EFFECTS ON OPERANT LEARNING AND BRAIN ACETYLCHOLINE ESTERASE-ACTIVITY IN RATS FOLLOWING CHRONIC INORGANIC ARSENIC INTAKE

1 Very young and adult Wistar rats were given As5+, 5 mg arsenic kg(-1) body weight day(-1) (sodium arsenate). 2 Operant learning was tested in a Skinner box at the end of exposure and, in the case of developing animals, also after a recovery period. 3 Acetylcholine esterase (AChE) activity was estimated in discrete brain regions of these animals. 4 The animals exposed to arsenic took longer to acquire the learned behaviour and to extinguish the operant. AChE activity was inhibited in some regions of the brain.