Korean J. Oral. Med. Vol. 26, No. 3, 2001 Ultrastructural Changes on the Synovial Membrane of Rat Temporomandibular Joint under Mild Restraint and Cold Stresses Jung-Kyun Ryu, D.M.D.,M.S.D, Kyung-Hwan Mun, D.M.D., Yang-Hyun Chun, D.M.D.,M.S.D.,Ph.D., Jung-Pyo Hong, D.M.D.,M.S.D.,Ph.D. Department of Oral Diagnosis & Oral Medicine, College of Dentistry, Kyung Hee University CONTENTS various organs at cellular and molecular levels starting with cellular responses to injury: cell Ⅰ. INTRODUCTION adaptive response, cell stress response (production Ⅱ. MATERIALS AND METHODS of stress protein), reversible cell injury and Ⅲ. RESULTS ultimately irreversible cell injury such as apoptosis Ⅳ. DISCUSSION (programmed cell death)3),4) In that way, the Ⅴ. CONCLUSIONS extremely complex self-regulating system can alter REFERENCES the internal functions down and cause various KOREAN ABSTRACT diseases1)5) Modern medicine has relatively little interest in cognitive functions, psychological Ⅰ. INTRODUCTION techniques, or the effects of naunces of belief, faith, self-suggestion, or yogic exercises on the internal Nowadays, everyone seems to be talking about functions in treatment regimens. On the other side stress. You hear it not only in daily conversation but of the therapeutic coin, psychology has fostered few also through television, radio, the newspapers and formal applications for medicine. There are, the constantly increasing number of conferences, however, emerging concepts of the cause and stress centers and university courses that are treatment of emotional, psychosomatic, and related devoted to the topic. Stress, one type of the problems, now popularly designated as stress- interaction, is the nonspecific response of the body related problems, that are directed toward both to any demand.1) In the course of daily life, there is psychophysiological relationships in health and a continuous ongoing interaction between the illness and the influences of higher-order mental individual and environment.2) Stress can have an function.1) So the term 'psychoneuroimmunology' effect on human body which is apt to maintain has developed in order to elucidate the relationship homeostasis and modulate three main systems such between psychosocial stress and diseases. There are as autonomic nervous system, the hormonal system many stress-related symptoms and diseases in the and immune response system.1) Then, it can affect orofacial tissue such as lichen planus, aphthous 205 Jung-Kyun Ryu, Kyung-Hwan Mun, Yang-Hyun Chun, Jung-Pyo Hong stomatitis, geographic tongue, recurrent herpes immediately and stored in the glutaraldehyde in labialis, xerostomia, halitosis, burning mouth phosphate buffer (PB) after rinsed in PB. syndrome, muscle tension headache, atypical odontalgia and temporomandibular disorders (TMD). 2. Electron Microscopy 6) Among the stress-related orofacial diseases, although increasing attention has been recently The tissues were rinsed in 0.1 M cacodylate addressed to TMD, the pathologic mechanism of buffer 3 times 10 min each, postfixed in 1% osmium TMD induced by stress remains vague. Like most tetroxide for 90 min, and rinsed in 0.1 M malate joint diseases, TMD is associated with alterations in buffer 3 times 5 min each. They were prestained the synovial membrane.7) It is essential to observe with 1% uranyl acetate for 90 min and washed in temporomandibular joint (TMJ) synovial cell layers 0.1M malate buffer 3 times 5 min each, and in respond to a broad variety of stress condition dehydrated through an ascending series of ethanol because synovial membrane plays an important role concentration (50% to 100%, 15 min each). And in maintaining normal joint physiology while they they were placed in 100% ethanol and prophylene can be easily affected by stress like other membrane oxide (1:1) for 45 min, prophylene oxide for 45 min, boundaries between fluid and tissue compartment and prophylene oxide and epon (1:1) for 1 hr. After such as salivary glands, esophagus, vagina and then, they were placed in epon in a vacuum oven ovarian granulosa cells.8) In order to have a better overnight, embedded with fresh epon which was understanding of the pathologic mechanism in TMD, polymerized at 60 ℃ for 3 days. The embedded emphasizing the significant role of stress in the tissues were cut with a diamond knife 50 nm thick disease, the present study was performed to and stained with uranyl acetate and lead citrate. investigate the cellular adaptability and the The tissues were observed by the transmission ultrastructural change of TMJ synovial membrane electron microscopy (JEM-1010, JEOL Ltd, Japan). under physical and psychological stress. Ⅲ. RESULTS Ⅱ. MATERIALS AND METHODS In the normal control group, many rough 1. Experimental animals endoplasmic