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Cell differentiation and secretory products of hypophyseal pars tuberalis

垂体结节部细胞分化及分泌产物

基本信息

批准号：
11670018
负责人：
KAMEDA Yoko
金额：
$ 1.86万
依托单位：
KITASATO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2000
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-11670018/
关键词：
Hypophyseal pars tuberalis Alpha-subunit of glycoproteins Alpha-subunit mRNA Immunoelectron microscopy In situ hybridization Ontogeny Circadian rhythm Pinealectomy クロモグラニンA ニワトリ

项目摘要

The hypophyseal pars tuberalis surrounding the median eminence and infundibular stalk is composed of specific secretory cells and sustentacular or follicular cells. The pars tuberalis (PT)-specific cells are immunoreactive for α-subunit of glycoprotein hormones and express α-subunit mRNA.In chick embryos, the α-subunit mRNA and protein began to appear in the Rathke's pouch at embryonic day (E) 3.5. At E6, gonadotrophs immunoreactive for LH were first detected in the pars distalis. At E8, the pars tuberalis primordium located close to the median eminence was formed at the lateral apical end of the par distalis. The primordium expressed intense signal for α-subunit mRNA and protein. Thus, both primordia of the pars distalis and pars tuberalis expressed α-subunit. This subunit may play a role in the cytodifferentiation of the adenohypophyses. In addition, α-subunit mRNA level in the pars tuberalis was changed depending on photoperiods. In chicks exposed to continuous light for 30 days, the PT-specific cells were filled with enlarged secretory granules, showing the reduction of secretory activity and α-subunit mRNA level in the pars tuberalis markedly decreased. On the other hand, in chicks exposed to continuous darkness for 30 days, the PT-specific cells displayed enlarged cytoplasmic and nuclear areas and exocytotic features of secretory granules were more frequent. Alpha-subunit mRNA level was increased under continuous darkness. These data indicate that the PT-specific cells are responsive to photoperiodic changes. After pinealectomy, α-subunit mRNA level in the pars tuberalis was increased. However, in chicks under continuous light or darkness after pinealectomy, the cell activity and α-subunit mRNA level in the pars tuberalis were similar in changes to those of unoperated animals.

围绕正中隆起和漏斗柄的垂体结节部由特殊的分泌细胞和支持细胞或滤泡细胞组成。结节部（PT）特异性细胞对糖蛋白激素的α亚基呈免疫反应性，表达α亚基mRNA，鸡胚在胚龄（E）3.5天，Rathke囊内开始出现α亚基mRNA和蛋白。在E6，促性腺激素细胞LH免疫反应首先检测到的远侧部。E8时，靠近正中隆起的结节部原基在远侧部的外侧顶端形成。原基表达α亚基mRNA和蛋白质的强信号。因此，远部和结节部的原基都表达α-亚基。该亚基可能在腺垂体的细胞分化中起作用。此外，茎部α-亚基mRNA水平随光周期的变化而变化。连续光照30 d后，PT特异性细胞内充满增大的分泌颗粒，表现为分泌活性降低，结节部α-亚基mRNA水平显著降低。另一方面，在连续黑暗暴露30天的雏鸡，PT特异性细胞显示扩大的细胞质和核面积和分泌颗粒的胞吐特征更频繁。α亚基mRNA水平在持续黑暗下增加。这些数据表明，PT特异性细胞对光周期变化有反应。松果体切除后，结节部α-亚基mRNA表达增加。而在松果体切除后持续光照或黑暗条件下，鸡结节部细胞活性和α亚基mRNA水平的变化与未手术动物相似。