Four-week-long tabun low-level exposure in rats

Prolonged administration of sublethal doses of organophosphorus cholinesterase inhibitors results in adaptation to their toxicity. In order to investigate this phenomenon, we exposed rats to 0.2, 0.3 or 0.4 LD50 of taboo se daily during four weeks. AChE activities in erythrocytes, diaphragm and brain were inhibited dose-dependently after days 7 and 14 of the study and started to recover thereafter, except after 0.4 LD50. Tabun 0.3 LD50 decreased body weight gain, food and water consumption during the first two weeks of the study. Spontaneous locomotor activity was significantly increased in the same interval and decreased thereafter. These findings support the assumption that both the biochemical and receptor mechanisms are responsible for the occurrence of tolerance to whim in rats.