Effects of undernutrition on the serotonin neuron system in the developing brain: an immunohistochemical study

The effects of undernutrition during the first 3 weeks of postnatal life on the serotonin neuron system were investigated using a peroxidase-antiperoxidase immunohistochemical method. Undernourishment was induced by increasing the litter size from 6 to 18 mice during the first 3 weeks of postnatal life. At 15 days of age a morphological change (large swelling of serotonin-immunoreactive axons) was noted in various parts of the brain of the undernourished mice with no remarkable changes in dendrites and cell bodies. Quantitative immunohistochemical analysis at 60 days of age showed a significant decrease in serotonin-immunoreactive cell bodies in the nucleus linearis intermedius, the nucleus raphe obscurus, the total raphe system and the subpyramidal region. These results suggest that undernutrition during early postnatal life affected the serotonin neuron system with regional differences.