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Trophic effects of somatostatin on calcium flux: dynamic analysis and correlation with pituitary hormone release
Abstract:
Somatostatin (SRIF) modulates many aspects of normal physiology, appears useful as a potent antineoplastic agent, and may influence the development of degenerative brain disorders such as Alzheimer's disease. Regulation of cellular calcium flux by SRIF may contribute greatly to many of these interactions, yet remains controversial. SRIF rapidly causes a sustained inhibition of fractional calcium efflux from prelabeled dispersed rat pituitary cells (IC50, approximately 40 pM) and evokes a large rebound increase in efflux after the infusion, each coinciding temporally with expected physiological effects on GH release. These data support a particular role for SRIF-regulated calcium flux in the normal pulsatile pattern of GH secretion and a more general role in the varied biological actions of the peptide.
Insights
Somatostatin (SRIF) regulates calcium flux in pituitary cells, impacting growth hormone (GH) secretion. This peptide
Area of Science:
- Endocrinology and Neuroendocrinology
- Cellular Physiology
- Molecular Pharmacology
Background:
- Somatostatin (SRIF) is a peptide hormone with diverse physiological roles, including modulation of normal physiology.
- SRIF shows potential as an antineoplastic agent and may influence neurodegenerative disorders like Alzheimer's disease.
- The precise role of SRIF in regulating cellular calcium flux remains a subject of ongoing research and debate.
Purpose of the Study:
- To investigate the effect of Somatostatin (SRIF) on cellular calcium flux in rat pituitary cells.
- To elucidate the relationship between SRIF-mediated calcium regulation and growth hormone (GH) secretion.
- To clarify the controversial role of SRIF in calcium flux and its physiological implications.
Main Methods:
- Utilized prelabeled dispersed rat pituitary cells to measure fractional calcium efflux.
- Administered Somatostatin (SRIF) and monitored immediate and subsequent changes in calcium efflux.
- Correlated temporal changes in calcium efflux with known physiological effects on GH release.
Main Results:
- SRIF demonstrated rapid, sustained inhibition of fractional calcium efflux from pituitary cells with an IC50 of approximately 40 pM.
- A significant rebound increase in calcium efflux was observed following SRIF infusion.
- The observed changes in calcium flux coincided temporally with expected physiological effects on GH release.
Conclusions:
- SRIF plays a critical role in regulating calcium flux within pituitary cells.
- SRIF-regulated calcium flux is integral to the normal pulsatile pattern of GH secretion.
- These findings support a broader role for SRIF in mediating various biological actions through calcium modulation.