reticulum(rER), mitochondria were observed in a normal synovial cell. Sprague-Dawley rats (8-week-old, 323-367 In the mild restraint stress group, in lapse of time, g/bw) were purchased from Dae-Han Experimental according to the mild restraint stress, ultra- Animal Research Center, Seoul, Korea. They were structural changes appeared gradually. maintained at 20-23℃ and fed ad libitum on a normal laboratory diet. The rats were divided into 1. Mitochondria were partially condensed, and the 3 groups: 1) Normal control group; 2) Mild restraint number and the size of mitochoundria were stress group; 3) Cold stress group : the rats of decresed gradually. restraint stress group were placed in the stress 2. rERs were gradually dilated with irregular shape. cage permitting slight movement throughout the 3. Double layer of nuclear envelope were slightly period of experiment and the rats of cold stress corrugated at day 7. group were immersed in cold water (4℃) for 6 min once a day throughout the experiment. All the In the cold stress group, in lapse of the time, animals were then sacrificed at day 1, 3, 5, and 7 according to the cold stress, ultrastructural changes day of the experiment and the synovial membrane are as follows. of temporomandibular joint(TMJ) were excised 206 Ultrastructural Changes on the Synovial Membrane of Rat Temporomandibular Joint under Mild Restraint and Cold Stresses Fig. 1. The TMJ synovial membrane Fig. 2. The TMJ synovial membrane Fig. 3. The TMJ synovial membrane of the normal control rat. of the rat under mild of the rat under mild (X10,000) restraint stress at day 1 of restraint stress at day 3 of the experiment. (X10,000) the experiment. (X10,000) Fig. 4. The TMJ synovial membrane Fig. 5. The TMJ synovial membrane Fig. 6. The TMJ synovial membrane of the rat under mild of the rat under mild of the rat under cold stress restraint stress at day 5 of restraint stress at day 7 of at day 1 of the experiment. the experiment. (X10,000) the experiment. (X10,000) (X10,000) 1. Mitochondria had shown slight swelling shapes, changed to dilated pattern at day 1, 3, but were and were decreased in number at day 1, 3, but gradually recovered and activated at day 5, 7. again increased in number at day 5, 7, with very 3. Nucleus was almost intact in all cold stress sound shapes. group during all period of the experiment. 2. The lamellated structures of the rER were 207 Jung-Kyun Ryu, Kyung-Hwan Mun, Yang-Hyun Chun, Jung-Pyo Hong Fig. 7. The TMJ synovial membrane Fig. 8. The TMJ synovial membrane Fig. 9. The TMJ synovial membrane of the rat under cold stress of the rat under cold stress of the rat under cold stress at day 3 of the experiment. at day 5 of the experiment. at day 7 of the experiment. (X10,000) (X10,000) (X10,000) Ⅳ. DISCUSSION the central nervous system without any contact with the organism. Common stressors of this type Stress is defined as a complex dynamic condition include immobilization or restraint.10) Two types of in which normal homeostasis is disturbed.9) The stressors have been widely used to illustrate the physiological stress response comprises three main influence of stress on the body. Stresses may be systems such as autonomic nervous system, further classified into psychological stress, social hormonal system and immune response system.1) stress, economic stress and physiological stress.1) The systems are extremely complex and One of the most important pathways involved in self-regulating, involve multiple causal factors, and stress is HPA axis(Hypothalamo-pituitary adrenal key basic functions of them are surveillance, axis).(AP : Harris GW 1948) When stress activates mobilization of resources and feedback. Depending the HPA axis, glucocorticoids are massively on the type and degree of stress, the tissue secreted by adrenal cortex. the HPA axis is response to it could be physiologic or pathologic. If stimulated by corticotrophin-releasing factor(CRF), stress exceeds adaptability of the tissue, it may resulting in a down-regulation of immune function. affect various organs starting with alterations at Stress-induced aterlation in endocrine function and cellular and molecular levels by cellular responses potential pathophysiologic effects of endocrine to injury: cell adaptive response, cell stress change lead to a depletion of subject's ability to response (production of stress protein), reversible resist stress, which ultimately leads to the disease cell injury, and ultimately irreversible cell injury process.11) such as apoptosis. (programmed cell death)3),4) The HPA axis releasing endogenous glucocor- This distinction identifies stressors as 'physical' ticoid is thought to play a role in the stress or 'psychological.' Physical stressors have direct responses including apoptosis