Feedback inhibition of ecdysteroids: Evidence for a short feedback loop repressing steroidogenesis
✍ Scribed by Rong-Jing Jiang; Jan Koolman
- Publisher
- John Wiley and Sons
- Year
- 1999
- Tongue
- English
- Weight
- 75 KB
- Volume
- 41
- Category
- Article
- ISSN
- 0739-4462
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✦ Synopsis
In insects evidence from several laboratories indicates that feedback effects of moulting hormone are involved in the control of steroidogenesis. The effects were detected in intact animals in vivo. We have investigated the existence of feedback control of steroidogenesis in vitro using moulting glands dissected from larvae of the blue blowfly, Calliphora vicina. The rate of ecdysone secretion by ring glands was measured. To mimic the glandular product (ecdysone), the non-steroidal ecdysone agonist RH-5849 was used. When incubated with ring glands this compound reduced ecdysone secretion within 2 h by more than 50%. The extent of the effect was stage and dose dependent. It is concluded that the 20-hydroxyecdysone agonist RH-5849 can act as a negative feedback effector in blowfly larvae. It acts directly on the moulting gland and is mediator of a short loop of feedback inhibition. The observations also indicate that moulting glands have to be included in the list of target tissues of ecdysone agonists. Arch. Insect Biochem.