| Popis: |
Cholinesterase (ChE) activity in blood (plasma and erythrocytes) and in different parts of the brain, open field behavior and response-to-change in a "T" maze were investigated in separate groups of rats after a single intraperitoneal exposure to an organophosphorus pesticide - chlorphenvinphos. The doses used were 3.0 mg/kg or 1.0 mg/kg which amounted to approximately, 1/3 and 1/10 of LD50 for this species. The exposure resulted in a dose dependent inhibition of ChE in blood, as well as in the brain. No marked differences in the level of ChE inhibition in plasma, erythrocytes, and in selected parts of the brain (cerebellum, brain stem, diencephalon, hippocampus and the anterior part of the hemisphere) were noted after a given dose. In general, 3 hours after the exposure, ChE was inhibited by about 80% in the case of the 3.0 mg/kg dose and by no more than 50% in the case of the 1.0 mg/kg dose. In blood as well as in the brain, the normalization of ChE activity proceeded at a similar rate, being accomplished within 14 days and within 94 hours after the 3.0 mg/kg and 1.0 mg/kg dose, respectively. No changes suggesting an impairment of short-term memory were observed in the "T" maze until the end of testing (i.e. up to the fourteenth day after the exposure). In the open field, a short-term decrease (up to the third day) in locomotor and exploratory activity was observed only in rats exposed to 3.0 mg/kg of the pesticide. At the end of testing (10-14th day after the exposure) the introduction of a new object into the open field resulted in an increase of locomotor and exploratory activity in control animals but not in the rats exposed to chlorphenvinphos in the 3.0 mg/kg as well as in the 1.0 mg/kg. This suggests that exposure to chlorphenvinphos may result in some behavioral disturbances lasting longer than the ChE recovery. |
