Abstracts

Rationale: The aim of this study is to evaluate the maturation of the newborn neuron in the hippocampal dentate gyrus using human specimens from the patients with temporal lobe epilepsy. Methods: Human hippocampal specimens were obtained at surgery for temporal lobe epilepsy and divided into two groups: with or without hippocampal sclerosis (HS). We stained them for newborn neurons by PSA-NCAM, and counted positive cells in the subgranular cell layer (SGCL) and hilus. We also stained for Hu, Doublecortine (DCX), NeuroD, NeuN with PSA-NCAM to analyze the maturation of these newborn neurons. We also used NKCC1 and KCC2 stains to demonstrate the maturation of ion-transporters. Results: More PSA-NCAM positive neurons were seen in the group without HS than with HS. Size of the newborn neurons in the group without HS was the same as the mature granular cell. However, 38.4% out of all newborn neurons in the HS group were large cells more than 30?m. From the large newborn neurons population, 79.5% were located in the hilus, and more than 80% stained with Hu, NeuroD, and NeuN. The percentages of DCX and KCC2 positive large neurons in the group with HS were less than those of the group without HS. The percentages of NeuroD, DCX, NKCC1, and KCC2 positive small newborn neurons in the hilus in the group with HS were less than those without HS. In the group without HS, NeuroD and NKCC1 positive newborn neurons in the SGCL were reduced in number. Conclusions: The large newborn neurons in the hilus are immature, and the maturation of those cells continues with their migration to SGCL and reduction of cell size. In the group with HS, few mature newborn neurons were located in the SGCL and the neuronal maturation was restricted.