cosecretion

Cosecretion, or co-secretion, is the process by which two or more substances are released from the same secretory cell or gland, typically stored together in the same secretory vesicles and expelled in a single exocytic event. It can involve hormones, enzymes, mucus components, neurotransmitters, or other signaling molecules. Cosecretion contrasts with the sequential or differential release of substances from separate cells.

Mechanisms: In many secretory cells, cargo molecules are packaged into vesicles as a unit; stimuli that raise intracellular calcium trigger exocytosis of vesicles, releasing all co-packaged contents. Regulation can modulate the relative amounts released, allowing partial or differential release if vesicles carry multiple cargoes with different release properties.

Examples: In pancreatic islets, insulin and amylin are co-secreted in response to high blood glucose. In neurons and neurosecretory cells, neurotransmitters such as norepinephrine may be released together with neuropeptides or hormones. In mast cells and basophils, mediators such as histamine, heparin, and proteases are released en masse during degranulation. In mucosal tissues, secretory cells may release mucus components alongside enzymes or antimicrobial peptides as part of a coordinated secretory response.

Significance: Co-secretion supports coordinated physiological actions, rapid response to stimuli, and efficient use of secretory vesicles. Dysregulation can contribute to disease states, such as altered hormone ratios in diabetes or improper mediator release in allergic reactions. Ongoing research investigates the cellular and molecular mechanisms governing cosecretion and its role in health and disease.