Methionine-enkephalin induces hyperglycemia through eyestalk hormones in the estuarine crab Scylla serrata.
The hypothesis is tested that methionine-enkephalin, a hormone produced in and released from eyestalk of crustaceans, produces hyperglycemia indirectly by stimulating the release of hyperglycemic hormone from the eyestalks. Injection of methionine-enkephalin leads to hyperglycemia and hyperglucosemia in the estuarine crab Scylla serrata in a dose-dependent manner. Decreases in total carbohydrate (TCHO) and glycogen levels of hepatopancreas and muscle with an increase in phosphorylase activity were also observed in intact crabs after methionine-enkephalin injection. Eyestalk ablation depressed hemolymph glucose (19%) and TCHO levels (22%), with an elevation of levels of TCHO and glycogen of hepatopancreas and muscle. Tissue phosphorylase activity decreased significantly during bilateral eyestalk ablation. Administration of methionine-enkephalin into eyestalkless crabs caused no significant alterations in these parameters when compared to eyestalk ablated crabs. These results support the hypothesis that methionine-enkephalin produces hyperglycemia in crustaceans by triggering release of hyperglycemic hormone from the eyestalks.
Sreenivasula Reddy
P
P
Department of Biotechnology, Sri Venkateswara University, TIRUPATI - 517 502, India. psreddy@vsnl.com
Kishori
B
B
D000818:Animals; D001786:Blood Glucose / Q000378:metabolism*; D003386:Brachyura / Q000378:metabolism*; D004064:Digestive System / Q000378:metabolism; D004744:Enkephalin, Methionine / Q000494:pharmacology*; D005123:Eye / Q000187:drug effects / Q000378:metabolism; D006003:Glycogen / Q000378:metabolism; D006458:Hemolymph / Q000378:metabolism; D007447:Invertebrate Hormones / Q000502:physiology*; D007700:Kinetics
D001786:Blood Glucose; D007447:Invertebrate Hormones; D004744:Enkephalin, Methionine; D006003:Glycogen