Neuropeptide Control of Ecdysone Biosynthesis

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Gilbert 9300164 The studies by Dr. Gilbert on the mechanism by which a hormone from the brain of the insect Manduca sexta acts upon specialized glands (prothoracic glands) to cause these glands to begin synthesizing a specific steroid hormone, an ecdysteroid. Ecdysteroids are hormones that cause the insect to molt. i.e. shed its exoskeleton, so that it can grow. They also elicit metamorphosis, i.e. the means by which a caterpillar is transformed into a pupa and then into an adult moth or butterfly. The brain neurohormone is synthesized and released as a result of environmental cues such as photoperiod and the synthesis and release of Ecdysteroids by the prothoracic glands must be extremely precise if the insect is to survive and be successful. He is studying the means by which this peptide hormone interacts with the glands, i.e. to stimulate the synthesis of a compound, a second messenger, which in turn indirectly mediates the phosphorylation (addition of a phosphate group) of specific proteins that control ecdysteroidogenesis. By utilizing the prothoracic glands which are composed of a single layer of homogeneous cells, he should ultimately gain insights into the mechanism of peptide hormone induced steroidogenesis that would not be possible with the more heterogeneous adrenal gland. ***