Adipokinetic hormone (AKH)

Definition

A peptide neurohormone synthesized in the corpora cardiaca and released into the hemolymph to mobilize energy reserves during flight, starvation, or stress. AKH triggers the conversion of stored triacylglycerols in the fat body to diacylglycerols for transport to flight muscles, and also stimulates carbohydrate release from glycogen stores. Structurally related to vertebrate glucagon, AKH represents a convergent solution to metabolic regulation in arthropods.

Etymology

From Greek adipos (fat) + kinesis (movement), reflecting its role in mobilizing lipid reserves

Example

In the migratory locust Locusta migratoria, AKH release during sustained flight elevates hemolymph lipid levels within minutes, fueling the energy demands of long-distance migration; genetic knockdown of AKH receptors impairs flight endurance and starvation resistance.

Synonyms

• AKH
• adipokinetic peptide
• hyperglycemic hormone (historical, partial synonym)

Related Terms

• corpus cardiacum
• Fat body
• diacylglycerol
• Trehalose
• Juvenile hormone
• Ecdysone
• neurosecretory cell
• Hemolymph
• metabolic flight syndrome
• lipophorin

Usage Notes

AKH is often used interchangeably with 'hyperglycemic hormone' in older literature, though AKH more precisely denotes the lipid-mobilizing function. Multiple AKH isoforms (AKH-I, AKH-II, etc.) occur in many species with partially redundant or tissue-specific roles. The term applies broadly across insects and some other arthropods; crustacean analogs are typically called 'hyperglycemic hormones' (CHH family). AKH action is rapid and reversible, contrasting with the slower, developmental effects of juvenile hormone or ecdysteroids.