Dendritic morphology and orientation of pyramidal cells of the neocortex in two groups of early postnatal undernourished-rehabilitated rats.

Postnatal undernutrition in animals and in humans leads to significant reduction in basal dendritic arborization of layer Vth pyramidal cells of the neocortex. Under the hypothesis that there are critical developmental periods for undernutrition to produce alterations in dendritic differentiation, we studied apical dendritic morphology and orientation of pyramidal cells from the deeper layers of the neocortex in rats undernourished until day 10 (UP10), until weaning (UP21) and in a control group (C). Neurons were stained by the Golgi-Cox method. The main findings are: (i) an increased number of atypically oriented pyramids with apical dendrites extremely short in (UP10) and (UP21) groups and, (ii) the presence of classical pyramids with significantly longer apical dendrites in layers V and VI in (UP10) and (UP21) groups than in the control group (C). We believe that undernutrition may disturb critically the early postnatal brain development by altering intrinsic factors and extracellular molecular signals that guide and regulate the apical dendritic growth of neocortex large pyramidal cells.