Correlative Changes of Endothelial Nitric Oxide Synthase and Choline Acetyltransferase in the Hippocampus after Exercise / 대한해부학회지

We found that the expression and activity of endothelial nitric oxide synthase (eNOS) is increased in the hippocampus during exercise (Moon et al., 2006). However, the upstream regulatory factor on the eNOS expression in the hippocampus during exercise has not been clear. In this study, we investigate the role of acetylcholine (ACh) as a regulatory factor for the eNOS expression and activity in the hippocampus during exercise. The results of the present study demonstrate that voluntary wheel running exercise for two weeks increases the expression and activity eNOS. In addition, choline acetyltransferase (ChAT) immnunoreacitvity within the hippocampus was increased after 2 weeks exercise. We further found that the upregulation of ACh with treatment of physostigmine, a booster of ACh releasing, increase the expression and activity of eNOS in the hippocampus. This present study provides the evidence that the upregulation of eNOS during exercise may be mediated by ACh in the hippocampus.

Temporal Change of Calbindin-D28k Immunoreactivity in the Dentate Gyrus of Voluntary Running Mouse / 대한해부학회지

Voluntary running is known to dramatically increase the cell proliferation and neurogenesis in the dentate gyrus of the adult mouse hippocampus. However, it is crucial to realize that adding excitatory neurons could result in serious maladaptive outcomes for hippocampal circuit function. To investigate the response of mature granule cells on the increase of cell proliferation during voluntary running, we investigated the temporal change of calbindin-D28k (a marker for mature granule cells) using immunohistochemistry during voluntary running with upregulated neurogenesis. By using immunohistochemsitry for Ki-67 and doublecortin (DCX), we observed that the cell proliferation and differentiation of granule cells increased at 1 week of voluntary running. We found that, at 6 weeks of voluntary running, the cell proliferation and differentiation of granule cells returned to sedentary control levels. On the other hand, calbindin-D28k immunoreactivity decreased in the granular cell layer of the dentate gyrus and CA3 region of hippocampus after 1 week of voluntary running. At 6 weeks of voluntary running, the density of the calbindin-D28k in the granular cell layer and CA3 region was returned to the sedentary control level. These results demonstrate that the cell proliferation and differentiation are increased at early point of voluntary running, and the granule cell activity in the dentate gyrus is temporally changed for response to the increase of cell proliferation and differentiation during voluntary running.

The Effects of Repeated Restraint Stress on the Synaptic Plasticity in the Inner Molecular Layer of Mouse Dentate Gyrus / 체질인류학회지

Stress induces degeneration of brain structures and functions. Particularly, hippocampus is sensitive to stressful stimulations. In the present study, the change of synaptic related molecules in the mouse dentate gyrus was examined with immunohistochemistry after restraint stress. We subjected mice to restraint stress for 6 h per day for 4 days. As a result, the number of Ki-67, a marker for proliferation, and doublecortin (DCX), a marker for neurogenesis, immunoreactive cells was decreased in the stress group. On the other hand, the intensity of calbindinD-28k, a marker of pre-existing granule cells, immunoreactivity was increased in the granule cell layer after 4 days restraint stress. As well as, the immunoreactivity of synaptic related molecules, postsynaptic density-95 (PSD-95), growth association protein-43 (GAP-43) and beta-NADPH-d reactivity were increased in the inner molecular layer of dentate gyrus after 4 days restraint stress. In conclusion, this study shows that repeated restraint stress suppresses neurogenesis in dentate gyrus and strengthens synaptic plasticity of existing granule cells.