UPTAKE AND METABOLISM OF ECDYSONE AND 20-HYDROXYECDYSONE IN A LEPIDOPTERAN CELL-LINE DERIVED FROM WING DISKS OF PLODIA-INTERPUNCTELLA

The metabolism of ecdysone (E) and 20-hydroxyecdysone (20E) was studie d in an ecdysteroid-sensitive cell line derived from imaginal wing dis cs of Plodia interpunctella (IAL-PID2). Kinetic studies of ecdysteroid uptake showed that E and 20E accumulated in the cells during a limite d period of time, i.e. between 2 and 24 h after hormone addition in th e medium. 20E was slightly converted, mostly into 20,26-dihydroxyecdys one (20,26E) which accumulated during the first 24 h within the cells. E was rapidly hydroxylated in 20E. At 10(-7) M, all these ecdysteroid s exhibited a low stimulatory effect on uptake of GlcNAc by IAL-PID2 c ells. At higher concentrations (10(-6) M and 10(-5) M), activities of E and 20E increased whereas that of 20,26E remained low. 20E was 3 tim es more potent than E in the assay, but activity of E could not be onl y due to its conversion to 20E.