Plasma esterases in the tegu lizard Tupinambis merianae (Reptilia, Teiidae): impact of biological variables and organophosphorus in vitro exposure.

BASSO, A., ; A.M. ATTADEMO; LAJMANOVICH R.C.; P. M. PELTZER; C. M. JUNGES; CABAGNA M. C.; FIORENZA BIANCUCI, G; SANCHEZ-HERNANDEZ. J.C.

Environmental Science and Pollution Research

Springer

Año: 2012 p. 214 - 225

1614-7499

Purpose In this study, we determined normal serumbutyrylcholinesterase (BChE) and carboxylesterase (CbE)activities in Tupinambis merianae in order to obtain referencevalues for organophosphorus pesticide monitoring.Methods Forty-two T. merianae individuals were groupedby sex and size to identify potential differences in theirenzyme levels to allow for proper representation of normalvalues for females, males, juveniles, and hatchlings. MeanCbE was determined using two model substrates: alphanaphtylacetate(á-NA) and p-nitrophenyl valerate (4-NPV).BChE and CbE sensitivity to malaoxon (Mx) was alsoevaluated as well as the possibility of BChE reactivationwith pyridine-2-aldoxime methochloride (2-PAM).Results Mean adult females? BChE was significantly higherthan adult males, juveniles, and hatchlings. No significantdifferences were found between groups regarding CbE.CbE (4-NPV) activity showed slightly negative correlationwith lizard snout?vent length, while BChE and CbE (á-NA)showed no correlation with body size. Apparent IC50 valuesfor BChE and CbE (á-NA) suggested different sensitivitiesamong groups. CbE (4-NPV) could not be inhibited. AllMx-inhibited groups treated with 2-PAM in a final concentrationof 2.8 mM showed clear signs of reactivation.Conclusions In conclusion, the results demonstrate that (1)plasma esterase activity did not vary with age and sex,except for BChE activity, and (2) because biological andenvironmental variables could be confounding factors in theresponse of plasma cholinesterases, complementary biomarkerslike CbE inhibition and oxime-induced reactivationof esterases are strongly recommended.