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Updated: Jul 3, 2026
07:10
In Vesiculo Synthesis of Peptide Membrane Precursors for Autonomous Vesicle Growth
Published on: June 28, 2019
Hypotonicity and peptide discharge from a single vesicle
Jernej Jorgacevski1, Matjaz Stenovec, Marko Kreft
1Laboratory of Neuroendocrinology-Molecular Cell Physiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia.
American Journal of Physiology. Cell Physiology
|July 18, 2008
Summary
Hypotonicity triggers pituitary hormone prolactin release via transient vesicle fusion in rat lactotrophs. This mechanism differs from full fusion events, revealing new insights into neuroendocrine secretion.
Area of Science:
- Neuroendocrinology
- Cell Biology
- Physiology
Background:
- Neuroendocrine secretory vesicles release cargo upon stimulation, but the precise mechanism remains unclear.
- Prolactin, a pituitary hormone involved in osmoregulation, is released by lactotrophs.
- Understanding vesicle dynamics is crucial for comprehending hormone secretion.
Purpose of the Study:
- To investigate the mechanism of prolactin release from rat lactotrophs induced by hypotonicity.
- To characterize the fusion events of secretory vesicles with the plasma membrane during stimulation.
- To compare hypotonicity-induced release with depolarization-induced release.
Main Methods:
- Perfused rat lactotrophs were used to monitor prolactin release via radioimmunoassay.
- Confocal microscopy imaged fluorescently labeled cargo release from single cells.
- Cell-attached patch recordings measured membrane capacitance changes to detect vesicle fusion/fission events.
Main Results:
- Hypotonicity caused a transient increase then sustained decrease in prolactin release.
- Hypotonicity stimulated cargo release from ~2% of vesicles/cell, while KCl depolarization released from ~10%.
- Over 95% of stimulated fusion events were transient, characterized by increased fusion pore probability, dwell-time, frequency, and conductance.
Conclusions:
- Transient vesicle fusion, rather than full fusion, is the primary mechanism for hormone release in hypotonicity-stimulated lactotrophs.
- Hypotonicity primarily modulates existing fusion events rather than initiating new ones.
- This study elucidates a novel pathway for neuroendocrine secretion.
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