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Objectives: Exposure to organophosphorus (OP) pesticides, irreversible inhibitors of acetylcholinesterase (AChE), may result in long-lasting alterations in the functional state of the central nervous system. In earlier studies, we found that a single exposure of the rat to chlorphenvinphos (CVP), an OP pesticide, made the animal hyposensitive to amphetamine (AMPH) three weeks posttreatment. A repeated administration of AMPH is known to result in a progressive increase in the behavioral sensitivity to the psychostimulant. It makes it likely that treatment with AMPH after the CVP exposure may result in amelioration of the CVP-induced hyposensitivity to the psychostymulant. The purpose of the present experiment was to check out this supposition. Materials and Methods: At the first stage, the relationship between the CVP dose and the effect on sensitivity to AMPH was tested. The rats were given CVP once intraperitoneally (i.p.) at a dose of 0.0, 1.0 or 3.0 mg/kg. Three weeks later their open field behavior was assessed before and after i.p. administration of 0.25, 0.5 or 1.0 mg/kg of AMPH. At the subsequent stage, the susceptibility of the CVP-treated rats to AMPH sensitization by repeated AMPH treatment was investigated. For this purpose each of the rats was repeatedly treated with AMPH in its home cage (one injection/day for five days). At stage two, the daily AMPH dose received by each animal was of the same magnitude as that received at stage one. Two weeks after the last AMPH treatment dose, the motor response to a test AMPH dose (0.5 mg/kg) was measured in all rats. Results: The results of stage one confirmed a significant reduction of behavioral sensitivity to AMPH in the CVP-treated rats. The results of stage two indicated that the CVP-induced decrease in sensitivity to AMPH was not ameliorated by a repeated treatment with AMPH at any of the used doses. In fact, in the rats exposed to the high CVP dose, repeated treatment with AMPH resulted, dose dependently, in augmenting of the depressive effect of the pesticide. Conclusions: It appears then that treatment to an OP pesticide reduces the rat's sensitivity to AMPH and makes the animal resistant to sensitization by repeated treatment with the psychostimulant.

Female Wistar rats were instilled per os by gavage with different copper dust samples: P-25 obtained by passing the test material through a 25 μmsieve, and P-0.1 containing soluble matter and ultra-fine, non-soluble<100 nm particulate matter (PM) fraction. The control group received sterile saline. The effects were studied at day 1, 7, and 30 post-exposure, focusing on bronchoalveolar lavage fluid (BALF) analysis (including biochemistry, cell morphology, cell viability, and Clara cell 16 protein concentration) and pathomorphology of lung. Results of biochemical tests showed a strong pro-inflammatory effect of both particulate fractions. The morphological studies after exposure to P-25 and P-0.1 fractions showed multi-focal infiltrations in the alveoli. Changes in behavioral (radial maze and passive avoidance tests) have shown that memory in groups exposed to dust was impaired. Our findings indicate that both samples of dust from Copper Smelter cause greater and lesser intensity (P-25 > P-0.1) of the symptoms of acute inflammatory reaction immediately 24 h after instillation to rats. Exposure results in dropping CC16 protein level in serum of rats. After one month, previous acute inflammation was resolved and transformed in persistent low-grade inflammation. The low-grade inflammation resulted in induction of neurobehavioral effects probably by changes in "cholinergic anti-inflammatory pathway" in which acetylcholine modulates neurotransmission.

Objectives: Methylmercury (MeHg) and polychlorinated biphenyls (PCBs) are ubiquitous environmental pollutants. Both are neurotoxic, especially for the developing brain. The main source of human exposure to MeHg and PCBs is seafood. The aim of the present work was to find out whether and how separate or combined perinatal exposure to these neurotoxicants affects neurobehavioural functions in maturity. Materials and Methods: The study was performed on adult Wistar rats, the progeny of rat mothers exposed to MeHg (0.5 mg/kg/day or 2.0 mg/kg/day), PCB 153 (1.0 mg/kg/day or 5.0 mg/kg/day), or to MeHg 0.5 mg/kg/day + PCB 153 5.0 mg/kg/day, from day 7 of pregnancy to day 21 post partum. The following functions were assessed: spontaneous locomotor activity (open field test), spatial short-term memory (radial maze test), long-term memory (passive avoidance test), sensitivity to pain and vulnerability to stress (hot plate test), efficiency of the sensorimotor gating (startle response test), and sensorimotor coordination (the rotarod test). Results:The results obtained in the MeHg part of the study showed a reduced locomotor activity in the female progeny of both exposed groups, an impaired passive avoidance in the male progeny of the high and low exposure group and a faster recovery from the effects of the stressful experience (hot plate test) in the male progeny of the high dose group. Results obtained in the PCB part showed an increased locomotor activity in the female progeny of both exposure groups and impairment in rotarod performance in males of the high dose group. Neurobehavioural alterations were not found in either the females or males exposed jointly to MeHg and PCB 153. Conclusions: The results suggest that in condition of the combined exposure, MeHg may protect against the effects of PCB 153 and vice versa.