Pro-apoptotic Action of Corticosterone in Hippocampal Organotypic Cultures.

Elevated levels of glucocorticoids exert neurotoxic effects, and the hippocampus is particularly sensitive to the effects of glucocorticoids. Because some data have indicated that an increased action of glucocorticoids in the perinatal period enhances the susceptibility of brain tissue to adverse substances later in life, the main purpose of the present study was to compare necrotic/apoptotic corticosterone action in hippocampal organotypic cultures obtained from control animals with the effect of this steroid in tissue from prenatally stressed rats. Because the adverse effects of glucocorticoid action on nerve cell viability appear to result mainly from an increase in the intensity of the effects of glutamate and changes in growth factor and pro-inflammatory cytokine synthesis, the involvement of these factors in corticosterone action were also determined. In stress-like concentration (1 µM), corticosterone, when added to hippocampal cultures for 1 and 3 days, alone or jointly with glutamate, did not induce necrosis. In contrast, in 3-day cultures, corticosterone (1 µM) increased caspase-3 activity and the mRNA expression of the pro-apoptotic Bax. Moreover, corticosterone's effect on caspase-3 activity was stronger in hippocampal cultures from prenatally stressed compared to control rats. Additionally, 24 h of exposure to corticosterone and glutamate, when applied separately and together, increased Bdnf, Ngf, and Tnf-α expression. In contrast, after 72 h, a strong decrease in the expression of both growth factors was observed, while the expression of TNF-α remained high. The present study showed that in stress-like concentrations, corticosterone exerted pro-apoptotic but not necrotic effects in hippocampal organotypic cultures. Prenatal stress increased the pro-apoptotic effects of corticosterone. Increased synthesis of the pro-inflammatory cytokine TNF-α may be connected with the adverse effects of corticosterone on brain cell viability.

Hematological Alterations as a Response to Exposure to Selected Fungicides in Common Carp (Cyprinus carpio L.).

The aim of the present study was to assess the hematological response of common carp to fungicides and to determine recovery patterns in fungicide-free water. Fish were exposed to mancozeb, prochloraz or tebuconazole (at concentrations of 1.0, 1.0 and 2.5 mg 1⁻¹, respectively) for 14 days followed by a 30-day recovery period. The following hematological parameters were examined after 1, 3 and 14 days of exposure as well as after recovery time: red blood cells (RBC), hematocrit (Het), total hemoglobin concentration (Hb), mean corpuscular volume (MCV), mean corpuscular hemoglobin concentration (MCHC), mean corpuscular hemoglobin (MCH), total number of leukocytes (WBC) and leukograms. All analyzed parameters revealed alterations in relation to control samples. The pattern of these changes was irregular, showing either an increase or decrease at different time points of the experiment and not all observed differences were statistically significant. The most noticeable fungicide-specific changes were,observed on the 1st and 14th days of chemical exposure. The majority of the parameters under investigation returned to the control levels after a detoxication period. However, some of the exerted effects were irreversible (Hb, MCH, MCHC and WBC for fish subjected to mancozeb; Hb, MCH, MCHC and monocyte count for fish subjected to prochloraz; Hct and monocyte number for fish subjected to tebuconazole). All of the observed hematoloaical changes were not toxin-soecific.

Hematological Alterations in Common Carp (Cyprinus carpio L.) Exposed to Herbicides: Pendimethalin and Ethofumesate Tested Separately and in Mixture.

Herbicides are used in large amounts in agriculture and the evaluation of their toxic effects is of major concern to environmental safety. The aim of the present study was to investigate common carp hematological alterations caused by herbicide exposure. Fish were treated with pendimethalin and ethofumesate tested separately and in mixture administered to aquarium water. Peripheral blood of treated fish was collected after 1, 3 and 7 days of exposure and compared to control. The total number of erythrocytes (RBC), total number of leukocytes (WBC), hematocrit value (Hct), total hemoglobin concentration (Hb), mean corpuscular hemoglobin (MCH), mean corpuscular volume (MCV), mean corpuscular hemoglobin concentration (MCHC) and leukograms were determined at once. The results indicate that herbicide exposure caused different changes in the hematological profile of the fish. In the case of exposure to individual herbicides, short-term fluctuations of various hematological indices were noted. Moreover, a significant increase in RBC and Hct after a short period of exposure (1-3 days) in fish exposed simultaneously to both tested herbicides was observed. Exposure to herbicides affected the leukocyte profile after 3 and 7 days of duration. Fluctuations of hematological parameters are a typical change in fish exposed to pesticides.

The influence of low concentration of cypermethrin and deltamethrin on phyto- and zooplankton of surface waters.

Pyrethroids play an important role in modern agriculture but their use is not without risks to non-target organisms and habitats. They have high toxicity to a broad spectrum of aquatic organisms. The aim of the study was to investigate the effect of low concentration (0.02 µg l(-1)) of two widely used pyrethroids--cypermethrin and deltamethrin on phyto- and zooplankton. The acute bioassays were conducted using Chlorella vulgaris and Thamnocephalus platyurus. Then, the chronic bioassays were conducted using Chlorella vulgaris, Daphnia magna and Brachionus calycilforus. The 24h LC50 values for cypermethrin and deltamethrin to Thamnocephalus platyurus were 0.89 µg l(-1) and 1.51 µg l(-1), respectively. The 48h EC50 values for cypermethrin and deltamethrin to Brachionus calycilforus were 3.828 mg l(-1) and 8.425 mg l(-1), respectively. 13% growth inhibition of Chlorella vulgaris (statistically insignificant) after 14 days of exposure to deltamethrin as well as cypermethrin was observed.