Variation of crustacean hyperglycemic hormone (cHH) level in the eyestalk and haemolymph of the shrimp Palaemon elegans following stress

This study investigates (by means of bioassays andELISA using an antibody against recombinant cHH) thevariation of cHH levels in the eyestalks and haemolymphof Palaemon elegans (Decapoda, Caridea) followingexposure to various stresses (heavy metals andlipopolysaccharide), and correlates them with thevariation in amount and time course of blood glucose. Thedose-relationship between exposure to copper and quickrelease of cHH from the eyestalk into haemolymph wasconfirmed by variation of blood glucose with a doserelated hyperglycaemia, that peaked 2·h after immersionin contaminated seawater. Animals exposed to a sublethalconcentration of mercury showed the same dose relationbetween toxicant, release of cHH from the eyestalk,increment of circulating hormone level and subsequenthyperglycaemia as observed for copper contamination. Itis of note that although the highest lethal mercuryconcentration induced the release of cHH from theeyestalk into the haemolymph, it was not followed by asignificant variation of blood glucose. Step doses of abacterial contaminant [such as lipopolysaccharide (LPS)from E. coli injected into shrimps] confirmed the doserelationshipand convergent chain of events that bringabout hyperglycaemia. These are the first data that relatethe release of cHH from the eyestalk, the circulatinghormone level and the consequent glycaemic response to stress. Moreover, they confirm the dose-related pathway that leads to variation of blood glucose as a quantitativebiomarker of environmental quality, even at sublethaltoxicant concentrations.