cosecreted

Co-secreted, or co-secreted substances, describes the situation where two or more chemical products are released from the same cell in a coordinated fashion, typically during a single secretory event. This phenomenon is common in endocrine, exocrine, and nervous systems. Co-secretion can occur when different cargos are stored in the same secretory granule or when separate vesicles fuse synchronously, releasing their contents together.

In many secretory cells, Ca2+-triggered exocytosis ties release to cellular activity; the secretory pathway may package multiple peptides, hormones, or neurotransmitters into a single granule, or corelease. The relative proportions of co-secreted substances can be fixed by packaging or modulated by stimuli, cell type, and metabolic state.

Examples include pancreatic beta cells, which secrete insulin and C-peptide in equimolar amounts as products of proinsulin processing, and often co-secrete amylin (IAPP). In neurons, co-transmission occurs when neurotransmitters and neuropeptides are released from the same nerve terminal, such as norepinephrine with NPY or dopamine with ATP, affecting signaling dynamics.

Clinical and research relevance: measuring co-secreted products can provide diagnostic information, such as using C-peptide alongside insulin to assess endogenous insulin production in diabetes. Understanding co-secretion informs models of hormone regulation, neural communication, and how disorders may disrupt coordinated release.

Methods to study co-secretion include immunoassays to quantify secreted molecules, mass spectrometry for complex secretomes, and live-cell imaging of vesicle fusion, enabling researchers to observe co-packaging and synchronous release.