Role of biogenic amines and cHH in the crustacean hyperglycemic stress response

In this study, we nvestigated (using bioassays and ELISA) the variation of cHH (crustacean hyperglycemichormone) level in the yestalks and hemolymph ofPalaemon elegans (Rathke) (Decapoda, Caridea) followinginjection of serotonin (5-HT) and dopamine (DA) andcorrelated cHH profile with the variation in amount andtime course of glycemia.5-HT induced in P. elegans a rapid and massive releaseof cHH from the eyestalk into the hemolymph followed byhyperglycemia. On the contrary, DA did not significantly affect cHH release and hyperglycemia. In addition, we measured the level and variation of 5-HT in the eyestalk and hemolymph of P. elegans following coppercontamination. The release of 5-HT from the eyestalk is very rapid and dose dependent. In the hemolymph, a peak of 5-HT occurs after 30·min, and again the circulating concentration of 5-HT is dose dependent on copper exposure. After 1·h, the level of 5-HT slowly decreases to basal level.The release of 5-HT from the eyestalk into the hemolymph after copper exposure precedes the release ofcHH, confirming its role as a neurotransmitter acting oncHH neuroendocrine cells. The fact that copper induced arapid and massive release of 5-HT from the eyestalk canexplain its demonstrated role in inducing the release ofcHH and the consequent hyperglycemia in intact but not eyestalkless animals.