autoinduction

Autoinduction is a self-regulating process in which a molecule or biological system promotes its own production, activation, or response. The term is used in several contexts, most commonly pharmacology, microbiology, and biotechnology.

In pharmacology, autoinduction refers to a drug increasing the activity or abundance of the enzymes that metabolize it, producing progressively faster clearance with continued dosing. This is typically hepatic enzymes such as cytochrome P450s (CYPs). Mechanisms involve activation of nuclear receptors such as PXR and CAR, which upregulate drug-metabolizing enzymes and conjugation pathways. Clinically, autoinduction can reduce drug exposure, necessitating dose adjustments and monitoring; onset may take days to weeks and may reverse after the drug is stopped. Drugs known for autoinduction include certain anticonvulsants like carbamazepine and phenytoin, as well as rifampin and barbiturates.

In microbiology, autoinduction is related to quorum sensing, where bacteria synthesize signaling molecules called autoinducers that accumulate as the population grows. When their concentration crosses a threshold, collective gene expression is activated, regulating behaviors such as virulence, bioluminescence, and biofilm formation. The term emphasizes the self-sustaining nature of the signaling loop rather than a single step.

In biotechnology, autoinduction can describe growth media that automatically induces recombinant protein expression, typically in Escherichia coli, by shifting from a growth to an expression phase as preferred carbon sources are exhausted and lactose becomes available as an inducer.