Neurogenesis in the adult rat dentate gyrus is enhanced by vitamin E deficiency

Neurogenesis occurs throughout adult life in rat dentate gyrus. Factors and mechanisms of adult neurogenesis regulation are not well known. Vitamin E deficiency has been found to deliver a neurogenetic potential in rat dorsal root ganglia. To determine whether the role of tocopherols in adult neurog enesis may be generalized to the central nervous system, changes in adult r at dentate gyrus neurogenesis were investigated in vitamin E deficiency. Ne urogenesis was quantitatively studied by determination of the density of 5- bromo-2'-deoxyuridine (BrdU)-labeled cells and by determination of the tota l number of cells in the granule cell layer. The BrdU-labeled cells were im munocytochemically characterized by demonstration of neuronal marker calbin din D28K. The following results were found: (1) the volume of the granule l ayer increased in controls from 1 to 5 months of age, mainly due to cell de nsity decrease; (2) the volume increased by a similar amount in vitamin E-d eficient rats, mainly because of an increase in cell number; (3) BrdU-posit ive cells were more numerous in vitamin E-deficient rats in comparison to a ge-matched controls; (4) the increase in proliferated cells was located in the hilus and in the plexiform layer. This study confirms that neurogenesis occurs within adult dentate gyrus and demonstrates that this process is en hanced in vitamin E deficiency. This finding indicates that vitamin E may b e an exogenous factor regulating adult neurogenesis. (C) 1999 Wiley-Liss, I nc.