Effect of protein malnutrition on CA3 hippocampal pyramidal cells in rats of three ages.

Prenatal and postnatal protein deprivation effects on CA3-hippocampal pyramidal cells were investigated in 30-, 90- and 220-day-old rats. Female rats were fed either a 6% or a 25% casein diet 5 wk before conception and the litters were maintained on their respective diet until sacrificed. In 216 rapid Golgi-impregnated cells, we measured somal size, length and diameter of apical dendrite, number of apical dendrites intersecting 10 concentric rings 38 microns apart, thorny excrescence area and length, head diameter and density of synaptic spines on 50-microns segments of apical dendrite. The present experiments showed that malnutrition produced significant reductions of somal size in animals at 220 days of age. There were significant reductions of apical dendrite diameters in animals of 30 and 90 days, and of density and head diameter of synaptic spines at the three ages studied, and significant decrease of the thorny excrescence area at 220 days of age. At this latter age, dendritic branching was significantly decreased in the last four rings representing the area into which the perforant pathway projects. In 30-day malnourished rats, dendritic branching showed a significant increase in rings 4-6 representing the area in which the Schaffer collaterals synapse. The location of the deficit in dendritic spines corresponds to the sites where mossy fibers synapse on the apical dendrites of CA3 neurons. Age-related changes normally observed in control rats (e.g., the 30-day-old control group showed the smallest somal size and 220-day-old controls the largest size) failed to occur in the malnourished rats. The deficits in spine density and dendritic branching (in animals of 220 days old) were similar to those found in our previous studies on fascia dentata.