Phosphorylase (both total and active) activity levels were significantly increased in both hepatopancreas and muscle after the injection of methionine-enkephalin (Tables 4, 5).
Effects of bilateral eyestalk ablation and injection of methionine-enkephalin into ablated crabs on carbohydrate metabolism
Injection of methionine-enkephalin into eyestalkless crabs did not significantly change hemolymph carbohydrate levels compared to Ringer-injected eyestalkless crabs (Table 1).
An increase in phosphorylase activity and a decrease in glycogen and TCHO levels in hepatopancreas and muscle of Scylla serrata, followed by hyperglycemia after the injection of methionine-enkephalin, indicate glycogenolysis and mobilization of sugar molecules from tissues to hemolymph.
Our results clearly demonstrate that methionine-enkephalin is involved in the regulation of carbohydrate metabolism in the crab Scylla serrata.
The mechanisms whereby methionine-enkephalin causes release of neurohormones are still uncertain.
In summary, we have shown that methionine-enkephalin is a potent hyperglycemic regulator in the crab Scylla serrata.
Evidence for hyperglycemic effect of methionine-enkephalin in prawns Penaeus indicus and Metapenaeus monocerus.
Release of the dark-adapting hormone by methionine-enkephalin and FMRF-amide, Pigm.
A neurotransmitter role for methionine-enkephalin in causing hyperglycemia in the fresh water crab Ozioteiphusa senex senex.