Correlation between electrical activity and ACTH/beta-endorphin secretion in mouse pituitary tumor cells

Area of Science:

• Neuroendocrinology
• Cell Physiology

Background:

• Mouse pituitary tumor cells (AtT-20/D-16v) are known to contain and release adrenocorticotropic hormone (ACTH) and beta-endorphin.
• Understanding the regulation of peptide hormone secretion is crucial for neuroendocrine research.

Purpose of the Study:

• To investigate the relationship between the electrical activity and secretory function of AtT-20/D-16v cells.
• To elucidate the role of calcium influx in stimulated hormone release.

Main Methods:

• Intracellular recordings were used to measure the electrical activity of AtT-20/D-16v cells.
• Radioimmunoassays were employed to quantify the release of ACTH and beta-endorphin.
• Pharmacological agents like barium and isoproterenol were used to modulate cell activity.

Main Results:

• Depolarizing current pulses induced calcium-dependent action potentials in AtT-20/D-16v cells.
• Barium and isoproterenol treatments enhanced both electrical activity and hormone secretion.
• Increased extracellular calcium concentration augmented action potential frequency/amplitude and stimulated ACTH/beta-endorphin release.
• Blockade of action potentials did not affect basal hormone secretion.

Conclusions:

• Stimulated hormone secretion in AtT-20 cells is closely correlated with increased electrical activity and calcium influx.
• The mechanisms governing stimulated hormone secretion differ from those responsible for basal secretion.
• Increased calcium influx via action potentials likely initiates stimulated hormone release.