Effects of prenatal protein deprivation on postnatal development of granule cells in the fascia dentata

Abstract

The effect of prenatal protein deprivation on the postnatal development of granule cells in the fascia dentata in the rat was studied at 15, 30, 90, and 220 days of age. The granule cells showed a significant reduction in cell size, decreased number of synaptic spines throughout their dendritic extent, and reduced complexity of dendritic branching in the outer two-thirds of the molecular layer. All of these deficits were present at 15 days and persisted throughout the study (220 days). The least deficits in synaptic spine density occurred at 90 days and in dendritic branching at 30 days. Partial restitution of earlier, more severe deficits was associated primarily with maturational events occurring in the protein deprived rats, whereas later increases in deficits were related primarily to a failure of the protein deprived rats to keep pace with neuronal development occurring in the controls. The present results are similar to those noted in our previous study in this journal of the effect of a low protein diet (8% casein) on these neurons that extended from pregnancy until the time of sacrifice at 30, 90, and 220 days of age (Cintra et al., '90; 532:271-277). Taken together, these two studies suggest that the postnatal adaptation of the granule cells to prenatal protein deprivation is primarily due to events that occur during pregnancy and that the site of predilection for the deficit is their dendrites in the outer two-thirds of the molecular layer of the fascia dentata.

Electrophysiological properties of rat hippocampal principal cells are unaltered by prenatal protein malnutrition

“…These data are somewhat surprising in light of previous findings showing that the morphological properties of dentate granule cells are significantly altered in 6/25 rats (Cintra et al, 1990;1997;Díaz-Cintra et al, 1991). Clearly, the membrane alterations (e.g., decreases in soma diameter and decreases terminal dendritic extent) seen in the 6/25 rats are of insufficient magnitude to be reflected in such intrinsic membrane properties as membrane time constant and input resistance which were completely unchanged in the present study.…”

“…These delays may in turn disrupt the development of appropriate afferent and efferent connections of these principal cells and lead to dysfunctional synaptic physiology. In addition, Golgi impregnation studies have demonstrated a decrease in the diameter of somata, density of dendritic spines and terminal dendritic arborization of dentate granule cells in response to prenatal protein malnutrition (Cintra et al, 1990;Díaz-Cintra et al, 1991). A recent study by Cintra et al (1997) demonstrated that CA1 pyramidal cells, in contrast, are largely spared, with the only significant change being a reduction in the density of dendritic spines in prenatally malnourished animals.…”

Dendritic Branching of Claustral Neurons in Neonatally Undernourished Rats

“…In this regard, projec tions from the visual cortex to the claustrum originating in the fourth layer and returning from the claustrum to the same cortical areas to layers IV and VI establishing a reciprocal modulator circuit, which may regulate senso ry influx to this zone [ 18], In undernourished rats the reduced dendritic arbor in the claus tral neurons may generate a deficient regula tory process that may be associated with inad equate locomotion [28,29] or with impaired visuospatial integration as observed in be 52 Escobar/Salas Neonatal Undemutrition and Claustrum Development havioral studies [30][31][32], This possibility is strengthened by data showing the high vulner ability of polysensory nervous structures to perinatal undernutrition in the thalamus [1,9], the amygdala [5], the hippocampus [3, 33,34], the cerebellar granular layer [35] and the intemeurons of the cerebral cortex [36], How ever, further morphological and behavioral studies will be needed in order to corroborate this proposal.…”

Response threshold to aversive stimuli in stimulated early protein-malnourished rats

“…Certainly, brain weight is a gross measurement, and it would be desirable to perform a more detailed and specific morphological or neurochemical analysis of different brain regions in response to malnutrition and environmental factors since other studies have shown significant alterations in behavior-related regions of the brain (43)(44)(45)(46).…”