brains that had been exposed to lavender oil. CONCLUSION: The lavender oil activated not only the olfactory region but also the hearing and language-related regions of the brain. These results imply that the essential aroma oil introduced through the olfactory pathway has effects on other regions of the brain.

Quantitative and Ultrastructural Analysis of Afferent Terminals from Tooth Pulp in the Trigeminal Principal Sensory Nucleus / 대한해부학회지

To analyze the synaptic characteristics of axon terminals originated from tooth pulp in the trigeminal principal sensory nucleus, and find morphological evidence that p-endings on these terminals use GABA as neurotransmitter, labeling of tooth pulp afferents with wheat -germ agglutinin conjugated horseradish peroxidase, postembedding immunocytochemistry and morphometric analysis were performed. The results obtained were as follows. The labeled boutons contained clear and round synaptic vesicles, and the mean number of synaptic contacts was 4.21 +/- 2.58. The postsynaptic profiles were usually middle or distal dendrites and dendritic spines rather than soma or proximal dendrites. The mean number of synaptic contacts with p -endings was 2.62 +/- 2.01. The volume of labeled bouton was 4.39 +/- 3.08 micro meter 3 and highly correlated (P<.01) with surface area (r = 0.96), total apposed surface area (r = 0.84), total active zone area (r = 0.84), mitochondrial volume (r = 0.95), the number of synaptic vesicles (r = 0.92), the number of synaptic profiles (r = 0.76) and the number of synaptic p -endings (r = 0.67). The p -endings contained pleomorphic synaptic vesicles. The volume of p -ending was 0.91 +/- 0.47 micro meter 3 and highly correlated (P<.01) with surface area (r = 0.94), total apposed surface area (r = 0.76), total active zone area (r = 0.62), mitochondrial volume (r = 0.70) and the number of synaptic vesicles (r = 0.94). P -endings were GABA immunoreactive. These results suggest that tooth pulp afferent terminals in trigeminal principal sensory nucleus may be related to complex processing of sensory information and presynaptic p -endings using GABA as neurotransmitter, are important in this sensory processing. The "size principle" of Pierce and Mendel (1993) is also applicable to tooth pulp afferent terminals and presynaptic p -endings.

Ultrastructural Analysis of GABA- and Glycine-Immunoreactive Nerve Terminals on Jaw-Closing and Jaw-Opening Motoneurons in the Rat / 대한해부학회지

Previous studies have shown that inhibitory synaptic inputs are different between in spinal and trigeminal motor systems and activities of jaw closing and opening alpha motoneurons are different during a chewing cycle. This study examined the distribution of inhibitory synapses made on masseter and digastric motoneurons by using retrograde tracing of wheat germ agglutinin conjugated to horseradish peroxides (WGA-HRP) combined with postembedding immunogold labeling on serial ultrathin sections.Many boutons IR (immunoreactive) to GABA and/or glycine were found to appose on two kinds of motoneurons, which were containing pleomorphic vesicles (a mixture of round, oval and flattened vesicles) and exhibited symmetrical synaptic contacts on the somata. Packing density and synaptic covering % were higher in digastric than in masseter motoneurons. Of 703 boutons apposing on 12 masseter motoneurons, 6.08+/-3.51, 29.67+/-8.89 and 17.78+/-5.22% were IR to GABA only, glycine only, and both GABA and glycine, respectively. Of 637 boutons apposing on 11 digastric motoneurons, 6.37+/-4.64, 19.74+/-8.25 and 12.01+/-5.38% were IR to GABA only, glycine only, and both GABA and glycine, respectively. Proportions of glycine IR boutons were higher than that of GABA IR boutons in both masseter and digastric motoneurons. Packing density and proportion of boutons IR to GABA and/or glycine were higher in jaw closing than in jaw opening motoneurons (packing density, 12.03+/-1.58 vs 10.28+/-2.99; proportion of IR boutons, 53.54+/-8.94% vs 38.12+/-9.38% in jaw closing and opening motoneurons, respectively). These results provide ultrastructural evidence that GABA and glycine act as important neurotransmitters for modulation of jaw movement and that proportion of inhibitory synapses is higher in jaw closing than in jaw opening motoneurons.

