Sex Related Differences in Rat’s Behavior and Brain Morphology After the Toxic Effect of Manganese

Abstract

Exposure to heavy metals is a common phenomenon, which is due to contaminated drinking water and industrial activities. The toxic effect of different forms of metals is not only related to the environment, but also related to the metabolism and detoxification mechanism of the organism. In order to explore the difference of manganese toxicity on male and female rats, we studied the impact of manganese compounds on rat behavior and brain morphology. Four-week-old Wistar rats with body weight between 80-120g (n=42, including 21 males and 21 females) were studied. Wistar rats were assigned to four groups: rats in control groups (male, female) were given regular water, while rats in other groups drank water with ?nal manganese concentration of 15 mg/ml (male, female) for three months. To study exploratory and anxiety behavior rats were tested in open field, home cage and elevated plus maze. To estimate learning and memory status multi-branched maze was used. The behavioral disturbance of male rats was more noticeable than that of female rats in the same group. It is found that excessive manganese ions also had more toxic effects on male animals than females. It was revealed that manganese poisoning increased Mn contents in the brains of both genders, caused slight damage of neurons, and produced notable gliosis. However, in hippocampus there were bioaccumulation differences between gender. Excess amount of manganese in the brain had a strong impact on learning processes. It was concluded that, under this experimental design, Mn exposure causes metal deposition in CNS. The effect of this dose of manganese was gender-dependent and males had more pronounced behavioral damage compared to females, but females had an indication of motor damage. Gender differences in neuron morphology were not due to differential accumulation of Mn in brain regions. But the effect of manganese exposure was not similar in all observed brain regions (Motor Cortex, Prefrontal Cortex, Hippocampus-CA1, CA3 area and Dentate Gyrus).