Immunological and biochemical responses in Mya arenaria (Mollusca Bivalvia) exposed in vivo to estradiol-17beta.

Soft-shell clams Mya arenaria were injected with 10, 20 or 40 nmol of estradiol 17beta (E2). We observed a significant inhibiting effect of E2 on phagocytic activity of hemocytes from clams exposed to 10 and 20 nmol. A dose-response increase of the glycogen phosphorylase in the gonad tended to show a remobilisation of glycogen reserves involved in vitellogenesis although the exposure time must have been too short to observe a decrease in glycogen reserves or an increase in RNA concentration. Both results corroborate those of other studies about estrogen involvement in controlling immune capacity and energy metabolism related to vitellogenesis in bivalves. We can assume that immune parameters should now be taken into consideration in assessing endocrine disruption in bivalves. Nevertheless further studies are needed to understand the controlling pathways of E2 with a special regard on its interactions with other effectors involved in bivalve immunity and reproduction as well.