The analysis of the mechanism of the thymic atrophy with the aging.

Research Project

Project/Area Number	10832005
Research Category	Grant-in-Aid for Scientific Research (C)
Allocation Type	Single-year Grants
Section	一般
Research Field	老化(加齢)
Research Institution	Tokyo Medical and Dental University Graduate School
Principal Investigator	UTSUYAMA Masanori Department of Pathology and Immunology, Aging and Developmental Sciences, Tokyo Medical and Dental University Graduate School. Research Associate, 大学院・医歯学総合研究科, 助手 (70167287)
Co-Investigator(Kenkyū-buntansha)	HIROKAWA Katsuiku Department of Pathology and Immunology, Aging and Developmental Sciences, Tokyo Medical and Dental University Graduate School. Professor, 大学院・医歯学総合研究科, 教授 (00014093)
Project Period (FY)	1998 – 2000
Project Status	Completed (Fiscal Year 2000)
Budget Amount *help	¥3,100,000 (Direct Cost: ¥3,100,000) Fiscal Year 2000: ¥700,000 (Direct Cost: ¥700,000) Fiscal Year 1999: ¥1,100,000 (Direct Cost: ¥1,100,000) Fiscal Year 1998: ¥1,300,000 (Direct Cost: ¥1,300,000)
Keywords	Thymus / Hypothalamus / Growth hormone / Growth hormone releasing hormone / Growth hormone release inhibitory hormone / Aging
Research Abstract	Removal of pituitary gland results in atrophy of the thymus. As the pituitary gland is under the control of the hypothalamus, destruction of the anterior portion of the hypothalamus (AHTL) is expected to negatively influence the thymic function. Contrary to our expectation, the thymus became hypertrophic and the serum level of the growth hormone (GH) markedly increased, when the anterior portion of the hypothalamus was widely destroyed in rats at 1 month and over. The results suggested that AHTL removed the cells secreting GHRIH (growh hormone release inhibitory hormone), but not GHRH (growth hormone releasing hormone), leading to increased secretion of GH from pituitary gland and thymic hyperplasia In other words, the development and aging of thymus appears to be under the balance of the positive (GHRH) and negative (GHRIH) signals of the hypothalamus. It is most likely that the positive signal is high just after the birth and decreases thereafter with a concomitant increase of the negative signal , leading to the onset of thymic atrophy at around puberty.