Single p.o. doses of manganese chloride (MnCl2 x 4H2O; 50 mg/kg) induced significant and reversible decreases in total activity in white rats, along with worsening of the acquisition of an avoidance reaction in response to unconditioned and conditioned stimuli, increases in the latent period of conditioned reflex activity, and a temporary worsening of the learning process. Chronic manganese poisoning (daily p.o. manganese chloride at 20 or 50 mg/kg for one month) led to significant impairment of learning processes in a multipath maze but had no significant effect on reproduction of previously acquired stereotypical behavior.

Morphological changes in neurons and the distributions of nerve and glial cells were studied, the glial index was calculated, and manganese (Mn) contents were determined in the caudate nucleus, the nucleus accumbens, the dorsal and ventral septal nuclei, and the frontoparietal areas of the cerebral cortex in the 40-day-old offspring of rats given different doses (10 and 20 mg/kg) of manganese chloride (MnCl2.4H2O) 15-20 days before pregnancy, during pregnancy, and for one month after parturition with the first portion of food. Mn poisoning increased Mn contents in the brains of rat pups, damaged a small proportion of neurons, and produced marked gliosis. These changes are believed to underlie previously described impairments to learning processes and emotional state in rat pups.

No abstract

No abstract