Developmental changes of the activity of monoamine oxidase in pre- and postnatally lead exposed rats

The effects of prenatal and postnatal lead exposure on monoamine oxidase (MAO) activity were investigated in rat brain. MAO activity was examined in 2, 4, 6, and 8 weeks old rat to investigate the effects of lead in the different stages of rat brain development. Prenatal lead exposure was achieved by providing mother rats with drinking water containing either low (0.05%) or high (0.2%) concentration of lead acetate from gestation to birth. Postnatal lead treatment was performed through drinking water to mothers and pups from birth to the day of experiment. MAO activity was gradually increased with the development in all the brain regions examined, i.e. telencephalon, diencephalons, midbrain, pons/medulla, and cerebellum. Lead exposure increased MAO activity in most of the brain regions especially at early developmental stages (2 weeks of age) and the toxicity was gradually decreased with the development of rats. High concentration of lead showed greater effects on MAO activity compared to low concentration. Postnatal lead exposure showed stronger effects on MAO activity compared to prenatal lead exposure demonstrating the importance of preventing lead exposure to lactating mother. The increased MAO activity by lead intoxication may contribute to the neurobehavioral changes such as cognitive and attention deficit as well as hyperactivity, which is commonly observed both in lead intoxication and perturbed monoaminergic neurotransmission.