Perinatal dietary supplementation with a soy lecithin preparation: effects on development of central...

Previous work has shown that exposure of developing rats to soy lecithin preparations (SLP) influences macromolecular constituents of immature brain cells and causes abnormal behavioral patterns. To determine if synaptic mechanisms are adversely affected by SLP, we examined the developmental characteristics of noradrenergic and dopaminergic pathways in discrete brain regions. Although transmitter levels were unaffected, the utilization rates of both catecholamines were profoundly disturbed in an age-dependent, regionally-selective manner. Utilization tended to be subnormal in the preweanling stage, but demonstrated a postweaning elevation in cerebellum and midbrain + brainstem. Enhanced utilization persisted in the latter region only, and cerebral cortex actually showed a lowered utilization rate in adulthood (60 days of age). Transmitter uptake capabilities were also affected by developmental exposure to SLP, as was tyrosine hydroxylase activity. The patterns of effects on these two variables indicated that the altered transmitter utilization rate probably reflected a change in impulse activity in the affected neuron populations, with promotion of activity in the midbrain + brainstem and reduced activity in the cerebral cortex. These data indicate that dietary supplementation with SLP throughout perinatal development alters synaptic characteristics in a manner consistent with disturbances in neural function.