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

Abstract

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 neurogenesis may be generalized to the central nervous system, changes in adult rat dentate gyrus neurogenesis were investigated in vitamin E deficiency. Neurogenesis was quantitatively studied by determination of the density of 5-bromo-2Ј-deoxyuridine (BrdU)-labeled cells and by determination of the total number of cells in the granule cell layer. The BrdU-labeled cells were immunocytochemically characterized by demonstration of neuronal marker calbindin D28K. The following results were found: (1) the volume of the granule layer increased in controls from 1 to 5 months of age, mainly due to cell density decrease; (2) the volume increased by a similar amount in vitamin E-deficient rats, mainly because of an increase in cell number; (3) BrdU-positive cells were more numerous in vitamin E-deficient rats in comparison to age-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 enhanced in vitamin E deficiency. This finding indicates that vitamin E may be an exogenous factor regulating adult neurogenesis.

Opiates inhibit neurogenesis in the adult rat hippocampus

“…Although the importance of identifying factors that regulate adult neurogenesis is clear, there is still significant debate about the functional implications of this phenomenon. It has been proposed that neurogenesis plays a role in cognitive aspects of hippocampal functioning (6,7,55,56). For example, evidence suggests that the survival of newly born cells in the adult dentate gyrus is positively influenced by hippocampal-dependent learning (7,55).…”

α-Tocopherol and Hippocampal Neural Plasticity in Physiological and Pathological Conditions

“…In addition, various intrinsic factors (such as developmental morphogens, neurotrophic factors, neurotransmitters, and steroids) have been reported to influence hippocampal neurogenesis events [194,196,203,204,205]. Finally, a number of exogenous factors has been discovered to modulate hippocampal new neuron generation, among which, we have well documented the involvement of vitamin E, mainly α-T [64,67,206,207,208]. …”

“…To validate this hypothesis, we quantified the number of newborn cells in hippocampal dentate gyrus in vitamin E-deficient rats, by using 5-bromo-2′-deoxyuridine (BrdU) cell proliferation marker, administered over two months after the ascertainment of the decreased tocopherol plasmatic level. The results showed that adult hippocampal neurogenesis was enhanced in vitamin E deficient rats [207], suggesting that this compound could play an antiproliferative role in vivo, as it was already known to do in vitro [12,213]. However, since the actual number of BrdU-labelled cells in the dentate gyrus could be regarded as a balance between precursor proliferation and labeled cell survival, the increase in the number of BrdU-labeled cells observed in vitamin E deficiency could be due, in principle, to changes in cell proliferation, in newborn cell survival or in both.…”

Adult stem cells and neurogenesis: Historical roots and state of the art

“…Finally, several studies have shown that adult neurogenesis can be influenced by environmental factors such as psychosocial stress (Gould et al, 1997), lithium administration (Chen et al, 2000), vitamin E deficiency (Ciaroni et al, 1999), and neuronal damage (Doetsch et al, 1999;Magavi et al, 2000).…”

“…Moreover, the demonstration that neurogenesis can be modulated by environmental factors (Chen et al, 2000;Ciaroni et al, 1999;Doetsch et al, 1999;Gould et al, 1997) holds very good prospects for neuronal replacement therapies (Bjö rklund and Lindvall, 2000;Magavi et al, 2000).…”