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

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 dehydration by 2% NaCl drinking for 7 days significantly decreased the numbers neurosecretory granules microvesicles but not mitochondria. Moreover, dehydrated rats, making neurovascular contacts enlarged, whereas apposition to astrocytes, i.e., neuroglial contacts, became smaller. Western blot significant decreases levels F3 Thy-1 together those AVP- OXT-neurophysin, synaptophysin, SNAP-25, GAP-43 were unchanged. Both recovered buffer-insoluble pellet, phosphatidyl inositol-specific phospholipase C treatment released both molecules from crude membrane fraction, indicating they are attached terminal membranes glycosylphosphatidyl inositol anchors. Confocal microscopic observations colocalized same neurons. In contrast, level calretinin, a Ca2+ binding protein was increased Thus, present results suggest enhancement rearrangement terminal-astrocyte terminal-vessel rather than enlargement or sprouting themselves. The down-regulation may contribute accompany peptide release J. Comp. Neurol. 434:413–427, 2001. © 2001 Wiley-Liss, Inc.