[Show abstract][Hide abstract] ABSTRACT: Worldwide radiation exposure is increasing due to recent nuclear accidents, space travel, atomic weapons testing and use, and medical treatments. In adult animals, ionizing radiation can significantly impact hippocampal neurogenesis and negatively affect hippocampal functions such as cognition. However, there is considerable uncertainty regarding the mechanisms underlying these effects. This article reviews in vivo and in vitro studies on the effects of irradiation on hippocampal neurogenesis and function in order to gain new mechanistic insights. This information will provide complementary views of our understanding of the normal brain's tolerance to radiation exposure, the potentially serious implications of radiation exposure to cognition, and lead to a discussion of potential strategies for pharmacotherapy and behavioral intervention.
Histology and histopathology 03/2013; 28(3):301-10. · 2.24 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: This in vitro study compared the detrimental effect and relative biological effectiveness (RBE) of high-linear energy transfer (LET) fast neutrons on rat immature hippocampal cultured cells with those of low-LET γ rays. Immature hippocampal cells were exposed to fast neutrons or γ rays. Cytotoxicity and cell viability were analyzed using a lactate dehydrogenase (LDH)-release assay and a 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide (MTT) assay, respectively. The cytotoxicity and cell viability with fast neutrons or γ rays varied in a dose-dependent pattern. In the LDH release and MTT assay indices, the RBEs of fast neutrons were approximately 2.35 and 2.42, respectively. Fast neutrons markedly induced apoptotic changes in immature hippocampal cells with increased expression of active caspase-3 and cleaved poly(ADP-ribose) polymerase. Increased cytotoxicity and decreased cell viability in immature hippocampal cells were seen in a dose-dependent pattern after fast-neutron and γ irradiation. Fast neutrons have a higher RBE for cell death indices than γ rays.
Radiation Research 06/2011; 176(3):303-10. DOI:10.2307/41318194 · 2.45 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The present study compared the dose-response curves for the frequency of apoptosis in mouse hippocampal dentate gyrus (DG) and intestinal crypt using whole-body gamma irradiation. The incidence of gamma-ray-induced apoptosis was measured using the terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick-end-labelling (TUNEL) method. TUNEL-positive apoptotic nuclei in the DG and intestinal crypt were increased in a dose-dependent pattern (0-2 Gy). The dose-response curves were linear-quadratic, with a significant relationship between the appearance of apoptosis and irradiation dose. The slopes of the dose-response curves in the DG were much steeper (~5-6-fold) than those in the intestinal crypt within the range of 0-1 Gy exposure. Hippocampal DG might be a more effective and sensitive evaluation structure than the intestinal crypt to estimate the degree of radiation exposure in damaged organs of adult mice exposed to low irradiation dose.