Dendritic spine pathology in infants with severe protein-calorie malnutrition

Abstract

Background: Experimental undernutrition in animals, during the critical brain development period, produces retardation of brain growth as well as a number of different morphologic and functional abnormalities in neurons, mainly in the dendritic synaptic apparatus. These alterations are the cause of the poor neurointegrative development that occurs in experimental malnutrition. Severe malnutrition during early postnatal life in humans is known to produce similar neurointegrative disorders as well as mental retardation, but there are very few studies describing the morphology of the dendritic apparatus in infants suffering from this condition.

Objective: To study the dendritic spine density and morphology in dendrites from cortical neurons in infants dying from severe malnutrition.

Methodology: Brain sections from the somestesic, motor, and occipital cortical areas of 13 infants who died of severe malnutrition and 7 eutrophic infants who died of other causes were studied by means of the rapid Golgi method. Apical dendritic spines from neurons of the fifth cortical layer were studied and counted in all sections.

Results: Apical dendrites were significantly shorter in malnourished infants than in the control group (581.54 +/- 54.32 microm in severe malnutrition vs 846.3 microm in normal infants). The number of dendritic spines per dendrite was also significantly diminished (185.3 +/- 36.1 in malnourished vs 374.3 +/- 41.6 in eutrophic infants). There were marked morphologic abnormalities in the dendritic spines of infants dying of severe malnutrition that were classified as dysplastic.

Conclusions: Short apical dendrites, fewer spines, and dendritic spine abnormalities occur in severe infant malnutrition. These anatomic anomalies might be related to the neuropsychological deficits that occur in these children.