Delayed behavioral effects of perinatal action of neurotoxin 6-hydroxydopamine in the experiment

6-Hydroxydopamlne (6-OHĐA, 75 mkg), producing selective degeneration of dopaminergic neurons in the brain, was injected intraamniotically to every rat fetus on the 13th and 17th days of embryogenesis. A similar experiment was performed, when 6-OHDA was administered i.p. to newborn rats on the 4th and 10th days of life. All rats were raised, and several dopamine-dependent types of behavior were investigated in adult animals: rotation behavior, anxiety in elevated cross-like maze, conditional place preference, differentiation of novel and known alleys of Y-maze Prenatal administration of 6-OHDA initiated rotations and stereotypy, decreased anxiety in elevated maze, reduced the reinforcing properties of amphetamine in place preference test and disturbed the differentiation of novel and known alley in Y-maze less than did the postnatal injection of neurotoxin. Therefore, the early postnatal period is more sensitive to neurotoxin action than the prenatal period of development. This phenomenon is connected to the critical periods of dopaminergic system development in ontogeny.