PubMed · 11453392
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D Parkinson. 2001. Lateral sellar nerve plexus.. https://doi.org/10.3171/jns.2001.95.1.0167
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Acetylcholinesterase (AChE) inhibition is widely regarded as a good biomarker of exposure to organophosphorus pesticides (OP). However, less is known about the relationship between AChE inhibition and consequences for growth, reproduction and survival on organisms. Acute toxicity tests with fish have shown that high percentages of AChE inhibition are needed to cause detrimental effects, but not much is known about the consequences of chronic exposure to this group of chemicals for both AChE activity and higher levels of biological organisation. In this study, zebrafish (Danio rerio) were exposed to sublethal concentrations of the OP parathion for 250 days in a flow-through system. Besides AChE activity, a variety of other parameters were measured: whole-body protein and lactate content, consumption rate, survival, growth and reproduction. AChE inhibition was correlated with exposure concentration, but not with exposure time, and was significant above 0.9 microg/l after 144 days and above 4.3 microg/l after 250 days of exposure. Both parathion and the cosolvent dimethylsulfoxide (DMSO) significantly increased food consumption rate of the fish. Survival, growth, reproduction and lactate content were not affected, while protein concentrations showed only minor effects. These findings support the hypothesis that AChE is a very sensitive biomarker for exposure, but not accurately predict higher level adverse effects following long-term exposure to OPs.
In this laboratory study the effects of the cyanobacterium Nodularia spumigena (strain AV1) that produces hepatotoxic nodularin (NODLN), non-toxic Nodularia sphaerocarpa (strain UP16f) and purified NODLN on the infaunal clam Macoma balthica from the Baltic Sea were examined. N. sphaerocarpa (2.4 and 12.5 mg dw l(-1)), N. spumigena (4 and 20 mg dw l(-1), intracellular NODLN content ca. 4 and 20 microg l(-1)) and purified NODLN (10 and 50 microg l(-1)) were applied in experimental tanks at 24 h intervals for 96 h. Water samples were taken during the experiment for the measurement of soluble NODLN concentrations. The concentrations of total hepatotoxins in the soft tissues were analysed with enzyme-linked immunosorbent assay (ELISA) and NODLN with high-performance liquid chromatography/diode array detection (HPLC/DAD). Acetylcholinesterase (AChE) activity was measured from the foot tissue samples taken at 0, 24 and 96 h. In the water phase, 60-100% of NODLN in the pure-toxin treatments and all the NODLN in N. spumigena treatments appeared as a yet unidentified form with NODLN-like spectral characteristics. The compound was present in similar quantities also in the non-toxic N. sphaerocarpa treatments. In the toxic N. spumigena treatments the tissue concentration of hepatotoxic NODLN-like compounds (measured with ELISA) increased from the control levels of 0.16 to 16.6 microg g(-1) dw (24 h), reaching 30.3 microg g(-1) dw at 96 h. However, <5% of the toxin detected by ELISA could be shown to be NODLN in HPLC/DAD analysis. Matrix-assisted laser desorption/ionisation-time of flight mass spectrometry (MALDI-TOF/MS) analyses revealed no NODLN-glutathione (GSH) conjugates in the tissues of M. balthica. Combining the responses in the AChE activity recorded after 24 and 96 h exposure, increases by 46% (N. spumigena) and 36% (soluble NODLN) compared with the control activity were observed in the low-level toxic exposures. Oppositely, decreases by 19% (N. spumigena) and 27% (soluble NODLN) of control activity were observed in the high-level exposures. Only the differences between the increased and decreased AChE activities were statistically significant, with individuals exposed to high levels expressing approximately 55% of the activity of those exposed to low concentrations. The results show that M. balthica readily ingests toxic N. spumigena and that accumulation of peptides takes place rapidly, which has potential food chain effects through toxin enrichment. However, it appears that M. balthica is at least partly able to metabolise NODLN. In addition to hepatotoxicity, NODLN seems to induce concentration-dependent neurotoxic effects; this must be taken into consideration when applying AChE activity as a biomarker of specific anthropogenic contamination (e.g. organophosphate and carbamate pesticides).
Five enzymes, considered keys to the correct function of the central nervous system (CNS) were chosen to study their utility as markers of the possible neurotoxic effects produced by the perinatal exposure to lead and/or cadmium. With this aim, lead acetate (300 mg/l) and/or cadmium acetate (10 mg/l) were administered to pregnant Wistar rats from day 1 of pregnancy to parturition (day 0) or until weaning (day 21). Brains were used to determine the activity of acid phosphatase (ACP), alkaline phosphatase (ALP), catalase (CAT), acetylcholinesterase (AchE) and ATP-ases (Na(+)/K(+) and Mg(2+)/Ca(2+) dependent). The general decrease of the activity of these enzymes observed after the treatment with heavy metals suggests that lead and cadmium are able to reach the CNS and impair its function by neurochemical changes. On the other hand, the results showed an increase of the activity of CAT; which possibly indicates that lead and cadmium might have other mechanisms of action, such as increasing oxidative damage in the CNS. Finally, the study of the effects produced by the simultaneous administration of lead and cadmium suggests that, in general, both metals exert an additive effect, either competing for the same inhibitory binding sites or increasing cellular damage. In conclusion, the study of the activity of enzymes is revealed as an effective method to measure the neurotoxicity induced by lead and cadmium.