Synaptic connection and GABA-immunoreactivity of periodontal afferent terminals and their presynaptic endings in the trigeminal motor nucleus of the rat / 대한해부학회지

Periodontal-masseteric reflex is implicated in the control of jaw movement and masticatory force during chewing foods. This study is aimed to investigate the synaptic arrangement of mesencephalic periodontal afferents in the trigeminal motor nucleus and to identify the neurotransmitter involved in the presynaptic control of them through the intra-axonal staining of horseradish peroxidase combined with postembedding immunogold methods. Most of the labeled terminals showed synaptic contacts with the small sized dendritic shafts or distal dendrites, while synaptic contacts with the somata or proximal dendrites were not observed. More than one third of the analyzed labeled boutons received presynaptic input from pleomorphic vesicles containing ending (p-ending). About 11% of labeled boutons showed synaptic triads. All the analyzed boutons made synaptic contacts with one to four neuronal profiles and those showing synaptic contact with five or more were not observed. Labeled terminals were larger than presynaptic p-endings. A large number of the analyzed p-endings showed GABA like immunoreactivity. These observations provide evidence that periodontal afferent terminals show very simple and characteristic synaptic arrangements in the trigeminal motor nucleus and that p-endings presynaptic to them may use GABA as a neurotransmitter for presynaptic inhibition.

Quantitative Analysis of GABA and/or Glycine Like Immunoreactive Synaptic Terminals on Masseter gamma-motoneurons for Jaw Closing Muscle of the Rat / 대한해부학회지

The distribution of GABA and/or glycine like immunoreactive nerve terminals on the soma of the masseteric gamma motoneurons were investigated using retrograde tracing of WGA-HRP (wheat germ agglutinin conjugated horseradish peroxidase) and postembedding immunogold labeling methods in serial ultrathin sections. Quantitative analysis of 140 nerve terminals apposing on somata of gamma motoneuron size less than 21 mm in average diameter was performed. The results obtained were as follows. 1. Synaptic covering % of apposing nerve terminals was 21.45+/-11.48% and packing density was 12.85+/-6.17. 2. Nerve terminals immunoreactive (IR) to GABA or glycine were F type containing pleomorphic vesicles with round shape predominant. Majority of nerve terminals immunonegative to GABA or glycine were S type containing spherical vesicles and few of them were F type. 3. 11.42+/-10.00% of examined nerve terminals were IR to GABA only, and 12.71+/-9.85% were IR to GABA and glycine, and 15.21+/-9.58% were IR to glycine only. 4. Synaptic covering % of nerve terminals IR to glycine only was highest (4.58+/-4.50%), followed in order by GABA and glycine (3.18+/-2.77%), and GABA only (2.38+/-2.06%). 5. Among all terminals, immunonegative nerve terminals (60.66+/-14.65%) were much more than nerve terminals immunoreactive to GABA and/or glycine (39.34+/-14.65%) These results show that inhibitory synaptic input and synaptic organization of the masseteric gamma motoneurons reveal characteristic features in contrast to that of alpha motoneurons and which may correlated to the electrophysi-ological characteristics of masseteric gamma motoneurons.

Changes in CGRP-immunoreactive nerve fibers during expansion of midpalatal suture of the rat / 대한치과교정학회지

