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Calmodulin modulates prolactin secretion in vitro: studies with calmodulin containing liposomes
G Schettini1, T Florio, O Meucci
1Department of Pharmacology, II School of Medicine, University of Naples, Italy.
Life Sciences
|November 30, 1987
Summary
Calcium and cyclic AMP regulate prolactin secretion. Calmodulin, a key calcium-binding protein, plays a crucial role in this process, influencing prolactin release from pituitary cells.
Area of Science:
- Endocrinology
- Molecular Biology
- Cell Signaling
Background:
- Prolactin secretion is a complex process regulated by various intracellular signaling pathways.
- Calcium (Ca++) and cyclic AMP (cAMP) are known second messengers involved in pituitary hormone release.
Purpose of the Study:
- To investigate the role of Ca++ and calmodulin in the regulation of prolactin secretion.
- To elucidate the interplay between Ca++ influx, cAMP accumulation, and prolactin release.
Main Methods:
- Primary cultures of anterior pituitary cells were used for in vitro studies.
- Calcium ionophore A23187 was employed to stimulate Ca++ influx.
- The effects of a calmodulin antagonist (W7) and exogenous calmodulin were assessed.
- Cyclic AMP levels and prolactin release were measured.
Main Results:
- A23187 stimulated both cAMP accumulation and prolactin release, with cAMP increase preceding prolactin release.
- The calmodulin antagonist W7 dose-dependently inhibited basal and A23187-stimulated cAMP accumulation and prolactin secretion.
- Introduction of Ca++ calmodulin into cells stimulated prolactin secretion independently of cAMP levels.
- W7 blocked the prolactin-releasing effect of intracellular Ca++ calmodulin.
Conclusions:
- Calmodulin is a significant mediator in the process of prolactin secretion.
- The findings suggest a critical role for calmodulin in translating Ca++ signals into prolactin release from pituitary cells.