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.

Temporal Changes of Post Synaptic Signaling Molecules, Post Synaptic Density-95 and Neuronal Nitric Oxide Synthase, in the Inner Molecular Layer of the Mouse Dentate Gyrus during Voluntary Running / 대한해부학회지

Here, we investigated the temporal change of post synapse signaling molecules, post synaptic density-95 (PSD-95) and neuronal nitric oxide synthase (nNOS) using immunohistochemistry during voluntary running with upregulated neurogenesis. Rate of running was stabilized after two weeks of the six week trial. By using immunohistochemsitry for phosphorylated cAMP response element binding protein (pCREB) and polysialylatedneural cell adhesion molecules (PSA-NCAM), we observed that the differentiation in dentate granule cells of adult mouse hippocampus increased at 1 and 2 weeks of voluntary running. We found that, at 6 weeks of voluntary running, the differentiation in dentate granule cells of adult mouse hippocampus returned to sedentary control levels. On the other hand, PSD-95 and nNOS immunoreactivity decreased in the inner molecular layer in the dentate gyrus of hippocampus after 1 and 2 weeks of voluntary running. At 6 weeks of voluntary running, the density of the PSD-95 and nNOS in the inner molecular layer was returned to the sedentary control level. The reactivity of nicotinamide dinucleotide phosphate diaphorase (NADPH-diaphorase), the marker of nitric oxide synthase activity, confirmed the change of nNOS in the inner molecular layer during voluntary running. These results demonstrate that the differentiation and the synaptic activity of granule cells during voluntary running are changed reciprocally once the rate of running has stabilized. These granule cell changes during voluntary running suggest an adaptation response to the new environment.