In vitro effects of lead ions on peripheral benzodiazepine receptors and adenylyl cyclase activity in the mantle of Mytilus galloprovincialis

Decreases in binding capacity of the mitochondrial 18 kda translocator protein accompany oxidative stress and pathological signs in rat liver after DMBA exposure

7,12-Dimethylbenz[a]anthracene (DMBA) presents a pollutant implicated in various toxicological effects. The aim of this experiment was to study the effects of DMBA administration on oxidative stress, histopathological signs, and 18 kDa translocator protein (TSPO) binding characteristics in rat liver. We also studied the effects of dose stoichiometry, dose frequency, and duration of protocol of DMBA administration. In this study, rats surviving eighteen weeks after DMBA exposure showed mild to moderate histopathological changes in the liver, mainly characterized by glossy appearance of hepatocytes, heterochromatic nuclei, and glycogen overload in the midzonal region of the hepatic lobe. These changes were accompanied by significant rises in oxidant levels, along with declines in nonenzymic antioxidants, indicating that DMBA induced oxidative stress in the liver. This finding correlated well with decreases in TSPO binding capacity in the liver of the rats in our study. Other studies have shown that TSPO can be affected by oxidative stress, as well as contribute to oxidative stress at mitochondrial levels. Further studies are needed to assay whether the decreases in TSPO density in the liver are part of the damaging effects caused by DMBA or a compensatory response to the oxidative stress induced by DMBA.

Neurochemical effects of benzodiazepine and morphine on freshwater mussels

The purpose of this study was to examine the neurochemical effects of morphine, diazepam, a common benzodiazepine, and an effluent concentrate on the endemic freshwater mussel Elliptio complanata. Mussels were exposed to the drugs and to the solid-phase concentrate of a municipal effluent and left to stand at 15 degrees C for 48h. Neurochemical effects were determined by monitoring changes in dopamine, serotonin, glutamate and gamma-aminobutyric acid (GABA) levels in the visceral mass (containing the nerve ganglia) of mussels. The activities of acetylcholinesterase (AChE), dopamine and serotonin-dependent adenylyl cyclase (ADC) were also determined in the mussels. Oxidative stress was determined by tracking changes in lipid peroxidation (LPO) in the mitochondrial and post-mitochondrial fractions. The results revealed that the drugs and the effluent extract were biologically active in mussels. Morphine reduced serotonin and increased dopamine in mussel tissues while reducing AChE activity and increasing GABA levels. This suggests the induction of a relaxation state in mussels. Diazepam also reduced serotonin levels but produced no change in dopamine levels. However, dopamine-sensitive ADC activity was readily activated, indicating the potential effect on opiate signaling. Diazepam increased glutamate levels slightly, but AChE remained stable. The increase in both dopamine ADC activity and glutamate concentrations was also associated with greater oxidative stress on the mitochondrial and post-mitochondrial fractions in cells. A comparison of the global response pattern of these drugs with those of the effluent extract revealed only a relative proximity to morphine. In conclusion, the data warrant more studies on the analysis of opiates and benzodiazepines in municipal effluents to better address the potential environmental hazard of these neuroactive drug classes to aquatic organisms.

Introduction of cAMP and establishment of neutral lipids alterations as pollution biomarkers using the mussel Mytilus galloprovincialis. Correlation with a battery of biomarkers

The results of the present study suggest that the signaling molecule cAMP could constitute a reliable biomarker of pollution monitoring. Increased levels of cAMP were observed in tissues of mussels Mytilus galloprovincialis exposed to PAHs, 2,4-dichlorophenoxyacetic acid and lindane for 15 days. cAMP levels were higher in mantle/gonad complex, in relation to other tissues studied (digestive gland and gills). In support of our suggestion, cAMP was significantly correlated with established biomarkers, such as lysosomal membrane stability, AChE activity and metallothionein content. In addition, our results support the establishment of morphometrical alterations of neutral lipids as biomarker of organic pollution, since high accumulation of neutral lipids in the digestive gland of mussels exposed to organic pollutants in relation to non-exposed mussels was noted. In addition, correlation analysis between cellular and biochemical biomarkers showed that the volume density of neutral lipids negatively correlated with both lysosomal membrane stability and AChE activity. Regarding micronucleus test, our results do not support its use as a biomarker of organic pollution, since no statistical differences were found between control and exposed mussels. On the other hand, significant correlations were observed among the battery of biomarkers, such as lysosomal membrane stability, AChE activity and metallothionein content after the mussels' exposure to the specific organic compounds, thus supporting the important role of these biomarkers as reliable indicators of organic pollution. In conclusion, our results support cAMP and morphometrical alterations of neutral lipids as biomarkers of environmental pollution.