Involvement of juvenile hormone in regulation of prothoracicotropic hormone transduction during the early last larval instar of Bombyx mori

We previously reported that a deficiency in prothoracicotropic hormone (PTTH) transduction during the early last larval instar of Bombyx mori plays a role in leading to very low ecdysteroid levels in the hemolymph, inactivation of corpora allata, as well as larval–pupal transformation. In the presen...

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Bibliographic Details
Published in:Molecular and cellular endocrinology 1997-03, Vol.127 (1), p.109-116
Main Authors: Gu, Shi-Hong, Chow, Yien-Shing, Yin, Chih-Ming
Format: Article
Language:English
Subjects:
Animals
Bombyx - drug effects
Bombyx - embryology
Cyclic AMP - metabolism
Ecdysteroidogenesis and cAMP
Fatty Acids, Unsaturated - pharmacology
Heterologous regulation in signal transduction
Insect Hormones - genetics
Insect Hormones - metabolism
Juvenile hormone
Juvenile Hormones - pharmacology
Larva - drug effects
Larval-pupal transformation
Prothoracicotropic hormone
Signal Transduction - drug effects
Silkworms
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Summary:We previously reported that a deficiency in prothoracicotropic hormone (PTTH) transduction during the early last larval instar of Bombyx mori plays a role in leading to very low ecdysteroid levels in the hemolymph, inactivation of corpora allata, as well as larval–pupal transformation. In the present study, the role of juvenile hormone (JH) in the regulation of PTTH transduction was clarified. When JH analog (hydroprene) was applied to early last instar larvae, the development of larvae was greatly inhibited. It was found that it was not PTTH release, but prothoracic gland competency in both cAMP generation and ecdysteroidogenesis to the stimulation of PTTH which was developmentally inhibited by hydroprene application. Glands in hydroprene-treated larvae showed no response in ecdysteroidogenesis to either PTTH or 1-methyl-3-isobutylxanthine (MIX) until day 7, 4 days later than those of control larvae. JH-I application showed the same effects as those of hydroprene. By contrast, allatectomy on day 0 of the last instar accelerated development, and glands showed the activation response to either PTTH or MIX in both cAMP generation and ecdysteroidogenesis 1 day after allatectomy. From these results, we conclude that the absence of JH is a prerequisite for successful PTTH transduction and for acquisition of the cAMP generating system of gland cells.
ISSN:0303-7207
1872-8057
DOI:10.1016/S0303-7207(96)03995-0