Variation of crustacean hyperglycemic hormone (cHH) level in the eyestalk and haemolymph of the shrimpPalaemon elegansfollowing stress

Abstract

SUMMARY This study investigates (by means of bioassays and ELISA using an antibody against recombinant cHH) the variation of cHH levels in the eyestalks and haemolymph of Palaemon elegans (Decapoda, Caridea) following exposure to various stresses (heavy metals and lipopolysaccharide), and correlates them with the variation in amount and time course of blood glucose. The dose-relationship between exposure to copper and quick release of cHH from the eyestalk into haemolymph was confirmed by variation of blood glucose with a dose-related hyperglycaemia, that peaked 2 h after immersion in contaminated seawater. Animals exposed to a sublethal concentration of mercury showed the same dose relation between toxicant, release of cHH from the eyestalk,increment of circulating hormone level and subsequent hyperglycaemia as observed for copper contamination. It is of note that although the highest lethal mercury concentration induced the release of cHH from the eyestalk into the haemolymph, it was not followed by a significant variation of blood glucose. Step doses of a bacterial contaminant [such as lipopolysaccharide(LPS) from E. coli injected into shrimps] confirmed the dose-relationship and convergent chain of events that bring about hyperglycaemia. These are the first data that relate the release of cHH from the eyestalk, the circulating hormone level and the consequent glycaemic response to stress. Moreover, they confirm the dose-related pathway that leads to variation of blood glucose as a quantitative biomarker of environmental quality, even at sublethal toxicant concentrations.

Serotonin, but not dopamine, controls stress response and anxiety-like behavior in crayfish, Procambarus clarkii.

“…Moreover, in contrast to 5HT, endogenous levels of DA after stress were not significantly correlated to ALB and the injection of exogenous DA triggered neither ALB nor a stress response that was observable through glucose titers. This last observation is in accordance with previous studies showing that DA injections in crayfish have no or opposite effects on CHHs or glucose levels (Luschen et al, 1991;Zou et al, 2003;Lorenzon et al, 2004Lorenzon et al, , 2005. In vertebrates too, the primary role of DA is not to mediate stress and anxiety.…”

“…Moreover, the link between 5-HT and glucose has been previously highlighted using 5-HT antagonists, which are able to block the increase in glucose concentrations in crayfish (Lee et al, 2000). Various stressors elicit the release of CHHs and the subsequent increase in blood glucose in crustaceans, such as hypoxia and emersion, disease, thermal stress, heavy metals exposure or social interactions (Webster, 1996;Chang et al, 1998;Stentiford et al, 2001;Wilcockson et al, 2002;Lorenzon et al, 2004;Elwood, 2011;Aquiloni et al, 2012). Thus, it would be interesting to further study the consequences of such stressors in terms of ALB and of 5-HT accumulation in the brain.…”

The adaptive significance of crustacean hyperglycaemic hormone (CHH) in daily and seasonal migratory activities of the Christmas Island red crab Gecarcoidea natalis

“…Functions related to energy metabolism might be readily defined by experimental manipulation and careful measurement of hormone titres, together with the measurement of changes in glucose levels, yet in relatively few instances has this been done with sufficient precision and temporal resolution to enable unequivocal conclusions to be drawn. CHH release occurs after stressful episodes (Keller and Orth, 1990;Webster, 1996;Chang et al, 1998;Wilcockson et al, 2002;Zou et al, 2003;Chung and Webster, 2005;Chung and Zmora, 2008), exposure to heavy metal pollutants (Lorenzon et al, 2004) or parasite load (Stentiford et al, 2001). Nevertheless, we still know relatively little about the adaptive roles of CHH in the life history of crustaceans.…”

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

“…Hyperglycemia is a typical response of many aquatic animals to pollutants. In crustaceans, increased circulating cHH and hyperglycemia are reported to appear during exposure to several environmental stressors (Durand et al, 2000;Lorenzon et al, 1997Lorenzon et al, , 2002Lorenzon et al, , 2004bSantos et al, 2001) in intact, but not eyestalkless animals, suggesting a cHH-mediated response (Fingerman et al, 1981;Reddy et al, 1994Reddy et al, , 1996Lorenzon et al, 2000). In the crab Cancer pagurus, emersion induced an increase in the hemolymph cHH after 4·h (Webster, 1996).…”