engleski

Quantitative study of dendritic spine morphology in infants with Down's syndrome

Background: It is not known how seriously are cortical circuitries in infants with Donw's syndrome (DS) affected at early postnatal stages. Goal: The aim of this study was to show maturation of dendritic spine morphology on associative layer IIIc pyramidal neurons in human prefrontal cortex during postnatal life in normal and DS infants. Methods: Brain tissue from area 9 of normal adult, newborn, 1- and 2.5-month-old infants, as well as of 2.5- and4.5-month-old infants with DS were prepared by rapid-Golgi method. We measured stalk length (SL) and bulb diameter (BD) of dendritic spines on basal and oblique dendrites. Data were quantitatively analysed using Student-Newman-Keuls test with one-way Anova (p<0.05). Results: In control subjects we found a decrease in SL between 1-month-old (1.08 micrometer) and 2.5-month old infants (0.717) when values become very close to adult (0.635). In 2.5-month-old DS infants this decrease is not observed (1.163). In the 2.5-4.5-month period SL decreases at a lower rate than in control infants (0.966). In control subjects there is a continuous decrease in BD between newborn (0.7) and 2.5-month-old infant (0.603), and this continues to adulthood (0.529). In 2.5-month-old DS infants BD is lower than in control infants (0.553) and lower than in 4.5-month-old DS infants (0.605). Conclusion: Our data showed a delayed and lower level of maturation in dendritic spine morphology in DS infants during early postnatal stage. As the distribution and number of synapses and the size of postsynaptic area (dendritic and soma surface) is not affected in DS infants during the early postnatal stage, we concluded that pathological changes in cortical circuitries are at this stage connected only with ultrastructural pathology of synapses.

dendritic spine morphology; Down's syndrome

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