Midpalatal suture expansion if often used for patients having narrow maxillary arch, cleft palate, respiratory handicap with narrow nasal cavity. CGRP has been known as a modulator of pain transmission in central nervous system and a local effector to peripheral tissue causing vasodilation, increase of blood flow, modulation of immunesystem, regulation of macrophagic function and stimulation of bone formation. To investigate changes of CGRP-immunoreactive nerve fibers in midpalatal suture during the expansion, immunohistochemical study was performed by using rats. Experimental rats (10 weeks, 250 gm) were divided into five groups (control, 1, 4, 7, 14 days group (each n=4) and applied orthodontic force (approximately 200gm) to upper anterior incisors. Frozen sections of midpalatal suture area were immunostained by using rabbit antisera. The results were as follows: The CGRP-immunoreactive nerve fibers were hardly observed in control group. In 1 day group, the CGRP-immunoreactive nerve fibers were more increased around the vessels than control group. In 4 days group, the CGRP-immunoreactive nerve fibers were more increased than control group, but nor more increased than 1 day group. Vascular diameter was more enlarged. In 7 days group, especially, hematoxilin affinity of cells was remarkable and cells were arranged along the bone margin. The CGRP-immunoreactive nerve fibers were more reduced than 4 days group and vascular diameter was also reduced. In 14 days group. the CGRP-immunoreactive nerve fibers were similar to those of 7 days group and the irregularity of bone margin was almost recoverd. In Conclusion, the CGRP-immunoreactive nerve fibers may be related to intial neurogenic inflammatory reaction in expanding mid-palatal suture.

Synaptic connectivity and ultrastructrue of the masseteric muscle spindle afferent trigeminals according to geometric location in the trigeminal motor nucleus of the cat / 대한해부학회지

The purpose of this study was to investigate any relationship between the geometric factors of synaptic contacts of muscle spindle afferent terminals and masseteric motor neurons in the trigeminal motor nucleus. Terminals from the masseteric muscle spindle afferents were stained with intra-axonal injection of HRP and were examined electronmi-croscopically with serial sections at the central and peripheral regions of trigeminal motor nucleus of the cat. The number of terminals examined were 76 in peripheral and 105 in central region. The results obtained were as follows. 1. Most of the labeled terminals showed simple synaptic connectivity. Each terminals in peripheral and central region made synaptic contact with 1 to 5 neuronal profiles. Two or three labeled terminals were occasionally seen to make synaptic contact with the same dendrite. 2. The average number of postsynaptic proximal dendrite per labeled terminal was higher in the central region than in the peripheral region. In contrast, that of postsynaptic distal dendrite per labeled terminal was higher in the peripheral region than in the central region. 3. The average diameter of postsynaptic dendrites in the central region was larger than that in the peripheral region. This imply terminals in the peripheral region contacted with further distal part of the distal dendrite than that in the central region. These results indicate that synaptic connectivity associated with the spindle afferents from masseteric muscle is different according to their geometric location within the trigeminal motor nucleus and suggest that there will be precise interrelationship between the morphology, pattern of synaptic connectivity and functions of muscle spindle afferents.

Bucco-lingual Implant Path in the Posterior Mandible / 체질인류학회지

The purpose of this study is to investigate the cross -sectional anatomy of posterior mandibular body for proper determination of bucco -lingual implant path. Using fifty -four human mandibles, negative images of each mandible were made of agar impression material. The agar blocks were cut through the imaginary long axis of each root of three molars (M1M, M1D, M2M, M2D and M3). The depth of submandibular fossa, the angulation of long axis of mandibular body and tooth, and the length, angulation and ratio of alveolar bone superior to mylohyoid ridge and basal bone inferior to mylohyoid ridge were measured. The results obtained were as follows; 1. All of the measured angulations were decreased as it moves from M1M to M3. 2. The correlation coefficients among the angulation of the mandibular bone and the crown axis showed the high relationship (r=0.793), and the crown axis was steeper than the mandibular bone axis by 6.2 at M1M and 7.6 at M2M. 3. The length of upper alveolar bone was decreased, but that of inferior basal bone was increased as it moves from M1M to M3. 4. The depth of submandibular fossa was increased as it moves from M1M to M3. These results indicate that the angulation of implant path at the posterior mandible must be tilted more than wax -up crown axis by 6.2 at mesial root of 1st molar and by 7.6 at mesial root 2nd molar area for prevention of lingual cortical bone perforation during implant surgery.