2004 Fiscal Year Final Research Report Summary
Analyzes of the diversity of secretory granules in the anterior pituitary endocrine cells.
| Project/Area Number |
14570001
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (C)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
General anatomy (including Histology/Embryology)
|
|---|
| Research Institution | Asahikawa Medical College |
|---|
Principal Investigator |
SAKAI Yuko Asahikawa Medical College, Dept.of Anatomy II, Research Assistant, 医学部, 助手 (40041826)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
WATANABE Tsuyoshi Asahikawa Medical College, Dept.of Anatomy II, Professor, 医学部, 教授 (80220903)
|
|---|
| Project Period (FY) |
2002 – 2004
|
| Keywords | anterior pituitary / secretory granules / postnatal development / immunocytochemistry / chromogranins / secretogranins / gonadotropes / sexual maturation |
|---|
| Research Abstract |
Five types of endocrine cells are known to be present in the anterior lobes of mammalian pituitary glands : corticotropes, gonadotropes, thyrotropes, mammotropes, somatotropes. Each endocrine cell possesses characteristic secretory granules and secretes distinct peptide hormones in response to appropriate stimuli. To elucidate the diversity of the secretory granules in this tissue, we first investigated the immunocytochemical localization of granins in the rat anterior pituitary in detail. As results, the localization pattern of SgIII in the anterior pituitary gland was similar to that of CgB at both light and electron microscopic levels, suggesting that the expressions of these two granins are regulated by common mechanisms. Moreover, we observed SgIII-positive intermediate endocrine cells that expressed both PRL and TSH, probably common precursor-like cells of these two endocrine cells. These findings suggest that the pituitary-specific transcriptional factors could regulate both the
… More
fate of pituitary stem cells and the expression of granins, which might contribute to the establishment of characteristic ultrastructures and the sizes of secretory granules in the pituitary endocrine cells. Based on these findings, we further examined changes in the expression level of granins and ultrastructure of pituitary gonadotropes during postnatal development of rats. Until 3 weeks after birth, no significant sex-related differences were found in the ultrastructure of pituitary gonadotropes ; gonadotropes of both sexes at birth possessed only a few small-sized secretory granules, and gradually large-sized secretory granules containing CgA appeared in these cells. However, the difference in pituitary gonadotropes between male and female rats became prominent since 3 weeks after birth ; large-sized granules containing CgA disappeared from female gonadotropes after this time point, whereas those granules were retained in male gonadotropes. These findings suggest that the expression of CgA is differently regulated by sex steroids after the beginning of sexual maturation, resulting in the sex-related differences in the composition and ultrastructure of secretory granules.
Summing up, these findings suggest that the expression levels of granins affect the ultrastructure and size of secretory granules. Further investigations on the regulatory mechanisms of each granin expression would be required to clarify the diversity of secretory granules in the pituitary endocrine cells. Less
|
Research Products
(8 results)
