Effects of protein deprivation on pyramidal cells of the visual cortex in rats of three age groups

Abstract

The effect of protein deprivation on rapid Golgi impregnated pyramidal neurons in layers II/III and V of the rat visual cortex was studied at 30, 90, and 220 days of age using morphometric methods. In order to mimic human under-nutrition female rats were adapted to either an 8% or control 25% casein diet 5 weeks prior to conception and maintained on these diets during gestation and lactation. The pups were then weaned and maintained on their respective diets. The undernourished rats showed a significant decrease in brain weight only at 90 days, indicating that the protein deprivation had a mild effect on brain development. Correspondingly, the number of significant histological differences between the two diet groups were least at 30 and 220 days of age. The effect of the diet was greater on layer V than on layer II/III pyramids. At 30 days of age the effect of the diet was different on the pyramids of these two cell layers, at 90 days there was a mixture of similar and dissimilar effects, and at 220 days the pyramids of these two cell layers showed only minor differences between the two diet groups. Analysis of age-related changes indicated that the effect of the diet was different on layer II/III pyramids compared to layer V pyramidal cells. These different effects apparently accounted for the progression from a dissimilar effect of the diet at 30 days on the pyramids of the two cell layers to only minor differences between them at 220 days. Further analysis of these age-related changes shows that two prominent effects of protein deprivation are for age-related changes to occur in undernourished rats but not in controls and for age-related changes to be out-of-phase with each other in the two diet groups. From these findings, and a review of similar studies in the literature, we propose that these mechanisms are a prominent effect of undernutrition in the post-weaning period and help account for the unexpected increases in morphometric measurements noted in undernourished rats in this and other studies.

Contrast sensitivity function of sine-wave gratings in children with acute malnutrition.

“…Contrast sensitivity reduction related to PEM was already expected because the literature shows functional and structural damages in the malnourished brain (Galler et al 1996;Levitsky & Strup, 1995;Scrimshaw, 1998) and PEM also affects the visual system in animals (Bedi et al, 1983(Bedi et al, ,1989Bonavolonta et al, 1989;1991;Diaz-Cintra et al, 1990;Gundappa & Desiraju, 1988). Furthermore, the results of this study corroborate recent evidence showing electrophysiological changes in the vision of infants and children in preschool age with PEM (Dantas et al, 2005;McDonald et al, 2007;Thordstein et al, 2004).…”

Effects of Early Malnutrition on Mental System, Metabolic Syndrome, Immunity and the Gastrointestinal Tract

“…The smaller volume and width of cerebral cortex of rat were normalized after later nutritional rehabilitation [23]. The increase in cell packing and dendritic branching observed in the cortex in rat during early malnutrition was reversed by subsequent nutritional rehabilitation [15].…”

“…Early malnutrition obviously reduced the size of the brain [29,23]. The cerebral cortex, which is the brain region that is most closely linked to cognitive and intellectual functioning, showed reductions in volume [7] and width [29] after neonatal malnutrition.…”

Adjustable fortification of human milk fed to preterm infants: does it make a difference?

“…Inadequate nutrition during vulnerable periods of development has been shown to be associated with impaired brain development in animal models [1][2][3][4][5][6][7][8] and with impaired neurocognitive development in human preterm infants. 9,10 Breast milk is the preferred feeding for very low birth weight (VLBW) infants, [11][12][13][14][15][16][17][18][19][20][21][22][23][24] but it alone cannot meet the high nutrient needs of VLBW infants without nutrient fortification.…”