Plasticity of neurohypophysial terminals with increased hormonal release during dehydration: Ultrastructural and biochemical analyses

被引:59
作者
Miyata, S [1 ]
Takamatsu, H
Maekawa, S
Matsumoto, N
Watanabe, K
Kiyohara, T
Hatton, GI
机构
[1] Kyoto Inst Technol, Dept Appl Biol, Sakyo Ku, Kyoto 6068585, Japan
[2] Kobe Univ, Grad Sch Sci & Technol, Div Biosci, Nada Ku, Kobe, Hyogo 6578501, Japan
[3] Tokyo Metropolitan Inst Gerontol, Dept Cell Recognit, Itabashi Ku, Tokyo 1730015, Japan
[4] Univ Calif Riverside, Dept Cell Biol & Neurosci, Riverside, CA 92521 USA
关键词
F-3; Thy-1; calretinin; CAMs; oxytocin; vasopressin;
D O I
10.1002/cne.1184
中图分类号
Q189 [神经科学];
学科分类号
071006 ;
摘要
Arginine vasopressin- (AVP) and oxytocin- (OXT) secreting magnocellular neurons undergo gross structural changes with chronic physiological stimulation. Here, we investigated subcellular aspects of plasticity in rat neurohypophysial terminals during dehydration. Ultrastructural analyses demonstrated that chronic dehydration by 2% NaCl drinking for 7 days significantly decreased the numbers of neurosecretory granules and microvesicles but not the numbers of mitochondria. Moreover, in dehydrated rats, terminals making neurovascular contacts enlarged, whereas terminals in apposition to astrocytes, i.e., neuroglial contacts, became smaller. Western blot analyses demonstrated significant decreases in the levels of F3 and Thy-1 together with those of AVP- and OXT-neurophysin, but the levels of synaptophysin, SNAP-25, and GAP-43 were unchanged. Both F3 and Thy-1 were recovered in the buffer-insoluble pellet, and phosphatidyl inositol-specific phospholipase C treatment released both molecules from the crude membrane fraction, indicating that they are attached to terminal membranes by glycosylphosphatidyl inositol anchors. Confocal microscopic observations demonstrated that F3 colocalized with Thy-1 in the same terminals of magnocellular neurons. In contrast, the level of calretinin, a Ca2+ binding protein was significantly increased with chronic dehydration. Thus, the present results suggest that enhancement of neurovascular contacts results from rearrangement of terminal-astrocyte and terminal-vessel contacts rather than enlargement or sprouting of magnocellular terminals themselves. The down-regulation of F3 and Thy-1 may contribute to enhancement of neurovascular contacts that accompany increased peptide release during dehydration. J. Comp. Neurol. 434:413-427, 2001. (C) 2001 Wiley-Liss, Inc.
引用
收藏
页码:413 / 427
页数:15
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