EFFECTS OF PROTEIN UNDERNUTRITION ON THE DENTATE GYRUS IN RATS OF 3 AGE-GROUPS

The effect on an 8% and a control 25% casein diet on the granule cells in the dorsal blade of the dentate gyrus of the rat hippocampal formation was studied at 30, 90 ans 220 days of age. Female rats were fed wither an 8% or 25% casein deit 5 weeks prior to conception and the letters were maintained on these respective deits until killed. In rapid-Golgi-impregnated cells, we measured major and minor axes of the soma of the dentate granule neurons, the number of spines on 50-μm segments of proximal, middle and terminal regions of the largest dendrite per granule cell and the number of te dendrites intersecting 8 concentric rings 38 μm apart. At all 3 ages undernourished rats showed, when compared to controls, significant reductions of the major and minor axes od the somata and significant reductions in the number of spines on dendrites in the middle ans terminal denderitic segments. Dendritic branching was significantly reduced in undernounrished rats compared to control in all but the 4th concentric rings, with the greartest effect being seen on the outer 3 concentric rings at 90 and 220 days of age. The location of the deficit in dendric synaptic spines and the greatest dificit in dendritic branching correspond to the sites termination of the lateral and medial perfonant pathway projection to the dentate gyrus on the terminal and middle dendritic segments of the granule cells. The deficits noted in the granule cells of the detate gyrus in this study were more severe than those found in our previous studies on the effect of the low protein diet in these same rats on visual cortical pyramidal cells and on the 3 cell types nucleus raphe dorsalis and nucleus locus coerules. © 1990.