1997 Fiscal Year Final Research Report Summary
Analysis of mechanism of goiter formation ; involvement of apoptosis
| Project/Area Number |
08671173
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
内分泌・代謝学
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| Research Institution | Nagasaki University |
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Principal Investigator |
YOKOYAMA Naokata Nagasaki University, School of Medicine, Hospital, Assistant, 医学部・附属病院, 助手 (10240219)
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| Co-Investigator(Kenkyū-buntansha) |
KOJI Takehiko Nagasaki University, School of Medicine, Associate Professor, 医学部, 助教授 (30170179)
KIRIYAMA Takeshi Nagasaki University, School of Medicine, Assistant, 医学部, 助手 (10264219)
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| Project Period (FY) |
1996 – 1997
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| Keywords | Goiter / Apoptosis / Fas / Fas ligand / Cell proliferation |
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| Research Abstract |
Apoptosis, a physiological process of cell death, may modulate the mass of the thyroid gland. We investigated the role of apoptosis and the possible involvement of Fas/Fas ligand (FasL) system in apoptosis during goiter formation and involution in a rat model of goiter. Rats were fed a low iodine diet (LID) and a goitrogen, 6-propy1-2-thiouracil (PTU), to induce goiter. Rats with goiter were then fed a high iodine diet (HID) to study the phase of involution. We examined the presence of apoptosis by electron microscopy (EM) and terminal deoxy-UTP nick end labeling (TUNEL). We also investigated the association between Fas and FasL expression and thyrocyte apoptosis using immunohistochemistry and western blotting. To evaluate the proliferation of thyrocytes, proliferating cell nuclear antigen (PCNA) was examined immunohistochemica11y. The number of apoptotic cells increased during goiter formation and the early stage of involution, which were also associated with increased number of Fas-positive thyrocytes and some of these cells contained TUNEL-positive nuclei. However, the expression of FasL was almost constant throughout the experiment. PCNA/TUNEL ratio markedly increased during goiter formation but decreased particularly during the late stage of goiter involution. Our results indicate that apoptosis of thyrocytes is a main factor of cell loss during goiter formation and involution, and suggest that the Fas/fasL system is involved in the induction of apoptosis of these cells. Moreover, the delicate balance between apoptosis and cell proliferation may play an important role in the control of thyroid gland mass.
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