Involvement of Adipokinetic Hormone in the Homeostatic Control of Hemolymph Trehalose Concentration in the Larvae of Bombyx mori

摘要

Prior to wandering, 5th ins tar larvae of the silkworm, Bombyx mori, maintain constant hemolymph titers of trehalose. Head ligation of day 3, 5th instar larvae significantly decreased the hemolymph trehalose concentrations, but the concentrations did not decrease in starved larvae. Mter being diluted by re- placement of larval hemolymph with insect Ringer's solution, the trehalose concentrations recovered the initial levels in 90 min in the non-ligated larvae, while they were not restored in 90 min in the neck-ligated larvae. These results suggest that a head factor(s) with hypertrehalosemic activity is involved in the homeostatic control of hemolymph trehalose concentration. When adipokinetic hormone (AKH) was injected into neck-li- gated larvae, the trehalose concentrations increased in 2 hand decreased thereafter. Repeated injections of AKH every 4 h maintained the concentrations for 12 h. These findings sug- gest that AKH induces a hypertrehalosemic response and is involved in the homeostasis of hemolymph trehalose concen- tration in the larval feeding period.