Cyproheptadine-induced alterations in clonal insulin-producing cell lines

Area of Science:

• Endocrinology
• Cell Biology
• Pharmacology

Background:

• Cyproheptadine (CPH) is known to inhibit glucose-stimulated insulin synthesis and secretion.
• CPH also depletes pancreatic insulin content in rats.
• The mechanism by which CPH affects insulin cell function, particularly in relation to glucose signaling, requires further investigation.

Purpose of the Study:

• To investigate whether the inhibitory effects of Cyproheptadine (CPH) on insulin cell function are linked to glucose-stimulated insulin synthesis and secretion.
• To compare the effects of CPH in glucose-responsive and glucose-unresponsive insulin-producing cell lines.
• To determine if CPH directly inhibits insulin secretion and biosynthesis.

Main Methods:

• Utilized two insulin-producing cell lines: HIT-T15 (glucose-responsive) and RINm5F (glucose-unresponsive).
• Cultured cells with varying concentrations of CPH (0-10.0 microM) for 48 hours.
• Measured cellular insulin content, media insulin levels, insulin biosynthesis, protein synthesis, cell growth, and viability.

Main Results:

• CPH decreased cellular insulin stores and media insulin levels in both cell lines in a concentration-dependent manner.
• At 10.0 microM CPH, insulin content in RIN and HIT cells decreased to 33-34% of controls.
• Insulin levels returned to normal 48 hours after CPH removal.
• CPH inhibited glucose-, K+-, alanine-, and glyceraldehyde-stimulated insulin release.
• CPH inhibited insulin biosynthesis without affecting total protein synthesis, cell growth, or viability.

Conclusions:

• Cyproheptadine (CPH) inhibits insulin synthesis and secretion in pancreatic cells.
• The inhibitory actions of CPH on insulin cell function are independent of glucose signaling pathways.
• CPH exerts reversible effects on insulin content and secretion, suggesting a direct impact on the insulin production machinery.