Methionine-enkephalin raises blood sugar by triggering hormone release from the eyestalk in estuarine crabs

Injection of methionine-enkephalin leads to hyperglycemia in the estuarine crab Scylla serrata in a dose-dependent manner.

• Methionine-enkephalin stimulates the release of a hyperglycemic hormone from the eyestalks.
• Total carbohydrate and glycogen levels decrease in the hepatopancreas and muscle following methionine-enkephalin injection.
• Phosphorylase activity increases in intact crabs after methionine-enkephalin injection.
• Bilateral ablation of eyestalks results in a 19% decrease in hemolymph glucose and a 22% decrease in total carbohydrate levels.
• Eyestalk ablation also leads to an increase in total carbohydrate and glycogen levels in the hepatopancreas and muscle.

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