effects of dietary pb and cd and their combination on acetyl cholinesterase activity in digestive gland and foot of the green garden snail, cantareus apertus (born, 1778)

the present study was focused upon the assessment of acetyl-cholinesterase (ache) activity in the digestive gland (main metabolic center) and foot (highly innervated organ) of the green garden snail, cantareus apertus (born, 1778), exposed to different nominal dietary concentrations of pb (25 and 2500 mg pb/kg), cd (10 and 100 mg cd/kg) and their combination (25 mg pb + 10 mg cd/kg and 2500 mg pb + 100 mg cd/ kg) for 60 days. ache activity was lower in the foot than in the digestive gland (~50%) and decreased with experimental time in both tissues. in metal treated snails, ache activity was significantly decreased in both tissues to a 50-60% of the values recorded in control snails. this decrease followed a dose depending trend at each exposure time, albeit the response was attenuated at the long-term (60 d) in comparison with the short-term (7 d). besides, the combination of both metals provoked interactive effects not seemingly related with the tissue levels of the metals. thus, it was concluded that model toxic metals such as pd and cd cause a reduction in ache activity in both studied tissues, more markedly at the short-term, although antagonistic effects were elicited by both metals in combination. as a whole, lowered ache activity in c. apertus can be considered as a useful biomarker of the effects provoked by metals on cell signaling and therefore it may be suitable for ecosystem health assessment in metal polluted soils using this species as sentinel organism.